Research On High Confining Pressure Loading Control Based On STM32 And Servo Motor

In recent years, water resources and hydropower engineering has a great development. Many large reservoirs are in the phase of being designed and constructed. Earth and rockfill dam frequently is selected owing to its strong earthquake resistance and fast construction speed. The number explosion of earth and rockfill dams inevitably brings about many problems of technology. Especially the design parameters of dam foundation are hard to measured, and they are urgent problems for construction side. Currently the parameters of dam foundation are usually acquired by triaxial test in laboratory. But because of the factors of development period, funds and technology, the domestic market of triaxial apparatus is monopolized by foreign manufacturer, and in addition the dynamic performance and precision of homegrown triaxial apparatuses are hard to satisfy realistic demand. So a set of triaxial confining pressure loading system with high loading accuracy and good dynamic performance are urgently designed to satisfy the experimental and actual demand. Under the support of National Natural Science Foundation of China, a set of confining pressure loading system based on SCM and servo motor is developed by means of triaxial equipments in this paper to solve problems above, the research contents and methods of this paper are as follows:Firstly, concrete implementations of confining pressure loading device, water hydraulic technology and fuzzy control technology are introduced in this paper at great length. Based on the introductions, a general scheme is put forward, and relevant hardware circuits and mechanical parts are selected and designed.Secondly, vector control technology of PMSM is detailedly dissected in this paper, and then double closed-loop mathematical model of servo motor is established in d-q coordinate system. So a general mathematical model of confining pressure loading system is established. Based on the model, stability of loading system and adjustment of PID controller parameters with critical proportional band are analyzed and designed.Then, for the condition of nonlinear control targets and parameter variability of loading system, this paper tries to adjust the PID parameters with fuzzy control technology. Based on the fuzzy controllers and mathematical model, the new simulation system is analyzed by means of the Simulink tool kit. Finally, the fuzzy PID have stronger adaptation, better dynamic properties and higher control accuracy compared with conventional PID.Finally, upper computer human-computer interaction interface and codes of lower computer are debugged and designed in this paper by means of the software development platforms of Lab VIEW and RVMDK. Then the function relationship model between water pressure and piston displacement are measured, calibrated and fitted by the experiment. For two control modes of fuzzy PID and conventional PID, the loading system is respectively given the same input signal, experimental result indicates that fuzzy PID has higher holding precision, faster response speed and less overshoot (dropped by 20.7%), compared with conventional PID. In addition, the loading system can reach the high frequency of 5Hz, and attain the design goal at the beginning.