Muscle-like actuators have recently emerged to serve bionic robots and human-robot interaction systems. In order to enhance the performance of exoskeletons, we have introduced an artificial muscle based on the Hill muscle model, which incorporates a compliant structure and muscle-like elastic properties. By drawing inspiration from antagonistic muscle pairs, we develop a compound tendon-sheath artificial muscle (CTSAM) capable of bidirectional movement. To address control challenges arising from the nonlinear transmission characteristics of the CTSAM, this paper establishes an elongation model and proposes a control method that combines elongation model compensation with sliding mode control. This control method is subsequently validated through experiments involving various motion trajectories. The experimental results demonstrate that control errors are effectively reduced, and error fluctuations with changes in movement frequency are significantly mitigated.
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