Accurate Trajectory Control of an Electro-Hydraulic Servomechanism with a Nonsymmetrical Cylinder

• Published in: Hydraulics & Pneumatics Vol. 16; no. 7; pp. 522 - 529
• Main Authors: AWA, Keizo, ARAI, Yasuhiko, KURATA, Tadao
• Format: Journal Article
• Language: Japanese
• Published: The Japan Fluid Power System Society 1985
• ISSN: 0286-6900; 2185-5285
• DOI: 10.5739/jfps1970.16.522

This paper deals with the "Continuous Path" control method of a servomechanism with an electro-hydraulic servo valve and a nonsymmetrical cylinder. The nonsymmetrical cylinders have nonlinear characteristics such as piston displacement drift and a difference in speeds of the reciprocating motion due to their nonsymmetrical structure. Therefore, the application of an optimal servo system to a nonsymmetrical cylinder is difficult by reason of its linear theory. We have eliminated the nonlinearities from this cylinder system by utilizing the velocity feedback method. Experimental results suggest that the characteristics of the nonsymmetrical cylinder system compensated by velocity feedback are identical with the characteristics of the symmetrical cylinder system regarding the static and dynamic characteristics. In order to realize accurate CP control, an error system is applied to this compensated system. Therefore, it is verified from experimental results that the adoption of this optimal servomechanism serves to eliminate the position deviation, velocity deviation and acceleration deviation together in the steady state. Furthermore, as the parameters of the performance criterion can be denoted by physical coefficients, the relation between these coefficients and the characteristics of this optimal servo on the basis of computer simulations is indicated by using figures. Consequently, the characteristics of this optimal system can be clearly recOgnized, and designed simply.