U.S. patent application number 09/988605 was filed with the patent office on 2002-03-28 for heart rate monitor and method using detection to eliminate errors from interference.
Invention is credited to Gorman, Peter.
Application Number | 20020038094 09/988605 |
Document ID | / |
Family ID | 21872672 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020038094 |
Kind Code |
A1 |
Gorman, Peter |
March 28, 2002 |
Heart rate monitor and method using detection to eliminate errors
from interference
Abstract
A monitor-exercise equipment apparatus for measuring a
biomedical response such as heartbeat rate, and for using the
measured response to control the exercise equipment, where the
monitor includes a transmitting unit and a receiving unit located
in the exercise equipment. The monitor detects a biomedical
response (heart rate) and produces a digital pulse train
representing this response. The digital pulse train is then encoded
to produce an encoded digital signal having a first identification
part identifying the transmitting unit and a second data part
representing the person's biomedical response. This encoded digital
signal is wirelessly sent to the receiving unit which reads the
received signal to determine if it is from the transmitting unit.
If it is from that transmitting unit, the data part is read. If
there are too many errors in the data part, a new frequency of
wireless transmission is used in the monitor. If the errors are
within a reasonable bound, the data bits representing the
biomedical response are sent to a memory and/or a display. If the
received signal were not from the correct transmitting unit, the
received signal is rejected. Interference from other monitors or
electrical equipment is minimized, and the data displayed is very
accurate. The receiving unit provides a signal to a parameter
control means in the exercise equipment. The parameter control
means automatically regulates the resistance offered to the user in
accordance with the measured heart rate of the user to provide a
proper workout. Memory is included for providing exercise profiles
unique to the user. An identification unit allows each user to
identify himself/herself to the equipment to access the proper
stored exercise profile for that person.
Inventors: |
Gorman, Peter; (Mahopac,
NY) |
Correspondence
Address: |
COBRIN & GITTES
750 LEXINGTON AVENUE, 21ST FLOOR
NEW YORK
NY
10022
US
|
Family ID: |
21872672 |
Appl. No.: |
09/988605 |
Filed: |
November 20, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09988605 |
Nov 20, 2001 |
|
|
|
09589311 |
Jun 7, 2000 |
|
|
|
09589311 |
Jun 7, 2000 |
|
|
|
09263763 |
Mar 4, 1999 |
|
|
|
6304774 |
|
|
|
|
09263763 |
Mar 4, 1999 |
|
|
|
08684302 |
Jul 18, 1996 |
|
|
|
5913827 |
|
|
|
|
08684302 |
Jul 18, 1996 |
|
|
|
08380370 |
Jan 30, 1995 |
|
|
|
5538007 |
|
|
|
|
08380370 |
Jan 30, 1995 |
|
|
|
08065563 |
May 21, 1993 |
|
|
|
5459065 |
|
|
|
|
08065563 |
May 21, 1993 |
|
|
|
08033826 |
Mar 19, 1993 |
|
|
|
5400794 |
|
|
|
|
Current U.S.
Class: |
600/520 |
Current CPC
Class: |
Y10S 128/903 20130101;
A61B 5/30 20210101; A61B 5/0245 20130101; A61B 5/222 20130101; A61B
5/002 20130101 |
Class at
Publication: |
600/520 |
International
Class: |
A61B 005/044 |
Claims
1. An apparatus for controlled exercise of a user, including in
combination: a transmitting unit for producing an encoded digital
signal representative of a person's heart rate, said transmitting
unit including a transmitter for wirelessly transmitting said
encoded digital signal over a first frequency to a receiver-control
unit, a receiver-control unit located on a piece of exercise
equipment for control of said exercise equipment in response to
said user's heart rate, said receiver-control unit including a
receiving means for receiving said wirelessly transmitted encoded
digital signal and display means for displaying said person's heart
rate and other information, a microprocessor located in said
receiver-controller unit for reading said encoded digital signal
and for controlling a parameter control means in response to said
person's heart rate, parameter control means responsive to said
microprocessor for continuously adjusting a parameter of said
exercise equipment in response to said person's heart rate,
identification means located in said receiver-control unit
responsive to an entry by said user for identifying said user,
first memory means for storing a profile of heart rate response of
said user of said exercise equipment, input means connected to said
microprocessor for enabling said user to control said parameter
control means dependently of said stored profile, and second memory
means coupled to said microprocessor for receiving a recording of
an exercise program specific to a particular user.
2. The apparatus of claim 1, where said transmitting unit includes
means for detecting and correcting errors in said measured heart
rate.
3. The apparatus of claim 2, further including frequency change
means for automatically changing the frequency over which said
encoded digital signal is transmitted if a specified error exists
in the encoded digital signal received by said receiver.
4. The apparatus of claim 3, where said frequency change means
includes means for wirelessly transmitting a frequency change
signal from said receiver-control unit to said transmitting unit
when said specified error is determined.
5. The apparatus of claim 4, further including means for enabling
said transmitting unit to know that said frequency change signal is
from said receiver-control unit.
6. An apparatus for exercise based on a human biomedical response,
including in combination: a transmitting unit for producing an
encoded digital signal representative of a biomedical response of a
person, said transmitting unit including a transmitter for
wirelessly transmitting said encoded digital signal to a receiver
located on a piece of exercise equipment, a receiver located on
said exercise equipment for receiving said encoded digital signal,
a display means located on said exercise equipment for displaying
said biomedical response, detection means for detecting errors in
said received encoded digital signal, correction means for
automatically changing said transmitter and said receiver to
provide accurate transmission therebetween, a microprocessor for
reading said encoded digital signal to determine the identity of
the person whose biomedical response is being measured, parameter
control means responsive to said biomedical response as determined
by said microprocessor for continuously adjusting a parameter of
said exercise equipment in response to the biomedical response
determined by said microprocessor, memory means for storing
programs for the operation of said microprocessor and for storing a
profile of the biomedical response of said user of said exercise
equipment, input means connected to said microprocessor for
enabling said user to control said parameter control means
independently of a profile stored in said first memory means, and
second memory means coupled to said microprocessor for receiving a
recording of an exercise program specific to said user, said
microprocessor controlling said parameter control means in response
to said recording of an exercise program and in response to the
continuous measurement of said biomedical response in said
microprocessor.
7. The apparatus of claim 6, where said correction means includes
frequency change means for changing the frequency over which said
encoded digital signal is wirelessly transmitted.
8. The apparatus of claim 6, further including identification means
for determining that the encoded digital signal received by said
receiver is from said transmitting unit.
9. The apparatus of claim 6, where said biomedical response is
heart rate.
10. The apparatus of claim 6, where said transmitting unit is
capable of being worn on a person using the exercise equipment.
11. An apparatus for controlled exercise in response to a user's
heart rate, comprising: a transmitting unit for producing an
encoded digital signal representative of a person's heart rate,
said transmitting unit including transmitter means for wireless
transmission of said encoded digital signal to a display unit
located on a piece of exercise equipment, encoding means for
producing said encoded digital signal, said encoding means being in
said transmitting unit and producing an encoded digital signal
having a first part identifying said transmitting unit and a second
part representative of said user's heart rate, a display unit
located on said exercise equipment for displaying information
representing the user's heart rate, a receiving means located on
said exercise equipment for receiving said encoded digital signal
via wireless transmission from said transmitting unit, means for
determining if said received encoded digital signal is from said
transmitting unit, frequency change means for changing the
frequency over which said encoded digital signal is transmitted
from said transmitting unit if errors beyond a specified amount
occur in said second part of said encoded digital signal received
by said receiving means, a microprocessor for reading said received
encoded digital signal and for providing a signal to a parameter
control means, parameter control means responsive to said signal
from said microprocessor for continuously adjusting a parameter of
said exercise equipment in response to the measured heart rate of
said user, memory means located in said exercise equipment for
storing a profile of heart rate response of said user, input means
connected to said microprocessor for enabling said user to control
said parameter control means independent of said stored profile of
heart rate response, and identification means located in said
exercise equipment, said identification means being responsive to
an entry by said user identifying said user to said exercise
equipment.
12. The apparatus of claim 11, further including additional memory
means coupled to said microprocessor for receiving a recording of
an exercise program specific to said user.
13. The apparatus of claim 11, further including error detection
and correction means located in said transmitting unit for ensuring
the correctness of heart rate wirelessly transmitted to said
receiving means.
14. The apparatus of claim 13, where said first memory means
contains memory for storing information representative of the
person's most recent use of said exercise equipment.
15. The apparatus of claim 11, where said frequency change means
includes means for wirelessly transmitting a digital frequency
change signal from said exercise equipment to said transmitting
unit, said frequency change signal containing information
identifying the exercise equipment from which it is sent.
16. The apparatus of claim 11, where said microprocessor controls
the user's warm-up and cool-down periods of use of said exercise
equipment.
17. The apparatus of claim 11, where said identification means is a
magnetic card reader for reading a magnetic code identifying said
user.
18. The apparatus of claim 11, where said parameter control means
operates under control of a signal from said microprocessor in
response to said user's heart rate independently of the exercise
program being provided by said first or second memory means.
19. The apparatus of claim 11, where said exercise equipment
includes means located therein for determining that said encoded
digital signal is from said transmitting unit.
20. An apparatus for controlled exercise in response to continuous
monitoring of a person's heart rate, comprising in combination:
exercise equipment having resistance determining means therein for
increasing or decreasing the resistance offered by said exercise
equipment to a user of said equipment, parameter control means in
said exercise equipment for changing the resistance offered by said
exercise equipment to said user, microprocessor means in said
exercise equipment for providing a signal to said parameter control
means for determining tie resistance offered by said exercise
equipment to said user, said signal being proportional to a
measured heart rate of said user when operating said exercise
equipment, a transmitting unit adapted to be worn by said user for
detecting and digitally encoding a signal representative of the
user's heart rate, said transmitting unit including encoding means
for producing an encoded digital signal having a first part
identifying said transmitting unit and a second part representative
of the user's heart rate, receiving means located in said exercise
equipment for receiving said encoded digital signal via wireless
transmission from said transmitting unit and for providing said
received digitally encoded signal to said microprocessor means,
error correction means located in said transmitting unit for
ensuring the accuracy of said measured heart rate, memory means
located in said exercise equipment for storing an exercise program
specific to said user, identification means in said exercise
equipment responsive to the entry of an identification code
specific to said user, and display means in said exercise equipment
for displaying the user's heart rate and other information relative
to the parameters of exercise being undertaken by said user.
21. The apparatus of claim 20, further including additional memory
coupled to said microprocessor means for receiving a recording of
an exercise program specific to said user.
22. The apparatus of claim 21, including memory means for storing a
plurality of exercise profiles specific to said user.
23. The apparatus of claim 21, further including input means
connected to said control means for enabling said user to override
control of said parameter control means.
25. The apparatus of claim 24, including means for determining a
warm-up exercise profile, a cool-down exercise profile and a
sustained exercise profile for maintaining an aerobic workout of
said user.
25. The apparatus of claim 20, further including frequency change
means for changing the frequency over which said encoded digital
signal is wirelessly transmitted from said transmitting unit to
said exercise equipment.
Description
BACKGROUND ART
[0001] For many applications, it is necessary to measure and
display a person's body response, such as his or her heartbeat. In
particular, in exercise and fitness training, it is often the
situation that a person wishes to measure his or her heartbeat in
order to achieve the maximum benefits of the exercise without the
danger of increasing the heartbeat to a rate where adverse effects
could occur. Of course, such measurements are also useful for many
health applications such as biofeedback and exercise programs where
the participants only mildly exercise and do not approach greatly
elevated heart rates. Over the years, various types of equipment
have been marketed for the measurement of heart rate, such
instruments being popular in a wide variety of applications
extending from all forms of exercise to biofeedback. Continuous
accurate heart measurement is an important part of all aerobic
exercise and rehabilitation programs and for this reason many types
of apparatus have been commercially available for personal use by
individuals and in fitness clubs, etc. Some of this equipment
includes heart rate monitors that are used to control the intensity
of the workout based on the user's measured heart rate. As will be
discussed later, the problem of providing a good monitor
necessarily affects the quality of an exercise program that is
responsive to a measured heart rate.
[0002] Some of the most popular heartbeat monitor designs use
wireless data transmission from a sensor-transmitter unit to a
display unit. This type of design allows optimal and flexible
positioning of both units while not limiting a person's freedom of
movement. Unfortunately, the increasing popularity of heart
measurement, and therefore the use of these heart monitors, has
demonstrated the limitations of currently available designs. An
example is the recurring interference effects brought about when a
person wearing a heart monitor is in close proximity to another
person wearing another heart monitor. These people run the risk
that their individual monitor readings are influenced by the
monitor worn by the other person. Further, it is equally
frustrating for a person wearing a heart monitor to find that
electromagnetic equipment of all types, such as exercise equipment,
power lines etc. will create electromagnetic fields that interfere
with the successful transmission of his or her heartbeat, thereby
causing an erratic display which is uncorrectable without moving
away from the interfering exercise equipment, power lines, etc.
[0003] Various types of wireless measuring methods have been
proposed. Some of these are based on radio waves while others use a
magnetic proximity field. Most of these prior techniques transmit
an analog ECG signal of a person. However, as noted, these prior
techniques and apparatus are not simultaneously usable by several
persons in close proximity to one another or by persons who are
using such apparatus in close proximity to electrical or electronic
equipment. In such cases, the reliability of transmission of
heartbeat is significantly reduced with the result that a
continuous and accurate monitoring of the heartbeat is no longer
possible. As is readily appreciated, this lack of reliability is a
problem for anyone using the monitor and is especially
disconcerting to a person who is exercising to a level where his or
her heartbeat is close to the maximum desired for that person.
[0004] Examples of some prior art monitors include U.S. Pat. No.
4,625,733; U.S. Pat. No. 4,425,921; U.S. Pat. No. 3,212,496; and
U.S. Pat. No. 3,949,388. The first of these describes a heartbeat
monitor using a magnetic proximity field as a basis for analog
wireless transmission, which a particular arrangement of magnetic
coils is used in the transmitter and the receiver units.
[0005] U.S. Pat. No. 4,425,921 describes a portable heartbeat
monitor which can be used to check either pulse rate or heart rate
using separate sensors for detecting heartbeat and pulse beat. The
apparatus shares a common indicator for displaying the heartbeat
rate or pulse beat rate depending upon a switch means for
connecting either of the sensors to a microcomputer. Analog signals
are used in this monitor, which does not use wireless transmission
between a transmitter and receiver.
[0006] U.S. Pat. No. 3,212,496 describes an apparatus for
simultaneously measuring ECG, respiration rate, and respiration
volume. A pair of electrodes on or in a person's body have current
passed therebetween and sense an impedance change and a heartbeat
voltage. A frequency modulated signal can then be telemetered to a
receiving and display unit.
[0007] U.S. Pat. No. 3,949,388 describes a portable apparatus that
can be used for analog biomedical telemetry, and is particularly
adapted for use in a hospital where each sensor-transmitter unit is
used on a single patient and will not normally be used on another
patient. The transmitter is designed to produce a very narrow
frequency spectrum where a steady pulse rate accurately represents
the measured temperature of the patient. In order to avoid
interference from adjacent units, the receiver unit is located
within only a few feet of the transmitting unit. Further, a very
low power continuously sending transmitting unit is used so that
only the closest receiver will detect the analog signal. This
avoids the possibility that the receiver will pick up signals from
another transmitter. Thus, the selectivity of the receiver is based
on its close proximity to the associated transmitter unit, not on
any circuitry which would prevent interference by a transmitter
broadcasting a high power signal, even though such interfering
transmitter may be far away. Further, the frequency range intended
for operation is selected to be very narrow. As noted in this
patent, frequency sweeping can occur due to saturation of a
transistor in the oscillator circuit. In order to prevent this
undesirable frequency sweeping, an isolating impedance is used in
the circuit design to prevent feedback current of the type which
causes the transistor saturation.
[0008] U.S. Pat. No. 5,157,604 describes a hospital monitoring
system in which many patient transmitter units are coupled to a
central station. Wireless transmission of a signal including an
identifier and heartbeat data occurs from each patient unit to the
central station. Each patient unit transmits on its own frequency
so there will be no interference between the patient units. The
responses of the patient units are time multiplexed since these
units respond to the central station only in response to the
receipt of a timing signal from the central station. Error
detection and correction of an incorrect heartbeat due to faulty
transmission is not mentioned.
[0009] In the prior art monitors for measuring and displaying
heartbeat, it is usually not possible to provide a technique and
apparatus for determining if the received signal in the display
unit is from the properly associated transmitter unit or is instead
from another transmitter unit. Further, if there are errors
occurring in the data representing the heartbeat, such as missing
portions of the signal due to interference from outside sources,
the display in these prior monitors will either indicate a wrong
value, not indicate heartbeat, or maintain the previous reading
without making the user aware of the problem. In these prior art
monitors, there is no way to account for transient errors in
heartbeat which are momentarily caused but which do not necessarily
render inaccurate the later readings of heartbeat. If these prior
art monitors are used to control exercise equipment, there is a
problem due to interference from the motors in the equipment and
also from other monitors on equipment that is closely located to
the user's exercise equipment.
[0010] It is therefore a primary object of the present invention to
provide an improved technique and apparatus for monitoring and
displaying a biomedical function (body response) such as heartbeat,
wherein the above-described problems are addressed and corrected
and to provide exercise equipment using this improved
apparatus.
[0011] It is another object of the present invention to provide
exercise equipment using an improved personal use heartbeat monitor
which automatically rejects interfering signals from
sensor-transmitter units other than the one with which the display
unit is properly associated.
[0012] It is another object of the present invention to provide a
heartbeat monitor in which the presence of transient errors in the
signal representing the heartbeat does not render inaccurate the
heartbeat displayed to the person wearing the monitor, where this
monitor is used to control exercise equipment in accordance with
the person's instantaneous heart rate.
[0013] It is another object of this invention to provide a wireless
heartbeat monitor which can be easily worn by a person engaged in
all forms of physical exercise, and which will nonetheless provide
accurate measurement of the person's heartbeat even in the presence
of other heartbeat monitors and/or electrical or electronic
equipment in which components of the monitor are located.
[0014] It is another object of the present invention to provide
exercise equipment in which a part of a person's ECG signal is
digitally encoded for wireless transmission to a receiver-display
unit located in the exercise equipment, where the coding allows a
receiver-display unit to identify the encoded digital signal as
having been sent from a particular sensor-transmitter unit.
[0015] It is another object of the present invention to provide
exercise equipment using a heartbeat monitor which will
automatically change the frequency range over which signals
representing the heartbeat are wirelessly sent from a
sensor-transmitter unit to a receiver-display unit, the
transmission frequency being changed in response to the occurrence
of errors in the received signal.
[0016] It is a further object of this invention to provide a
technique and apparatus for monitoring heartbeat where the monitor
is used in exercise equipment without adversely affecting the
accuracy of the data displayed to the person using the monitor.
[0017] It is another object of this invention to provide improved
exercise equipment for isolating monitor signals relating to a
biological function, such as heartbeat, wherein the monitored
signals are digitally encoded to provide user identifiers that are
wirelessly transmitted.
[0018] It is a still further object of this invention to provide
automatic transmission error detection and correction in a wireless
biological response monitoring system used to control exercise
equipment in accordance with a user's biological response.
BRIEF SUMMARY OF THE INVENTION
[0019] This invention broadly relates to exercise equipment that
uses an improved technique and monitor for measuring and
displaying, preferably on a continuous basis, a physical condition
or biomedical response, such as a heartbeat rate. The monitor
includes a transmitter unit for producing an encoded digital signal
representing the biomedical response and for wirelessly
transmitting the encoded digital signal to a receiver unit for
display of the measured biomedical response. The monitor also
includes a detection means for detecting errors in the received
encoded digital signal, and correction means for automatically
changing the transmitter unit and the receiver unit to provide
accurate wireless transmission therebetween of the measured
biomedical response. In a preferred embodiment this monitor
includes unique identification between a transmitter and an
associated receiver.
[0020] This monitor is particularly suitable for personal use such
as would occur in a home or office or even in a gym or fitness
center where it can be a part of exercise equipment. In one
embodiment, the transmitter unit is adapted to be worn and would be
battery operated while the receiver unit can be part of exercise
equipment and can be used to control a workout in response to a
measured biological response. As long as the receiver is within the
transmission distance from the transmitter, it will receive the
wirelessly transmitted signal. In one aspect of this invention the
monitor measures a person's heartbeat and displays an indication of
the monitored heartbeat. In this embodiment, the apparatus is
comprised of a sensor-transmitter unit (chest unit) adapted to be
worn in contact with a person's chest and having electrodes which
receive the person's ECG signal. This signal is amplified and
digitally encoded to contain an identification portion and a data
portion. This encoded signal is transmitted in a wireless manner to
a receiver-display unit (wrist unit), where the receiver-display
unit contains a display for displaying the person's heartbeat.
While the receiver-display portion of the monitor can be adapted to
be worn, for exp. on a person's wrist, this unit need not be worn
and could be located elsewhere, for example on exercise equipment.
In the invention of this continuation-in-part application the
receiver-display unit is used to control the exercise equipment in
response to a continuous monitoring of the exercising person's
biological response (heart rate, etc.). Further, while chest
electrodes generally provide the best ECG signals, the transmitter
unit could be placed elsewhere, such as on a person's wrist.
[0021] Because the person's ECG signal is digitized and encoded,
two purposes can be achieved. The first is that an identification
is provided which is different for each heart monitor. That is,
after the receiver-display unit receives the transmitted encoded
signal, it checks this signal to see if it contains the proper
identification code. If this comparison fails, the incoming signal
to this unit is not accepted because it is not from the proper
chest unit. However, if the identification compares with the
reference identification in the receiver unit, the incoming signal
will be accepted. This prevents two heart monitors working in close
proximity to each other and transmitting on the same frequency from
receiving and displaying signals from the wrong person.
[0022] The second purpose of the digital encoding is to provide
transmission error detection and correction of the heartbeat data.
In practice, it is possible that a valid signal may be rejected by
the receiver-display unit due to an outside noise source. The data
portion of the transmitted signal is therefore encoded into a
particular bit sequence. When the incoming data bit sequence is
checked against a reference data bit sequence in the
receiver-display unit, errors in the received signal can be
detected. The receiver unit can be set so that infrequently
occurring errors (such as transient errors) will be corrected but
not result in a change of the transmitting and receiving units. On
the other hand, if too many errors are present, the receiver unit
will notice it and provide a frequency change signal to change the
transmission frequency in the chest unit and also to change the
receiving frequency in the receiving unit. In a preferred
embodiment the power of the frequency change signal is also
increased to ensure that the frequency change is made. While the
receiving unit will automatically cause a change in frequency if
persistent errors occur, the user can also change the transmission
and reception frequency if it is anticipated that a problem may
occur. This feature of a change in transmission and receiving
frequency also allows the use of multiple units in close proximity
to one another without reciprocal disturbances.
[0023] The chest unit generally contains an input sensor means for
receiving the ECG signal, amplifying means, comparator means for
producing a digital pulse train corresponding to the analog ECG
pulses, encoder means for encoding the digital pulse train into
coded signals having bits corresponding to an identification
portion and further bits corresponding to a data portion of said
encoded signal, and means to receive a frequency change signal from
the wrist (receiving) unit for changing the transmitting frequency
of the chest unit. This latter means includes a receiver for
receiving via wireless transmission the frequency change signal
from the receiving unit when the transmission frequency is to be
changed and a signal evaluator for reading the identification code
in the frequency change signal to determine that it is from the
associated receiving unit and for providing a signal to the
transmitter means for changing the transmission frequency for the
outgoing signals from the chest unit. Part of the identification
signal may serve for synchronization of a clock signal in the
receiving and transmitting units.
[0024] The receiving unit broadly includes a receiver for receiving
output signals from the chest unit and a signal evaluator for
separating the identification portion and the data portion of the
incoming encoded signal and for determining if the incoming signal
is from the associated chest unit. The signal evaluator also checks
the data portion of the incoming signal to determine if it has the
proper data pattern for the associated chest unit. The signal
evaluator provides an output to a memory means for storing
heartbeat data and also provides in output that is sent to a
display, for displaying the heartbeat rate. The signal evaluator
further provides an output that is sent to a transmitter means
located in the receiving unit if the signal evaluator determines
that the frequency of errors in the data portion of the incoming
signal is beyond a given bound, that is, if the bit patterns
indicate that the errors are not merely transient but are
sufficiently repetitive as to provide potentially inaccurate
monitoring of person's heartbeat. The output of the transmitter
means in the receiving unit is sent in a wireless manner to the
receiver in the chest unit. At the same the signal evaluator also
provides a signal to the receiver in the receiving unit to change
its reception frequency to match the new transmission frequency in
the chest unit. The receiving unit also contains an input terminal
by which the user can directly initiate a change in
transmitter/receiver frequency, or can block an automatic change of
frequency in the chest and receiving units. For example, the user
may sense that the external condition which is causing an error in
the received encoded signal will soon cease so that it is not
necessary to change frequency. Another situation where a user may
want to prevent a frequency change is where there are multiple
users in close proximity. Rather than have everyone's monitor
change frequency, some monitors can be held at fixed frequencies
while other monitors change frequency.
[0025] This design will overcome most of the limitations of the
currently available wireless heart monitors. Additionally, it will
compensate for minor errors and enable the user to avoid certain
error sources by purposely changing the transmission frequency. Of
course, the user can allow the monitor to automatically change
frequencies. Since the range of the human heart rate is fairly
restricted, this design allows the detection of uncorrectable
errors by taking into account the elapsed time between two
successful data transmissions. Since it is highly improbable that
the wrist unit will receive the correct identification pattern from
a source other than the associated chest unit, the user can have a
very high level of confidence in the accuracy of the displayed
heart rate. This is accomplished even though the chest and
receiving units are separate from one another and communication
therebetween is via wireless transmission.
[0026] The invention uses the improved monitor to control exercise
equipment in response to a measured biomedical function such as
heart rate. The receiving unit is located on the exercise equipment
and provides a control signal to change (increase or decrease) or
maintain the resistance offered to the user by the exercise
equipment. This resistance is changed in accordance with the
measured heart rate (for exp.) in a continuous manner to provide an
exercise workout including warm-up, cool-down and sustained aerobic
exercise.
[0027] Memory means and a microprocessor are used to maintain an
up-to-date profile of the exercising person and to continuously
regulate the resistance of the equipment in accordance with the
user's instantaneous heart rate. Identification means allows the
user to identify himself or herself to the exercise equipment in
order to have the equipment access the proper exercise profile from
memory. Additional memory is provided to allow the user to enter a
different exercise profile if it is not desired to use the exercise
profile already stored in memory. An input control to the
microprocessor allows the user to override any profile control that
the microprocessor would usually select.
[0028] The invention is most useful in the case of personal use
equipment which allows the user to have complete mobility while
undergoing heartbeat monitoring. The various components of the
chest and wrist units are easily provided by known microelectronic
integrated circuit chips that can be packaged together in small
volume and battery operated. The major use of this monitor will be
for continuous display during personal activities by an individual,
including exercise, biofeedback, and general health monitoring. In
these activities wireless transmission will be over a relatively
short range, particularly if both the transmitter and receiver
units are worn or if the receiving unit is located in the exercise
equipment.
[0029] These and other objects, features, and advantages will be
apparent from the following more particular description of the
preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic illustration of the heart rate monitor
of the present invention, showing the chest unit (transmitting
unit) and the wrist unit (display) which receives the signal from
the chest unit via a wireless transmission and displays the
heartbeat of the person being monitored.
[0031] FIG. 2 shows a typical ECG signal and the train of digital
pulses representing each of the analog pulses in the ECG
signal.
[0032] FIG. 3A shows a typical format of the encoded digital signal
wirelessly transmitted from the chest unit to the wrist unit, this
digital signal consisting of a synchronization part, an
identification part unique to this particular chest monitor and a
data part unique to the person's heartbeat.
[0033] FIG. 3B represents a sequence of bits corresponding to the
data part of the outgoing digital signal from the chest unit (FIG.
1) where each data part is represented as a two-bit binary code in
this example.
[0034] FIG. 4 is a schematic illustration of the chest unit in more
detail, showing the various components of this unit.
[0035] FIG. 5 is a schematic illustration of the wrist unit in more
detail, showing the components comprising this unit.
[0036] FIG. 6 is a schematic illustration of a modified chest unit,
where the encoded digital signal represents the full heartbeat
rate.
[0037] FIG. 7 schematically illustrates the use of this inventive
monitor to control exercise equipment in accordance with a user's
heart rate.
[0038] FIG. 8 shows the various components of the
receiver-controller unit in the exercise equipment depicted in FIG.
7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] The practice of this invention will be represented by the
example of a heartbeat monitor, where it is desired to accurately
measure heartbeat and to provide a technique which eliminates many
of the errors found in the use of presently available wireless
heartbeat monitors, particularly those of the portable type adapted
to be used by people undergoing exercise, biofeedback etc. Such
problems generally relate to interference effects that can occur if
two wireless heartbeat monitors are operating in close proximity to
one another, noise attributable to sources other than another heart
monitor, confusion between received signals wherein the heartbeat
being displayed may not be that of the person being monitored and
situations where the user would be unaware that the displayed
heartbeat is inaccurate.
[0040] FIG. 1 schematically represents the heartbeat monitor 10,
which is comprised of a chest unit 12 (transmitting unit) and a
complementary wrist unit 14 (receiving or display unit). Wireless
transmission over a plurality of frequency ranges can occur from
chest unit 12 to wrist unit 14, as represented by the arrows 16.
Wireless transmission from the wrist unit 14 to the chest unit 12
is used to correct transmission errors but usually over only a
single frequency as represented by the single arrow 17. As will be
described later, wireless transmission from the display unit 14 to
the chest unit 12 will occur when it is desired to change the
transmission frequency from the chest unit. This can be done either
automatically or on command by the user. In practice, the
transmitter of the chest unit is frequency matched to the receiver
in the wrist unit so that an encoded digital signal wirelessly
transmitted from the chest unit 12 will be correctly received by
the wrist unit 14.
[0041] FIG. 2 illustrates a typical ECG signal 18 from a person
being monitored, and the digital pulse train 20 corresponding to
the ECG signal. Each digital pulse corresponds to the onset of a
positive slope portion 22 of the analog pulses forming the ECG
signal train 18. As an alternative, each digital pulse can
correspond to another portion of the analog pulses, such as the
peak of each pulse. In the present invention, the ECG signal is
digitized prior to wireless transmission from the chest unit 12 to
the wrist unit 14. The purpose of this apparatus is to monitor
heartbeat and therefore it is sufficient to transform the ECG
signal into a digital pulse train. The particular characteristics
relating to a person's ECG signal are not of importance in the
present invention.
[0042] Prior to the transmission of a digital signal from chest
unit 12 to wrist unit 14, the digital signal is given a specific
binary identification sequence.
[0043] Further, the individual digital pulses in the pulse train 20
are each encoded into m bits. A sequence of digital pulses will
therefore result in a sequence of these m bit signals. This
sequence is predetermined and is known to the wrist unit 14. A
certain bit sequence can precede the identification portion with
the encoded digital signal to facilitate synchronization of the
transmitter and receiver. FIG. 3A shows a typical format of the
encoded digital signal transmitted from the chest unit 12 to the
wrist unit 14 where the signal is comprised of a 3 bit
synchronization part, an 8 bit identification part and a two bit
data part. FIG. 3B shows a sequence of four digital pulses
represented by a code having two bits per pulse, i.e., m=2. In this
sequence, the first encoded group 00 represents the first digital
pulse, the second encoded group 01 represents the second digital
pulse, the third encoded group 11 represents the third digital
pulse, and the next encoded group 10 represents the fourth digital
pulse. This pattern, and its order, will be used each time the ECG
signal is sampled and encoded. The pattern and its order will be
changed if m is changed.
[0044] In operation, it is possible that a transmission error can
occur. Sometimes these errors are only transient, in which case the
last display reading will be maintained. It can also be the
situation that the errors continue to occur due to interference
from some outside source (such as an adjacent heartbeat monitor)
where the errors are for example, missing bits during repeated
transmissions. Since the wrist unit 14 knows the predetermined code
for the data portion of the signal, the missing of up to 2.sup.m-1
continuous signals will be immediately noticed and the missing
signals can be accounted for. If too many signals (>2.sup.m-1)
are missing and therefore the interference is not a transient one,
the frequency of the transmitter and receiver will be changed
automatically. This can also be done on demand by the user. Thus,
encoding of the digital pulse train 20 to include an identification
part and a data part enables the receiving unit to accept only
those signals sent from the associated chest unit and to detect and
correct errors in the data part corresponding to the person's
heartbeat. Details of how this occurs will be explained with
respect to the apparatus of FIG. 4 (chest unit) and FIG. 5 (wrist
unit).
[0045] Heartbeat Monitor Technique
[0046] This section will describe in general terms the technique of
the present invention in which heartbeat monitoring is achieved in
an advantageous manner. In a first step, a person's ECG signal is
detected and then sufficiently amplified. This amplified signal is
transformed into a digital pulse signal which can be used to
initiate the wireless transmission of an encoded digital signal
from the chest unit 12 to the wrist unit 14. The digital signal
being transmitted includes an identification part and a data part
as illustrated in FIG. 3A. The transmitted encoded data signal is
received by a complementary receiver in wrist unit 14 and
transformed therein back into the encoded digital signal. The
resulting digital signal is separated into its identification part
and its data part. Wrist unit 14 verifies the identification
sequence to determine that the received signal is from the proper
chest unit. If not, the signal is not accepted. If the
identification step is satisfied, the data portion of the received
signal is then checked to see whether it has the expected value. If
the expected value is present in the received signal, then the
display portion of the wrist unit is updated. Some or all of the
data can also be stored in a memory contained in the wrist unit. As
an option, the data can be first sent to the memory prior to being
displayed.
[0047] The data portion of the transmitted encoded signal can
represent a full heartbeat rate, or just a portion of it. For
example, the number of ECG pulses in a 3-second interval can be
represented. If this number is multiplied by 20, the approximate
heartbeat rate in beats per minute will be known. This calculation
can be done in the receiver unit or in the transmitter unit if the
full heartbeat rate is to be transmitted to the receiver.
[0048] If the full heartbeat rate is transmitted, then less
transmissions will be needed. In turn, this means that there will
be less likelihood of interference from other sources and less
power will be consumed. Of course, the number of transmissions in a
given time from the transmitter to the receiver can be determined
as a design parameter in accordance with considerations such as
power, likelihood of interference, clocking requirements, etc.
Various coding schemes are well known for selecting the number of
ECG pulses to sample and the sampling repetition rate. In the
practice of this invention, any of these known coding schemes, or a
different one, can be chosen.
[0049] If the sequence of bits forming the data portion of the
received signal is not maintained in the expected sequence, an
error has occurred and the number of missing digital pulses is
determined. These missing digital pulses are assumed to be evenly
distributed in a corresponding time range and the display will be
updated and/or the data will be stored in memory together with some
annotation about the error.
[0050] In this embodiment, the occurrence or a certain number of
errors (>2.sup.m-1) within a given time frame means that the
indicated heart beat rate will be unreliable. This will result in
an automatically generated request for a frequency switch that is
initiated in the wrist unit 14. This request for a change in
transmission frequency can be blocked by the user or can be
initiated on demand by the user. For example, the user may see that
he or she will be in the presence of others using heartbeat monitor
devices or maybe near exercise or other types of equipment which
would interfere with the signals being transmitted from the chest
unit. Knowing that such an interference may occur and may extend
for a period of time, the user may wish to change the transmission
frequency in order to avoid problems. Alternatively the user may
recognize that any interference will be only transient, and
therefore may wish to block a frequency change. In actual use, most
persons would allow the monitor to automatically adjust. The amount
of errors that will trigger a frequency change is a parameter that
can be varied, according to the logic incorporated in the
monitor.
[0051] If a change in transmission frequency is needed, a digital
signal (frequency change signal) will be sent via wireless
transmission from the wrist unit to the chest unit. This digital
signal can include an identification part and a data part which
specifies the new transmission frequency. The identification part
of this digital signal allows the chest unit to know that the
frequency change signal has been sent from the associated wrist
unit and is therefore a correct command to change frequency. At the
same time, the wrist unit changes the frequency of the receiver in
this unit to match the new transmitter frequency of the chest unit
12. The transmission path from the wrist unit 14 to the chest unit
12, commanding a new transmission frequency, is not often used.
However, once it is used the probability of a correct transmission
must be high. For these reasons, it is preferable that there be
only one possible transmission frequency for this path and that
this transmission frequency be different from the frequencies used
on the main transmission path, i.e., the transmission frequencies
normally used to transmit the encoded digital signals from the
chest unit to the wrist unit 14. As a further measure to increase
the reliability of the second transmission path from the wrist unit
14 to the chest unit 12, the power of the frequency change signal
from the wrist unit to the chest unit is higher than the power
normally used for the transmission of encoded digital signals from
the chest unit 12 to the wrist unit 14. This ensures that the
necessary frequency change in the main transmission path will be
made.
[0052] The following description will detail the components
comprising the chest unit 12 and the wrist unit 14, which together
comprise the heartbeat monitor 10.
[0053] Chest Unit (FIG. 4)
[0054] FIG. 4 shows the various components of chest unit 12 which
are used to detect an ECG signal, amplify that signal and digitize
it, encode it into an identification portion and a data portion,
and then to wirelessly transmit it to wrist unit 14. The chest unit
also includes means for receiving a frequency change signal from
the wrist unit that will trigger a change in transmission frequency
of the outgoing signals.
[0055] In more detail, chest unit 12 is typically carried on the
breast of the target person such that this person's ECG signal 18
can be received by the input electrode terminals 24. These
terminals 24 can be a part of the chest unit or the chest unit can
be designed so that any sensor for detecting a biomedical response
can be plugged into it. The ECG signal 18 is then amplified in a
differential amplifier 26, producing the amplified signal
represented by arrow 28. Amplified signal 28 is transformed into a
digital pulse train 20 (FIG. 2) in the comparator 30, which has
hysteresis. This hysteresis feature prevents the generation of more
than one digital pulse from one heartbeat, due to outside
disturbances of any type. The correlation between the ECG signal 18
and the digital pulse signal 20 was described with respect to FIG.
2.
[0056] The digital pulse signal 20 is sent directly to the
transmitter 37 via line 32, and is also sent to an encoder means 34
via interconnection line 36. The rising flank of a digital pulse
will trigger transmitting means 37 to wirelessly transmit an
encoded electromagnetic signal 16 to a receiving means in the wrist
unit 14. The rising flank of a digital pulse also triggers encoder
34 to provide the synchronization part, the identification part and
the data part of the encoded digital signal represented by arrow 38
which is transmitted by the transmitting means 37. The digital
pulse on line 32 is used only as a clock or timing pulse. Line 32
can be eliminated in an alternative design wherein clocking is
internal in transmitter 37 or is provided by a portion of the
encoded signal from encoder 34.
[0057] Encoded digital signal 38 is shown in FIG. 3A, while a
sequence of signals corresponding to the encoded data portion is
shown in FIG. 3B. Every digital pulse in pulse train 20 (FIG. 2)
results in advancing one step in the cycle of the encoded data
signals. Therefore, FIG. 3B illustrates a pulse sequence
corresponding to four digital pulses in the pulse train 20. Only a
small and predetermined number of encoded signals must be
transmitted by transmitting means 37.
[0058] Chest unit 12 also contains a receiver 40 and a comparator
42, termed a signal evaluator. Units 40 and 42 are used to receive
a frequency change signal from wrist unit 14 indicating that a
transmission frequency change is required, and to thereby provide a
signal to the transmitter 37 to achieve this. In more detail, if
errors beyond a given bound are noted in the data portion of the
incoming digital signals in the wrist unit 14, a transmitted
frequency change signal 17 will be wirelessly sent to chest unit 12
and is received by the receiver 40. This received signal contains
the binary identification pattern unique to this heartbeat monitor
and a data portion which will trigger a change in frequency. In
this embodiment, chest unit 12 need not be equipped with error
detection and correction means. It is only necessary that the data
portion of the frequency change signal indicate that a new
transmission frequency is desired. The data portion can also
specify this new frequency or logic in signal evaluator 42 can
specify the new frequency range over which the encoded digital
signals will be sent.
[0059] The frequency change signal is sent to the comparator 42
(signal evaluator) which compares the coded identification pattern
in the received digital signal with the coded identification
pattern for this heartbeat monitor 10. As noted, this
identification pattern is unique to this heartbeat monitor. If the
comparison shows that the identification portion of the incoming
signal matches that for this heartbeat monitor, comparator 42 will
determine the new transmission frequency from the data portion of
the received signal and will generate a digital frequency select
signal 44 that is sent to the transmitter 37. As will be explained
later, a signal evaluator in the wrist unit will provide a
corresponding signal to the receiver therein in order that the
reception and transmission frequencies will be matched.
[0060] Wrist Unit 14 (FIG. 5)
[0061] FIG. 5 illustrates the components which make up the wrist
unit 14 (display). This unit provides the general functions of
receiving the encoded digital signal representing a person's
heartbeat, comparing the identification portion of the encoded
signal to the inappropriate reference identification pattern, and
displaying and/or storing the data representing this heartbeat.
Another function that is accomplished is a check of the data
portion of the encoded signal to determine if any errors therein
are within an acceptable bound or, if they are not, generating a
signal to change the transmitter frequency as well as the frequency
of the receiver in the wrist unit. As noted, this error detection
and correction means takes into account transient errors which do
not repeat and for which a frequency change is not required as well
as persistent errors which necessitate a change in transmission
frequency in order to provide accurate data transmission. In this
continuation-in-part application, the "wrist" is located in the
exercise equipment and is used to control the part of the equipment
which regulates the resistance offered to the user.
[0062] In more detail, wrist unit 14 contains a receiver 46 for
receiving the encoded digital signals 16 from chest unit 12, a
comparator or signal evaluator 48 for analyzing the received
encoded signals, a memory unit 50 in which data representing
heartbeat can be stored, a display unit 52 for displaying to the
user his or her heartbeat, and a transmitter 54 for the wireless
transmission of frequency change signals to the chest unit in order
to change the frequency of transmission.
[0063] The electromagnetic signal 16 is received by receiver 46 and
transformed into a digital signal that is sent to the comparator
48. This digital signal is identical to the outgoing digital signal
transmitted from chest unit 12 to wrist unit 14. In the comparator
48, the received digital signal is separated into its
identification part and its data part. The identification part of
the signal is compared to the preset and unit-specific
identification unique to this heartbeat monitor. If the
identification part of the incoming signal does not match the
reference identification part, the incoming signal is ignored. If
there is a match, comparator 42 then checks whether the data
portion of the incoming signal is in the proper pattern order shown
for example, in FIG. 3B for a situation in which m=2. If the data
bit sequence matches the reference sequence, then the transmission
from the chest unit 12 to the wrist unit 14 was error free and the
necessary signal evaluation can be done. This means that the
information can be sent directly to display 52 and/or stored in
memory 50.
[0064] If the data portion is not the expected pattern, the number
of missing patterns is determined. This number also gives
information about the severity of the transmission error. The
necessary approximations to compensate for this error are then done
in the signal evaluation unit 48 in order to compensate for the
error. For example, if only one bit is missing from the expected
pattern, the signal evaluator would have built-in logic that would
provide the bit so that the heartbeat rate corresponding to that
data pattern would be displayed. If the error is a major one but
does not repeat itself, the signal evaluator will cause the last
displayed heartbeat rate to remain displayed.
[0065] If the occurrence of transmission errors is beyond a given
bound then the signal evaluator unit will automatically generate a
frequency change signal 56. This signal will be sent to the
transmitter 54 for wireless transmission (represented by arrow 17)
to the receiving means 40 in chest unit 12 (FIG. 4). The selection
of the new transmission frequency takes into account the recent
history of transmission failures for the various frequencies. This
can be done by a table look-up feature in signal evaluator 48 where
the number of transmission errors is stored for each of the
transmission frequencies. Signal evaluator 48 also provides a
frequency change signal 58 to the receiver 46. This enables
receiver 46 to have a receiving frequency matching that of the new
frequency used in the transmitter 37 (FIG. 4).
[0066] As an alternative, the user can use input terminal 60, which
is connected to the signal evaluator 48, in order to either block
the change of frequency or to initiate a change in frequency.
[0067] Normally a change(s) in transmission frequency will provide
accurate data to the receiving unit. However, if the monitor
detects errors that continue to occur after several frequency
changes, the internal logic in the monitor will prevent the further
display of heartbeat rate (blank screen), and/or will provide an
alarm signal. In this way, the user is not fooled by the display of
an inaccurate heartbeat as occurs with presently available
monitors.
[0068] The data evaluation leading to information for updating the
display can be sent to the memory 50 besides being entered into the
display 52. Later this stored data can be displayed in the display
52. Microprocessor 62 would control the flow of heartbeat data from
memory 50 to display 52. Display 52 can be of the visual type such
as an LCD display and/or can be audible, as for example an alarm or
other sound representing a heartbeat count.
[0069] The transmitter receiver pair 37-46 can communicate on
several frequencies and uses a relatively low power signal in order
to preserve battery life. The transmitter receiver pair 54-40
communicates on only one frequency and uses a relatively high power
signal, in a preferred embodiment. This takes into account that the
transmitter-receiver pair 37-46 is in constant use and that
hardware is provided for error detection and correction. In
contrast, the transmitter-receiver pair 54-40 is only rarely used
and the monitor 10 has no error detection/correction facility with
respect to the encoded signal representing a frequency change
selection.
[0070] The transmitter 54 will continue transmitting an
electromagnetic signal 17 until a correct electromagnetic signal 16
is delivered by transmitter 37 to receiver 46 in the wrist unit. If
for some reason this synchronization fails, the user can
synchronize the chest and wrist units by external means.
[0071] FIG. 6 illustrates a modification of the transmitter unit
which is particularly adapted for wireless transmission of the full
heartbeat rate. The same reference numerals will be used in this
figure as were used in FIG. 4, for components having the same or
similar functions. Of course, the unit of FIG. 4 can also be used
to encode and transmit the full heartbeat rate.
[0072] In more detail, the transmitter of FIG. 6 includes the
amplifier 26, comparator 30, encoder 34, transmitter 37, receiver
40 and signal evaluator 42 shown also in FIG. 4. However, a timer
64 is now used to trigger the transmitter 37 for wireless
transmission of the encoded digital signal from encoder 34. In this
embodiment, a data check circuit 66 is used to enable error
detection and correction of the encoded digital signal prior to its
being transmitted to the receiver unit. For example, this can be
done by use of a parity bit. This helps to ensure accuracy if the
entire heartbeat rate is to be transmitted, particularly if the
heartbeat rate is not transmitted at a high repetition frequency,
i.e., if there is a long time duration between each wireless
transmission of heartbeat rate. The receiver unit of FIG. 5 can be
used to receive and evaluate the full heartbeat rate sent by the
transmitting unit.
[0073] Many different types of encoding can be used to represent
the identification and data portions of the transmitted signals.
Also, the rate of sampling of the ECG pulses can be varied, as can
the repetition rate at which wireless transmissions of the encoded
digital signal are made. The frequency change signal used to
trigger a new transmission frequency can be transmitted over a
multiple frequency range rather than over a single selected
frequency. The frequency ranges used in the main transmission path
can be chosen by the designer in accordance with known principles
of wireless transmission, which in personal use monitors is of a
short range.
[0074] As noted, the principles of digitization of the transmitted
heartbeat signal, transmission frequency changes, and signal
encoding to ensure the accuracy of the communicated results are
used to provide personal use monitors far superior to those
presently being marketed. However, such principles may be applied
to other than personal use monitors. It is recognized, though, that
the provision of such features is unique in a wearable heartbeat
monitor where the monitor includes a wearable transmitting unit and
an associated display unit. These features are also unique to
monitors where the display (receiver) unit is located on exercise
equipment or is a small unit that can be placed in a suitable
location for viewing by the user. Such units are distinguishable
from large hospital units wherein a central computer is used to
coordinate a multiplicity of transmitting and/or display units.
[0075] While the monitor has been illustrated in an embodiment
thereof for monitoring heartbeat rate, it will be understood by
those of skill in the art that a signal indicative of another
physical condition can be monitored. For example, an acoustical
sensor can detect a pulse or a thermometer sensor can detect a
temperature. This type of monitor can be applied to measure and
display any type of life function, in persons or animals.
Additionally, wireless monitors for measuring physical conditions
other than life functions can utilize the principles of error
detection and correction described herein.
[0076] While it has been mentioned that the display (receiver) unit
can be located on exercise equipment, the monitor can be used for
controlling intensity and type of workout on exercise equipment
based on continuously monitoring a body response of the target
person. For example, the exercise equipment can be programmed to
receive a continuous heart rate response of the target person and
then adjust the intensity (such as resistance) of the exercise to
maintain the person's heart rate within a preselected range.
[0077] The monitor of this invention is particularly suitable for
use with exercise equipment since it is insensitive to the
closeness of other exercise equipment, motors within the equipment
being used by the person, and other closely located monitors
operating on the same or close frequency ranges. This allows the
receiver-display unit to be located anywhere on the exercise
equipment without concern for interference effects which would
yield the wrong heart rate and correspondingly provide an incorrect
workout.
[0078] It is well known that exercising in a correct amount plays
an essential role in any effort to fight cardiovascular disease and
certain forms of cancer. However, the best result can only be
achieved when the correct way of exercising is selected. In the
past, this has led to certain rules of thumb such as exercising at
70% of the maximum heart rate, where the maximum heart rate is
given by the expression (220 minus age). In order to obtain this, a
constant monitoring of the heart rate during exercise is required
and there must be an adaptation of the intensity level of the
exercise based upon the heart rate. As the heart rate of a person
depends on a variety of daily factors such as sleep, diet, health
etc., it is not sufficient to determine the best type and intensity
of exercise for a person only one time, e.g., in a doctor's office,
and then stay with this level over a long period of time.
Additionally, the training effect of exercise itself leads to a
gradual shift in the exercise level which is best suited for the
individual.
[0079] Until only recently, the control of the intensity level of
the exercise equipment was left completely to the exercising
person. Even when the person had an accurate heart monitor he/she
still had to adjust the intensity of the exercise according to the
reading on the monitor. Only in closely supervised programs such as
those undertaken by professional athletes or persons in a cardiac
rehabilitation program was this task taken over by a trainer or a
doctor.
[0080] Since exercise equipment is now used in many forms of
exercise activities, it is appropriate to incorporate some means of
exercise level control into the equipment. A first step has been
done by some companies which offer exercise bikes allowing the
constant measurement of heart rate as long as the exercising person
touches two electrodes with his/her hands. The measured heart rate
is then used by the bike control circuit to increase or reduce the
resistance of the bike in order to keep the heart rate of the
target person within a selected range.
[0081] Although this type of exercise bike is certainly a step in
the correct direction, this equipment has several significant
disadvantages. While it may be somewhat inconvenient, a target
person can probably be convinced to keep a firm grip on the handles
of the exercise bike. However, this technique cannot be used for
other kinds of exercise equipment such as treadmills or
stairclimbers, where a constant contact of the skin with electrodes
on the equipment cannot be guaranteed. It is also doubtful that
this technique can be generalized to be used for measuring other
body responses, such as blood pressure. Further, this type of heart
monitoring does not allow for warm-up and cool-down phases which
are essential in the design of proper exercise. In some cases,
doctors will even suggest that for persons with limited available
time that the exercise should consist only of a warm-up and
cool-clown phase. In such an event, the aforementioned exercise
bike will not provide the proper workout.
[0082] As the heart rate is supposed to change during the phases of
warm-up, aerobic workout, and cool-down, a more complex control
mechanism is necessary than for a phase in which a constant target
heart rate is sought. Further, in an exercise bike, like in many
other exercise equipments, there are often multiple parameters
which determine the intensity of the exercise. For the exercise
bike, these parameters are the pedal speed and the resistance. In
presently available exercise bikes, only the resistance is
controlled by the heart rate. Still further, these exercise bikes
cannot keep track of the exercise history of the target person and
take this into account in deriving the best exercise type and
level. Although the heart rate has a very short response time to a
change in exercise intensity, this may not be the case for other
body responses. If there is a significant delay between a change in
the exercise intensity and a corresponding change of the body
response, this must be anticipated by a more complex control
algorithm; that is, the exercise equipment control should not be
restricted to a feedback type regulation but should also
incorporate a feed-forward control in which the equipment
parameters are adjusted ahead of time in order to eliminate excess
overshoots and undershoots of the measured body response.
[0083] There are also some exercise bikes being marketed which use
wireless monitors to measure heart rate of the exercising person
and to use that heart rate to adjust the exercise work load. In
some instances, different exercise programs can be incorporated
into the equipment, where these programs have predetermined
resistance levels to simulate hills or flat terrain.
[0084] FIG. 7 schematically illustrates the use of this monitor
with exercise equipment, in this case an exercise bike. The
transmitter unit of the monitor is located on the person while the
receiver unit is located on the exercise equipment. The receiver
includes a display which indicates the biomedical response, such as
heart rate, and also provides an electrical signal for controlling
one or more exercise parameters, such as pedal rate and resistance.
In FIG. 7, the transmitter unit 12 provides a digitally encoded
signal 16 in a wireless manner to the receiver 14, which is coupled
to the display and controller in the exercise bike 70.
[0085] The use of a wireless transmission ensures that the user
will not be constrained in his freedom of body movements regardless
of the type of exercise equipment that is employed. The features of
error detection and error correction, together with the means for
changing transmission frequency allow accurate heart rates to be
transmitted even in rooms which are crowded with exercise equipment
or with numerous people wearing heart rate monitors.
[0086] It is desirable that the exercise profile of the present
exercise be derived from an input from the user. An already stored
history of this specific user and the baseline of the user's body
response will provide more appropriate exercise. Of course, the
user can also override this feature and enter his own profile. In
this invention, the whole exercise profile including the warm-up
and cool down and any other interval portions are continuously
adjusted depending upon the measurement of the body response.
[0087] The receiver-controller unit on the exercise equipment is
operated in response to the measured biomedical function, such as
heart rate. As different parameters of the exercise equipment may
employ different muscle groups, the composition of the parameter
selection will depend on the exercise history of the target person.
For example, both arms and legs may be subject to different
exercises, each of which will affect heart rate.
[0088] For each exercise run, key characteristics of this run will
be stored in memory and used to refine the exercise profile of the
same person. Since this requires a technique to distinguish between
different persons using the exercise equipment, identifiers are
used as are used with the digitally encoded signal (i.e., the
identification portion).
[0089] A microprocessor in the exercise equipment will take into
account the present and previous heart rates of the person and make
these rates subject to a weight function in order to give the most
consideration to most recent heart rate, but not to disregard the
previous heart rates. For instance, the same present heart rate
must result in different actions if it is a sudden increase over
the previous heart rates or if it is the same as the previous heart
rate or even a decline in heart rate. After the exercise run, the
key characteristics of the run are extracted and stored in a memory
of the equipment to be available for future exercise activity of
the same person.
[0090] FIG. 8 shows the various components of the
receiver-controller unit. This unit can include the various
components shown on FIG. 5, where FIG. 8 shows the receiving means
46 for receiving the digitally encoded signal 16 from the
transmitting unit 12. Although it is not shown in FIG. 8, the
receiver/controller unit would include the transmitter 54 (FIG. 5)
used to change frequency if there is excess interference. The
functions of the other components (signal evaluator 48, memory 50,
display 52, input terminal 60, and microprocessor 62 of FIG. 5) are
provided by the components shown in FIG. 8.
[0091] Microprocessor 72 is a major component of the
receiver-controller and provides the logic, signal recognition and
identification, and instructions to the exercise parameter control
unit 74 for controlling the exercise intensity in accordance with a
desired exercise profile based on the target person, the type of
exercise to be undertaken, and the time period for the
exercise.
[0092] A magnetic strip reader 76 is used as an identification
means in order to identify the target person. Other forms of
identification could also be used, including a keyboard entry of a
coded identifier. The purpose of this component is to identify the
exercising person to the equipment so that the receiver in the
receiver-control unit will be synchronized with the transmitting
unit assigned to that user. Further, the use of an input device,
such as a magnetic strip card which can be read by reader 76,
enables a person to load his or her personal data into an internal
memory 78 so that a proper profile can be assigned by
microprocessor 72. It may be that the internal memory 78 already
has stored information relative to that user which can be directly
implemented by the microprocessor 72 in establishing the exercise
parameter control unit 74 for a particular resistance, pedal speed,
elevation, etc. depending upon the type of exercise equipment to be
used (exercise bike, stairclimber, etc.).
[0093] A console input 80, such as a keyboard mechanism or remote
control, is also electrically connected to the microprocessor 72.
The console input unit 80 allows the user to manually control the
exercise parameters he/she wishes to employ, thereby overriding the
profile control that the microprocessor 72 would normally adopt.
Console input 80 allows the user to deviate from programmed control
of the exercise equipment at any time depending on personal needs
and desires.
[0094] Console display 82 receives inputs from microprocessor 72
and displays the person's heart rate. Displays are also for
indicating exercise parameters such as pedal speed, resistance,
elevation, etc., as well as time, height, weight, age etc. In a
normal program, one third of the complete exercise time would be
used for warm-up and one third would be use for cool down. The
remaining one third would be used to provide an exercise regimen at
the desired heart rate, which could, for example, be at an aerobic
rate (about 70% of the desired maximum heart rate for that
individual.
[0095] Internal memory unit 78 contains stored programs for the
operation of the microprocessor, including those programs which
enable it to analyze the incoming digitally encoded signal in order
to read the identification part, error correction part, and heart
rate data portion, as described previously. Memory 78 also provides
storage of data of the user at that time, including the user's
previous workout data. The advantage of internal memory 78 is that
it enables the receiver-controller unit to recognize the past
performance of a person in order to better control fluctuations
that might be seen when a new exercise program starts. In this
manner, the microprocessor 72 will not call for radical changes of
the exercise parameter control 74 due to nonsignificant changes in
heart rate. For example, it may be that a person's heart rate jumps
to a high level very quickly in the warm-up phase of exercise, and
thereafter stabilizes. Having this data in internal memory 78
prevents the microprocessor from radically decreasing the
resistance, etc. of the exercise equipment which would not provide
the proper warm-up for this type of person. Of course, the user can
override any preprogrammed profile by using the console input
80.
[0096] An external memory unit 84, using for example a magnetic or
optical disk, provides a universal way for allowing any piece of
exercise equipment to be used by any individual. For example, a
person can take his/her disk to any gym and enter a desired profile
using the external memory unit 84 which interacts with the
microprocessor 72. When this is done, there will be an override of
any profile program from internal memory 78, or the user can elect
to use a default program stored in internal memory 78.
[0097] The following will now detail the use of exercise equipment
operated under control of the receiver-controller unit of FIG. 8,
where the biomedical response is illustratively a heart rate as
measured and wirelessly transmitted using the monitor of this
invention. In operation, the user first identifies himself at the
console of the exercise equipment prior to the exercise, e.g., by
entering a password or by using the magnetic strip reader 76. If
there already exists an exercise history file for this user, the
user is asked to enter some information about the exercise which
he/she plans to do. This information is entered using the console
input unit 80 and may include the planned exercise time and the
type of exercise, such as interval training or cardiovascular
workout. The user can also override the automatic profile
generation stored in internal memory 78 by entering his/her own
intensity or heart rate profile. This can be done, for example, by
inserting the user's disk in the external memory reader 84. If
there is no exercise history file for the user in internal memory
78 and no stored data is entered using unit 84, the user is asked
to enter various personal data such as age, weight, height, gender
etc. These data will then be stored in the exercise history file of
the user in internal memory 78, and will be used for his/her future
exercises. The user then receives various default profiles from
which to choose. These profiles will include a warm-up time, a
cool-down period and a period of time in which an aerobic heart
rate will be maintained.
[0098] The user then attaches the heart rate monitor to the
appropriate body part, usually the chest, and takes the desired
position on the exercise equipment without starting exercising. The
microprocessor 72 controls whether a heart rate is obtained and
whether the transmission is reliable, that is, whether the heart
rate is not fluctuating in a large range or is outside the expected
range. If anything unusual is registered, the user is asked to take
corrective action, such as moistening the electrodes of the
transmitter unit. The user can also override this feature if he/she
is convinced that everything is fine and if the user knows that
his/her heart rate is unusually high or low.
[0099] After this, the user is asked to start exercising. The first
short time frame of low intensity exercise is used for the
microprocessor 72 to establish a baseline for the user. This
baseline reflects the present state of the user and thus considers
momentary health, possible lack of sleep, diet etc. Based on this
baseline and on the selected exercise profile, microprocessor 72
makes a preliminary assignment of exercise parameters to time
points during the exercise run and the expected heart rate.
[0100] After these preliminaries, the user starts his/her exercise.
The heart rate is continuously monitored and transmitted to the
receiver 46 in the exercise equipment. Receiver 46 transfers the
data to the microprocessor 72 where the integrity of the data is
checked. If the data passes this integrity check, meaning that no
error has been detected, the measured heart rate is used to adjust
the exercise intensity level based on the deviation of the measured
heart rate from the projected heart rate. If the exercise equipment
has several parameters to be set, for example pedal rpm and
resistance in an exercise bike, the user receives a proposed value
for a parameter that he/she can control. For example, the user can
set the pedal rpm at 80 rpm while the other parameter (resistance)
is adjusted by the receiver-controller in accordance with the
continuously monitored heart rate. If it can be detected that the
user cannot maintain the suggested parameter, the proposed
parameter is modified. For example, the proposed pedal rpm value
can be reduced to 70. If microcomputer 72 detects a sequence of
errors in the received data, it notifies the user via the console
display 82 that it cannot any longer control the run based on the
measured heart rate. Microprocessor 72 then gives the user the
choice to continue the exercise run without this control or to
gradually stop the exercise. This operation runs under control of
instructions received from internal memory 78. If the heart monitor
senses recurrent errors beyond that which can be corrected by the
error detection and correction means, a frequency change is used to
determine another frequency in which correct wireless transmission
of the correct heart rate will be obtained.
[0101] After the exercise run, microprocessor 72 will extract the
key characteristics of the exercise, such as maximum heart rate
after a specified exercise time, the relevant intensity level,
warm-up and cool-down times, and baseline values at the beginning
and at the end of the exercise run. These key characteristics will
be stored in internal memory in the exercise history file for the
specific user. They can also be written into an external memory
disk placed in the receiver-controller external memory unit 84.
[0102] In contrast with existing equipment, the apparatus shown in
FIGS. 7 and 8 uses a microprocessor and associated memories to
store background information indicative of a particular person, and
uses identification means to tailor an exercise run to a user's
specific profile. Further, this equipment is based on an
instantaneous heart rate measurement at all times, not just on a
single set heart rate or on preprogrammed times for setting various
exercise levels. Because the monitor of this invention provides
error detection and correction, and because it has the capability
of changing frequency in order to eliminate interference effects,
it can be used on all types of exercise equipment and in the
presence of many users in the same exercise room. That is, the
proximity of many users wearing heart monitors and closely spaced
motor-driven exercise equipment will not lead to errors. This is
particularly important where the exercise run is being controlled
throughout its time duration in accordance with a continuously
monitored heart rate. Thus, the use of the monitor of this
invention to provide continuous control exercise equipment offers
several unique features and advantages.
[0103] While this invention has been described with respect to
particular embodiments thereof it will be apparent to those of
skill in the art that variations may be made without departing from
the spirit and scope of the present invention, which is to be
measured only by the appended claims. Body responses other than
heart rate, such as temperature, blood pressure etc. can also be
used to automatically control exercise using this monitor.
* * * * *