Model-Based Control of Muscle Contraction With Consideration of Muscle Fatigue

Bioactuators composed of cultured skeletal muscle have unique features such as self-repair and glucose-driven, and are expected to be applied to welfare and medical devices. For the industrial application of bioactuators, it is desirable to model the mechanism of muscle contraction by electrical stimulation and to achieve precise control based on the model. In this study, we developed a model-based control method that can apply appropriate stimulation to the skeletal muscle to generate reference contraction force. To further improve control accuracy, a new model that reproduces muscle fatigue, a phenomenon unique to muscle, has been incorporated to enable contraction control over long periods of time when the effects of fatigue cannot be ignored. To evaluate the validity of the proposed control method, a bioactuator made of toad skeletal muscle was fabricated and tested. First, model parameters that could reproduce the contractile response of the muscle were identified. Next, the optimized stimulation voltage to exert the reference force was calculated by the proposed method and control was conducted on the simulation. As a result, the model outputs agreed well with the reference force, and these results demonstrated the feasibility of bioactuator control under fatigue conditions.