Increasing highway traffic congestion and real estate costs that limit
the building of new highways has brought about a renewed interest in
an Automated Highway System (AHS) where the vehicle steering task (''l
ateral control'') and the braking/throttle tasks (''longitudinal contr
ol'') are taken over by computers to increase the throughput of existi
ng highways. Since safety plays a key role in the development of an AH
S, fault-tolerant control is vital. In this paper, we develop a robust
longitudinal sliding-mode control algorithm and prove that this contr
ol algorithm is stable for a certain class of faults, In addition, we
show that intervehicle spacing errors will not become amplified along
the AHS in the event of a loss of lead vehicle information, The perfor
mance of the sliding-mode controller is demonstrated through a series
of simulations incorporating various vehicle and AHS faults.