A Myoelectric Switching, Multi-Mode, Movement-Based Approach for Versatile Prosthetic Elbow Control

Modern upper-limb prostheses offer a high number of functional degrees of freedom that still cannot be controlled in an intuitive manner. Movement-based control approaches aim to overcome these limitations by leveraging the user's natural motor behavior as a control input. Methods such as Compensation Effect Amplification Control (CEAC) have been shown to be intuitive and effective for various tasks, but CEAC exhibits a significant loss in performance in situations where a single postural control mapping (i.e. the relationship between human and prosthetic movement) is insufficient. To increase the versatility of CEAC, we propose a hybrid control architecture, combining the postural input with a discrete voluntary input. The proposed framework was evaluated in a study with ten asymptomatic subjects wearing a supernumerary prosthesis to perform an advanced reach-tograsp task. Trunk flexion served as the postural control input for the prosthetic elbow, while a 2-channel-myoelectric signal was used to open/close the prosthetic hand and to modulate the postural control law. Using simple cocontraction patterns, users could temporarily switch to either of two additional control mappings. ... mehrPerformance was compared against a fixed postural controller (CEAC) and a remote-controlled elbow as a fully reliable, deterministic benchmark. The new control architecture allowed participants to significantly reduce compensatory movement compared to CEAC. The results indicate that adding a sparse auxiliary signal such as EMG presents a viable approach to increasing the versatility of movement-based control for upper-limb prostheses.