Accurate Measurement Of The Gap High Degree Between Drop-weight And Top Of Earth-machinery In Test Bench Of FOPS

Test bench of FOPS can test level and shape of rigid deformation of the earth-machinery cab after it hit by rockfall, to provide data and program that it can support acceptance and improvement the FOPS. But the level of automatic of the testing equipments of our school Earth-machinery Testing Lab is low, it is not only threat to the testing personnel safety but also low the accruement of the testing result, it difficult the data acquisition and the proposition of the improvement program. For these reasons, our proposed the engineering requirements that the equipments im-provement involved in this paper.Improvement of equipment of this thesis is as follows:1. Unchange asynchronous motor;2. Compose the sensor which measurement the length of distance of that tight-wire movement with base support and pulley with photoelectric encoder;3. Sent the pulse signal that generated by the photoelectric encoder into the MCU and processing;4. Sent the signal that processed by the MCU into the asynchronous motor driver, drive the motor enhance the drop-weight to the designated height;The thesis include the hardware design, software design, VVVF regulator control research and so on, the following sections will be expanded in detail description.Taking the MCU STC89C516RD+ as the core control element; cooperate with the external auxiliary circuit, include with photoelectric encoder interface circuit, keyboard interface circuit, LCD driver circuit and VVVF regulator drive circuit etc. Which the sensor measure the length of distance of that tightwire movement select incremental photoelectric encoder; Chose keyboard matrix as the input device; it is the typical circuit of the keyboard of MCU at present; Chose ET-G12232 as the LCD module in display system; Because MCU can not drive the three-phase alternating current motor, select AC motor drives interface circuit cooperate with VVVF regula- tor as the drive circuit of motor.Software portion of this thesis include photoelectric encoder counting program, keyboard matrix scanning and encoding program, LCD driver program, three-phase AC motor driver and control program and so on. Photoelectric encoder count program is mainly to count the input pulses of photoelectric encoder; Keyboard scanning pro-gram is mainly to scan the electric level when the key is pressed and code it to the character encoding and stored the corresponding data in the register for use it to proc-ess the corresponding data; LCD drive program show the data that from the keyboard in the appropriate location of the LCD, and real-time show the high degree of varia-tion of the drop-weight; Three-phase AC motor driver control the AC motor to start and stop and the real-time speed according to the control algorithm program; Control algorithm program is under the calculation of the corresponding input data to optimize the control of the VVVF regulator.The thesis also carry out study on the VVVF control method. Study on the con-trol method of variable frequency speed control, first must establish the mathematical model, and establish the mathematical model for the controlled object namely three-phase asynchronous motor and VVVF.The PID control is the mainstream control method recently, so according to the mathematical model that established in the thesis, we chose the PID as the controller, analyze and calculate the parameter of PID controller to achieve the satisfactory re-sults, and validated by Matlab simulation.