Design Of Leveling Control System For A High Lift Platform Based On PLC

Aerial work vehicle is mainly used for construction, fire control, rescue and disaster relief, installation, maintenance and other work. As the major projects including electric power, environmental protection, high-speed train, high-rise buildings have been started constructing, the growing demands for high altitude working vehicles are more and more large. In addition, high-rise residential rescues also need those aerial vehicles. Currently in the national market aerial vehicles with operating height more than 60 m are imported, special and expensive products, and the market has only a small amount, which can’t meet the needs of constructions and rescues. It is to put forth a design concept to add a work platform with its own control apparatus to the local-made auto-cranes for a higher reach, which is of great meaning in shorting product developing cycle, lowering researching coast, improving equipment manufacturing industry level.The concept placed PLC as a kernel for control, hydraulic cylinders as actuating units, angular sensors as the dialog box, to have designed an electrohydraulic leveling control system there-for which can realize such functions as auto leveling, remote control, and put up warning in state. To ensure no motion interference during leveling process between such agencies as auto-crane’s body(including outriggers), slewing gear, luffer, hanging arm stretching device, leveling mechanism and working platform, the models of these agencies are built and the motion simulations are completed by using Pro/Engineer software. Mathematical models of control system are established, based on which the system transfer function is arrived, then the digital simulation and control strategy of the system are studied under the condition of MATLAB/Simulink software. By comparing the simulation results of the PID controller and the fuzzy-PID controller, it is showed that: the fuzzy-PID controller makes the system’s steady-state error, overshoot and rise time meet the design requirements. In this thesis hardware components selection and circuits are designed by using Protell99 software, and leveling control system programs are written by utilizing GX Developer software.The experiment system is set up, and the debugging and program optimization are carried out in the laboratory, and the field loading test is carried out in Shijiazhuang city transportation company. Two modified prototypes of the system have been practically used in a 60 m height ball type tank for coal storage as located in QingYuan Power Plant, HeBei Province, with better results to indicate its broad prospect in application. Compared with foreign high altitude working vehicle, this design is more advantageous in manufacturing cost, productive cycle; compared with single function crane, this design also has two functions of crane and aerial vehicle at the same. In addition, this technology also can be applied in modification existing truck crane of large transportation companies and construction units to constitute different heights aerial work vehicle, which has a broad application prospect in the market.