When testing vehicles it is often difficult to assess whether changes to suspension, tyres, vehicle loading, etc. have made a significant change to the performance or stability of the vehicle. One of the main problems is that it is very hard for a driver to drive in a consistent manner and this, in turn, changes the results between runs.
The RT3000 can be linked to an Anthony Best Dynamics (ABD) steering robot and configured to drive down a predefined path. The whole system can follow the same path to within 2cm to 15cm depending on the conditions of the test. Changes to the vehicle can then be made and their effect can be assessed.
In this short article we present some data from a series of tests using the Path Following Robot System and compare them to three human drivers attempting to perform the same tests.
The Steering Robot was installed in place of the steering wheel (or hand wheel). The Steering Robot included a separate steering wheel that can be used when the robot is not active. This steering wheel was used by the human drivers when driving the course.
The RT3002 system was installed in the vehicle on a rigid pole in the centre of the vehicle. To ensure good yaw stiffness, the pole had two mounting points at the bottom, one in each rear foot-well.
The path that the vehicle should follow was predefined in the robot’s software. To help the human drivers follow the same path cones were laid on the road. The easiest way to do this was to use the robot to drive the path at a slow speed, walk behind the vehicle and drop cones where the centre-line of the vehicle was. Then the human drivers can follow the path of the cones.
The Path was driven 9 times using the robot; three human drivers drove the course three times each giving a total of 18 runs. The graphs below plot the position on the road and the steering wheel angle for each of the runs. Plots of roll angle and slip angle are also shown. During each of the tests the vehicle was driven at 72 km/h (or as close to this as could be achieved).
From the plots it is clear that the robot is capable for much more repeatable results than the three drivers. This, in turn, enables much smaller changes to the performance of the vehicle to be detected.
Robot (blue) vs. Human (coloured) Drivers – Position on the Road
Robot (blue) vs. Human (coloured) Drivers – Steering Wheel Angle
Robot (blue) vs. Human (coloured) Drivers – Roll Angle
Robot (blue) vs. Human (coloured) Drivers – Body Slip Angle