| The electro-hydraulic load simulator(EHLS) is mainly used to simulate theexternal load acted on the tested system in different conditions in the experimentof detecting and checking the performance of tested system under actual load.EHLS can be used to carry out forecasting experiment in the experimentalcondition rather than the real field tests. Through the simulation experiment, thetesting conditions can be simplified, the development period can be shortened,the development cost can be saved. And with the increasing of loading precisionof EHLS, the reliability of experiment and the success rate of projects alsobecome higher. EHLS is mainly used in the side of aerospace and the nationaldefense military. However, national security is critical to a country, and it alsoidentifies the importance of studying the load simulator. The load simulatorsystem needs to load the tested system being moving, and it is rigidly connectedwith the tested system. So the load simulator system is a strong coupling systemin which position and force are mutual interference. All the time, the critical ofstudy of load simulator is to reduce the surplus force.With the development of electric hydraulic technology, today, the most westudy about load simulator is EHLS. Up to now, There are a variety of compensation schemes to reduce the surplus force. It is mainly devided into twoparts: the structure compensation and the control compensation. For structurecompensation, various facts such as synchronous compensation method’complex structure and huge cost, accumulator correction method reducing thesystem bandwidth, synchronous reverse compensation method being difficult torealize, result its not being used widely. However, the control compensationmethod only can partly eliminate the surplus force for the control part alwaysowning higher-order control link. For all the solutions existing having their ownlimitations, a new method is proposed. A Specialized pump speed loop is addedto the original EHLS which is only controlled by one valve. The pump speedloop controls the speed of load simulator independently so that speed controland force control could be decoupled in the EHLS. Considering the performanceand cost of EHLS, the variable frequency speed control circuit of inductionmotor is selected. Then the simulation model is built on the basis ofSimulationX. First of all, the pump speed loop model should be built anddebugged. Its performance indexes are achieved by analysis the simulationresult of the pump speed loop model. Then the model of originalelectro-hydraulic load simulator only controlled by one vavle is established andits control parameters manually adjusted to the best. After that the pump speedloop should be paralleled to the two oil port of the hydraulic cylinder of EHLSand maybe micro adjust is needed. Having been adjusted to the best state, theintegral EHLS model using multiplexed pump-valve control is finished. Thenwe begin analyze the surplus force. According to the simulation results, it isproved that the new method can effectively eliminate the surplus force.Especially when the motion frequency of the tested system is1Hz, the surplusforce was almost completely eliminated. After the analysis of surplus force,according to load force being constant or not and the tested system beingmoving or not, it is divided into four cases to analyze the dynamic tracking performance of EHLS. The simulation results show that, no matter in what kindof working conditions, the EHLS using multiplexed pump-valve control showsits good load performance all the time.This paper put forward using multiplexed pump-valve control method toenhance the load precision of EHLS, and its feasibility is verified by theoreticalanalysis and simulation. Which further promotes the development of EHLS inour country. |
PDF Full Text Request