Motion control of the electric wheelchair powered by rim motors based on event-based cross-coupling control strategy

In this study, an event-based cross-coupling control strategy for a differential driven electric wheelchair powered by rim motors (rim motor wheelchair) was proposed in order to maintain the turning curvature of the desired driving path. When the wheelchair drives on roads with ramps, slopes, or non-homogeneous pavements, unsymmetrical disturbances would cause the unbalanced speed error in each motor, hence affect its performance. Because there is no cross-talk between two speed controllers, lacking of coordination causes wheelchair veering from the intended course and could even lead to loss of control. The modified cross-coupling control strategy is developed to compensate the reference wheel speeds input to the controllers for maintaining the wheelchair in right direction. Besides, we combine the event-based control with the modified cross-coupling control to eliminate the accumulation of compensation error due to the low resolution characteristic of Hall-effect sensors in the rim motors of the wheelchair. The results show that the proposed control approach can enhance the operating performance of the rim motor wheelchair system efficiently under disturbances.