Decoupling identification method of serial two-link two-inertia system for robot motion control

Junji Oaki, Shuichi Adachi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Abstract

The goal of our study is to obtain a precise dynamic model by applying the technique of system identification for the model-based control of a nonlinear robot arm, taking joint-elasticity into consideration. We previously proposed "decoupling identification method" for a planar serial two-link robot arm with elastic-joints caused by the Harmonicdrive reduction gears. First, this paper reviews the decoupling effectiveness of the proposed identification method. This method serves as an extension of the conventional rigid-joint-modelbased identification, and treats the robot arm as a serial two-link two-inertia system with nonlinearity. The main idea of the decoupling method is nonlinear interaction torques between two links are utilized as identification inputs besides motor inputs. The torques can be computed using the rigid-joint-model parameters and link-accelerometer signals, and enable the serial two-link two-inertia system to be divided into two linear one-link systems. Typical multi-input multi-output linear model estimation algorithms can be applied for the identification method. Physical parameters such as motor inertias, link inertias, joint-friction coefficients and joint-spring coefficients of the dynamic model are estimated by applying the coefficient comparison method to the transfer functions of the one-link two-inertia systems. This is a gray-box modeling approach. Second, this paper extends the proposed method to closed-loop identification from open-loop identification. Thus the method is applicable for not only a SCARA (Selective Compliant Assembly Robot Arm) but also a PUMA (Programmable Universal Manipulation Arm) under gravity. Third, this paper unveils the robustness of the decoupling method against estimation errors of coupling-inertia parameters for computing nonlinear interaction torques; these parameters are obtained by the conventional rigid-joint-model-based identification. Several experiments using the planar serial two-link robot arm with elastic-joints are conducted to demonstrate the effectiveness and robustness of the decoupling identification method.

Original languageEnglish
Title of host publicationIFAC Proceedings Volumes (IFAC-PapersOnline)
Pages14359-14366
Number of pages8
Volume18
EditionPART 1
DOIs
Publication statusPublished - 2011
Event18th IFAC World Congress - Milano, Italy
Duration: 2011 Aug 282011 Sep 2

Other

Other18th IFAC World Congress
CountryItaly
CityMilano
Period11/8/2811/9/2

Fingerprint

Motion control
Robots
Identification (control systems)
Torque
Dynamic models
Accelerometers
Error analysis
Transfer functions
Gears
Elasticity
Gravitation
Friction
Experiments

Keywords

  • Closed-loop identification
  • Frequency response
  • Gray-box modeling
  • Mechanical resonance
  • Multivariable systems
  • Nonlinear optimization
  • Nonlinear systems
  • Robot arms

ASJC Scopus subject areas

  • Control and Systems Engineering

Cite this

Oaki, J., & Adachi, S. (2011). Decoupling identification method of serial two-link two-inertia system for robot motion control. In IFAC Proceedings Volumes (IFAC-PapersOnline) (PART 1 ed., Vol. 18, pp. 14359-14366) https://doi.org/10.3182/20110828-6-IT-1002.00982

Decoupling identification method of serial two-link two-inertia system for robot motion control. / Oaki, Junji; Adachi, Shuichi.

IFAC Proceedings Volumes (IFAC-PapersOnline). Vol. 18 PART 1. ed. 2011. p. 14359-14366.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Oaki, J & Adachi, S 2011, Decoupling identification method of serial two-link two-inertia system for robot motion control. in IFAC Proceedings Volumes (IFAC-PapersOnline). PART 1 edn, vol. 18, pp. 14359-14366, 18th IFAC World Congress, Milano, Italy, 11/8/28. https://doi.org/10.3182/20110828-6-IT-1002.00982
Oaki, Junji ; Adachi, Shuichi. / Decoupling identification method of serial two-link two-inertia system for robot motion control. IFAC Proceedings Volumes (IFAC-PapersOnline). Vol. 18 PART 1. ed. 2011. pp. 14359-14366
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