The adaptive impedance control with desired force fuzzy adjustment for underwater manipulator-compliant operation

To achieve versatile target grasping, ensure successful holding, and minimize potential damage to the target, we propose an adaptive impedance control method for underwater manipulators. This method entails establishing a force-tracking control system based on the position impedance model and identifying target impedance parameters using the recursive least squares method. By adjusting the grasping force’s desired value according to impedance parameters and manipulator characteristics, adaptive proportional–integral–derivative (PID) control is realized for the desired position. This adjustment process considers the error between the desired force and the environmental force, allowing the system to track different desired force signals while ensuring accurate position tracking. To validate the effectiveness of the proposed method, we conducted simulation with the MATLAB platform and experiment verification. The results demonstrate the adaptive impedance control method’s excellent position-tracking performance in both free and constrained spaces. The real-time adjustments of the desired force effectively accommodate various grasping targets, while the adaptive adjustment of the desired position enables precise tracking of the desired force value, eliminating static errors. Overall, the entire control system exhibits flexibility and robustness.