Stabilization of Electropneumatic Valve Positioner with Long Pneumatic Tube and Experimental Studies

Abstract

This paper is concerned with the stabilization of an electropneumatic valve positioner, whose dynamics is described by a nonlinear time delay system. When the neumatic tube between the controller and the actuator exceeds, for the explosive-proof, a certain length, the actuator will generate hunting due to the time lag of pneumatic pressure signals. To prevent hunting, a new stabilizing method has already been proposed by the authors. This work verifies the validity of the new controller from experimental viewpoints. First, the experimental apparatus with the new controller is explained. Next, the dynamic characteristics are examined, and especially, the pneumatic tube model which is important for the construction of controller is identified. Third, the stabilization of an electropneumatic valve positioner and its robust stability are verified through experimental studies. Moreover, the improvement of transient response is discussed considering the addition of a pressure-compensating circuit.