Research And Design Of Speed Regulating System Of Current Meter Calibration Vehicle Based On Fuzzy Self-tuning PI Control

In this paper,the main content is the research and design of current meter calibration vehicle speed control system and the control algorithm.When using common PI algorithm for speed control system,there exist shortages that it is difficult for small overshoot and fast adjustment to balance with each other and setting multiple sets of PI parameters is always an hard work.So in this thesis,fuzzy self-tuning PI control algorithm plays the role of controller of speed loop to overcome the shortage of PI control so as to achieve high-efficiency and high-precision speed control system.This thesis is based on widely investigating current meter automatic verification platform and hydrology related calibrating standards all over the world.From the working principle of the current meter and the current meter calibration system,a overall design is done for the calibration system,including calibration vehicle controlling system,current meter velocity acquisition system,communication system between the vehicle and the console cabinet,water channel,rail and so on.Based on the above,detailed analysis and design are conducted for the calibration vehicle regulation system and its related supporting facility.Because the calibration vehicle's speed range is very big and the response of the speed is required smooth within the range,this thesis chooses DC speed regulation method for the calibration vehicle.In order to ensure the completeness and rationality of the speed regulation system,the selection of the DC motor is done.Meanwhile,estimating on related parameters of the speed control system is conducted with design and configuration of the Simens 6RA8025 DC speed regulator in the system.Because it is the basic condition for the calibration task to obtain more than one set of stable speed point to simulate different flow velocity,high precision and high efficiency control of calibration vehicle is the emphasis of this article.Because the dc double closed loop speed control system has excellent performance of speed adjustment,this paper adopts double closed loop speed control.Making use of typical type ? and ? system respectively to the current loop,speed loop,the two controller parameters are obtained.Through Matlab simulation,it is easy to obtain the response of the dc double closed loop speed regulation system.Due to the limiting effect joint in each of the output link in the simulation model according to the actual situation,it is difficult for the controller with fixed parameter P and I to meet the speed control requirements of rapidity,small overshoot and high precision.Meanwhile,the calibration vehicle needs to work at least 16 speed points,so there will be groups of corresponding parameters.Aimed at that the PI controller can't be automatically tuned and needs groups of parameters,this paper uses the fuzzy self-tuning PI control algorithm by adjusting proportional and integral strength of the PI controller in different stage.The algorithm makes the the rapidity and small overshoot in better balance in order to improve the calibration vehicle speed control performance.In the meantime,the quantization factor and scaling factor of fuzzy controller are optimized by the genetic algorithm to obtain the better control performance for the regulation system.Through the comparison simulation,overshoot significantly decreases from more than 10%down to less than 3%and the corresponding adjustment time is shortened by about 0.2s in high and low speed range after adopting the fuzzy self-tuning PI control compared with adopting the PI control,which verifies the fuzzy self-tuning PI control has better control performance than PI control.