Control of input delayed pneumatic vibration isolation table using adaptive fuzzy sliding mode

Abstract

Pneumatic isolators are promising candidates for increasing the quality of accurate instruments. For this purpose, higher performance of such isolators is a prerequisite. In particular, the timedelay due to the air transmission is an inherent issue with pneumatic systems, which needs to be overcome using modern control methods. In this paper an adaptive fuzzy sliding mode controller is proposed to improve the performance of a pneumatic isolator in the low frequency range, i.e., where the passive techniques have obvious shortcomings. The main idea is to combine the adaptive fuzzy controller with adaptive predictor as a new time delay control technique. The adaptive fuzzy sliding mode control and the adaptive fuzzy predictor help to circumvent the input delay and nonlinearities in such isolators. The main advantage of the proposed method is that the closed-loop system stability is guaranteed under certain conditions. Simulation results reveal the effectiveness of the proposed method, compared with other existing time -delay control methods.

Stability analysis of virtual passive actuator with time delay and parameter uncertainties

“…In some haptic rendering systems, the concept of a virtual spring and damper is used: for example, in a teleoperation control system, the master hand could mimic the environment that the slave hand is in contact with, it could copy the dynamic characteristic of the environment, so the human operator could 'feel' the environment. 21 The influence of time delay, 22 sampling rate and even the sensor quantization error on the stability region is discussed, as well as these factors' influence on system response accuracy. [23][24][25] In this work, the advantages of the linear model, discrete model and linear discrete hybrid model are discussed.…”