Design and evaluation of a seat orientation controller during uneven terrain driving

• Risk of tips and falls is common in EPW users when driving in ground slopes due to the shift in center of mass and loss of stability.
• A seat orientation controller is proposed to maintain the seat of a novel electric power wheelchair (EPW) horizontally leveled when driving in uneven terrains, hills and cross slopes.
• The EPW was placed in a dynamic platform that simulates these ground slopes in order to evaluate the effectiveness of the seat orientation controller.
• The wheelchair seat stays horizontal within ± 0.5° up to 5° of ground angle.
• The Center of Pressure of the wheelchair and test dummy remains within the footprint of the wheelchair when the controller is activated throughout the test.

Electric powered wheelchairs (EPWs) are essential devices for people with disabilities as aids for mobility and quality of life improvement. However, the design of currently available common EPWs is still limited and makes it challenging for the users to drive in both indoor and outdoor environments such as uneven surfaces, steep hills, or cross slopes, making EPWs susceptible to loss of stability and at risk for falls. An alternative wheel-legged robotic wheelchair, “MEBot”, was designed to improve the safety and mobility of EPW users in both indoor and outdoor environments. MEBot is able to elevate its six wheels using pneumatic actuators, as well to detect changes in the seat angle using a gyroscope and accelerometer. This capability enables MEBot to provide sensing for a dynamic self-leveling seat application that can maintain the center of mass within the boundaries of the wheelchair, thereby, improving EPW safety. To verify the effectiveness of the application, MEBot was tested on a motion platform with six degrees of freedom to simulate different slopes that could be experienced by the EPW in outdoor environments. The results demonstrate the robustness of the application to maintain the wheelchair seat in a horizontal reference against changes in the ground angle.