Control Barrier Function-Based Force Constrained Safety Compliance Control for Manipulator

In this paper, a safety-critical compliance control with force constraint is proposed for the interaction task of a manipulator in the Cartesian space. Different from the conventional impedance control approach, the interaction force constraint is considered and interpreted by designing a new Force Constrained Control Barrier Function (FCCBF) with exploiting the environment model. By formulating and solving a quadratic programming with modifying the baseline impedance controller under the FCCBF constraint, the proposed controller can not only make manipulator's interaction process satisfy expected compliance without exceeding permissible contact force range, but can also improve the dynamic characteristics of the system by eliminating force overshooting phenomena. Furthermore, with using the technique of nonlinear disturbance observer, a force sensor-less FCCBF approach is also provided, where the contact force is treated as an external disturbance. Finally, the effectiveness of the proposed algorithms is verified by both simulations and experimental tests on a 6 degree-of-freedom manipulator.