Workstation-Based Man-in-the-Loop Simulation for Multibody Systems

This paper presents a general approach to achieving real-time man-in-the-loop simulation for multibody dynamic systems. Emerging real-time dynamic simulation methods are used to demonstrate the potential for creating interactive design workstations with a human operator in the control loop. The recursive formulation of multibody system dynamics with relative coordinates is employed for efficient numerical analysis and implementation on parallel computer. A workstation-based simulator is developed by integrating the real-time dynamics program, a realistic graphics display, and the operator’s control interface. High speed computer graphics techniques are employed to create realistic visual cues for the simulator. Real-time man-in-the-loop simulation is analyzed, as regards the goal of real clock time, not only with respect to dynamic simulation but also with respect to graphics display and the operator interface. Synchronization of the simulation is found to be most important for realism of the simulator. A backhoe simulation is implemented to demonstrate the capability for man-in-the-loop simulation. The backhoe simulator is developed by modeling backhoe dynamics and hydraulic systems with the recursive formulation to achieve real-time simulation, developing an interactive graphics program for visual cues, and interfacing the operator’s control action with the dynamic simulation through a pair of joysticks.