Analysis of the Compliance Properties of an Industrial Robot with the Mozzi Axis Approach

Abstract

In robotic processes, the compliance of the robot arm plays a very important role. In some conditions, for example, in robotic assembly, robot arm compliance can compensate for small position and orientation errors of the end-effector. In other processes, like machining, robot compliance may generate chatter vibrations with an impairment in the quality of the machined surface. In industrial robots, the compliance of the end-effector is chiefly due to joint compliances. In this paper, joint compliances of a serial six-joint industrial robot are identified with a novel modal method making use of specific modes of vibration dominated by the compliance of only one joint. Then, in order to represent the effect of the identified compliances on robot performance in an intuitive and geometric way, a novel kinematic method based on the concept of “Mozzi axis” of the end-effector is presented and discussed.

Advances in Mechanical Systems Dynamics

“…In particular, the authors investigated the possibility and performance of replacing a conventional weighting device with a vision on inspection system. The paper [18] focuses at robot compliance modeling for achieving a compensation of small position and orientation errors of the end-effector as well as reducing chatter vibrations. In this paper, joint compliances of a serial six-joint industrial robot are identified with a novel modal method making use of specific modes of vibration dominated by the compliance of only one joint.…”

Effect of End-Effector Compliance on Collisions in Robotic Teleoperation

“…The matrices D q and K q are diagonal and independent of the robot configuration q. In particular, the terms of these matrices represent the viscous damping coefficient and the stiffness of each joint around its rotation axis, and they can be identified by means of an impulsive modal analysis of the robot [17,18]. The movement of the tool and its collision with an object in the plane of motion are described in the operational space, so it is necessary to transfer the description of robot dynamics from the joint space to the cartesian space.…”

Variable Stiffness Mechanism for the Reduction of Cutting Forces in Robotic Deburring

“…Therefore, it is possible to achieve functional redundancy [23], and the robot can perform the same task using different configurations. For example, if the stiffness and inertial properties of the robot are known or experimentally identified [24,25] it is possible to choose a proper configuration so that the kinematic chain of the robot is stiff enough to perform the grinding operation. However, this field of research has only been partially explored.…”