A common problem with sports-utility-vehicles is the low rollover threshold, due to a high center of gravity. Instead of modifying the vehicle to increase the rollover threshold, the aim of the control system is to prevent the vehicle from exceeding speeds that would cause the vehicle to reach its rollover threshold. The aim of the autonomous longitudinal control system, discussed here, is to improve the vehicle’s safety by controlling the vehicle’s longitudinal behavior.

In order to develop a control system that autonomously controls the longitudinal degree of freedom, an experimentally validated mathematical model of the test vehicle (a 1997 Land Rover Defender 110 Wagon) was used — the model was developed in MSC.ADAMS/View. The control system was developed by generating a reference speed that the vehicle must track. This reference speed was formulated by taking into account the vehicle’s limits due to lateral acceleration, combined lateral and longitudinal acceleration and the vehicle’s performance capabilities.

The MSC.ADAMS/View model of the test vehicle was used to evaluate the performance of the control system on various racetracks for which the GPS coordinates were available. The simulation results indicate that the control system performed as expected by limiting the vehicle’s acceleration vector to the prescribed limits.

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