Vehicle Lateral Control under Fault in Front and/or Rear Sensors

The objectives of the project are: (1) to study the behavior of existing vehicle lateral control systems in the event of magnetometer failures, (2) to design controllers that use the output from only one set of magnetometers, and (3) to develop an autonomous lateral control scheme that uses no magnetometers. The performance of existing lateral control systems subject to magnetometer fail- ures is evaluated based on both linearized and complex nonlinear vehicle models. Simulation results indicate that rear magnetometer failures result in degraded oper- ation, and that front magnetometer failures cause instability in the control system. Two output feedback controllers, one using the output of front magnetometers alone and the other using the output of rear magnetometers alone, are designed based on the H1 optimal control technique. The H1 optimal control procedure synthesizes optimal controllers which minimize the e ects of disturbance and sensor noise on the lateral error and control e ort. Simulations performed with these two controllers show satisfactory performance for longitudinal velocities up to 30m=s. When both front and rear magnetometers fail, autonomous lateral control based on Intelligent Ranging using Infrared Sensors (IRIS) allows the vehicle to follow its preceding vehicle. Simulation results for a platoon of three vehicles show that the lateral error of the leading vehicle is ampli ed by the following vehicles. An integrated controller that combines the information from IRIS and rear magnetometers is de- signed. Simulations show that this control scheme provides better tracking accuracy than autonomous lateral control. Keywords: vehicle lateral control, bicycle model, H1 optimal control, autonomous lateral control, vehicle following.