Papers by Keyword: Micro-Positioning

Abstract: Piezoelectric (PZT) material is widely used to drive micro-positioning platform, but the energy density of PZT is low, which restricts the application of PZT micro-positioning platform. In order to overcome its disadvantages, A kind of new micro-positioning platform actuated by giant magnetostrictive material (GMM) was presented in the paper. Based on integrated optimization method, structure designing, magnetic circuit designing and temperature control designing were carried out. The dynamic performance of GMM micro-positioning platform was simulated, and simulation result shows the designing is feasible. The prototype was manufactured, and the measurement system was set up. The experiments on the platform were carried out, and experiment results show that the platform has good output performance with positioning accuracy of ±0.03μm and load capacity of 50kg, and can meets the requirements of large-power system.

Abstract: In this paper, a smart structure for the micro position control is proposed using the piezo stack actuator. The smart structure is comprised with PZT based stack actuator, mechanical displacement amplifier and positioning devices. Based on the bridge-type flexural hinge mechanism, a displacement amplifier is designed and integrated with a piezo stack actuator to produce a desirable positioning stroke of the device. In order to achieve the high precision control performance in a positioning device, a stick-slip phenomenon should be suppressed in contacting surfaces of the device, which is generally indispensable in the mechanically connected systems and particularly obvious for the micro-scale system. Therefore, the stick-slip model is enhanced by theoretically calculating the static friction based on the statistical rough surface contact model. Then, a PID feedback control algorithm with the developed stick-slip model is formulated for achieving accurate positioning of the device. Using the proposed smart structure, simulations of precise position control under the representative operating condition of positioning are conducted to demonstrate the stick-slip suppressing and micro positioning performance.

Abstract: In this paper, a stick-slip compensation for the micro-positioning is presented using the statistical rough surface contact model. As for the micro-positioning structure, PZT (lead(Pb) zirconia(Zr) Titanate(Ti)) actuator is used to drive the load for precise positioning with its high resolution incorporating with the PID (Proportional Integral Derivative) control algorithm. Since the stick-slip characteristics for the micro structures are highly nonlinear and complicated, it is necessary to incorporate more detailed stick-slip model for the applications involving the high precision motion control. Thus, the elastic-plastic static friction model is used for the stick-slip compensation considering the elastic-plastic asperity contact in the rough surfaces statistically. Mathematical model of the system for the positioning apparatus was derived from the dynamic behaviors of structural parts. Since the conventional piezoelectric actuator generates the short stroke, a bridge-type flexural hinge mechanism is introduced to amplify the linear motion range. Using the proposed smart structure, simulations under the representative positioning motion were conducted to demonstrate the micro-positioning under the stick-slip friction.

Abstract: For micro-positioning systems using piezoelectric actuators for precision grinding process control, sinusoidal command signals will be used and will give additional problems in comparison with the commonly used step signals due to the hysteresis effects, which require a good modeling approach. In order to avoid the discontinuity problem in obtaining the values of the piezoelectric constant, a new approach of direct mapping with polynomial fit is proposed. Theoretical and experimental studies are conducted and comparative studies are made. Compared with the single polynomial approach, the proposed method of direct mapping with polynomial fit is able to reduce the modeling error to 12.5%, which is 6.5% lower, and the problems in obtaining the values of the piezoelectric constant are avoided. The proposed approach is shown advantageous. Further studies are necessary to significantly reduce the modeling error.