Hydraulic Position Control on a Base without Sufficient Stiffness

• Published in: Transactions of The Japan Hydraulics & Pneumatics Society Vol. 31; no. 2; pp. 31 - 37
• Main Authors: MORIYAMA, Shinichirou, SUZUKI, Katsumasa
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Fluid Power System Society 2000; 社団法人 日本フルードパワーシステム学会
• Subjects: Construction machinery; H-Infinity control; Hydraulic actuator; Insufficient stiffness; Optimal control; Position control; Robust control; Servo mechanism
• ISSN: 1343-4616; 2185-5293
• DOI: 10.14888/jfps1998.31.31

Many building-site scaffolds on which construction equipment, e.g., power shovels, are used, lack sufficient stiffness.Heavy objects are often handled at these sites. When a load is moved on such a base, vibration can occur due to insufficient stiffness of the base, and the positioning control is not sufficient. The objective of this study is to develop an appropriate positioning control method that can be used even in the presence of the oscillation effect of the base. In this study, the base without sufficient stiffness is modeled by a vibration system with one degree of freedom. The base on a flat foundation is supported by a spring and (or) damper. Since hydraulic systems are usually used to obtain easily high power in construction equipment, an electro-hydraulic servo system is used for the positioning control in this research. In this research, the effect of the base without sufficient stiffness on positioning accuracy and settling time is investigated, and basic data for realizing high-speed and high-precision positioning control with a reduction in oscillation under such conditions are provided. Optimal control is introduced. Using this optimal control can reduce the vibration and settling time. Next, the H -Infinity control method is examined. The condition of the base without sufficient stiffness is considered that the parameters of the model are varied from the nominal model of the fixed base, and H-Infinity control is applied. It can be clarified that the H-Infinity control is a robust control method for such conditional changes. Three different control methods are compared by testing the step responses of each control method.