Contents >> Engineering Mathematics >> Control Systems >> Dynamic Synthesis of Control System of Hydraulic Drive >> Conclusion

Control Systems - Dynamic Sinthesis - Conclusion


Problems of control by a power hydraulic drive of volumetric and throttle regulation with objective of maintenance of positioning of a cargo with the desired accuracy and the maximal speed have been considered. The executed analysis allows drawing the following conclusions.

Control process is divided into the two basic stages:
– so-called "rough" control providing the maximal speed within the limits of existing and imposed restrictions on phase coordinates and hit in some neighbourhood of a target point of positioning without use of feedback by position;
– so-called "precise" control providing high accuracy of positioning at small moving directly at a target point of positioning with use of the servo control system, closed by position.
The algorithms of the control realizing the first of specified control stages in which the basis two various methods can be used are developed:

– frequency ( the method of multiple periods of natural vibrations ), based on a choice of the period of control, multiple to the period of proper fluctuations of system «a drive – a load», allowing thus almost completely to eliminate them;

the method of the movement law planning , based on the fact that the first, proceeding from the desired boundary conditions is under construction polynomial dependence of the movement of the output link (the piston of the hydraulic cylinder) in function of time, and factors of a polynomial depend on time of control which is in turn defined by restrictions on the maximal pressure in the hydraulic system, admissible accelerations, limiting possibilities on expense of a working liquid; after that function of control by the hydraulic system is defined unequivocally by substitution of the planned law of movement and measured parameters in the mathematical model of the hydraulic drive.

More effective at the stage of "rough" control from the point of view of universality (invariance in relation to type and structure of the hydraulic circuit diagram) is the method of the movement law planning.
From the point of view of a received error of positioning of a cargo, maintenance maximal speed of system and dynamics of a hydraulic drive during control both algorithms are practically equivalent.
Received as a result of numerical experiment the error of positioning at the stage of "rough" control speaks of use in the control algorithms of more simple mathematical model in comparison with that which is laid in the program of the dynamic analysis of hydraulic systems HYDRA, and within the limits of the lead numerical experiment plays a role of analogue of the natural sample of hydraulic system.
Carrying out of similar numerical experiments has appeared methodologically justified as has allowed to establish, first, possibilities of investigated control algorithms at use during their synthesis of the most simple mathematical parities, and secondly, to simulate a deviation actual from modeled both due to more complex interrelations, and as a result of variation of some parameters of hydraulic system during work.
Carried out researches have shown, that for realization of the considered algorithms of control by a power hydraulic drive availability of the appropriating measuring and computing equipment possessing high speed and reliability is necessary. Besides the operating program, realizing those or other algorithms of control, including the analysis of current and emergency conditions of system is necessary. The last is possible at availability of effective algorithms and programs of modeling and the dynamic analysis of mechanisms and the drives similar to program HYDRA.

< Previous Contents Next >