Decoupling identification for serial two-link two-inertia system -Accuracy evaluation under introducing closed-loop-controlled elements and varying amplitude-setup of identification-input

Junji Oaki, Shuichi Adachi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The purpose of our study is to develop a precise model by applying the technique of system identification for the model-based control of a nonlinear robot arm, under taking joint-elasticity into consideration. We previously proposed a systematic identification method, called "decoupling identification," for a "SCARA-type" planar two-link robot arm with elastic joints caused by the Harmonic-drive®reduction gears. The proposed method serves as an extension of the conventional rigid-joint-model- based identification. The robot arm is treated as a serial two-link two-inertia system with nonlinearity. The decoupling identification method using link-accelerometer signals enables the serial two-link two-inertia system to be divided into two linear one-link two-inertia systems. The MATLAB®commands for statespace model estimation are utilized in the proposed method. Physical parameters such as motor inertias, link inertias, joint-friction coefficients, and joint-spring coefficients are estimated through the identified one-link two-inertia systems using a gray-box approach. This paper describes accuracy evaluations using the two-link arm for the decoupling identification method under introducing closed-loop-controlled elements and varying amplitude-setup of identification-input. Experimental results show that the identification method also works with closed-loop-controlled elements. Therefore, the identification method is applicable to a "PUMA-type" vertical robot arm under gravity.

Original languageEnglish
JournalIEEJ Transactions on Industry Applications
Volume129
Issue number12
DOIs
Publication statusPublished - 2009

Fingerprint

Robots
Identification (control systems)
Accelerometers
Gears
Elasticity
Gravitation
Friction

Keywords

  • Accelerometer
  • Elastic joint
  • Multivariable identification
  • Robot arm
  • Subspace identification method
  • Two-inertia resonant system

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Industrial and Manufacturing Engineering

Cite this

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title = "Decoupling identification for serial two-link two-inertia system -Accuracy evaluation under introducing closed-loop-controlled elements and varying amplitude-setup of identification-input",
abstract = "The purpose of our study is to develop a precise model by applying the technique of system identification for the model-based control of a nonlinear robot arm, under taking joint-elasticity into consideration. We previously proposed a systematic identification method, called {"}decoupling identification,{"} for a {"}SCARA-type{"} planar two-link robot arm with elastic joints caused by the Harmonic-drive{\circledR}reduction gears. The proposed method serves as an extension of the conventional rigid-joint-model- based identification. The robot arm is treated as a serial two-link two-inertia system with nonlinearity. The decoupling identification method using link-accelerometer signals enables the serial two-link two-inertia system to be divided into two linear one-link two-inertia systems. The MATLAB{\circledR}commands for statespace model estimation are utilized in the proposed method. Physical parameters such as motor inertias, link inertias, joint-friction coefficients, and joint-spring coefficients are estimated through the identified one-link two-inertia systems using a gray-box approach. This paper describes accuracy evaluations using the two-link arm for the decoupling identification method under introducing closed-loop-controlled elements and varying amplitude-setup of identification-input. Experimental results show that the identification method also works with closed-loop-controlled elements. Therefore, the identification method is applicable to a {"}PUMA-type{"} vertical robot arm under gravity.",
keywords = "Accelerometer, Elastic joint, Multivariable identification, Robot arm, Subspace identification method, Two-inertia resonant system",
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AB - The purpose of our study is to develop a precise model by applying the technique of system identification for the model-based control of a nonlinear robot arm, under taking joint-elasticity into consideration. We previously proposed a systematic identification method, called "decoupling identification," for a "SCARA-type" planar two-link robot arm with elastic joints caused by the Harmonic-drive®reduction gears. The proposed method serves as an extension of the conventional rigid-joint-model- based identification. The robot arm is treated as a serial two-link two-inertia system with nonlinearity. The decoupling identification method using link-accelerometer signals enables the serial two-link two-inertia system to be divided into two linear one-link two-inertia systems. The MATLAB®commands for statespace model estimation are utilized in the proposed method. Physical parameters such as motor inertias, link inertias, joint-friction coefficients, and joint-spring coefficients are estimated through the identified one-link two-inertia systems using a gray-box approach. This paper describes accuracy evaluations using the two-link arm for the decoupling identification method under introducing closed-loop-controlled elements and varying amplitude-setup of identification-input. Experimental results show that the identification method also works with closed-loop-controlled elements. Therefore, the identification method is applicable to a "PUMA-type" vertical robot arm under gravity.

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