This letter presents an enhanced external torque estimation algorithm for series elastic actuators (SEAs) expanding the usability of the residual-based technique. Although the residual method demonstrates online torque estimation capability in diverse applications and thus becomes popular, it is practically challenging to achieve accurate estimation performance in a wide stiffness range of SEAs. The performance degradation is mainly induced by inaccurate transmission torque information, which is stemmed from unexpected errors in the spring deflection based torque sensing. To overcome the issue, this letter analyses the limitation of the conventional approach in frequency domain and proposes the enhanced residual to be used over a wide stiffness range of SEAs. The performance of proposed method is comparatively verified with conventional method in the both of simulations and experiments.
Research on Human-friendly motion control; Development of human assistance;rehabilitation system; Design of robotic system based on human musculoskeletal system; Analysis of human walking dynamics and its application to robotics; 친인간적인 운동제어 설계연구; 인간 보조;재활 시스템의 설계 및 개발연구; 인간 근골격계에 기초한 로봇기구 개발연구; 보행운동 분석과 모델 및 로봇기구에의 응용