Vehicle dynamics

About: Vehicle dynamics is a research topic. Over the lifetime, 12909 publications have been published within this topic receiving 204091 citations.

String Stable Model Predictive Cooperative Adaptive Cruise Control for Heterogeneous Platoons

Abstract: Cooperative adaptive cruise control (CACC) is a potential solution to decrease traffic jams caused by shock waves, increase the road capacity, decrease fuel consumption and improve safety. This paper proposes an integrated solution to a combination of four challenges in these CACC systems. One of the technological challenges is how to guarantee string stability (the ability to avoid amplification of dynamic vehicle responses along the string of vehicles) under nominal operational conditions. The second challenge is how to apply this solution to heterogeneous vehicles. The third challenge is how to maintain confidentiality of the vehicle parameters. Finally, the fourth challenge is to find a method which improves robustness against wireless packet loss. This paper proposes a model predictive control approach in combination with a feed-forward control design, which is based on a shared vector of predicted accelerations over a finite time horizon. This approach is shown to be applicable to a heterogeneous sequence of vehicles, while the vehicle parameters remain confidential. In previous works such an approach has shown to increase robustness against packet losses. Conditions for string stability are presented for the nominal operational conditions. Experimental results are presented and indeed demonstrate string stable behavior.

A nonlinear model predictive control formulation for obstacle avoidance in high-speed autonomous ground vehicles in unstructured environments

Abstract: This paper presents a nonlinear model predictive control (MPC) formulation for obstacle avoidance in high-speed, large-size autono-mous ground vehicles (AGVs) with high centre of gravity (CoG) that operate in unstructured environments, such as military vehicles. The term ‘unstructured’ in this context denotes that there are no lanes or traffic rules to follow. Existing MPC formulations for passenger vehicles in structured environments do not readily apply to this context. Thus, a new nonlinear MPC formulation is developed to navigate an AGV from its initial position to a target position at high-speed safely. First, a new cost function formulation is used that aims to find the shortest path to the target position, since no reference trajectory exists in unstructured environments. Second, a region partitioning approach is used in conjunction with a multi-phase optimal control formulation to accommodate the complicated forms the obstacle-free region can assume due to the presence of multiple obstacle...

Application of Adaptive Sliding Mode Control for Regenerative Braking Torque Control

Abstract: In air hybrid vehicles, there are two independent braking systems: frictional and regenerative. Since the regenerative braking torque is proportional to the parameters such as tank pressure and engine speed, a controller is needed for the control of the regenerative braking torque generated by internal combustion engine, based on the driver preference. In this work, a nonlinear control approach based on adaptive sliding-mode control (ASMC) is employed to tackle the problem of engine torque control during regenerative mode. To this end, a novel mean value model for a recently proposed cam-based air hybrid engine is derived for the regenerative mode and employed for designing the controller. The adaptive sliding-mode controller incorporates the approximately known inverse dynamic model output of the engine as a model-base component of the controller, and an estimated uncertainty term to compensate for the unmodeled dynamics, external disturbances (e.g., gear shifting), and time-varying system parameters such as tank pressure. The robustness and performance of the controller for this particular application is investigated and compared with that of a high-gain PID controller and a smooth sliding-mode controller numerically and experimentally. The results show that the controller performs remarkably well in terms of the robustness, tracking error convergence, and disturbance attenuation. Chattering effect is also removed by utilizing the ASMC scheme.

Improvements in vehicle handling through integrated control of chassis systems

Abstract: In this paper, methods of improving vehicle stability and emergency handling using electronically controlled chassis systems are discussed. By analysing a simple nonlinear vehicle model in the yaw plane, it is shown that vehicles can become unstable during portions of handling manoeuvres performed at or close to the limit of adhesion. It is further demonstrated how small changes in the balance of tyre forces between front and rear axles may affect vehicle yaw moment and stability. The methods of effecting vehicle yaw dynamics using controllable brakes, steering, and suspension are discussed. Control authority of each chassis system, in terms of its ability to generate a corrective yaw moment, is evaluated and is shown to depend on the operating point of vehicle and tyres. Consequently, regions of effectiveness of each subsystem are defined, which is a prerequisite for development of integrated chassis control systems. Preliminary test results for a vehicle with integrated closed loop control of brakes and suspension, performing typical handling manoeuvres, are presented. They demonstrate the benefits of integrated control in terms of improved handling response, stability, and reduced driver steering effort.