A 9-DoF Wheelchair-Mounted Robotic Arm System: Design, Control, Brain-Computer Interfacing, and Testing

Abstract

A wheelchair-mounted robotic arm (WMRA) was designed and built to meet the needs of mobility-impaired persons, and to exceed the capabilities of current devices of this type. Combining the wheelchair control and the arm control through the augmentation of the Jacobian to include representations of both resulted in a control system that effectively and simultaneously controls both devices at once. The control system was designed for coordinated Cartesian control with singularity robustness and task-optimized combined mobility and manipulation. Weighted Least Norm solution was implemented to prioritize the motion between different arm joints and the wheelchair. Modularity in both the hardware and software levels allowed multiple input devices to be used to control the system, including the Brain-Computer Interface (BCI). The ability to communicate a chosen character from the BCI to the controller of the WMRA was presented, and the user was able to control the motion of WMRA system by focusing attention on a specific character on the screen. Further testing of different types of displays (e.g. commands, picture of objects, and a menu display with objects, tasks and locations) is planned to facilitate communication, mobility and manipulation for people with severe disabilities. Testing of the control system was conducted in Virtual Reality environment as well as using the actual hardware developed earlier. The results were presented and discussed.