Experimental Study Of Tracking And Vibration Suppression For A 2R Flexible Manipulator By PZT Based On Fuzzy Control

Compared with traditional rigid robot, the flexible robot has a lot of advantages such as high speed, high carriage ratio, low power consumption and high precision, so as to improve the system structure and the overall performance. It has gradually become the research frontier since 1970s. However, the elastic vibration must be considered when the link is made flexible, as the existence of vibration has a great impact on the normal use of flexible robot, and sometimes even leads to instability of the system, resulting in terrible accidents. So it's very necessary and meaningful to carry out the research of vibration suppression of flexible links.After the vibration suppression methods for flexible arms are summarized and the main research results in home and abroad are described,a 2R flexible robot system is put into research, in which pieces of strain gauge are used as sensors and optical encoders as the motor position sensors. On the tracking and vibration suppression experiment platform, PZT plays the key part as the actuator to suppress the elastic vibration, and the servo motors are chosen to drive the robot arms. Then four tracking experiments based on fuzzy control by PZT to actively suppress the vibration of the flexible manipulator are carried out. The content of this paper is as follows:Firstly, the dynamics modeling of 2R flexible robot system is built with assumed modes method and a simulation is carried out by Matlab, making a theoretical preparation for the followed experimental study. Then a fuzzy controller and a PID controller are designed based on fuzzy theory and PID control technology. Secondly, the control system for the experiment is programmed by Visual C++ which is composed of several function blocks, such as graphic display, the target path planning, the closed-loop computation for servo motors, voltage deduction for PZT, the data transmission interface, data recording and the data preservation. The closed-loop computation for servo motors and the drive voltage of PZT are cores of the software. Then, the hardware system of the experiment structure is set up.Finally, using the well-built experimental devices, the fuzzy control method is adopted to produce a control voltage for vibration suppression and PID algorithm is introduced to compute the driving torque for joint tracking and tip tracking. Four tracking and vibration suppression experiments are carried out which are the joint tracking without load experiment, the joint tracking with load experiment, the tip tracking without load experiment and the tip tracking with load experiment. Based on the experiments, the effectiveness of the fuzzy controller and the PID controller are validated, and the effect of vibration suppression and its impact to the tracking characteristics are revealed. The experimental data shows that the PZT can suppress the elastic vibration significantly; the tracking accuracy and the driving performance are improved obviously, too.