Modeling and Identification of Impact Dynamics of Robot Manipulators with Instantaneous Joint Motion.

Abstract

The problem of impact dynamics of robot manipulators which make instantaneous joint motion or displacement with some disturbance torque, is addressed. Due to unknown joint effect, like back-drivability or frictional displacement, and dynamic coupling between the manipulator and its supporting base, the motion of the system is very difficult to predict after making impulsive contact with environment. A method that uses the Extended Inversed Inertia Tensor and the Virtual Rotor Inertia is proposed to estimate the motion of such systems after impact. The method covers any class of rigid manipulator arms supported by a fixed-base, a flexible deployable structure, or a free-floating satellite. The experiments using the MIT Vehicle Emulation System (VES II) are carried out to observe the impact behavior and identify the values of the Virtual Rotor Inertia and the restitution coefficient. The results clearly show that the effective mass we can feel during impact varies depending on manipulator configuration and joint conditions, but there are consistent values for the Virual Rotor Inertia. Once those values are identified, we can predict force impulse and post impact velocity with relatively high fidelity.