Improved Adaptive Impedance Control Based on Force Error and Its Rate of Change

To mitigate the excessive instantaneous contact forces exerted during the excavation of fermented grains from ground tanks using conventional impedance control strategies, an improved adaptive impedance control strategy that dynamically adjusts the damping coefficients is proposed based on a real-time force error and its change rate. First, to address the excessive overshoot of the exerted contact force, the adaptive impedance control algorithm is integrated with the proportional-differential(PD) control concept. Specifically, an improved adaptive impedance control law is formulated using the force error and its change rate as inputs. Thus, by adjusting the damping coefficient in real time, the force overshoot is suppressed while achieving force tracking. Subsequently, the parameter selection criteria for system stability are obtained based on Lyapunov′s stability theory. Finally, the simulation and experimental results reveal that the proposed method can effectively suppress force overshoot during contact while maintaining a low force-tracking error, thereby enhancing the stability of robot operation.