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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synchronous motion of two-cylinder electro-hydraulic system with unbalanced loading

Liu, Li-Chiang 08 July 2002 (has links)
Abstract Traditional synchronous motion control of a multi-cylinder system was always achieved by using hydraulic loops design and constrained linkage mechanisms. Therefore, these control methodologies always have many disadvantages, such as inaccuracy, cost expensive, and huge volume of the equipment, and so on. In this paper, the nonlinear control strategy was proposed to control the proportional directional valves of two-cylinder electro-hydraulic system in order to achieve synchronous motion under the consideration of unbalanced and uncertainty loading. Besides, in order to explore influence of different loading to the system, two-cylinder mechanism was designed to have individual loading device without any hardware constrain between two pistons. And the maximum loading capacity for one piston is 210kg. Due to the highly complicated coupling effect of internal pressure and flow rate for two cylinders, in this paper, feedforward controller with three fuzzy controllers was designated to overcome the problem of synchronous motion. In the first, the feedforward controller of each cylinder is developed to track a desire velocity trajectory. Then, the fuzzy control of each cylinder was specified to improve the individual tracking performance. Finally, the third fuzzy controller was performed to compensate the coupling effect of two-cylinder in order to progressively improve the performance of synchronous motion. According to the experimental results, the proposed control strategy for synchronous motion of two-cylinder system was verified and the maximum synchronous error of the total system was controlled to be within 10mm. Keyword: synchronous motion; proportional directional valve; fuzzy controller; feedforward controller

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