Wheel chair abstract
A wheel chair with independent electric motors for the respective
drive wheels. Free wheeling hand rims are journalled outwardly adjacent
to and coaxially with the drive wheels. The free wheeling hand rims
are connected to respective velocity transducers generating electrical
velocity signals which are used to respectively control the speed
of the wheel motors. The motor speeds are in proportion to the hand
rim velocities. Minimal force is required to rotate the hand rims.
Wheel chair claims
What is claimed is:
1. In a motorized wheelchair for providing transportation for human
passengers, said chair including ground-engaging drive wheels and
respective independent electric motors drivingly coupled to the
drive wheels, the improvement comprising hand rim means freely journalled
on said wheel chair, transducer means comprising means for generating
electrical signals responsive to the rotational velocity of said
hand rim means relative to said wheel chair, and velocity controller
means, connected to and energizing said motor, for controlling the
speed of the motors responsive to and in accordance with said electrical
signals.
2. The motorized wheel chair of claim 1, and wherein said hand
rim means is journalled adjacent to each of said ground-engaging
drive wheels.
3. The motorized wheel chair of claim 1, and wherein the hand rim
means includes a hub portion and the transducer means is located
at said hub portion.
4. The motorized wheel chair of claim 1, and wherein the transducer
means further comprises an electrical tachometer mounted on the
hand rim means and arranged to generate an electrical output signal
in accordance with the rotational velocity of the hand rim means.
5. The motorized wheel chair of claim 4, and wherein said hand
rim means has a hub portion including said electrical tachometer.
6. The motorized wheel chair of claim 4, and wherein said output
signal is substantially proportional to the rotational velocity
of the hand rim means.
7. The motorized wheel chair of claim 4, and wherein the polarity
of the output signal is in accordance with the direction of rotation
of the hand rim means.
8. The motorized wheel chair of claim 1, and wherein said hand
rim means comprises respective hand rim members journalled to the
wheel chair substantially coaxially with respect to and adjacent
to the ground-engaging drive wheels.
9. The motorized wheel chair of claim 8, and wherein each hand
rim member is provided with a hub portion and wherein said transducer
means further comprises respective electrical tachometers located
at said hub portions.
10. The motorized wheel chair of claim 9, and wherein said wheel
chair includes a transverse axle, said ground-engaging drive wheels
being journalled on said axle, and wherein said electrical tachometers
are mounted to sense rotation relative to said axle.
Wheel chair description
FIELD OF THE INVENTION
This invention relates to motorized wheel chairs, and more particularly
to a motorized wheel chair having manually operated transducers
to control the drive motors of the chair in accordance with the
speed of actuation of the transducers.
BACKGROUND OF THE INVENTION
There is a definite need for easily-controllable power-driven wheel
chairs for use by non-ambulatory patients. At the present time most
of the available power-driven wheel chairs use a joy-stick type
of control wherein a single lever is employed to correspondingly
control the power drive means of the wheelchair. It has been found
that with such a type of control the response and maneuverability
of the wheel chair are unsatisfactory, especially in close quarters,
due to insufficient sensitivity of the control system and inflexibility
of the interface arrangements provided between the joy-stick, or
equivalent control element, and the driving structures of the system.
In the previously issued U.S. Pat. No. 4,050,533 to Woodrow Seamone,
it is proposed to employ an angular-position transducer incorporated
in the coupling system between a hand rim element and a driving
wheel, the hand rim element being resiliently coupled to the driving
wheel. The transducer is in the form of a potentiometer adjusted
in accordance with the amount of manual torque applied to the hand
rim element. Upon sensing a change in resistance of the transducer
caused by said torque an output is provided causing a desired change
in the rotational motion of the driving wheel. In practice it has
been found that a motorized wheel chair using this system is very
jerky and uneven in operation because when the hand rim element
is rotated it works against the torque of the motor until the transducer
becomes effective, and because it is difficult to establish the
desired new value of resistance adjustment of the potentiometer
within a reasonably short time period. In other words, it is not
possible to quickly set the transducer to its desired new-resistance
position corresponding to that required for the desired new control
signal value. Therefore, using merely a change of angular position
of the hand rim element as the controlling factor does not appear
to be a practical method of providing the required type of wheel
chair control. Furthermore, this proposed system requires the patient
to employ considerable muscular effort, and many patients do not
possess the required strength to exert this effort.
SUMMARY OF THE INVENTION
The present invention overcomes the problems associated with the
prior art devices by providing a motorized wheel chair which is
used substantially in the same manner as a conventional wheel chair,
i.e., the user rotates a pair of rims disposed on opposite sides
of the wheel chair. Instead of these rims, or hand rails, being
directly fixed to the drive wheels of the wheel chair, they are
free wheeling, and very slight amounts of force, applied in exactly
the same manner as force would be applied to a non-powered wheel
chair, will permit the wheel chair to be maneuvered by the user.
Velocity transducers are provided on the free wheeling hand rims,
and the velocity at which the hand rims are moved is translated
through velocity controller circuitry into drive motion imparted
by drive motors to the wheels of the wheel chair. As a result, very
minimal effort on the part of the user, in the form of the effort
of merely rotating the hand rims, will cause a proportional driving
force to be applied to the associated drive wheels of the wheel
chair. By employing a separate hand rim and drive motor for each
of the two drive wheels of the wheel chair, conventional maneuverability
of the wheel chair is maintained, and only minimal effort is required
on the part of the user to accomplish directed movement of the wheel
chair.
Accordingly, a main object of the invention is to provide an improved
motorized wheel chair which overcomes the disadvantages and deficiencies
of previously known motorized wheel chairs.
A further object of the invention is to provide an improved motorized
wheel chair employing hand rim members movable by minimal manual
effort to control and direct the motion of the wheel chair and controlling
the speed of the wheel chair driving motors in accordance with the
manually imparted rotational speed of the hand rims, so that the
wheel chair is highly maneuverable and requires minimal effort on
the part of the occupant to control the movement of the wheel chair,
even in limited areas.
A still further object of the invention is to provide an improved
motorized wheel chair which employs free wheeling hand rims adjacent
its drive wheels and velocity transducing systems to translate the
rotational velocity of the hand rims into corresponding changes
of the driving torque applied to the driving wheels of the wheel
chair by the wheel chair motors, the manual actuation of the hand
rims by the occupant of the wheel chair being applied exactly in
the same manner as in the use of a non-powered wheel chair but requiring
much less effort, and enabling the occupant to easily maneuver the
wheel chair.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages of the invention will become apparent
from the following description and claims, and from the accompanying
drawings, wherein:
FIG. 1 is a perspective view of a motor-powered wheel chair constructed
in accordance with the present invention.
FIG. 2 is an enlarged fragmentary transverse vertical cross-sectional
view taken substantially on line 2--2 of FIG. 1.
FIG. 3 is a block diagram showing the general electrical circuitry
of one side portion of the wheel chair of FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to the drawings, and more particularly to FIG. 1, there
is shown therein a wheel chair 10 incorporating the features and
principles of the present invention. The wheel chair is of a conventional
design, with the exception of the components hereinafter described.
A pair of ground-engaging drive wheels 12 are disposed on either
side of the wheel chair 10 and are journalled thereto on an axle
14. The axle 14 may be rigidly connected to the wheel chair frame,
as shown in FIG. 2. The wheels 12, being thus journalled to the
frame, shown at 15 in FIG. 2, engage the ground, and when driven
into rotation, cause the wheel chair to be propelled. A pair of
hand rims 16 are rotatably mounted on the axle 14 and are permitted
to independently spin on axle 14.
A hand rim velocity sensor assembly 18 includes an electrical tachometer
19 which is located at the hub of the associated hand rim 16. Said
hub is connected to the hand rim by radial spokes 17. A velocity
sensor assembly 18 is provided on each side of the wheel chair 10.
As the hand rim 16 is spun on the axle 14, the direction and velocity
of the hand rim are measured by the tachometer 19, which generates
a corresponding electrical signal at its output, shown at 27 in
FIG. 3. This output signal has a strength and polarity representing
the velocity and direction of rotation of the associated hand rim
16.
A suitable power source, such as a battery 24, is provided for
driving the associated ground-engaging wheel 12 via a drive motor
22 and a conventional drive wheel direction and velocity-controlling
unit 20. The voltage signal at 27 is employed as the controlling
command signal for the wheel velocity controller 20.
A control system such as is shown in FIG. 3 is provided for each
wheel 12. The drive motors 22 are frictionally coupled to the peripheries
of the ground-engaging wheels 12 in a conventional manner by friction
rollers 29, as shown in FIG. 1.
In operation, the user turns the hand rims 16 in the same manner
as he would apply force to the hand rims of a conventional non-powered
wheel chair but at a much lower level. The hand rim velocity sensor
assembly 18 associated with each hand rim 16 measures the direction
and velocity at which the hand rim 16 is turning and translates
this into an electrical signal which is employed as a command signal
to the associated drive wheel velocity controller 20, which energizes
the associated drive motor 22 to provide a proportional velocity
of its associated driven wheel 12 and in the direction indicated
by the sensor output signal at 27.
It should be apparent that although hand rims 16 are illustrated
as being mounted on opposite ends of the axle 14, if so desired
the hand rims could both be mounted on the same side of the wheel
chair if a patient had use of only one arm. Furthermore, the hand
rims could be mounted at other locations on the wheel chair suitable
to a patient's individual need.
While a specific embodiment of a motorized wheel chair has been
disclosed in the forgoing description, it will be understood that
various modifications within the scope of the invention may occur
to those skilled in the art. Therefore it is intended that adaptations
and modifications should and are intended to be comprehended within
the meaning and range of equivalents of the disclosed embodiments.
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