Adaptive Admittance Control for Cooperative Manipulation using Dual Quaternion Representation and Logarithmic Mapping

This thesis addresses the problem of admittance control for bimanual and cooperative manipulators. In this work we propose our cooperative adaptive admittance controller (CDAC), a novel solution that integrates compliance behaviour defined within the dual quaternion logarithmic space—that accounts for the coupled translation and rotation kinematics as well as for the cooperative variables defining the motion. The overall scheme of the proposed framework consists of a stiffness adapter, cooperative admittance controller, and wrench adapter complete with an inner motion controller along with the cooperative system. By describing the coupled motion exploiting the geometric features of dual quaternions, the desired compliant behaviour is enforced on the whole dual-arm system and not on the single manipulator separately. The proposed control, in addition with a stable stiffness adaptation policy within the cooperative task-space, is tested and validated by thorough simulation studies on two Franka Emika Panda robots carrying a shared object under varying loading conditions