Design On Controller Of Electro-hydraulic Proportional Direction Valve

The digital proportional direction valve amplifier in this passage is based onAT91R40008, the power drive circuit, Sensor amplifier circuit and other interfacecircuit are extened. In order to simplify the design of hardware circuit, and improvethe reliability of the system, many pecial integrated chips are used in the design. Onthe software design, this passage program on ARM bare machine, thus Improved theefficiency of the process, and reduced the redundancy of code.First of all, the properties of the proportional directional valve are analyzedbased on the technical documents, and then the relevant technology of theelectrohydraulic proportional controller is formulated. Besides, the overall hardwareand software solutions are designed. Then, each module of the hardware circuit isintroduced in detail, including the CPU module, power module, analog input module,power drive module, etc. Among them, the performance of the power drive circuit isthe key factors affecting steady-state and dynamic characteristics of proportionalcontroller. This design adopts the reverse unloading drive circuit, which improves thedynamic characteristic of the proportional electromagnet. The development ofsoftware includs the designing of ARM control program and PC parameterconfiguration software. This passage program on ARM bare machine, thus improvesthe execution efficiency of the program.Secondly, according to the characteristic of reverse unloading drive circuit,flutter signals in electro-hydraulic proportional control is studied in detail and theirsuperposition methods are also discussed, and its influence on hysteresis is verifiedby the experiments. It’s proved by simulation and experiments that the viscous forcewill change its value and direction while valve core doing reciprocating motion in thewhole stroke, and thus is the key factor that affects hysteresis and dynamic responsecharacteristics of the valve, however, it’s difficult to eliminate viscous force in thewhole stroke by superimposing fixed dithers to the valve coil. This paper adds fuzzyclosed-loop control of dither amplitude, the difference and second difference betweenset and measured values of dither amplitude are taken as the fuzzy controller’s input and the dither amplitude is modified in real time after fuzzy reasoning, on the base ofensuring the control precision, it dramatically decreases the hysteresis of theproportional direction valve, and effectively improves the dynamic responsecharacteristics in the whole stroke.Finally, a lot of performance test experiments on the controller are carried out onthe hydraulic valve testing platform in state laboratory of fluid of Zhejiang University.At the same time, a certain domestic controller is chosen to make contrastexperiments. The results show that the controller developed in this passage has goodcontrol performance both on dynamic response time and steady-state error.