Accurate and Efficient End-Effector Tracking for Quadrupedal Mobile Manipulators through Coordinated Motion and Decoupled Control

Quadrupedal mobile manipulators are receiving increasing attention due to their excellent terrain adaptability and nearly unlimited workspace. Recent achievements have integrated legged mobility with manipulation capabilities, yet the accuracy of end-effector trajectory tracking remains a challenge, which is crucial for practical applications. This study proposes an innovative approach that integrates coordinated trajectory generation with decoupled tracking control to enhance the accuracy of end-effector trajectory tracking. This approach also expands the end-effector's workspace and improves the smoothness of the robot's movements. The trajectory optimization-based coordinated trajectory generator leverages the active motion of the quadruped's body to produce smooth movements. Meanwhile, the decoupled tracking control models the robotic arm and quadrupedal robot as independent floating-base systems, incorporating interaction forces to enhance the overall system's tracking accuracy. Finally, a series of experiments demonstrate that the proposed method can successfully perform a variety of trajectory-tracking tasks, reducing the root mean squared error by 82.7% compared to independent control in the stance mode, and cutting additional computational overhead by 53.4% compared to the unified control.