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Control of a Hydraulically Actuated Mechanism Using a Proportional Valve and a Linearizing Feedforward Controller

by Dobchuk, Jeffery William

Abstract (Summary)
A common problem encountered in mobile hydraulics is the desire to automate motion control functions in a restricted-cost and restricted-sensor environment. In this thesis a solution to this problem is presented. A velocity control scheme based on a novel single component pressure compensated ow controller was developed and evaluated.

The development of the controller involved solving several distinct technical challenges. First, a model reference control scheme was developed to provide control of the valve spool displacement for a particular electrohydraulic proportional valve. The control scheme had the effect of desensitizing the transient behaviour of the valve dynamics to changes in operating condition. Next, the pressure/flow relationship of the same valve was examined. A general approach for the mathematical characterization of this relationship was developed. This method was based on a modification of the so-called turbulent orifice equation. The general approach included a self-tuning algorithm. Next, the modified turbulent orifice equation was applied in conjunction with the model reference valve controller to create a single component pressure compensated flow control device. This required an inverse solution to the modified orifice equation. Finally, the kinematics of a specific single link hydraulically actuated mechanism were solved. Integration of the kinematic solution with the flow control device allowed for predictive velocity control of the single link mechanism.

Bibliographical Information:

Advisor:Burton, Richard T.; Crowe, Trever G.; Dolovich, Allan T.; Fotouhi, Reza; Nikiforuk, Peter N.; Schoenau, Greg J.; Silva, G.

School:University of Saskatchewan

School Location:Canada - Saskatchewan

Source Type:Master's Thesis

Keywords:predictive control off highway equipment hydraulics

ISBN:

Date of Publication:08/25/2004

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