Improved tracking and switching performance of an electro-pneumatic positioning system

Abstract

For robotic systems that use on/off (solenoid) pneumatic actuators, a sliding mode control law for precise position control and low switching (open-close) activity of the valves is presented in this paper. Given a pneumatic actuator with two chambers and four solenoid valves, there are sixteen possible input combinations defined directly from the state of the four on/off valves present in the system; however, only seven of these discrete operating modes are considered both functional and unique. Therefore, we introduce a novel seven-mode sliding controller that minimizes the position tracking error using modes that have both the necessary and sufficient amounts of drive energy and, thus, involve reduced switching activity. An analysis of the closed-loop system stability is carried out. The performance of the proposed control design is experimentally verified on a single pneumatic actuator setup comprising of two chambers with four on/off valves.

Dynamical model averaging and PWM based control for pneumatic actuators

“…The modelling of a pneumatic actuator with its chamber and four solenoid valves is visible in [12]. It is possible to write the dynamics of the open-loop pneumatic actuator in a discrete input form, assuming that the temperature variation in chambers is negligible with respect to the supply temperature (thus T P = T N = T ):…”

“…Also, b 8 and b 9 are approximately equal to 0 and can be positive or negative. As in [12], we will focus on the modes…”

“…In our previous works, a sliding mode control based on a seven mode switching law has been proposed [12]. It has been shown in these works that four additional modes allow not only to decrease the coarseness of the drive force for lower position tracking errors but also to reduce the number of switching.…”

Performance Test of Full Range Suspension Pneumatic Lifting System

“…The pneumatic lifting system takes the compressed air as the power source, through the cylinder and other actuators to overcome the gravity to increase the load [1][2][3]. Compared with cranes, hoists, electric hoists and other lifting appliances, pneumatic hoisting system not only can load or promot, but also achieve stepless speed regulation with environmentally friendly, safe and reliable.…”

Pneumatic-Piezoelectric Hybrid Vibration Suppression For a Flexible Translating Beam Using Adaptive Fuzzy Sliding Mode Control Algorithm

“…However, pneumatic systems suffer from several drawbacks, such as 1nonlinear friction force and highly nonlinear pneumatic system dynamics. 1 The nonlinearities in the pneumatic system are mainly the couplings between the pressure and the motion, the flow rate, and the friction force. 2 Moreover, for a longstroke pneumatic rodless cylinder, higher nonlinear dynamics due to a large operation range may occur; thus, it is difficult to design an effective controller.…”