ANALYSIS AND CONTROL OF A WATER HYDRAULIC MANIPULATOR FOR ITER DIVERTOR REMOTE MAINTENANCE

Authors

  • Likui Zhai Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland
  • Tapio Virvalo Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland
  • Jouni Mattila Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland
  • Hannu Saarinen Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland and VTT Technical Research Centre of Finland, Tampere, Finland

Keywords:

hydraulic manipulator, coupling, kinematic model-based decoupling, vibration mode analysis, ITER

Abstract

This paper focuses on the analysis and control of a water hydraulic manipulator, which is specific for the International Thermonuclear Experimental Reactor (ITER) cassettes’ (each weighing 10 tonnes) maintenance tasks. The manipulator comprises a closed-chain main body and an open-chain end-effector. Following a systematic way of analyzing differential kinematics and vibration modes, it is revealed that from a control point of view the manipulator faces two main restrictions. The first one is that the closed-chain structure degrades tracking performances, rising from kinematic coupling. Secondly, as the end-effector drives a very high inertial load instead of a gravitational load, small actuators are used, resulting in low system natural frequency and damping. To solve the first issue, a kinematic model-based decoupling controller is designed. Moreover, to improve the steady-state accuracy in spite of low frequency and damping, acceleration feedback is adopted, achieving higher damping and position loop gains. Experimental results show that decoupling controller brings five times smaller tracking errors, while acceleration feedback controller reaches three times better accuracies than proportional controller. This study also confirms that in spite of using commercially available water hydraulic components, the achieved positioning accuracies and dynamic behavior are competitive with oil hydraulics.

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Author Biographies

Likui Zhai, Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland

Likui Zhai Born in Xintai, China, 1981, he received his BS and MS in mechanical engineering from Nanjing University of Sci & Tech (China) in 2004 and Zhejiang University (China) in 2006 respectively. He is now a postgraduate student in Tampere University of Technology (Finland). His main research fields are modelling and control of electrohydraulic servo system.

Tapio Virvalo, Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland

Tapio Virvalo He received his MS in mechanical engineering from Helsinki University of Technology, Finland in 1967, and PhD degree from Tampere University of Technology, Finland in 1995. He is presently as the professor of machine automation in Department of Intelligent Hydraulics and Automation (IHA) at Tampere University of Technology. His current research interests are motion control, especially, in fluid power applications including pneumatics and water hydraulics. His long term interests have also been in mechatronics and control engineering.

Jouni Mattila, Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland

Jouni Mattila He received his PhD degree (2000) in mechanical engineering from Tampere University of Technology. At present he is a senior researcher and project manager of FUSION/ DTP2 in Department of Intelligent Hydraulics and Automation (IHA) at Tampere University of Technology. His research interests have been in robotics and control engineering.

Hannu Saarinen, Department of Intelligent Hydraulics and Automation, Tampere University of Technology, Tampere, Finland and VTT Technical Research Centre of Finland, Tampere, Finland

Hannu Saarinen Born in Finland, 1967. He received his MS (1993) in mechanical engineering from Tampere University of Technology. Currently he is a senior research scientist working at the ROVIR team of VTT, where he is coordinating the tasks for designing and developing CMM control software. His scientific interests include robotics, virtual reality and real-time control systems.

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Published

2010-03-01

How to Cite

Zhai, L., Virvalo, T., Mattila, J., & Saarinen, H. (2010). ANALYSIS AND CONTROL OF A WATER HYDRAULIC MANIPULATOR FOR ITER DIVERTOR REMOTE MAINTENANCE. International Journal of Fluid Power, 11(1), 47–59. Retrieved from https://journals.riverpublishers.com/index.php/IJFP/article/view/488

Issue

2010: Vol 11 Iss 1

Section

Original Article