Design of Calibration Experiments for Identification of Manipulator Elastostatic Parameters

TL;DR

This paper presents a novel calibration experiment design method for industrial robot elastostatic parameters, improving accuracy in large-part machining by optimizing test configurations and forces while considering kinematic constraints.

Contribution

It introduces a user-defined test-pose concept and an optimization framework for designing effective calibration experiments for robot elastostatic modeling.

Findings

Optimized calibration configurations improve model accuracy.

The method accounts for kinematic constraints and collision avoidance.

Application example demonstrates effectiveness in robot-based machining.

Abstract

The paper is devoted to the elastostatic calibration of industrial robots, which is used for precise machining of large-dimensional parts made of composite materials. In this technological process, the interaction between the robot and the workpiece causes essential elastic deflections of the manipulator components that should be compensated by the robot controller using relevant elastostatic model of this mechanism. To estimate parameters of this model, an advanced calibration technique is applied that is based on the non-linear experiment design theory, which is adopted for this particular application. In contrast to previous works, it is proposed a concept of the user-defined test-pose, which is used to evaluate the calibration experiments quality. In the frame of this concept, the related optimization problem is defined and numerical routines are developed, which allow generating optimal set of manipulator configurations and corresponding forces/torques for a given number of the calibration experiments. Some specific kinematic constraints are also taken into account, which insure feasibility of calibration experiments for the obtained configurations and allow avoiding collision between the robotic manipulator and the measurement equipment. The efficiency of the developed technique is illustrated by an application example that deals with elastostatic calibration of the serial manipulator used for robot-based machining.