An integrated approach to autonomous vehicle systems: theory and implementation

Abstract

The field of autonomous vehicle dynamics as the theory of such a vehicle in motion is to control the vehicle's properties (vehicle running abilities) in the interaction of the vehicle and it's surroundings. This interaction itself appears through forces acting on a vehicle. To control these forces leads to control the properties of a vehicle in motion such as tractive and velocity properties, fuel consumption, turnability, ride stability and others. This paper proposes a novel theory of autonomous vehicles in motion. This theory allows parallel control of the forces acting on a vehicle, which leads to considerable improvement of the vehicle's running abilities. This paper presents the interrelation between the criteria of vehicle running abilities and output characteristics of vehicle systems, which control the vehicle forces. To optimise a vehicle's running abilities require optimisation of the combinations of forces acting on a vehicle. To provide optimum control of these forces, a methodical investigation of force combinations is proposed to be implemented for the sub-system of wheel patch – powertrain, and for the sub-system of wheel patch – suspension system – steering system – vehicle body. This is a way to research and design autonomous systems, too. To illustrate the process of defining the optimum combination of forces acting on a vehicle in motion, a multiple criteria optimisation problem of the wheel driving forces and, accordingly, output characteristics of wheel drive systems are being considered in this paper. Mathematically, the problem is based on the parallel controlling of tractive and velocity properties, fuel consumption performance, turnability, and ride stability of a vehicle. The problem is then reduced to a single criterion optimisation with limitations of the rest of criteria and limitations of optimised parameters. The development reported in the paper includes an application of the theory to a 12-wheeled highway truck. A mathematical model for studying the truck's running abilities is given based on the inverse dynamics problem. Optimal combinations of the wheel driving forces and a logical control strategy are presented to operate traction control (anti slip regulation – ASR).