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Unformatted text preview: PositionControlforLawsforElectromechanicalActuator Maurice Fadel LaboratoiredElectrotechniqueetdElectroniqueIndustrielle fNPT/ENSEEIHT/UMR C.N.R.S. 2,rueCharlesCamichel,31071 TOULOUSE CEDEX, France [email protected] Abstract - Various methods in order to control an electromechanical actuator position are presented here. The device undergoing of the significant variation of load we focalisemore particularlywith the robustcharacter ofthese control laws. This paper proposes comparative performance fora particularprofileincludingdifferentmotions rangeand variation of loads. The solutions suggested (RST regulator, state space feedback and series regulators) are tested on an experimental model. The device with teaching vocation is made up by one plate making itpossibleto move loads ina rectilinearway bythemeans screwand nutputinrotationby a motor supplied with a static converter of 4 quadrants structure. Indexterms Control law,RST regulator,seriesstructures, statespacefeedback,electromechanicalactuator. 1.INTRODUCTION The axis control requires an utilisation of control laws effective and defined in adequacy with the function desired.Itisthusasforthepositioningofloads it becomes important todefinetheregulatorswithmethod sotoobtain thelevelofperformancewished.Forthistypeofoperation itisnecessary toconsidertheloadvariationandto implant therobust function.For this we propose to defineseveral controlstrategieslikeRST regulation,feedbackstatespace control or cascade scheme with series regulators and to compare theperformancesobtained formotions and loads of various values. We focuse an interest to obtain a behavior limiting the transitory overshoot. The studied device (fig. 1)can transport variable loads in the range from0to50kgatdistanceswhichcangountil+/-30cm. Fig. 1 Electiomechaniicalactuator The control isensured by adigitalcomputer oftype PC integratinganInput/Outputchartand isprogrammed inC language. Measurements available are theposition ofthe rectilinearloadaccording totheaxisand thespeedofthe motor. II. MODELISATIONOF SYSTEM Iffinemodelling forrealisticsimulation allowing astudy of various efforts requires an investigation being able to becomecomplex, themodelbasedcontrolisverysimpleto work out. We here will expose several types of models based control allowing to define laws with different approaches.Fig.2representsthestudiedsystem. Additional Ioad Brac screw DcMotor-A . N u t . . . Fig.2System The DC motor iscontrolledwithcurrentcontrolloopand theperformancesaresuch aswillbe abletoconsiderthat theelectromagnetictorquecreated isdirectlyproportional tothecurrentofreference. In realitythisremains true as long as the supply voltage is sufficient to impose the desiredcurrent....
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