Mathematical modeling and prototype development of a pneumatically-actuated bench for sloping terrain simulation

Abstract

This paper presents the mathematical modeling of a nonlinear system for a sloping terrain simulation bench with pneumatic actuation, as well the prototype development of the adopted dynamic system. The use of pneumatics is advantageous in agricultural machinery for its easy maintenance, its relatively low cost and good power-to-size ratio, and also for its quick action with great speed variation. However, it introduces difficulties in control due to the nonlinear characteristics of the system. The mathematical modeling of this dynamic system is important because it enables the prediction of the same oscillation conditions found in the field through simulations, the controller design and the behavior study of its variables in prototypes. Thus, a fifth-order nonlinear mathematical model was developed to describe such slope from combination of the servo valve model with the pneumatic cylinder model, and includes dead zone nonlinearity, valve orifice flow rate, pressure dynamics and piston movement with dynamic friction, and also includes rotating platform dynamics. The motivation for the development of a test bench for sloping terrain simulation is to contribute for the improvement of the experimental prototype in agricultural machines.