Space Grant Consortium - University of Wisconsin - Green Bay

Results
Figure 5. Assembled hydraulic excavator model in ChronoEngine
Simple straight-line simulations were run on the tracked vehicle models in both multibody
dynamics programs as follows. At the onset of the simulation both models are in the same initial
configuration, slightly above the ground as shown in Figure 1. In the first second of the
simulation, the horizontal tensioner force is applied and the rotational speed of the drive sprocket
is increased from zero to maximum speed. After the first second of simulation, the vehicle
reaches an average speed and the simulation is allowed to continue in this quasi-steady-state
motion for a few more seconds.
Both the MSC/ADAMS and ChronoEngine simulations yield similar results as far as the general
vehicle model is concerned. As expected, the ChronoEngine simulations took almost an order of
magnitude less time to simulate. The forward velocity of both models is nearly the same, and
both models are correctly driven by the track shoes engaging the gears attached to the drive
sprocket. However, there were problems observed in the simulations, most likely due to do with
the collision geometry and collision settings. As shown in the result animations, the track shoes
have a tendency to ‘stick’ to the drive sprocket gears as they are disengaging.
As described in the convex decomposition section, the actual CAD geometry could not be used
and had to be broken into convex pieces manually. Each piece was created manually and this
procedure is prone to error because it is difficult to measure the accuracy of a collision shape.
Also, there is a relationship between some of the collision detection settings (e.g. outward
envelope and inward safe margin) and the integrator step size. Modifying collision detection
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