Biomimetic versus arbitrary motor control strategies for bionic hand skill learning

Abstract

A long-standing engineering ambition has been to design anthropomorphic bionic limbs: devices that look like and are controlled in the same way as the biological body (biomimetic). The untested assumption is that biomimetic motor control enhances device embodiment, learning, generalization and automaticity. To test this, we compared biomimetic and non-biomimetic control strategies for non-disabled participants when learning to control a wearable myoelectric bionic hand operated by an eight-channel electromyography pattern-recognition system. We compared motor learning across days and behavioural tasks for two training groups: biomimetic (mimicking the desired bionic hand gesture with biological hand) and arbitrary control (mapping an unrelated biological hand gesture with the desired bionic gesture). For both trained groups, training improved bionic limb control, reduced cognitive reliance and increased embodiment over the bionic hand. Biomimetic users had more intuitive and faster control early in training. Arbitrary users matched biomimetic performance later in training. Furthermore, arbitrary users showed increased generalization to a new control strategy. Collectively, our findings suggest that biomimetic and arbitrary control strategies provide different benefits. The optimal strategy is probably not strictly biomimetic, but rather a flexible strategy within the biomimetic-to-arbitrary spectrum, depending on the user, available training opportunities and user requirements.

Validity and Impact of Methods for Collecting Training Data for Myoelectric Prosthetic Control Algorithms

“…An alternative approach is non-biomimetic control, in which algorithms are trained to map arbitrary muscle patterns to arbitrary prosthesis actions. Non-biomimetic control offers the ability to have the user perform specific muscle patterns that minimize intraclass variability and maximize interclass separability, and has been shown to improve functional outcomes [ 47 ]. Future work should investigate how mimic and mirror training could be best utilized within the framework of non-biomimetic control strategies.…”