U.S. patent application number 17/373870 was filed with the patent office on 2021-12-23 for drive control system for powered wheelchair.
This patent application is currently assigned to Sunrise Medical (US) LLC. The applicant listed for this patent is Sunrise Medical (US) LLC. Invention is credited to Karl Jozef Chmielowiec, Andrew Joseph Parker.
Application Number | 20210393457 17/373870 |
Document ID | / |
Family ID | 1000005826015 |
Filed Date | 2021-12-23 |
United States Patent
Application |
20210393457 |
Kind Code |
A1 |
Parker; Andrew Joseph ; et
al. |
December 23, 2021 |
DRIVE CONTROL SYSTEM FOR POWERED WHEELCHAIR
Abstract
A powered wheelchair is operated by sensor-based control pads
that include force transducers to produce a variable output signal
that is proportional to a varying force applied. The control pad
provides an analog-type output that provides a variable speed
signal to a controller to operate the wheelchair at a variable
speed in both forward/reverse directions and in right or left
turning directions.
Inventors: |
Parker; Andrew Joseph;
(Lafayette, CO) ; Chmielowiec; Karl Jozef;
(Laredo, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sunrise Medical (US) LLC |
Fresno |
CA |
US |
|
|
Assignee: |
Sunrise Medical (US) LLC
Fresno
CA
|
Family ID: |
1000005826015 |
Appl. No.: |
17/373870 |
Filed: |
July 13, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15514720 |
Mar 27, 2017 |
11096844 |
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PCT/US15/52470 |
Sep 25, 2015 |
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17373870 |
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62056246 |
Sep 26, 2014 |
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62055100 |
Sep 25, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61G 2203/30 20130101;
A61G 5/121 20161101; A61G 2203/18 20130101; B60L 2250/16 20130101;
H03K 17/955 20130101; B60L 2250/22 20130101; A61G 2203/14 20130101;
A61G 5/042 20130101; B60L 2200/34 20130101; A61G 5/045 20130101;
A61G 5/1051 20161101; A61G 5/125 20161101; A61G 5/122 20161101;
A61G 2203/32 20130101; A61G 5/043 20130101; B60L 2240/12 20130101;
A61G 5/04 20130101 |
International
Class: |
A61G 5/04 20060101
A61G005/04; A61G 5/10 20060101 A61G005/10; A61G 5/12 20060101
A61G005/12; H03K 17/955 20060101 H03K017/955 |
Claims
1. A powered wheelchair drive control system comprising: a head
array having a left pad, a right pad, and a center pad, each pad
having a force sensor proportionally responsive to an applied force
from a user's head against each respective pad and a capacitive
sensor responsive to the proximity of a user's head relative to
each respective pad, wherein the capacitive sensor provides an
active state signal in response to the presence of the user's head
and an off state signal in the absence of the user's head; and a
controller configured to operate at least one wheelchair drive
motor in response to signals generated by the force sensor and
capacitive sensor activated by a user's head, the controller
programmed with instructions to operate the at least one wheelchair
drive motor at a predetermined speed level in response to the
active state signal of the capacitive sensor in the center pad to
activate the predetermined speed level in one of a forward or a
reverse direction and to activate the force sensor in response to
the active state of the capacitive sensor to generate a
proportional speed signal in the one of the forward or reverse
directions, the controller further configured to control the
proportional speed signal of the force sensor through a transfer
function.
2. The powered wheelchair drive control system of claim 1 wherein
the controller is programmable to modify the transfer function to
adjust an acceleration level commanded by the applied force onto
the center pad force sensor.
3. The powered wheelchair drive control system of claim 1 wherein
the proportional speed signal of the center pad force sensor in the
one of the forward or reverse directions advances the forward or
reverse speed above the predetermined speed level.
4. The powered wheelchair drive control system of claim 1 wherein
the right pad capacitive sensor generates a right turn command
signal that activates a right turn predetermined turn rate and the
right pad force sensor increases a right turn speed.
5. The powered wheelchair drive control system of claim 1 wherein
the left pad capacitive sensor generates a left turn command signal
that activates a left turn predetermined turn rate and the left pad
force sensor increases a left turn speed.
6. The powered wheelchair drive control system of claim 1 wherein
the right pad capacitive sensor activates the right pad force
sensor and the controller is programmed to vary the right
wheelchair drive motor speed proportionally to the right pad force
sensor and the left pad capacitive sensor activates the left pad
force sensor and the controller is programmed to vary the left
wheelchair drive motor speed proportionally to the left pad force
sensor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional patent application of U.S.
patent application Ser. No. 15/514,720, filed Mar. 27, 2017. U.S.
patent application Ser. No. 15/514,720, filed Mar. 27, 2017, is the
U.S. National Stage patent application of PCT/US2015/52470, filed
Sep. 25, 2015. PCT/US2015/52470 claims the benefit of U.S.
Provisional Application No. 62/056,246, filed Sep. 26, 2014, and
U.S. Provisional Application No. 62/055,100, filed Sep. 25, 2014.
The disclosures of these applications are incorporated herein by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates in general to power wheelchairs and,
in particular, to control devices for operating a power
wheelchair.
[0003] Power wheelchairs provide improved mobility to persons
having limited ambulatory capacity. In order for the power
wheelchair to be effective in improving one's mobility
independence, a user must be able to operate and control the speed
and direction of the wheelchair. Depending on the level of
disability, dexterity, and cognitive capability, various input
devices are used to provide desired commands to the controller for
operation of the unit. The joystick input device is a general input
device having a control stalk that translate forward and backward
movement of the stalk to forward and backward movement of the chair
and sideway motion to turn commands. This input device is common
and relies on a higher level of dexterity and ability in order for
the user to properly control the wheelchair.
[0004] For users having severely limited or nonexistent use of
their hands, a sip-and-puff input device permits control of the
wheelchair by pressure or vacuum signals activated by a user's
mouth. The sip-and-puff input devices generally provide a step
function type of input that lacks the analog-type control
capability of the joystick. Thus, control of the wheelchair may be
less fluid and comfortable for the user. This is a particularly
problematic condition since these users have a very limited range
of motion and no physical reaction capability to jerky or abrupt
control movements. Thus, it would be desirable to provide an input
device that can provide an analog-type of input which varies in
intensity of control; i.e., increases or decreases in speed and/or
direction; similar to a joystick input device.
SUMMARY OF THE INVENTION
[0005] This invention relates to an analog-type input device for
control of a power wheelchair that provides a continuously
proportional input signal in response to contact and pressure
commands from areas of a user's head. Alternatively, other areas or
appendages, such as a user's neck and chin, the palm and backside
of a user's hand, and a user's arm may actuate the sensor
arrays.
[0006] This invention relates to a powered wheelchair drive control
system having a head array and a controller. The head array has at
least one pad having at least one of a force sensor proportionally
responsive to an applied force from a user's head against the at
least one pad and a capacitive sensor responsive to the proximity
of a user's head relative to the at least one pad. The controller
operates a wheelchair drive motor in response to signals generated
by the at least one force sensor and capacitive sensor activated by
a user's head.
[0007] In another aspect of the invention, the capacitive sensor of
the powered wheelchair drive control system provides an active
state signal in response to the presence of the user's head and an
off state signal in the absence of the user's head. The controller
is programmed to operate a wheelchair drive motor at a
predetermined speed level in response to the capacitive sensor
generating an active state signal.
[0008] In yet another aspect of the invention, the head array
includes left, right and center pads, where each pad includes a
force sensor in addition to capacitive sensors. The controller is
programmed to be responsive to the capacitive sensor in the center
pad to activate a predetermined speed range in one of a forward and
a reverse direction. The force sensor generates a proportional
speed signal in the one of the forward and reverse directions
within the predetermined speed range.
[0009] In yet another aspect of the invention, the controller
responds to the capacitive sensor in the left pad to activate a
left turn direction and a predetermined left rate of turn and
responds to the capacitive sensor in the right pad to activate a
right turn direction and predetermined right rate of turn. The
controller may be programmed with the predetermined forward speed
range and the predetermined left rate of turn and the predetermined
right rate of turn and further programmed to adjust a force
parameter associated with the force sensor. The controller may also
be programmed to capture an output value of at least one of the
left, right, and center force sensors in response to an initial
active state signal from the corresponding left, right, and center
capacitive sensor. In certain embodiments, the controller is
programmed to equate the output value of the force sensor to a
threshold value such that the controller responds to force output
signals from the one of the left, right and center force sensors
that is above the threshold value.
[0010] In another aspect of the invention, the controller responds
to the capacitive sensor in the left pad to activate a left turn
direction and a predetermined left rate of turn and responds to the
capacitive sensor in the right pad to activate a right turn
direction and predetermined right rate of turn. The controller may
also include an algorithm having a transfer function that limits
the proportional output of the force sensor to a range between one
of the predetermined forward speed range, the predetermined left
rate of turn and the predetermined right rate of turn and a
corresponding maximum forward speed, maximum left rate of turn, and
a maximum right rate of turn.
[0011] Various aspects of this invention will become apparent to
those skilled in the art from the following detailed description of
the preferred embodiment, when read in light of the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a power wheelchair in
accordance with the invention.
[0013] FIG. 2 is an exploded perspective view of an embodiment of a
head array assembly and controller of the power wheelchair of FIG.
1.
[0014] FIG. 3 is a perspective view of another embodiment of a head
array assembly having alternative adjustment capability.
[0015] FIG. 4 is an exploded view of the head array of FIG. 3.
[0016] FIG. 5 is a schematic illustration of the head array sensor
and controller components in accordance with the invention.
[0017] FIG. 6 is a schematic illustration drive control system with
a programming input device in accordance with the invention.
[0018] FIG. 7 is a flow chart illustrating initialization steps of
a software algorithm that controls the various embodiments of the
sensor cushion pad in accordance with the invention.
[0019] FIG. 8 is a flow chart illustrating a software algorithm for
a nullification (zeroing) sequence of a force sensor portion of the
sensing cushion pad in accordance with the invention
[0020] FIG. 9 is a graph of a transfer function of the algorithm
for controlling the various embodiments of the sensor cushion pad
in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Referring now to the drawings, there is illustrated in FIG.
1 a power driven wheelchair, shown generally at 10. The exemplary
power wheelchair is illustrated as a mid-wheel drive wheelchair,
however, it should be understood that the power driven wheelchair
10 may be of a front wheel drive configuration, rear wheel drive
configuration, or other suitable drive configuration. The
wheelchair 10 includes drive wheels 12 and stabilizing caster
wheels 14 as are well known in the art. The wheelchair 10 further
includes a seat 16 and backrest 18. The backrest 18 supports a head
array assembly, shown generally at 20, as shown in detail in FIG.
2. The head array assembly 20 includes a headrest assembly, shown
generally at 22, having a center pad 24, and left and right side
pads 26 and 28, respectively. The left and right side pads 26 and
28 are adjustably hinged from the sides of the center pad 24 and
configured to be accessible by the user's temple region. In one
embodiment, each of the left, center, and right pads of the
headrest assembly 22 include at least one sensor configured to
receive an input signal from a user and output an operating command
signal to a controller 30. In another embodiment, the left and
right pads include sensors that send operating command signals to
the controller 30.
[0022] As will be explained in detail, the sensor may be configured
as a force or pressure sensor providing an output that that is
proportional to and responsive to a force applied thereto. The
sensor may also be configured as a capacitive sensor providing an
output indicative of and responsive to the proximate position of a
user's body portion to the sensor. The sensor may also be two or
more sensors responsive to force and position. It should be
understood that the head array is an exemplary embodiment. Other
cushion structures and drive control input configurations can be
used. For example, in one embodiment, the seat back and armrests
can be configured to function in a similar manner to the center pad
and side pad operation described below in detail. Alternatively,
the senor arrangement may be used in conjunction with a
conventional joystick or in the form of an elbow drive device, knee
drive device, and the like. In the illustrated embodiment, the
headrest assembly 22 may be supported by an angle adjustable and
linearly extendable support post system 32. Alternatively, the
headrest assembly 22 may be supported by any suitable mounting
arrangement such as a rod extending from an upper surface of the
backrest 18.
[0023] Referring now to FIGS. 3 and 4, there is illustrated an
alternative embodiment of a head array assembly, shown generally at
34. The head array assembly 34, when considered as a control
device, is functionally similar to head array assembly 20 with
respect to function and sensor types. The head array assembly 20
may have sensors in the left and right pads 26 and 28. Thus, left
and right turns of the wheelchair 10 are may by applying greater
pressure to pad situated toward the desired turn direction. Forward
motion of the wheelchair 10 is obtained by pressure applied to both
left and right pads 26 and 28. The head array assembly 34 includes
sensors in all three pads and additional adjustment capability to
position side pads relative to the user's head. The head array 34
includes a center pad, shown generally at 36 and left and right
side pads 38 and 40, respectively. The center pad 36, and left and
right side pads 38 and 40 are mounted to a support frame 42 that
connects to a pivot mount 44. The pivot mount 44 is also shown as
part of the support post system 32. The left and right side pads 38
and 40 are pivotally supported by axially adjustable rods 46 that
couple to the support frame by rod swivel mounts 48.
[0024] As shown in FIG. 4, the center pad 36 includes rear shell 50
configured to contain and support a circuit board 52, at least one
force sensor 54, a cushion 56, at least one capacitive sensor 58,
and a covering material 60. The circuit board 52 provides
electrical and communication connectivity between the sensors 54
and 58 and the controller 30. The force sensor 54 is configured as
a variable resistance device that changes resistance and provides a
signal output that is in proportion, or in an inverse proportion,
to the magnitude of the force applied to the sensor 54. One example
of such a force sensor is an FSR400-series sensor produced by
Interlink Electronics, though other proportional force sensors may
be used if desired. As a user's head presses against the center pad
36, a force is transmitted to the force sensor 54. An output signal
indicative of the force and proportional to changes in the applied
force (increases or decreases in force magnitude) is generated and
sent to the controller 30. In one particular embodiment, as the
force is applied to the force sensor 54, the resistance of the
sensor decreases. This force sensor output signal provides a first
command signal, such as a speed signal, to the controller 30. In
one embodiment, the force sensor 54 is a pair of force sensors 54,
as shown in FIG. 5 though any suitable number of sensors may be
used.
[0025] The capacitive sensor 58 is positioned on one side of the
cushion 56 (proximate to a user's head) and the force sensor 54 is
positioned on the other side of the cushion 56. The capacitive
sensor 58 provides an output signal indicative of the proximity of
the user's head relative to the center cushion 36. In one
embodiment, the capacitive sensor 58 acts as an on/off switch
device. An example of such a capacitive sensor is capacitive sensor
model no. CBN10-F46-E2, produced by Pepperl and Fuchs. In one
embodiment of a control strategy used by the controller 30 and a
control algorithm, the capacitive sensor 58 provides a signal that
is used to calibrate or null output of the force sensor 54 based on
the user's head position in the head array 34, as is shown in the
programming flow charts of FIGS. 7 and 8. In another embodiment,
the capacitive sensor 58 functions to reproduce the familiar step
function operation of a sip-and-puff type of input device, as will
be explained below. The center pad 36 is covered with the covering
material 60 to provide user comfort, protect the user against skin
abrasions, and provide an aesthetic appearance.
[0026] The side pads 38 and 40 will be described in conjunction
with the right side pad 40, though the side pads are the same for
each side. The side pad 40 includes a mounting plate 62 that
supports a split collar 64 to adjustably mount the side pad 40 to
swivel balls at the ends of the rods 46. A circuit board 66 is
supported by the mounting plate 62 and may include a force sensor
68. The force sensor 68 is similar in function and operation to
force sensor 54 of the center pad 36. A cushion 70, such as a foam
pad, is placed against and covering the force sensor 68. A
capacitive sensor 72 is supported on the opposite side of the
cushion 70 and the assembly is covered with a covering material 74.
An electrical line 76 conveys the signals produced by the force
sensor 68 and the capacitive sensor 72 to the controller 30. The
side pad 40 functions in a similar manner to the center pad 36. As
a user presses his right temple, for example, against the pad the
force sensor 68 measures the force and send a signal to the
controller that is proportional to the force applied. Side pad 38
provides a second signal indicative of a turning command, such as a
left turn command. Side pad 40 provides a third signal indicative
of a turning command, such as a right turn command. Thus in one
embodiment, as the user presses his head against the right side pad
40 with increasing pressure, the controller 30 causes the
wheelchair to turn right with an increasing turning rate. This
analog-type output provides the same response in the wheelchair as
moving a joystick to increasing positions toward the right causes
an increased right-hand turning rate.
[0027] In an alternative embodiment, the center, left, and right
pads 36, 38, and 40 may operate based on the capacitive sensor 58
of the center pad 36 and capacitive sensors 72 in each of the left
and right side pads 38 and 40. In such an operating mode, the
capacitive sensors 58 and 72 act as on/off switches to provide
operations of turning and driving functions of the wheelchair at
preselected speeds, similar to the step inputs of sip-and-puff
devices. As shown in FIG. 6, a programming input device 78, such as
for example a pendant, computer, joystick, or dongle, may be used
to program the controller 30. The pendant 78 provides the ability
to input discrete speed range settings 80, for example five speed
ranges 1-5, that set operating speeds from slow (1) to full speed
capability (5) in discrete step functions of increasing speed
capability. Additionally, the pendant 78 may be able to adjust the
force detection or response sensitivity by a force parameter 82.
This adjustment may also be able to tune the force parameter in a
temporal condition to account for spasms that may be inadvertently
inputted by the user. When the capacitive sensor 58 detects a user,
the wheelchair operates in a forward direction at the preprogrammed
speed associated with the center pad 36. Similarly, when the user
moves his head to activate capacitive sensor 72, the wheelchair
will turn at the preprogrammed speed associated with either the
left pad 38 or right pad 40.
[0028] In yet another embodiment of the drive control system, the
operation of the force sensor is overlaid on the operation of the
capacitor sensor, as will be explained in conjunction with
operation of the center pad 36 for forward or reverse control. In
this control strategy, the capacitive sensor 58 detects the
presence or absence of the user's head and functions as an on/off
switch. The output of the capacitor sensor 58 invokes the
preprogrammed speed range (1 through 5) in the controller 30.
Detection of the user initiates forward (or backward) movement of
the wheelchair 10 at the programmed speed range. The user then
actuates the force sensor 54 by pressing into the center pad 36.
This force signal actuates the controller 30 to increase the speed
of the wheelchair 10 in accordance with the force level detected by
the force sensor 54. In one embodiment, the coupled operation using
capacitive and force sensor inputs varies the speed in conjunction
with a transfer function 200 represented in FIG. 9.
[0029] In this configuration, the drive control system can be
customized to accommodate users having either reasonable neck
muscle usage or asymmetric coordination or muscle control. For
example, where a user has good, symmetrical neck muscle
coordination and control, the system may be configured such that
the capacitive sensor 58 initiates the lowest speed range setting.
The force sensor 54 responds to the user's pressure input to ramps
the speed up or down according to the transfer function 200. The
side pads 38 and 40 may be programmed to respond in the same
manner. Thus, the system operation mimics the operational
characteristics of a joystick input device. In situations where the
user exhibits asymmetrical muscle control, for example having more
ability to move his head to the left rather than the right, the
system may be customized where the left side pad 38 is programmed
with more reliance on speed control from the force sensor 54 and
using a slow speed setting triggered by the capacitive sensor 58.
The right side pad 40, where the user has less capability to
actuate pressure based speed increases, may be programmed with a
higher speed range triggered by the capacitive sensor 58. The
wheelchair 10 would turn right more in line with the familiar
functions of a step input device yet still respond to whatever
pressure signal the user may be able to provide.
[0030] Referring now to FIG. 5, there is illustrated schematically
an embodiment of the head array assembly 34 where the center pad 36
supports two force sensors 54 and two capacitive sensors 58. These
sensors are supported, at least electrically, by the circuit board
52 and may have common outputs as shown or separate outputs such
that the controller 30 provides a blended or combined force signal
and a separate blended or combined capacitive proximity signal.
[0031] Referring now to FIGS. 7 and 8, the programming flow charts
illustrate the steps of initializing and adjusting the pad
sensitivities of the system during a start up operation (FIG. 7)
and system function during the "drive mode" operating environment
(FIG. 8). As shown in FIG. 7, the startup sequence 100 begins at
step 102 when the system is initially powered. Preset parameters
stored in the memory of the controller 30 are recalled and the
system is initialized with a zero speed and turn input. The drive
mode 104 is entered. The drive mode 104 is shown in detail in FIG.
8. The drive mode 104 may be exited by a "set" step 106. The set
step 106 is entered by the operating programming pendant 78 and
activating the set button 106a. Once activated, each of the pads
and related sensors may be programmed and adjusted for a user's
specific needs. The sensor programming order is merely illustrative
and may be conducted in any sequence desired. In a first pad
programming step 108, a left pad programming button 108a is
activated permitting the ability to adjust the capacitive and force
sensor parameters, as described above. For example, an attendant
may program the speed range activated by the capacitive sensor 72
by stepping through entries with a speed or "crawl" button 110a at
prox. speed step 110. Then, a force parameter input step 112 may be
entered by activating a force button 112a. In one embodiment, the
force parameter may be related to the sensitivity of the force
sensor or the resistance range associated with the force sensor.
Other parameters associated with the force sensor may be varied
during this step, if desired. In one embodiment, the inputted
values may be stored by activating the set button 106a. Similar
programming may be conducted for a center pad programming step 114
and a right pad programming step 116. Once the parameters have been
saved, the drive mode 104 may be reentered.
[0032] As shown in FIG. 8, within the drive mode 104 the system
performs a check of each capacitive proximity sensor and force
sensor at step 120. The drive mode 104 portion of the algorithm
then check if one of the capacitive sensors has been activated at
step 122. In one embodiment, the algorithm may iterate between
steps 120 and 122 until all sensors have been checked. When a
capacitive sensors is determined to be active, a null point or
threshold value for the force sensor is created based on the force
sensor reading at that instant. The force sensor output is scaled
from the null setting such that the initially read force becomes
zero and additional pressure applied initiates movement from this
new zero point at step 126. The algorithm then iterates between
verifying that the capacitive sensor is still active at step 128
and, if so, maintains the null values and provides the force sensor
outputs in proportion to the pressure input from the user. If the
capacitive sensor output is not detected, the step 128 proceeds
back to step 120 and begins the sensor check again.
[0033] Referring now to FIG. 9, the transfer function 200
associates the various speed ranges triggered by the capacitive
sensors and the speed rate increases controlled by the force
sensors. For example, a slow initial speed range, shown generally
at 202, may be ramped at a rate that accounts for a user's ability
to apply a desired varying force on the control pad to reach a
chair set speed limit 204. The speed point 202 may be the set point
for the center pad 36, for example. This would give the user slow
initial speed and provide a wide range of speed control based on
force input. Alternatively, the set point may be a fast speed range
setting 206 and require little force input should a user not have
sufficient muscular control.
[0034] The principle and mode of operation of this invention have
been explained and illustrated in its preferred embodiment.
However, it must be understood that this invention may be practiced
otherwise than as specifically explained and illustrated without
departing from its spirit or scope.
* * * * *