On the Development of a Real-Time Simulator Engine for a Hydraulic Forestry Machine

This work focuses on the development of a real-time training simulator engine for a forestry machine. The rigid body dynamics of the machine's manipulator is integrated with electrohydraulic actuator dynamics and joint controllers. System numerical stiffness introduced by the closing valves, high order hydraulic dynamics, and simulator implementation using an interpreted language were identified as the prime reasons for slowing down the integration. Successive models of lower complexity and switching between models for the open and closed phases of the valves are proposed aiming to achieve a satisfactory simulator engine that can run in real-time. Simulation results demonstrate very good prediction of an actual machine behaviour with execution speeds improved by a factor of 35.