The Application of Optimising Control to an Hydraulic Drive

Abstract

An optimising control system has been designed for application to an hydraulic transmission. Optimisation is achieved by an extremum control system which seeks continuously to adjust the transmission to a point of maximum efficiency. The form of extremum control system employed was one developed from the technique of using a periodic perturbation as a probing signal. In these particular circumstances a number of distinctive features have been introduced as modifications of the technique. The performance of the system was investigated theoretically and it was shown that an optimum design exists. In this the need for rapid adaptation was weighed against the sensitivity of the system to changes of the operating conditions. A system designed to this optimum requirement has been tested experimentally. The results obtained have indicated that the extremum control system is capable of competing only with slow changes in the operating conditions. This is seen to be an inherent limitation of the technique, but some features of the particular form of hydraulic system used were shown to be disadvantageous to this type of control. In the design of the experimental equipment two significant subsidiary problems have been studied in detail. It was necessary to develop a novel form of control system to regulate the output speed of the transmission. There was also the need to obtain a continuous measurement of the mechanical efficiency and this was met by the development of a unique form of measuring system.