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.

What is claimed is: 
     
         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.