Control method for bio-actuators based on muscle contraction model.

For the practical application of bio-actuators, it is desired to develop a precise control method for skeletal muscles. In this study, a novel model-based control method has been proposed. The control method enables skeletal muscles to exert an arbitrary magnitude of contraction force, rather than just the conventional on/off control. First, we proposed a control system to obtain the optimized electrical stimulation voltage, that can reproduce reference force. In order to actually apply the method, a bio-actuator consisting of a skeletal muscle of a frog was manufactured for a verification experiment. First, muscle contraction model parameters that could reproduce the contractile response of the gastrocnemius muscle were identified from the experimental data. Next, based on this model, the proposed control method was used to calculate the stimulation voltage to exert the reference force. The voltage was applied to the bio-actuator to control the contraction force. As a results, the output of the actuator was able to follow the stepwise reference force. Our proposed control method demonstrates the feasibility of precise control of bio-actuators.Clinical Relevance- If skeletal muscles could be used as actuators for power-assistive suits, it would be possible to develop power-assistive suits that are more compatible with people and reduce the burden on caregivers in the field of nursing care. The method proposed in this study will enable the control of skeletal muscle contraction force by electrical stimulation, bringing skeletal muscle actuators closer to practical application.