Liquid level switch computer control system introduction

First, the purpose of the experiment
1. Familiar with experimental instruments to understand the two types of water level control systems.
2. Master the working principle, control process and control function of a control system.
3. Write a two-position control program, predict the processing procedure according to the deviation value, adjust the inlet valve opening procedure according to the deviation value, so that the liquid level is controlled at 20cm, the overshoot is not more than 10%, and the steady state error is 5%.
4. Three block diagram programming experiments (according to the deviation value prediction processing, adjusting the opening degree of the inlet valve according to the deviation value, determining the D/A value according to the deviation value algorithm) determining the D/A value experiment numerical simulation selection according to the deviation value algorithm The coefficient is such that the liquid level is controlled at 20 cm, the overshoot is not more than 10%, and the steady state error is 5%.
Second, the experimental equipment
Hardware: process control experimental device (cabinet), multimeter, EasyArm2200 development kit, experimental cable, software: ADS1.2 integrated development environment.
Third, the experimental principle
Two types of temperature control systems
The two-position control is a simple one in the position control law. The controlled object of this experiment is the water tank, and the controlled amount is the tank level. The so-called two-position control is essentially a typical nonlinear control. The actuator has only two limit output states: "on" or "off". Therefore, this controller is called a two-position regulator. In theory, our regulating valve is not suitable for two-position control, and a more suitable electromagnetic can be used. Valve (only open and closed) control, but due to the hardware environment of the experimental equipment, we choose the regulating valve to simulate the solenoid valve operation, the simulation process: we can make the regulating valve in two states, one is to adjust the valve opening It is %0 (equivalent to the solenoid valve is off), and the second is that the valve opening is 10% (equivalent to the solenoid valve is open), where 10% is not fixed, you can choose, but the smaller the valve opening, ** The greater the degree.
The working principle of the system is that when the controlled liquid level measurement value HP=H is smaller than the given value HS, that is, the measured value < given value, and when e=HS-HP≥dF, the regulating valve is in the opening state. As the liquid level H increases, HP also increases, and e correspondingly becomes smaller. If H is higher than the given value, that is, HP>HS, e is a negative value. If e≤-dF, the two-position regulating valve is in the closed state. Because this control method has impact, it is easy to damage the components, only in It is used only for systems that do not require high quality control.