U.S. patent application number 15/263357 was filed with the patent office on 2017-01-12 for position and behavioral tracking system and uses thereof.
The applicant listed for this patent is CASCUBE Ltd.. Invention is credited to Aijun CAO, Chi Shing CHAN.
Application Number | 20170010343 15/263357 |
Document ID | / |
Family ID | 50237717 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170010343 |
Kind Code |
A1 |
CHAN; Chi Shing ; et
al. |
January 12, 2017 |
POSITION AND BEHAVIORAL TRACKING SYSTEM AND USES THEREOF
Abstract
This invention provides a system and methods for tracking the
positions and behaviors of moving objects such as animals. In one
embodiment, the system comprises one or more tracking unit, one or
more base nodes, one or more remote data hubs, and one or more
remote processor with display. Each tracking unit (e.g. attached or
inserted into the tracked animals) could transmit acoustic signal
with a unique signature. The base nodes, after time stamping the
received signals, relate the signals to the remote processors where
the signals will be processed and the 3-dimensional spatial
coordinates of the tracking units, and hence the animals, can be
identified. Further processing of the positional information would
reflect the activities and behaviors of each animal. Additional
sensors included in the tracking unit provide further information
about the states of the animals such as temperature, heart rate or
blood pressure etc.
Inventors: |
CHAN; Chi Shing; (Katy,
TX) ; CAO; Aijun; (Sollentuna, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CASCUBE Ltd. |
Hong Kong |
|
CN |
|
|
Family ID: |
50237717 |
Appl. No.: |
15/263357 |
Filed: |
September 12, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14426383 |
Mar 5, 2015 |
9470776 |
|
|
PCT/IB2013/058297 |
Sep 5, 2013 |
|
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15263357 |
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61780766 |
Mar 13, 2013 |
|
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61697362 |
Sep 6, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/0205 20130101;
G01S 5/22 20130101; A61B 5/0028 20130101; A61B 2503/42 20130101;
A61B 5/01 20130101; A61B 5/0031 20130101; A61B 5/1113 20130101;
A61B 5/021 20130101; A61B 2503/40 20130101; G01S 5/30 20130101;
A61B 5/742 20130101; A61B 5/1123 20130101 |
International
Class: |
G01S 5/22 20060101
G01S005/22; A61B 5/0205 20060101 A61B005/0205; A61B 5/00 20060101
A61B005/00; A61B 5/11 20060101 A61B005/11; A61B 5/01 20060101
A61B005/01; A61B 5/021 20060101 A61B005/021 |
Claims
1. A system for tracking the positions and behaviors of one or more
experimental subjects, said system comprises: one or more tracking
units, wherein said tracking units are attached or connected to the
experimental subjects and are capable of emitting acoustic
ultrasonic signals that contain unique signature for each
experimental subjects; a plurality of base nodes, wherein said base
nodes receive acoustic signals sent from the tracking units,
process said signals and send the processed signals to a remote
data hub; one or more remote data hubs, wherein said data hubs
collect all the signals from the base nodes and relate the signals
to one or more remote processors; and one or more remote
processors, wherein the processors are capable of processing data
from the tracking units to generate three-dimensional positional
information for the experimental subjects in real time.
2. The system of claim 1, wherein the tracking units emit acoustic
ultrasonic signals at MHz range.
3. The system of claim 1, wherein the tracking units further
comprise sensors for monitoring bodily functions of the
experimental subjects.
4. The system of claim 3, wherein the bodily functions are selected
from the group consisting of body temperature, heart rate, and
blood pressure.
5. The system of claim 1, wherein the remote data hubs are physical
modules or functional modules of the remote processors.
6. The system of claim 1, wherein the remote processors further
process the three-dimensional positional information to generate
behavioral information for individual experimental subject.
7. The system of claim 6, wherein the behavioral information
comprises parameters selected from the group consisting of walking
speed, running speed, rearing frequency, percentage time of
activity vs. inactivity, and turning direction and frequency.
8. The system of claim 1, wherein the remote processors can
translate the positional information to reflect interactive
activities among multiple experimental subjects.
9. The system of claim 1, wherein the remote processors further
comprise a display so that information generated by the remote
processors can be visualized in real time.
10. The system of claim 1, wherein the remote processors are
further capable of sending feedback commands back to the tracking
units to control the operation of the tracking units.
11. The system of claim 1, wherein the experimental subjects are
plants, mice, rats, hamsters, grey mouse lemur, cats, dogs,
macaques, or non-human primates.
12. A method for tracking the positions and behaviors of one or
more experimental subjects in real time, said method comprises the
steps of: attaching or injecting one or more tracking units of the
system of claim 1 to the experimental subjects; transmitting
acoustic signals from the tracking units to the base nodes, and
vice versa, of the system of claim 1; sending signals from the base
nodes to the remote processor, and vice versa, of the system of
claim 1, wherein the remote processor processes the signals to
generate three-dimensional positional and behavioral information
for the experimental subjects in real time.
13. The method of claim 12, wherein the experimental subjects are
plants, mice, rats, hamsters, grey mouse lemur, cats, dogs,
macaques, or non-human primates.
14. In method of claim 12, wherein the base nodes are located on
the walls, on the cages, or fixtures surrounding the experimental
subjects.
15. The method of claim 12, wherein the behavioral information
comprises parameters selected from the group consisting of walking
speed, running speed, rearing frequency, percentage time of
activity vs. inactivity, and turning direction and frequency.
16. The method of claim 12, wherein the behavioral information
reflects interactive activities among multiple experimental
subjects.
Description
[0001] This application is the Continuation application of U.S.
Ser. No. 14/426,383, filed Mar. 5, 2015, which is the National
Stage of International Application No. PCT/IB2013/058297, filed
Sep. 5, 2013, which claims benefit of U.S. Ser. No. 61/780,766,
filed Mar. 13, 2013 and U.S. Ser. No. 61/697,362, filed Sep. 6,
2012. The contents of the preceding applications are hereby
incorporated in their entireties by reference into this
application. Throughout this application, various publications are
referenced. Disclosures of these publications in their entireties
are hereby incorporated by reference into this application in order
to more fully describe the state of the art to which this invention
pertains.
FIELD OF THE INVENTION
[0002] The present invention relates to a local positioning system
and uses thereof for precise tracking the position and behavioral
activities of a large number of moving objects simultaneously
and/or individually.
BACKGROUND OF THE INVENTION
[0003] The ability to track the precise location and behaviors of
experimental animals is highly desirable such as in laboratory
animal testing, which is an indispensable part of many areas of
biological research and drug discovery. The precision required in
the tracking of small animals is often in the centimeter to
sub-centimeter scale in order to detect their subtle movements.
GPS-based tracking systems, which have been used for larger animals
such as dogs and horses, are therefore inadequate to provide the
spatial resolution required.
[0004] Traditionally, motion tracking of small animals in
laboratories is done by beam breaking of infrared light. However,
this method suffers from poor spatial resolution, inability to
track more than one animal, and in many cases only two-dimensional
movement can be detected. Currently tracking of small laboratory
animal activities is based primarily on video capture or
pressure-sensing technology. Although providing an improved spatial
resolution, these methods still suffer many fundamental limitations
that greatly restrict their applications. Among those limitations
are: (1) inability to track a large number of animals (dozens to
hundreds) simultaneously; (2) no long-term tracking is practically
feasible without either enormous human labor and time or data
storage; (3) animals have to be transported to testing environments
where the tracking systems are located, thus subjecting the animals
to stress from the transfer and being in novel environments; (4)
setting up and executing the tests involves substantial human
interaction with the animals, thus adding stress or other unknown
factors to the animals; (5) for video tracking, proper tracking is
heavily dependent on the lighting conditions of the environment and
skin colors of the animals and thus requires frequent contrast
adjustments.
[0005] In addition to laboratory animals, precise localization and
monitoring of movements is much demanded in other subjects. For
example, in plant research, extremely high precision is often
required to track the minute movement or growth of different parts
within a period of time. Video tracking, though being the only
assistive method currently used, is of limited applications due to
some of the shortcomings listed above.
[0006] There are various principles previously published or
currently in use for localizing objects utilizing ultrasound as
signal carrier.
[0007] As described in U.S. Pat. No. 6,317,368, one ultrasound
system uses time delays between a transmitter and several receivers
to localize the transmitters and utilizes time division multiple
access method for sharing the same frequency channel. The drawbacks
of using such channel access method are (i) only one transmitter
can be tracked at one time slot, which is not suitable for tracking
a large number of objects, (ii) the whole system requires strict
synchronization, and (iii) interference may be created at a
frequency which is directly connected to the time slot length.
[0008] Another ultrasound system, such as that described in U.S.
Pat. No. 7,283,423, uses time of arrival from a transmitter to one
of the many receivers to localize the transmitters and utilizes the
method of frequency division multiple access for channel access.
The drawbacks of using such channel access method are that the
number of objects being tracked at one given time is limited by the
partitions of the frequency band and crosstalk may cause
interference among frequencies.
[0009] More importantly, the spatial resolution provided by the
aforementioned systems is limited by the nature of applied
techniques, therefore they are not applicable for more precise
localization (millimeter range), such as in tracking the movements
of laboratory mice or measuring the daily growth rate of plants
etc.
[0010] Another shortcoming of the aforementioned systems is that
the connection between the ultrasonic receivers and the control
center is wired for signal transmission. Such system design
requires elaborate hardware and infrastructure setup and is often
times not feasible to be carried out in well-established and
tightly controlled environments such as animal breeding rooms or
laboratories for animal testing.
[0011] The present invention uses wireless communication technology
as positioning and behavioral tracking system and is designed to
overcome the aforementioned limitations.
SUMMARY OF THE INVENTION
[0012] In one embodiment, the present invention provides a system
for tracking the positions and behaviors of moving objects such as
animals. Examples of animals that can be tracked by the present
system include, but are not limited to, laboratory mice, rats,
hamsters, grey mouse lemur, cats, dogs, macaques, and other
non-human primates. In one embodiment, the system comprises one or
more tracking units, one or more base nodes, one or more remote
data hubs, and one or more remote processors with display.
[0013] In one embodiment, the tracking unit is contained within a
capsule-like enclosure and includes an acoustic transceiver. In
another embodiment, the tracking unit may also comprise components
for monitoring bodily functions, for example, the tracking unit may
include sensors to measure body temperature, heart rate and blood
pressure etc. In one embodiment, the tracking unit can emit
acoustic ultrasonic signals that are outside the hearing range of
the animals, e.g. at 10 MHz range.
[0014] In one embodiment, each base node comprises an acoustic
receiver, an electromagnetic (EM) transceiver, a base band for
signal processing and synchronization as well as sensors with
automatic calibration for various environmental factors such as
temperature, humidity and air pressure etc.
[0015] Representative examples of remote processor with display
include, but are not limited to, workstations, laptop computers,
and mobile electronic devices such as mobile phones, tablets and
personal digital assistant (PDA) etc. The processors are capable of
extracting and processing data from the collected signals to
generate three-dimensional positional information of the tracking
units, hence the animals, at any time and in real time.
[0016] In another embodiment, the present invention also provides
methods of using the system disclosed herein to simultaneously
track and monitor the movement and behavior of a single to a large
number of animals, for example, up to 20 animals, or up to 50, 100,
500, 1000, 5000, or up to 10,000 subjects.
[0017] In one embodiment, the method comprises attaching or
injecting one or more tracking units to one or more animals,
transmitting acoustic signals from the tracking units to one or
more base nodes at various rates of data sampling or signal
transmission, and sending signals from the base nodes to the remote
processor, wherein the collected signals are processed to generate
three-dimensional positional information of the tracking units,
hence the animals, at any time and in real time.
[0018] In one embodiment, the tracking units are attached to the
animals via a collar worn by the animals. In another embodiment,
the tracking unit are injected into the animals, e.g. by
subcutaneous injection. The acoustic signals emitted from each
tracking unit carry a unique and specific "signature sequence" as
identifier for each animal. The system uses spread-spectrum
techniques to allow multiple tracking units to be multiplexed over
the same frequency channel at the same time and to minimize
potential interference among the transmitted signals.
[0019] In one embodiment, the base nodes are located on the walls,
on the cages, or other fixtures surrounding the animals. Signal
processing includes adding a timestamp to each received incoming
signal by the base nodes, sending the time-stamped signals in the
form of electromagnetic waves to the remote processors via a remote
data hub.
[0020] In one embodiment, the remote data hub is a physical module
that comprises an EM transceiver and a computer attachment
interface, e.g. an USB connector. In another embodiment, the remote
data hub is a functional module that is integrated with the remote
processor such that a computer attachment interface is not
necessary. Upon receiving the signals, the remote processors
determine the precise location of each tracking unit by measuring
their time of arrival (TOA), or time difference of arrival (TDOA)
at the base nodes and generate three-dimensional positional
information of the tracking units, hence the animals, in real time.
In one embodiment, the positional information is further processed
to generate activities and behavioral output for each individual
animal. Examples of behavioral output include, but are not limited
to, walking/running speed, rearing frequency, percentage time of
activity vs. inactivity, turning direction and frequency,
copulation duration and frequency, social interactions, aggressive
behaviors and maternal behaviors.
[0021] The system disclosed herein is capable of tracking movement
in the centimeter to sub-centimeter spatial resolution, e.g. in the
range of 10 cm to 5 cm, or 5 cm to 1 cm, or 1 cm to 0.5 cm, or 0.5
cm to 0.1 cm etc., in a controlled local area, for example, a
breeding room in an animal facility or a laboratory for animal
testing. Spatial resolution is achieved via the combination of
acoustics and spread spectrum. Spread spectrum techniques not only
allow a large number of objects to be tracked simultaneously,
individual arrival path can also be identified with a resolution of
higher than chip rate. Given that the current radio wave-based GPS
system can resolve a difference in location by as small as 1 m, the
aforementioned spatial resolution for the present system could
easily be achieved when acoustic wave/acoustic transceiver is used
instead of radio wave/radio transceiver while everything else
remains the same, with the achievable resolution up to almost 1/1
millionth of 1 m since the velocity of radio waves is almost 1
million times higher than that of acoustic waves.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 shows one embodiment of the tracking system as
described herein.
[0023] FIG. 2 shows one embodiment of the tracking unit as
described herein.
[0024] FIG. 3 shows one embodiment of introducing the miniature
tracking unit into the animal by subcutaneous injection into the
neck area.
[0025] FIG. 4 shows one embodiment of the base node as described
herein.
[0026] FIG. 5 shows one embodiment of the remote data hub as
described herein.
[0027] FIG. 6 shows one embodiment of signal processing as
described herein.
[0028] FIG. 7 illustrates the computation of the 3-dimensional
positional information by multilateration.
DETAILED DESCRIPTION OF THE INVENTION
[0029] In one embodiment, the present invention provides a tracking
system comprising one or more tracking units, one or more base
nodes, one or more remote data hubs and one or more remote
processors with display (e.g. workstations, laptop computers, and
mobile electronic devices such as mobile phones, tablets and PDA
etc.) (FIG. 1).
Tracking Units
[0030] In one embodiment, the tracking unit of the system comprises
an acoustic transceiver, a central processing unit (CPU), a
battery, an analog-to-digital converter (ADC) and a
digital-to-analog converter (DAC), and optional sensors. The
acoustic transceiver transmits and receives ultrasonic waves to and
from the base nodes. In one embodiment, the acoustic transceivers
are ultrasonic acoustic transceivers. In another embodiment, the
acoustic transceivers are piezoelectric transceivers or
magnetorestrictive transceivers. In yet another embodiment, the
acoustic transceivers comprise one or more film transducers. The
CPU controls all the transmission parameters (frequency, intensity,
duration etc.) and the timing of the transceiver according to the
requirements for a particular application. The battery supplies
power to all the components of the tracking unit. In one
embodiment, the battery can be supplemented with an energy
harvesting IC for extended power supply. Depending on the
requirements of an application, the optional sensors collect
additional physical and physiological information about the
animals. This information will then be processed by the CPU and
embedded in the transmitted ultrasonic waves. FIG. 2 shows one
embodiment of the tracking unit in which a thermo sensor, a
vibration sensor, and an energy harvesting IC-coupled battery are
included. In one embodiment, the battery in the tracking unit is
charged by wireless inductive charging. In another embodiment, the
battery is replaceable. In yet another embodiment, the tracking
unit is powered with an external power source. In one embodiment,
the battery in the tracking unit is lithium or zinc polymer-based
ultrathin and flexible type such that it can cover the inner
surface and provide sufficient power within the small tracking
unit.
[0031] The tracking unit emits acoustic ultrasonic signals at MHz
range, which is far beyond the animal's upper hearing limit and
therefore would not affect the animal's behavior. Since acoustic
waves travel at a much slower speed than electromagnetic waves
(.about.874,000 times slower), as acoustic waves travel within the
relatively small volume of space monitored by the present
invention, the time difference for the signal from a particular
tracking unit to reach each of the base nodes at two or more
distinct spatial locations would be sufficiently large to pinpoint
or detect a change in the spatial position of the source (i.e. the
tracking units). For example, in a typical indoor environment the
time difference for an acoustic signal emitted from a particular
tracking unit to reach each of the base nodes is in the millisecond
to microsecond range, which is far below the minimum accuracy level
of a common reference clock (e.g. 0.01 ppm at 10 MHz, in nanosecond
range) used in the base nodes and the remote processor. In this
way, the spatial resolution of the system can achieve millimeter
scale. This principal forms one of the key technologies of the
invention.
[0032] To distinguish all the individual signals, hence the
animals, each signal emitted from the transceiver of the tracking
unit is embedded in its carrying wave, e.g. by the on/off state or
the phase patterns of the waveform, a unique and subject-specific
signature sequence (e.g. Walsh Hadamard codes) as identifier that
is orthogonal to all other animals' signatures. In one embodiment,
the length of the sequence is dependent on the number of subjects
to be tracked. In another embodiment, each signature sequence is
orthogonal to any other signature sequence, e.g., the inner product
of any pair of signature sequences is zero. In this way the base
nodes can distinguish each and every animal in a small or large
group. In addition, the orthogonal signatures also serve as the key
to filter out interference of one signal from all the others. The
design of the signature sequence forms one of the key technologies
of the invention.
[0033] For small animals such as laboratory mice, rats, hamsters,
grey mouse lemur or other small non-human primates, one of ordinary
skill in the art would readily introduce a miniature tracking unit
with no more than 10% of the animal's body weight into the animal,
for example, by surgery or subcutaneous injection into the animal's
neck area using a syringe as shown in FIG. 3. The size of the
tracking unit can vary in accordance to the size of the animals.
One of ordinary skill in the art would readily construct a
capsule-like enclosure for the tracking unit. To aid in keeping the
enclosure easily injectable and being non-obstructive to the
animal's normal behaviors, e.g. at 1 cm (length) and 0.3 cm
(diameter) for laboratory mice, application-specific integrated
circuit (ASIC) can be used to further miniaturize the tracking unit
when necessary. The material used for the enclosure will be chosen
such that it does not interfere with signal transmission and is
biologically inert, e.g. polypropylene. Subcutaneous placement of
the tracking unit has the advantages of preventing the tracking
unit from being dislodged by the animal. Subcutaneous placement
would also allow accurate measurements of the animals'
physiological status. In one embodiment, the tracking unit may
comprise components for the monitoring of bodily functions; for
example, the tracking unit may include sensors to measure body
temperature, heart rate and blood pressure etc.
[0034] When larger animals such as cats, dogs, macaques or other
larger non-human primates are being monitored, the tracking unit
can be attached to or worn by the animals externally, e.g. enclosed
in a collar, for positional and behavioral tracking.
Base Node
[0035] In one embodiment, the base node of the tracking system
comprises an acoustic transceiver, an EM transceiver, a base band
processor, an AC/DC rectifier, ADCs and DACs, a thermo sensor and a
humidity sensor (FIG. 4). In one aspect of the invention, the base
nodes are located on the walls or other fixtures surrounding the
animals. The number of base nodes can vary depending on the spatial
resolution required for the application (more base nodes provide
higher resolution) and the capability supported by the remote data
hub on the remote processors. Three or more base nodes will be
needed for monitoring of events in 3-dimensional space. In one
embodiment, the acoustic transceiver is an ultrasonic acoustic
transceiver. In another embodiment, the acoustic transceiver is a
piezoelectric transducer or a magnetorestrictive transducer. In yet
another embodiment, the acoustic transceiver comprises one or more
film transducer.
[0036] The acoustic transceiver of the base node receives the
acoustic signals send from the tracking units and, if necessary,
e.g. when relaying instructions from the remote processor, sends
acoustic signals back to the tracking units. The EM transceiver
sends signals, e.g. radio or infrared, to and, if necessary,
receives signals back from the remote processor via the remote data
hub. The base band processor carries the timing mechanism of the
base node. The AC/DC rectifier converts alternating current
entering the base node into direct current and supplies power to
all the components of the base node. Since the speed of sound (c)
in air is proportional to the square root of temperature (T),
c= {square root over (.gamma.RT/M)}
(where .gamma. is the adiabatic index of air; R is the universal
gas constant; M is the molar mass of air) and both .gamma. and M
are dependent on humidity, the base node includes thermo and
humidity sensors for the precise calculation of the speed of the
acoustic waves transmitted from the tracking units.
[0037] Since it is crucial that all the clocks in the base nodes
and the tracking units are precisely synchronized, an
initialization process for clock synchronization must be carried
out and their internal clocks are kept synchronized relative to
each other. In one embodiment, one of the base nodes is set up as
the master, while the rest as slaves. The master node controls how
the slave nodes obtain the synchronization by issuing time
adjustment commands to the slave nodes. In one embodiment, the
master base node is configured such that it periodically transmits
a synchronization signature, which is specially designed whose
autocorrelation function is close to a sharp delta function, to all
the slave base nodes and the tracking units. During the
synchronization process the master node starts up, creates the
synchronization channel, and enters into the "configuration mode"
in which the master base node finds and detects all the slave nodes
around it, then transmits the synchronization signals. Upon
detecting the arrival of the synchronization signal, the slave base
nodes read the synchronization signal and send back an
acknowledgement signal to the master. The master base node might
then send a timing adjustment command to the slave nodes if needed.
This timing adjustment would happen multiple rounds when necessary
until all the slave nodes are synchronized to the master node with
an accuracy that equals or exceeds the minimum that is required for
a given spatial resolution. To prevent the clocks from drifting
with time after initialization, this synchronization process is run
in each base node periodically to check, correct and maintain the
synchronization in all the clocks. In one embodiment, the
synchronization process can be performed more frequently in the
slave base nodes while synchronization in the tracking units can be
performed much less frequently in order to save power.
[0038] In one embodiment, the base band processor carries the
entire signal processing functions of the base node, which include,
but not limited to: analog-to-digital and digital-to-analog
conversions, signal synchronization, detection, estimation,
equalization, coding and decoding. When a signal from the tracking
unit is detected, the base band processor records the position in
the time domain corresponding to the precise moment of arrival of
that signal. The base band processor then adds this temporal
information as a stamp to the subject-specific signature before
passing it to the EM transceiver and linking them to the remote
processors via the remote data hub in the form of electromagnetic
waves using, for example. WiFi. Bluetooth, infra-red or amateur
radio frequency band etc.
Remote Data Hub
[0039] The key function of the remote data hub is to collect all of
the signals with time-stamped signatures from the base nodes and
relate these signals to the remote processor. In one embodiment,
the remote data hub is a physical, standalone module that comprises
an EM transceiver, a CPU, an ADC and a DAC, and a power supply. The
power supply can be a battery, or in one embodiment, the power can
be obtained from the remote processor through a connector such as
USB (FIG. 5), FireWire or Thunderbolt connection. In another
embodiment, the remote data hub is a functional module that is
integrated with the remote processor such that a computer
attachment interface is not necessary. The EM transceiver receives
electromagnetic signals, e.g. WiFi, Bluetooth, Infrared, or amateur
radio signals etc., from the base nodes and, if necessary, sends
signals back to the base nodes. It is notable that although signal
transfer through wireless connection between the base nodes and the
remote data hub is the method of choice due to the ease and
flexibility of setting up the system, a wired connection presents
an obvious alternative option in circumstances where wireless
connection is not feasible or allowed. In one embodiment, the
remote data hub is connected to the Internet and transmits data to
the remote processor via the Internet. In another embodiment, the
remote processor can carry out its function anywhere with internet
connection. In yet another embodiment, the remote data hub can
store all the data and the remote processor can download the data
when there is Internet connection.
Remote Processor
[0040] In one embodiment, the remote processor of the tracking
system integrates and processes all the signals from every tracking
unit into 3-dimensional position information and translates them
into behaviors as a function of time. In one embodiment, the remote
processors can be any part of a computer or processing unit that
perform calculations and/or manipulations of data. For example, the
remote processors are the CPU of computing devices such as
workstations, laptop computers or hand-held mobile devices (e.g.
tablets. PDAs, mobile phones etc.)
[0041] One of the key functions of the remote processor is to
determine the arrival of a particular acoustic signal from a
tracking unit to a particular base node by performing complex joint
signal processing to each detected signal with time-stamped
signature. In one embodiment, a relative threshold will first be
set based on noise power calculation. Paths above the threshold
will be regarded as the effective paths, and the earliest arrival
path (line of sight) for each signature is taken as the path of
interest (see FIG. 6). In one period (positioning cycle) each
tracking unit transmits one positioning burst with a unique
positioning signature. Each base node receives the positioning
bursts and performs multipath searching. This can be done either
for each positioning signature one by one, or for all of the
positioning signatures at the same time in parallel, for example,
via matrix computation. By comparing the time difference a signal
from a particular tracking unit required to reach each of the base
nodes, hence the difference in distance between the tracking unit
to the different base nodes, the remote processor can compute by
multilateration the 3-dimensional positional information of the
tracking units, hence the animals, at any time and in real time. As
an example, in the case where 3 base nodes are used, the position
of a given tracking unit can be obtained as follows:
[0042] Suppose A (a,0,0). B (0, b,0) and C (0,0,0) represent the
positions of the 3 base nodes, and M (x,y,z) represents the
position of the tracking unit in a given space, as illustrated in
FIG. 7,
the distance between (M and A), (M and B), and (M and C) are L1, L2
and L3, respectively, where
L1.sup.2=(a-x).sup.2+y.sup.2+z.sup.2 (Eq. 1.1)
L2.sup.2=x.sup.2+(b-y).sup.2+Z.sup.2 (Eq. 1.2)
L3.sup.2=x.sup.2+y.sup.2+z.sup.2 (Eq. 1.3)
Solving for x, y and z:
[0043] x = L 3 2 - L 1 2 + a 2 2 a ( Eq . 1.4 ) y = L 3 2 - L 2 2 +
b 2 2 b ( Eq . 1.5 ) z = L 3 2 - x 2 - y 2 ( Eq . 1.6 )
##EQU00001##
Since the distance between the tracking unit (M) and a given base
node (L) can be calculated, i.e.,
L1=vt.sub.1 (Eq. 1.7)
L2=vt.sub.2 (Eq. 1.8)
L3=vt.sub.3 (Eq. 1.9)
where v is the speed of sound in air at room temperature, and
t.sub.1, t.sub.2, and t.sub.3 are the times the acoustic signal
takes to travel from the tracking unit to base node A, B and C,
respectively, the value of x, y, and z (i.e. the position of the
tracking unit M) can be computed when t.sub.1, t.sub.2, and t.sub.3
are measured (and hence the value L1. L2 and L3) using Eq.
1.4-1.6.
[0044] In one embodiment of the invention, the remote processor can
send feedback commands, via the remote data hub and base nodes,
back to the tracking units to control their properties. For
example, a remote processor can send back a new set of parameters
to the tracking units to change their rate of data sampling or
signal transmission dependent on the time of day. In another
embodiment, an additional component, e.g. an electrical pulse
generator connected to the muscles of the animals, is integrated as
part of and controlled by the CPU of the tracking unit such that a
remote processor can instruct this component to alter the
activities of the animals, e.g. by stimulating or attenuating
muscle contractions.
[0045] In one embodiment of the invention, the remote processor can
further translate the positional information over a period of time
into activities and behavioral output for each individual subject,
e.g. walking/running speed, rearing frequency, percentage time of
activity vs. inactivity, turning direction and frequency, circling
duration and frequency, jumping frequency, hanging duration and
frequency, degree of thigmotaxis etc., by determining the change of
positions, in three dimensions, as a function of time. For example,
by calculating the summation of all the distance traveled in the
horizontal axis per unit time over a defined period, the average
speed (S) of a subject within this time period can be found,
i.e.,
S = .SIGMA. t = 1 n ( x t + 1 - x t ) 2 + ( y t + 1 - y t ) 2 t n
##EQU00002##
where x and y are horizontal coordinates of the subject at a given
time (t.sub.n).
[0046] In another embodiment, the rearing-up frequency over a
defined period can be counted as the number of times in which the
positional change of the subject in the z-axis has exceeded a
predefined value, e.g. for mice to be 2/3 of the subject's body
length (i.e. approximately the distance between the floor and the
neck where the tracking unit is inserted).
[0047] In another embodiment, the percentage time of activity (%)
over a defined period (T) can be calculated as follows,
% = T active T 100 ##EQU00003##
where T.sub.active is the total time in which there is a change of
position of the subject in either x, y, or z axis.
[0048] In yet another embodiment of the invention, the remote
processor can translate the positional information into interactive
activities and behavioral output of multiple animals within a
group, e.g. copulation duration and frequency, social interactions,
aggressive behaviors and maternal behaviors etc., by analyzing and
comparing the relative positions of a selected pair, or multiple,
subjects at the corresponding unit time domain, for example, every
1 second. After validating the behavioral output with conventional
behavioral tracking methods, e.g. video tracking, the tracking
system of the present invention can provide a library of prescribed
behaviors for each animal species to allow automatic analysis of
the positional information into activities and behavioral
output.
[0049] In one embodiment of the invention, the information
generated by the remote processors can be visualized in real time
on the displays associated with the processors. In one embodiment,
the output positional and behavioral data can be presented in the
forms of texts, tables, charts and graphs etc. The output data can
also be exported to other statistics or predictive analytic
software. e.g. EXCEL, STATISTICA or SPSS etc., for further
customized analysis by the users.
[0050] In yet another embodiment of the invention, the remote
processor and/or its display, especially when presents in a mobile
form, e.g. a laptop or a tablet, should provide a convenient means
to pinpoint the identity of any one animal in situ within a group
through real-time visualization of the animals' activities. For
example, a researcher can select an animal that he wants by using a
tablet, located in front of the animal cage for example, that
displays real time activities and the identities of all the animals
in the cage.
[0051] The lifespan of the battery, e.g. lithium-ion or
lithium-air, in the tracking unit is designed to last for months so
that long-term animal studies can be supported by the tracking
system. In one embodiment of the invention, optimization of power
consumption of the tracking unit can be achieved by regulating the
rate of signal transmission to minimum without significant
reduction in the accuracy of tracking and behavioral prediction
through validating the behavioral output with conventional tracking
systems. In another embodiment, a two-axis motion sensor can be
included in the tracking unit such that the tracking unit is set to
remain in sleep mode without sending out signals and hence no
energy is consumed when no motion is detected from the tracking
unit. Mice, for example, roughly spend on average only a quarter of
the total time in a day in motion, while they are either sleeping
or awake but immobile during the rest of the time. Thus, the
battery life of the tracking unit can be extended 3-4 folds by not
transmitting signals while the animals are in the immobile state.
Notably, an even larger proportion of energy can be saved this way
in less active animals than mouse, e.g. rat. In yet another
embodiment, the battery life of the tracking unit can be prolonged
by linking the battery to an energy harvesting integrated circuits
e.g. from kinetic, thermal or piezo sources, such that it can
provide sufficient power to the battery throughout the course of
the animal study. In one embodiment, the battery in the tracking
unit is charged by wireless inductive charging. In another
embodiment, the battery is replaceable. In yet another embodiment,
the tracking unit is powered with an external power source. In one
embodiment, the battery in the tracking unit is lithium or zinc
polymer-based ultrathin and flexible type such that it can cover
the inner surface and provide sufficient power within the small
tracking unit.
[0052] In one embodiment of the invention, multiple tracking units
can be applied to a single animal to track different parts of the
animal simultaneously. For example, four tracking units can be
inserted into the four legs of the animal so that the motion of
each leg can be individually monitored. Such setup is highly useful
in monitoring animals with motor impairment, e.g. animal models for
Parkinson's disease, spinal cord injury, stroke etc., where the
pattern of motor deficit is important in defining the
pathophysiology and the corresponding therapeutic intervention.
[0053] In another embodiment of the invention, the tracking system
can be used to measure the movements of plants, e.g. elongation,
bending or turning of a growing stem tip or other biogenic
movements involving various parts of the plant in response to
different kinds of stimuli. In one embodiment, lightweight tracking
units are placed at the growing tips of the plants so that
movements and motion patterns of the growing tips are monitored for
an extended period of time. In another embodiment, tracking units
are placed on selected leaves such that the movements of the leaves
in response to various stimuli, e.g. light, gravity, chemicals, and
heat etc., can be monitored. In these embodiments, it is important
to ascertain that, by limiting the weight and the size, the
tracking units do not affect the native movements of the parts they
are monitoring per se.
[0054] In another embodiment, an additional component, e.g. a
chemical chamber with a release valve connected and controlled by
the CPU, is included in the tracking unit such that a remote
processor can instruct this component to alter the
micro-environment of the plant tissues, e.g. by releasing the
chemicals such as ethylene or nitric oxide from the chamber into
its vicinity.
[0055] In one embodiment, the present invention provides a system
for tracking the positions and behaviors of one or more
experimental subjects, said system comprises: one or more tracking
units, wherein said tracking units are attached or connected to the
experimental subjects and are capable of emitting acoustic
ultrasonic signals that contain unique signature for each
experimental subjects: a plurality of base nodes, wherein said base
nodes receive acoustic signals sent from the tracking units,
process said signals and send the processed signals to a remote
data hub; one or more remote data hubs, wherein said data hubs
collect all the signals from the base nodes and relate the signals
to one or more remote processors; and one or more remote
processors, wherein the processors are capable of processing data
from the tracking units to generate three-dimensional positional
information for the experimental subjects in real time. Examples of
the experimental subjects include, but are not limited to, plants,
mice, rats, hamsters, grey mouse lemur, cats, dogs, macaques, or
non-human primates.
[0056] In one embodiment, the above tracking units are capable of
emitting acoustic ultrasonic signals at MHz range. In another
embodiment, the tracking units further comprise sensors for
monitoring bodily functions of the experimental subjects. Such
bodily functions include, but are not limited to, body temperature,
heart rate, and blood pressure.
[0057] In one embodiment, the above remote data hubs are physical,
standalone modules that are physically attached or wirelessly
connected to the remote processors. In another embodiment, the
remote data hubs are functional modules that are integrated with
remote processor. In one embodiment, the remote processors further
process the three-dimensional positional information to generate
behavioral information for individual experimental subject. Such
behavioral information includes, but is not limited to, walking
speed, running speed, rearing frequency, percentage time of
activity vs. inactivity, and turning direction and frequency. In
another embodiment, the remote processors can translate the
positional information to reflect interactive activities among
multiple experimental subjects.
[0058] In one embodiment, the above remote processors further
comprise a display so that information generated by the remote
processors can be visualized in real time. In another embodiment,
the remote processors are further capable of sending feedback
commands back to the tracking units to control the operation of the
tracking units.
[0059] This invention provides a platform for position tracking of
subjects within a location defined by the base nodes. The tracking
system of the present invention is amendable for various home uses.
In one embodiment, the tracking units can be attached to young
children and warning signals will be initiated when they become too
close to sources of danger, for example, an opened window, or a hot
stove. In another embodiment, the tracking units are attached to
some or all the valuable objects in a home or a store and warning
signals will be initiated when the objects are being moved from
their original positions as a means of security measure. In yet
another embodiment, small objects in a home could be tracked so
that they could be located easily. For example, the tracking units
are attached to key chains so that keys could be easily located. In
yet another embodiment, the tracking units are attached to the end
of long wires, e.g. plugs. USB connectors etc., so that they could
be easily located when needed.
[0060] The present invention is also adaptable for various medical
uses. In one embodiment, the three-dimensional positional
information obtained by the present tracking system can be analyzed
by the remote processor and warning signals will be initiated when
certain criteria is met. For example, the tracking unit can be
attached to the neck or body of an elderly person and warning
signal will be initiated when the tracking unit is found near or on
the floor for a prolonged period of time. In another embodiment,
the tracking unit is attached to one or a large number of subjects
for tracking movement habits throughout a day. In another
embodiment, the tracking units can be attached to areas of interest
on subjects, e.g. around joints, to monitor for any abnormalities
in movement pattern. In comparison to conventional assessments such
as gait analysis, data from all daily activities would be captured
rather than the standard patterns such as walking. In yet another
embodiment, the present invention can be used for tracing the
progress of correction of orthopedic deformity. e.g. scoliosis
treatment, or improvement in motor function, e.g. physical
therapies after spinal cord injury for one or a large number of
patients at the same time.
[0061] In one embodiment, the present invention can be used in
farms for early identification of sick animals. For example, the
tracking units of the present invention can be attached to groups
of domestic fowl to detect and isolate sick birds before
large-scale disease outbreak that can cause huge economic
losses.
[0062] In another embodiment, the present invention can be used in
monitoring of motion of equipment. In one embodiment, the present
invention is used in tracking abnormal movement of delicate
equipment, such as high-speed centrifuge, during their daily
function. In another embodiment, the present invention can be used
for predicting the fatigue of mechanical components subjected to
daily repeated vibration.
[0063] In summary, the present invention provides a system for
tracking the positions and behaviors of one or more experimental
subjects. Examples of experimental subjects include, but are not
limited to, plants, mice, rats, hamsters, grey mouse lemur, cats,
dogs, macaques, or non-human primates. In one embodiment, said
system comprises: one or more tracking units, wherein said tracking
units are attached or connected to the experimental subjects and
are capable of emitting acoustic ultrasonic signals that contain
unique signature for each experimental subjects; a plurality of
base nodes, wherein said base nodes receive acoustic signals sent
from the tracking units, process said signals and send the
processed signals to a remote data hub; one or more remote data
hubs, wherein said data hubs collect all the signals from the base
nodes and relate the signals to one or more remote processors; and
one or more remote processors, wherein the processors are capable
of processing data from the tracking units to generate
three-dimensional positional information for the experimental
subjects in real time.
[0064] In one embodiment, the tracking units of the above system
emit acoustic ultrasonic signals at MHz range. In another
embodiment, the tracking units further comprise sensors for
monitoring bodily functions of the experimental subjects. Such
bodily functions include, but are not limited to, body temperature,
heart rate, and blood pressure.
[0065] In one embodiment, the remote data hubs of the above system
are physical modules of the remote processors, e.g. the remote data
hubs are physically attached or wirelessly connected to the remote
processors. Alternatively, the remote data hubs are functional
modules of the remote processors, e.g. the remote data hubs are
integrated with the remote processors.
[0066] In one embodiment, the remote processors of the above system
further process the three-dimensional positional information to
generate behavioral information for individual experimental
subject. Examples of behavioral information include, but are not
limited to, parameters such as walking speed, running speed,
rearing frequency, percentage time of activity vs. inactivity, and
turning direction and frequency. In another embodiment, the remote
processors can translate the positional information to reflect
interactive activities among multiple experimental subjects. In
another embodiment, the remote processors further comprise a
display so that information generated by the remote processors can
be visualized in real time. In yet another embodiment, the remote
processors are further capable of sending feedback commands back to
the tracking units to control the operation of the tracking
units.
[0067] In another embodiment, the present invention provides a
method for tracking the positions and behaviors of one or more
experimental subjects in real time, said method comprises the steps
of: attaching or injecting one or more tracking units of the system
disclosed herein to the experimental subjects; transmitting
acoustic signals from the tracking units to the base nodes, and
vice versa; sending signals from the base nodes to the remote
processor, and vice versa, wherein the remote processor processes
the signals to generate three-dimensional positional and behavioral
information for the experimental subjects in real time. Examples of
the experimental subjects include, but are not limited to, plants,
mice, rats, hamsters, grey mouse lemur, cats, dogs, macaques, or
non-human primates.
[0068] In one embodiment, the above method comprises putting the
base nodes on the walls, on the cages, or other fixtures
surrounding the experimental subjects. In one embodiment, the above
method would generate behavioral information such as walking speed,
running speed, rearing frequency, percentage time of activity vs.
inactivity, or turning direction and frequency for individual
experimental subject. In another embodiment, the above method would
generate behavioral information that reflects interactive
activities among multiple experimental subjects.
[0069] It will be understood that the foregoing description is of
preferred exemplary embodiments of the invention, and that the
invention is not limited to the specific forms shown. Various
modifications may be made in the design and arrangement of the
elements described herein without departing from the scope of the
invention as described herein.
* * * * *