On the development of a real-time simulator for an electro-hydraulic forestry machine

This paper focuses on the development of a real-time graphical simulator engine for a forestry machine. The rigid body dynamics of the machine's manipulator are integrated with electrohydraulic actuator dynamics and joint controllers. System stiffness introduced by the closing valves, high order hydraulic dynamics, and an interpreted implementation are identified as the prime reasons for slowing down the integration. Successive models are proposed aiming at achieving a faithful machine simulator that can run in realtime. Simulation results obtained, show very good prediction of an actual machine's behavior at execution speeds improved by a factor of 35.