Movement-Based Simultaneous Control of a Prosthetic Elbow and Wrist via Compensation Effect Amplification Control (CEAC)

Despite the increasing availability of powered upper-limb (UL) prostheses, robust and cost-efficient control of intermediate joints-specifically the elbow and wrist-remains a significant challenge. Current solutions, like high-density EMG arrays with pattern recognition or surgical interventions like Targeted Muscle Reinnervation (TMR), are complex and not universally accessible for robust simultaneous multi-joint control. Consequently, the reliance on limited myoelectric sites creates a bottleneck, restricting not only the use of multiple prosthetic joints but also the functional fidelity of available advanced prosthetic hands. In this work, we present a twodegree-of-freedom (2-DoF) extension of the Compensation Effect Amplification Control (CEAC) paradigm. This approach leverages natural body kinematics-including trunk flexion, lateral bending, and shoulder abduction and rotation-to drive the velocity of the prosthetic elbow and wrist. Crucially, this movement-based strategy liberates distal electromyography (EMG) signals, allowing them to be dedicated exclusively to hand actuation. To validate this hybrid control architecture, we conducted a study with ten able-bodied participants using a supernumerary prosthesis. ... mehrWe implemented a simultaneous control scheme where the elbow and wrist were driven by CEAC, while the hand was actuated via sEMG on the forearm. We benchmarked this system against a remote-controlled prosthesis serving as a deterministic, fully reliable sequential baseline. Participants achieved proficiency with CEAC within one hour, and the method outperformed the remote control benchmark in terms of both completion time and error rate. Furthermore, the approach significantly reduced unergonomic compensatory behaviors and was preferred by a majority of participants.