A robust and compliant framework for legged mobile manipulators using virtual model control and whole-body control

Quadruped robots can mimic animal locomotion mode and have great potential usage in unstructured environments. However, as mobile platforms, quadruped robots often lack manipulation capabilities. In this project, we equipped the quadruped robot SDU-ADog with a torque-controlled 6-DOF arm. A novel control framework which combines virtual model control (VMC) and prioritized whole-body control (WBC) for the whole system is proposed in this paper. VMC finds optimal target ground reaction forces while compensating the arm's inertia, and then makes the robot compliant to external disturbance. Prioritized WBC deals with multiple tasks in an optimal fashion and achieves efficiency and robustness of robot's locomotion and manipulation. The effectiveness of our framework has been evaluated through a set of robot dynamic simulations conducted in Webots. The robot can finish balance maintaining with moving arm, fixed point tracking while trotting, and locomotion over different obstacles with an end-point task.(c) 2023 Elsevier B.V. All rights reserved.