Vehicle Motion Management - A Model Predictive Control Approach to Realize Holistic Redundancy to Enable Actuator Fail Operational Autonomous Driving

Since the introduction of ABS (1978), TCS (1986) and ESC (1995) in series production, the number of modern vehicle dynamics control functions and advanced driver assistance systems (ADAS) has been continuously increasing. Meanwhile, many functions are available that influence vehicle motion (vehicle dynamics). Since these are only partially and not hierarchically coordinated, the control of vehicle motion is still suboptimal. Current megatrends (automated driving, electromobility, software-defined vehicles) and new key technologies (steer-by-wire, brake-by-wire, domain-based E/E architectures) lead to an increasing number of electrified, motion-relevant components being introduced into series production. These components enable the development of an integrated chassis control (ICC) that controls all motion-relevant components, networks them with each other and coordinates them holistically to optimally control the vehicle motion regarding an adjustable desired driving behavior. Vehicle Motion Management (VMM), which is being developed by IAV GmbH as ICC, uses model predictive control (MPC) to realize individually adjustable driving behavior. This not only combines and weights classic target criteria of driving safety (stability, controllability) and driving comfort with new target criteria of automated driving functions (energy efficiency, chassis emissions) but also enables fault-tolerant vehicle motion. This paper investigates in simulation whether the VMM is able to realize the lateral control of automated driving functions in the event of a failure of the steer-by-wire system by other motion-relevant components and maintaining the vehicle’s cornering. This paper compares three different powertrain topologies to find out which motion-relevant components are necessary to maintain cornering. The driving situation consists of stationary straight ahead driving and then cornering. When entering the corner, the steering system is not able to set a wheel steering angle due to a sudden failure. The VMM must control other motion-relevant components to maintain cornering. The path parameters (curve radius, clothoid parameter) are defined by the minimum parameters of the standardized long-distance German highway to map the corner case. This corner case is run for two different, statistically relevant driving speeds and three different powertrain topologies (with different motion-relevant components). To evaluate whether the vehicle maintains the lane, the maximum lateral deviation during cornering was calculated. The results show that cornering can be maintained at all driving speeds. The results also show that trajectory control is improved by adding further motion-relevant components.