This work presents a new methodology for dead zone nonlinearity identification in proportional directional pneumatic valves. It is based on observing the dynamic behaviour of the pressure in the valve gaps. Dead zone is common in hydraulic and pneumatic valves because the spool blocks valve orifices with some overlap, so that for a range of spool positions there is no fluid flow. The dead zone nonlinearity is a key factor that limits both static and dynamic performance in feedback control of fluid power systems. The usual method to cancel the harmful effects of dead zone is to add its fixed inverse function into the controller. This inverse is modelled by a set of parameters that need to be identified. The classic dead zone parameter identification uses expensive flow transducers and special test rig, while our proposed methodology needs only pressure transducers. Experimental results illustrate the efficacy of this methodology that is cheaper and faster.

Keywords: dead zone nonlinearity, pneumatics, proportional directional valves, dead zone identification