Dynamic joint stiffness determines the relation between joint position and torque, and plays a vital role in the control of posture and movement. Dynamic joint stiffness can be quantified during quasi-stationary conditions using disturbance experiments, where small position perturbations are applied to the joint and the torque response is recorded. Dynamic joint stiffness is composed of intrins...

This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented onseveral joints of a laboratory robot. The ...

We compare the different control methods in learning a robotic manipulation task. The task is to push an object (a cube and sphere) from varying beginning position to a fixed goal position. Complex contact dynamics is involved. We used PPO as the learning algorithm trained from scratch with dense rewards. Comparison is performed on two dimensions: learning at joint level vs. end-effector level,...