Experiment On The Speed Control Methods Of Tower Crane's Working Mechanism

With the demand of construction and the development of mechanization, tower crane is one of most important and indispensable construction machinery in the port or construction site, and its security, stability, and efficiency is made high requirements. But by the nature of its work, Tower crane needs starting and braking frequently, especially in the heavy lifting and luffing processtion, mading itself impact and shock. All of the above are not only to bring tower structural damage, but also risk factors, resulting in production accidents. Meanwhile, when using the traditional control mode, luffing car needs moving back and forth many times to accurately place, increasing impact once more to bring greater potential hazards. Therefore, traditional speed control methords are no longer satisfied the conditions of modern construction, and it is difficult to obtain better control performance.Fully considered the above factors, as mechanical structure of the tower crane has been identified, through the combination of the dynamic characteristic and control system design, frequency speed control system was designed to improve the performance of the tower crane.First, according to dynamics analysis of crane's luffing car and lifting mechanism respectively, dynamic mathematical model was established, and the relationships between the kinematics paramater of infuencing crane's vibration, shock and location, and the control were also found. Then dynamics mathematical model converted into the transfer function, adapted to the whole frequency conversion control system, with which, a closed-loop control system was built. Finally, Matlab Simulink software modules were applied to design respectively incremental PID and the BP neural netwok PID control system. Through simulation, comparative analysis of the tower crane's performances was made.Building crane's luffing and lifting system experiment platform of variable frequency speed-governing systerm, did the experiment. Analyzing the required modules, closed-loop frequency conversion control system was established with personal computer as control center, through the 232/485 conversion module communicating with inverter, sending digital signal, and also based on PCI-8000 series data acquisition card and senser as the feedback. Meanwhile, variable frequency control methods were designed with the PC controller. The conventional PID and neural network PID control experiments were did respectively, drawing the conclusion that neural network control system could get a better performance for tower crane.