Shared Control up to the Limits of Vehicle Handling

Despite significant advances in vehicle safety, roadway accidents remain a substantial danger. To bring about safer vehicles, researchers and manufacturers continue to develop new systems to assist drivers in dangerous situations. Current approaches often implement several independent systems, each of which can assist in only specific situations, leaving open critical paths for accidents to occur. We propose a general approach to driver assistance based on nonlinear model predictive control (NMPC). This system can intervene in both lateral and longitudinal commands to keep the vehicle safely within the boundaries of the road, but allows the driver freedom to maneuver the vehicle as they wish when they act safely. This work builds on previous MPC approaches by incorporating a notion of safe operating speed. Properly modulating speed ensures the vehicle's limits are never exceeded, and not reached unless necessary. Experimental results on a full-size steer-, brake-, and throttle-by-wire vehicle, validate the performance of this system. These experiments show that the controller effectively matches the driver's commands when possible but will deviate from those commands when necessary for safe operation.