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378 Multibody Systems Approach to Vehicle Dynamics
Fig. 6.45 Driver and vehicle behaviour for a post-limit turn-in event
(photograph courtesy of Don Palmer, www.donpalmer.co.uk)
The steering system on a vehicle has only 20–25 degrees (less on the rally
car) of lock and so realistically, control beyond these body slip angles is
unlikely without very large amounts of space indeed.
Most drivers are acutely sensitive to the rate of change of body slip angle,
albeit they do not always respond correctly to it. Instead a ‘threshold’
behaviour appears common, with drivers neglecting body slip angle until
either the angle becomes large or its rate of change becomes large. For road
cars, our goals are to have a road car manage its own body slip angle so as
not to put pressure on drivers in an area where in general skill is lacking.
For driver modelling purposes, a separate body slip angle control loop is
desirable to catch spins but need not be terribly sophisticated since if it is