Yunjian Ge

A method for measuring dynamic performance index of robot's multi-axis wrist force sensor

A novel method based correlation wavelet for online dynamic characteristic analysis and measurement of dynamic performance index of robot wrist sensor is developed in this paper. Based on the dynamic model of the force sensor, the simulations on the correlation wavelet method for extracting the IRF of wrist force sensor in two dynamic environments are presented. The simulation results show that the correlation wavelet method exhibits obvious advantages compared with the traditional FFT method, and the accuracy of the results is greatly improved. A test with cantilever under step excitation is carried out, the results obtained by using CWT method show that the method is effective and accurate. The way for generating step excitation automatically in robotic use is proposed for on-line dynamic characteristic analysis and measurement of dynamic performance index of robot wrist sensor. An example is given to illustrate the feature of the method. The method developed in the paper provides a new and effective way to measure the dynamic performance index of robot wrist force sensor, as well as other sensors.

A digital filter for application in robot wrist force sensor

Aimed at dynamic behavior compensation and its realization for robot wrist force sensor, a new design method for digital filter-pole-zero matched method based on bilinear transformation is developed in this paper. The design idea and the steps of this method are given. A design example and discussion are presented to show the features of the method. A dynamic compensation filter used in wrist force sensor is designed using the method developed in the paper, which improves dynamic performance of sensor efficiently.

ANALYSIS ON THE INFLUENCE OF MODELING ERRORS ON SENSOR DYNAMIC COMPENSATION

The relationship between modeling error of the system and widening multiple of the working frequency band was analyzed quantitatively and its spectrums were obtained. They offered a criterion to estimate the feasibility and effect in engineering practice of the compensating method to improve the sensors dynamic characteristics, and proved that the compensating method has good reliability. Conclusions were drawn clearly: For a first-order system, the compensation effect is conspicuous, which only relates to modeling error but is independent of time constant; for a second-order system, the compensation effect is determined by modeling error and damping ratio. Within a wide range, if the damping ratio is larger, the modeling precision required to obtain the same compensation effect can be lower. Through quantitatively analysis, we found that the modeling precision in dynamic compensation with analogy or digital filter should not be so high as one is taken for granted currently.