The novel damping disturbance-observer for enhanced torque tracking of damping series elastic actuator

Series elastic actuators (SEAs) are compliance actuators frequently employed in applications subjected to constant disturbances, yet they encounter challenges such as resonance effects and slow torque control responsiveness. To address these limitations, the physical damping SEA (PDSEA) was developed, incorporating physical damping to enhance torque tracking capabilities while maintaining the compliance characteristics of traditional SEA. This study introduces an advanced disturbance observer (DOB)-based torque controller, uniquely designed to differentiate physical damping effects from system disturbances, such as friction, to retain the functional advantages of PDSEA. By clearly isolating physical damping from external disturbances, the proposed controller allows for optimized torque tracking and improved control precision. Comparative analyses, conducted through simulations and empirical testing, demonstrate that this new control strategy surpasses conventional PI and standard DOB controllers, achieving notable improvements in torque tracking response time and accuracy.