Digital Controller Of Tire Endurance Testing Machine Hydraulic Servo System

In recent years, the overloading, overspeed phenomenon of middle and long distance logistics transportation cause a mass of early damage in tire usage, and bring a great threat for traffic safety. The appearance of tire endurance testing machine makes forecasting the tire quality ahead of schedule possible. The servo controller is the key part of tire testing machine, whose control precision directly influences the result of endurance test. Aiming at the insufficient of existing hydraulic control system of domestic tire testing machine, a digital control system based on MCU is proposed.By analyzing the practical work process of tire endurance testing machine hydraulic system, the digital control system which is designed in this paper is composed of digital controller and upper computer monitoring system. Servo controller is designed to accomplish the control of proportional servo valve, so as to realize the loading and speed control in the tire testing process. The upper computer monitoring system makes the observation of control results in the testing process easy.The core unit of the digital servo controller is MSP430F169 (16bits, TI corporation), which is rich in on-chip resources and has high interference rejection capability. Supporting by the lower computer software, the controller can accomplish processing and calculation of signals, and then its output realizes open-loop and closed-loop control of the servo valve. The isolated structure of power supply including analog linear power and digital switch power, and the measures for photoelectric isolation and shielding enclosure are all used to improve system interference rejection capability in the design of controller hardware. The software structure based on the combination of Super Cycle and Time Slice System has strong real-time performance and is simple in design; the piecewise PID control algorithm with multiple parameters is adopted in servo controller software development, and has got good effect in practice. The PC monitoring software used for setting and modifying and storing control parameters is developed by Visual Basic language, it can also realize working curves drawing and saving in the appointed path in BMP format.