TRACKING CONTROL OF NONLINEAR PNEUMATIC SYSTEMS USING INPUT/OUTPUT LINEARIZATION BY STATE FEEDBACK

摘要

The paper proposed a control design method for servo-controlled pneumatic systems, which is based on the feedback linearization theory. The pneumatic actuator system model is transformed into a linear system description first by regular static state feedback and state coordinate transformation. A servo/tracking controller is then developed for the linear model. Since there exists an inverse transformation for the new co-ordinate system, the designed servo control is finally transformed back to the original state co-ordinates and input. Two different cases are discussed in the paper - the pneumatic cylinder is driven by a single five-port proportional valve and driven by two three-port proportional valves. At the initial stage, for the convenience of finding a suitable set of new coordinates, the static friction forces are ignored. The static friction forces can be treated as uncertainties to the system for robust controller design.