Interaction Control Based on Position/Velocity Control by Means of Disturbance Observer

In the typical industrial applications, the object grasping or manipulation is usually implemented on industrial robots. However, the correct object manipulation also implies to avoid damages. On the other hand, interaction is an action which is influenced by other actions between two or more entities. In this paper an alternative method for interaction control, which is a combination of velocity and position controllers based on disturbance observer (DOB) is presented. The proposed control strategy is a velocity control while the gripper is moving without contact with the environment. When an object is reached, the DOB detects the contact force and the control strategy switches to position control, the switching is commanded by a torque threshold compared with the estimated torque. The control strategy is verified by numerical simulation considering an object with predefined stiffness.