Achievable Dynamic Response for Automotive
Active Suspensions
M.C. Smith
Abstract
A complete set of constraints is derived for the road
disturbance transfer functions in a quarter car model of an automotive
active suspension, for typical choices of measured outputs. It is shown
that any road disturbance responses which are achievable using
``full state feedback'' can be achieved, to within an arbitrary small
tolerance, using a dynamic compensator measuring suspension deflection
only. Also considered are the disturbance responses to loads acting
on the sprung mass, and a complete set of constraints is derived for these.
It is shown that road disturbance and load disturbance responses can be
determined independently if suspension deflection and sprung mass
velocity are measured. Indeed, any responses achievable separately with
``full measurements'' can be approximated
together to an arbitrary small tolerance.
Certain integral relationships are shown to follow from the derived
transfer function constraints. These relationships imply
fundamental limitations for certain responses (e.g.\ tyre
deflection) no matter what measurements are available for feedback.