Research On Vibration Control And Optimization Of Flexible Manipulator

Flexible manipulator has the advantages of high speed, high precision, high efficiency, low energy consumption and big payload mass ratio, and has been widely used in aerospace, advanced manufacturing, precision machining and positioning, etc. However, in the movement process of flexible manipulator, vibration caused by its flexible makes manipulator to be difficult to position accurately, so system performance will be affected seriously. In the actual operation of industrial, requirement on space precision and time indexes become more and more strictly, to the movement and position of system. Piezoelectric material is very important in research of vibration control and engineering application because of good performance of mechanical-electrical coupling. Therefore, it will be very necessary to investigate the vibration control of flexible manipulator and optimization configuration of piezoelectric sensors and actuators. In view of the above, this paper uses the piezoelectric elements as sensors and actuators, and mainly researches the system model, the time-frequency characteristics, optimization of piezoelectric elements and experimental verification, etc.Taking two-link flexible manipulator as research object, sensor/actuator equation of any size piezoelectric is obtained based on the direct and converse piezoelectric effect of piezoelectric material. Using assumed modes method and Lagrange equation, general coupling dynamics equation which contains a plurality of piezoelectric ceramics sheets is deduced. Dynamics model is simulated by Matlab software, and the modes, angle and elastic deformation characteristics in time domain are researched. Vibration signal of simulation is analyzed in frequency domain, which can research internal frequency component of the system. From the view of time and frequency domain, it's verified that flexible manipulator system is a high coupling, nonlinear, time-varying system.Feedback controller of two-link flexible manipulator system is established. From two respects of vibration control effect and energy consumption, optimizing configuration of sensors/actuators is considered. The minimizations of system vibration energy and input control energy of actuator are adopted as optimization criterions which are combined by the weight coefficient method, and optimal objective function is established. For number and placement, size and placement situation of piezoelectric sensors/actuator, optimization models are solved by genetic algorithm toolbox in Matlab software. Finally simulation models of piezoelectric flexible manipulator optimization control system are established, and optimized configuration results are contrasted and analyzed. Simulation results show that the optimization method can effectively restrain vibration of flexible manipulator. Experimental device of two-link piezoelectric flexible manipulator system are researched. Two arms motion in a horizontal plane which is controlled by motion control system of stepping motor. Vibration signals are collected into the computer control system by PCL-818L acquisition card, then Outputted to piezoelectric driving power by PCL-726 card. Piezoelectric actuators pasted in arm 2 are driven. Finally based on the experimental system, the following experimental verification works, which contain time and frequency domain characteristics of flexible manipulator, optimized configuration results. The experimental results verified the correctness of system theoretical modeling and the reliability of analysis method of time and frequency domain, and the results also indicated that vibration of flexible manipulator can be restrained effectively after optimized configuration.