An improved nonlinear modelling and identification methodology of a servo-pneumatic actuating system with complex internal design for high-accuracy motion control applications

Precise and smooth motion control of servo-pneumatic actuating systems can be improved only by using appropriate mathematical models and identification procedures. In this paper, an improved modelling and parameter identification methodology of a servo-pneumatic linear drive unit with complex internal design that takes into account the influence of dead volume in terms of system dynamics has been developed. The proposed modelling methodology considers the nonlinear mass flow characteristic, dead zone of the valve, polytropic temperature model, heat transfer and nonlinear friction behavior. Experimental results indicates that a proper identification of the dead volume improves model accuracy in terms of pressure dynamics, piston velocity and piston position and therefore the proposed modelling methodology can be a good starting point to design better motion controllers in the field of servo-pneumatic actuating systems.