ONLINE SYSTEM IDENTIFICATION OF HYDRAULIC SERVO ACTUATORS BY THE SELF-EXCITED OSCILLATION METHOD (APPLICATION TO ANGULAR VELOCITY CONTROL SYSTEM)

Authors

  • Takayoshi Ichiyanagi National Defense Academy, Department of Mechanical Systems Engineering, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, JAPAN
  • Takao Nishiumi National Defense Academy, Department of Mechanical Systems Engineering, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, JAPAN

Keywords:

hydraulic servo actuator system, system identification, limit cycle, second order transfer function

Abstract

It has been well known that hydraulic servo actuators can often be approximated with a standard second order transfer function when the controller is designed for these systems. Earlier research developed a simple method utilizing the self-excited oscillation caused from the hydraulic servo actuators to directly estimate the dynamic parameters such as the damping ratio and undamped natural frequency. The advantage of this method is an online identification ability that is able to identify these parameters while the operation conditions are continually changing. Although this method was confirmed to be very useful, it is available only when the spool valve is close to the neutral position, which corresponds to the operation of position control systems. In the practical situations, the spool valve sometimes operates at displaced position from the neutral center position such that a hydraulic motor speed is controlled. This paper proposes a revised self-excited oscillation method for this system. The experimental works are conducted by giving the various system pressures and angular velocities so as to validate the method. The resulting frequency characteristics of these identified transfer functions are then compared with those of the measured data by the frequency characteristics method. In addition, in order to demonstrate the effectiveness of the self-excited oscillation method, the dynamic parameters of two practical devices such as a motion seat and aircraft tail surface control simulator are identified and compared with the results from the frequency response method.

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Author Biographies

Takayoshi Ichiyanagi, National Defense Academy, Department of Mechanical Systems Engineering, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, JAPAN

Takayoshi Ichiyanagi Born in Tokyo. He received his doctor degree in Mechanical Engineering from Kanagawa University, Japan in 2001. Since then he works as an assistant professor of mechanical systems engineering at National defense academy of Japan. His research areas are noise reduction of fluid power system, system identification, development of fluid power components.

Takao Nishiumi, National Defense Academy, Department of Mechanical Systems Engineering, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, JAPAN

Takao Nishiumi Born in 1953 in Tokyo. He is a professor at National Defense Academy of Japan in the Department of Mechanical Systems Engineering. He published the books “Hydraulic Control System” and “Fluid Mechanics for Beginners” in Japanese.

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Published

2011-08-01

How to Cite

Ichiyanagi, T., & Nishiumi, T. (2011). ONLINE SYSTEM IDENTIFICATION OF HYDRAULIC SERVO ACTUATORS BY THE SELF-EXCITED OSCILLATION METHOD (APPLICATION TO ANGULAR VELOCITY CONTROL SYSTEM). International Journal of Fluid Power, 12(2), 5–14. Retrieved from https://journals.riverpublishers.com/index.php/IJFP/article/view/465

Issue

2011: Vol 12 Iss 2

Section

Original Article