Abstract
This paper presents the discrete state space mathematical model of the end-effector in industrial robots and designs the linear-quadratic-Gaussian controller, called LQG controller for short, to solve the low frequency vibration problem. Though simplifying the end-effector as the cantilever beam, this paper uses the subspace identification method to determine the output dynamic response data and establishes the state space model. Experimentally comparing the influences of different input excitation signals, Chirp sequences from 0 Hz to 100 Hz are used as the final estimation signal and the excitation signal. The LQG controller is designed and simulated to achieve the low frequency vibration suppression of the structure. The results show that the suppression system can effectively suppress the fundamental natural frequency and lower vibration of end-effector. The vibration suppression percentage is 95%, and the vibration amplitude is successfully reduced from ±20 μm to ±1 μm. The present work provides an effective method to suppress the low frequency vibration of the end-effector for industrial robots.
Highlights
The problem of vibration suppression has traditionally been a research hotspot of scholars, and studies on vibration control are increasing year by year [1]
Due to the advantages of lightweight, large output, fast response speed and high strain sensitivity, piezoelectric materials have been widely used for vibration control and other occasions [2].What is more, a piezoelectric patch can be attached to the cantilever structure which is the most used mechanism in the area of industrial robots and the most simplified model for transportation robots [3,4]
Piezoelectric material was introduced into the beam vibration by Crawley and Luis [5] for the first time, and subsequently, it was widely used in robot structure
Summary
The problem of vibration suppression has traditionally been a research hotspot of scholars, and studies on vibration control are increasing year by year [1]. Using piezoelectric materials for vibration suppression of beam structures has been widely studied. Dadfarnia [14] used a piezoelectric (PZT) patch as actuator which is bonded on the surface of the flexible beam to suppress residual vibration. When using PZT patch as actuator, in order to achieve vibration suppression, some people have studied the model identification identification of the system. Chen et al [28,29] studied an adaptive method and gave the relationship between the low frequency components andcomponents the modal order. Some identification models came frommodels experiments, proportion of low frequency and the modal order. Some identification came such [30].
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