Claims
- 1. In a motorized wheelchair assembly, comprising:
a wheelchair chassis; a motor-driven right wheel connected to and providing rolling support for said wheelchair chassis; a motor-driven left wheel connected to and providing rolling support for said wheelchair chassis; a castor subassembly connected to and providing rolling support for said wheelchair chassis; an input device which generates wheelchair chassis turn direction command signals and a wheelchair chassis linear velocity command signals in response to wheelchair operator manipulation; a closed-loop controller including a first angular rate-of-turn sensor, said controller receiving command signals from said input device and generating output control signals that regulate the rotational speeds of each of said motor-driven right and left wheels in response to differences between said input device turn direction and linear velocity command signals and detected wheelchair chassis actual turn directions and actual turn rates; and a detector for detecting the operation of and the failure of the first angular rate-of-turn sensor.
- 2. The assembly of claim 1, wherein upon detection of a failure of the first angular rate-of-turn sensor, the forward velocity of the wheelchair is limited to a maximum forward velocity.
- 3. The assembly of claim 2, wherein the maximum forward velocity does not exceed a limit determined by the actual forward tilt of the wheelchair.
- 4. The assembly of claim 2, wherein the maximum forward velocity is limited to about 3 miles per hour.
- 5. The assembly of claim 1, wherein the detector includes a second angular rate-of-turn sensor.
- 6. The assembly of claim 5, wherein the first angular rate-of-turn sensor generates signals which correspond to actual turn directions and turn rates of said wheelchair chassis, and the second angular rate-of-turn sensor generates signals which correspond to actual turn directions and turn rates of said wheelchair chassis.
- 7. The assembly of claim 6, wherein the signals generated by the second rate-of-turn sensor are opposite in polarity to those generated by the first angular rate-of-turn sensor.
- 8. The assembly of claim 7, wherein the detector compares the signals of the first and second rate-of-turn sensors; and as a result of such comparison, a maximum forward velocity signal is generated to limit the maximum forward velocity of the wheelchair.
- 9. The motorized wheelchair assembly invention defined by claim 8, further including forward and vertical linear acceleration sensors that are orthogonally supported by said wheelchair chassis and that detect wheelchair chassis actual forward tilt to thereby establish a wheelchair linear velocity control limit.
- 10. In a method of controlling motion of a motorized wheelchair assembly having separately-controlled, motor-driven right and left wheels that provide wheelchair assembly rolling support, the steps of:
providing turn direction command inputs and turn rate command inputs to the motorized wheelchair assembly to cause correlated wheelchair motion; sensing the actual turn direction and actual angular rate-of-turn of said motorized wheelchair assembly; comparing said sensed wheelchair assembly actual turn direction and angular rate-of-turn signals with wheelchair assembly provided turn direction and turn rate command inputs and developing their respective differences as control signals; utilizing said developed control signals to regulate differential rotation of said motorized wheelchair assembly motor-driven right and left wheels to thereby limit wheelchair actual rate-of-turn magnitude to a predetermined magnitude not exceeding the magnitude of said wheelchair assembly turn rate command input; and upon the failure to sense the actual turn direction and actual angular rate-of-turn of said motorized wheelchair assembly generating a maximum forward velocity to thereby limit wheelchair actual forward velocity.
- 11. A method of controlling a motorized wheelchair assembly, having a right motor-driven wheel and a left motor-driven wheel, comprising the steps of:
a) generating a first driving signal for driving the right motor-driven wheel and a second driving signal for driving the left motor-driven wheel; b) generating a wheelchair turn direction command signal and a wheelchair linear velocity command signal; c) sensing actual turn directions of the wheelchair and generating an actual turn direction signal; d) sensing actual turn rate and generating an actual turn rate signal; e) comparing said wheelchair turn direction and linear velocity command signals to said actual turn direction and actual turn rate signals; f) as a result of said comparison step modifying at least one of the first or second driving signals; and g) upon the detection of a failure to sense the actual turn rate, limiting the linear velocity command signal to a maximum value.
- 12. A method of controlling a motorized wheelchair assembly, having a right driven wheel and a left motor-driven wheel comprising the steps of:
a) generating a turn command input signal and a linear velocity command signal; b) sensing actual angular rates of turn of the wheelchair and generating a corresponding first actual rate-of-turn signal; c) sensing the first actual rate-of-turn signal; d) comparing said turn command input signal and the first actual rate-of-turn signal; e) in response to said comparison step, regulating differential rotation of the motor-driven right and left wheels; and f) upon the failure to sense the first actual rate-of-turn signal, limiting the linear velocity command signal to a maximum value.
- 13. The method of claim 12, wherein said step of sensing the actual rate-of-turn signal includes the steps of:
sensing actual angular rate-of-turn of the wheelchair and generating a corresponding second actual rate-of-turn signal; and comparing the first and second actual rate-of-turn signals.
- 14. The method of claim 13 further comprising the step of:
compensating the first and second actual rate-of-turn signals for changes in temperature.
- 15. The method of claim 13 further comprising the steps of:
averaging an output of each rate-of-turn sensor with the wheelchair at rest to determine a correction values and utilizing the correction values to compensate the first and second actual rate-of-turn signals.
- 16. The method of claim 12 further including the steps of:
g) determining a maximum linear deceleration of the wheelchair and a corresponding linear velocity. h) limiting the forward velocity of the wheelchair to the linear velocity of step (g) if the maximum value of step (f) is less than the linear velocity of step (g).
- 17. The method of claim 12 further including the step of:
controlling the deceleration of the wheelchair so as not to exceed a tilt limit value.
- 18. The method of claim 12 further comprising the steps of:
a) sensing vertical acceleration of the wheelchair and generating a vertical acceleration signal; b) sensing forward acceleration of the wheelchair and generating a forward acceleration signal; c) in response to said forward and vertical acceleration signals, determining a forward tilt limit; and d) adjusting the maximum value of the linear velocity command signal during deceleration.
- 19. A method of controlling a motorized wheelchair assembly, having a right motor-driven wheel and a left motor-driven wheel, comprising the steps of:
a) generating a first driving signal for driving the right motor-driven wheel and a second driving signal for driving the left motor-driven wheel; b) generating a wheelchair turn direction command signal and a wheelchair linear velocity command signal; c) sensing actual turn directions of the wheelchair and generating an actual turn direction signal; d) sensing actual turn rate and generating an actual turn rate signal; e) comparing said wheelchair turn direction and linear velocity command signals to said actual turn direction and actual turn rate signals; and f) as a result of said comparison step modifying at least one of the first or second driving signals.
- 20. A method of controlling a motorized wheelchair assembly, having a right driven wheel and a left motor-driven wheel comprising the steps of:
a) generating a turn command Input signal and a linear velocity command signal; b) sensing actual angular rates of turn of the wheelchair and generating a corresponding actual rate of turn signal; c) comparing said turn command input signal and the actual rate of turn signal; and d) in response to said comparison step, regulating differential rotation of the motor-driven right and left wheels.
- 21. The method of claim 20 further comprising the step of:
compensating the actual rate of turn signal for changes in temperature.
- 22. The method of claim 20 further comprising the steps of:
averaging an output of a rate of turn sensor with the wheelchair at rest to determine a correction value and utilizing the correction value to compensate the actual rate of turn signal.
- 23. The method of claim 20 further comprising the steps of:
regulating the turn command input so as not to exceed a maximum turn rate.
- 24. The method of claim 20 further comprising the steps of:
sensing vertical and lateral acceleration of the wheelchair; and in response to said sensed vertical and lateral acceleration, generating said actual turn rate.
- 25. The method of claim 20 further comprising the steps of:
a) determining actual wheelchair turn rate; b) comparing the actual wheelchair turn rate and a maximum wheelchair turn rate; and as a result of such comparison, adjusting the turn velocity of the wheelchair.
- 26. The method of claim 25 wherein the lateral tilt is determined by the following:
- 27. The method of claim 20 further comprising the steps of:
limiting the linear velocity command signal so that the wheelchair does not exceed a maximum linear deceleration.
- 28. The method of claim 27 further comprising the steps of:
a) sensing vertical acceleration of the wheelchair and generating a vertical acceleration signal; b) sensing forward acceleration of the wheelchair and generating a forward acceleration signal; and c) in response to said forward and vertical acceleration signals, determining an actual linear deceleration of the wheelchair.
- 29. The method of claim 27 further comprising the steps of:
a) measuring forward and vertical acceleration of the wheelchair; and b) determining the actual forward tilt by the following: Forward Tilt=ARC SINE 4FAFA2+V A2;wherein FA=Forward Acceleration VA=Vertical Acceleration.
- 30. The method of claim 20 further comprising the steps of:
a) determining actual wheelchair turn rate; b) comparing the actual wheelchair turn rate to a reference wheelchair turn rate; and c) as a result of said comparison adjusting the forward velocity of the wheelchair.
- 31. The method of claim 30 wherein the forward velocity of the wheelchair is adjusted so that the wheelchair does not exceed a maximum linear deceleration.
- 32. The method of claim 27 further comprising the steps of:
sensing forward acceleration of the wheelchair and generating a forward acceleration signal; comparing the linear velocity command signal to said forward acceleration signal; and c) as a result of said comparison adjusting the velocity of the right and left motor-driven wheels.
- 33. A method of controlling a motorized wheelchair, having first and second driven wheels, comprising the steps of:
a) generating a first driving signal for driving the first driven wheel; b) generating a second driving signal for driving the second driven wheel; c) generating turn and linear acceleration input signals; d) sensing forward, vertical, and lateral acceleration of the wheelchair and generating corresponding forward, vertical and lateral acceleration signals; e) sensing an angular rate of turn of the wheelchair and generating an actual rate of turn signal; f) comparing the linear acceleration input signal to said forward acceleration signal, and as a result of such comparison adjusting the first and second driving signals; g) comparing the turn acceleration signal to the actual rate of turn signal, and generating a turn compensation signal as a result of such comparison; and h) utilizing said turn compensation signal to decrease the first driving signal while increasing the second driving signal.
- 34. The method of claim 33 further comprising the steps of:
generating a maximum linear velocity signal as a function of the forward and vertical acceleration signals, and limiting the linear acceleration input signal so as not to exceed the maximum linear velocity signal; and generating a maximum rate of turn signal as a function of the vertical and lateral acceleration signals and limiting the turn rate input signal so as not to exceed the maximum rate of turn signal.
- 35. The method of claim 34 further comprising the step of:
compensating the actual rate of turn signal for changes in temperature.
- 36. The method of claim 35 wherein:
a) the actual lateral tilt is determined by the following: Actual Lateral Tilt=ARC SINE 5LALA2+V A2;and b) the actual forward tilt is determined by the following: Actual Forward Tilt=ARC SINE 6FAFA2+V A2;wherein LA=Lateral Acceleration FA=Forward Acceleration VA=Vertical Acceleration.
- 37. In a method of controlling motion of a motorized wheelchair assembly having separately-controlled, motor-driven right and left wheels that provide wheelchair assembly rolling support, the steps of:
providing turn direction command inputs and turn rate command inputs to the motorized wheelchair assembly to cause correlated wheelchair motion; sensing the actual turn direction and actual angular rate-of-turn of said motorized wheelchair assembly; comparing said sensed wheelchair assembly actual turn direction and angular rate of turn signals with wheelchair assembly provided turn direction and turn rate command inputs and developing their respective differences as control signals; and utilizing said developed control signals to regulate differential rotation of said motorized wheelchair assembly motor-driven right and left wheels to thereby limit wheelchair actual rate-of-turn magnitude to a predetermined magnitude not exceeding the magnitude of said wheelchair assembly turn rate command input.
- 38. The method invention defined in claim 37, wherein said sensing step is accomplished gyroscopically.
- 39. The method invention defined by claim 37, wherein said sensing step involves sensing said actual turn direction and said actual rate-of-turn of said motorized wheelchair assembly while said wheelchair assembly is at rest and utilizing the so-sensed turn direction and rate-of-turn as correction values during subsequent sensing of said actual turn direction and actual rate-of-turn of said motorized wheelchair assembly.
- 40. The method invention defined by claim 37, and further comprising:
sensing motorized wheelchair assembly forward deceleration rates; comparing said forward deceleration rates to a permissible deceleration rate based on wheelchair angle of actual wheelchair forward tilt, and developing their respective differences as control signals; and utilizing said developed control signals to regulate differential rotation of said motorized wheelchair assembly motor-driven right and left wheels to thereby limit wheelchair actual rate-of-turn magnitude to a predetermined magnitude not exceeding the magnitude of said wheelchair assembly permissible deceleration rate.
Parent Case Info
[0001] This application is a continuation-in-part of application Ser. No. 091785,744, filed Feb. 16, 2001, which is a divisional application of application Ser. No. 09/365,276, filed Jul. 30, 1999, now U.S. Pat. No. 6,202,773, the disclosure of each is hereby incorporated herein by reference.
Divisions (1)
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Number |
Date |
Country |
Parent |
09365276 |
Jul 1999 |
US |
Child |
09785744 |
Feb 2001 |
US |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09785744 |
Feb 2001 |
US |
Child |
09932182 |
Aug 2001 |
US |