Vehicle dynamics

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

A systematic design approach for two planetary gear split hybrid vehicles

Abstract: Multiple power sources in a hybrid vehicle allow for flexible vehicle power-train operations, but also impose kinematic constraints due to component characteristics. This paper presents a design process that enables systematic search and screening through all three major dimensions of hybrid vehicle designs - system configuration, component sizing and control, to achieve optimal performance while satisfying the imposed constraints. An automated dynamic modelling method is first developed which enables the construction of hybrid vehicle model efficiently. A screening process then narrows down to configurations that satisfy drivability and operation constraints. Finally, a design and control optimisation strategy is carried out to obtain the best execution of each configuration. A case study for the design of a power-split hybrid vehicle with optimal fuel economy is used to demonstrate this overall hybrid vehicle design process.

Nonlinear Model Predictive Lateral Stability Control of Active Chassis for Intelligent Vehicles and Its FPGA Implementation

Abstract: The rapid development of intelligent vehicles has paved the way for active chassis lateral stability, which is a novel issue and critical to vehicle stability and handling performance. To obtain active chassis lateral stability for intelligent vehicles, a nonlinear model predictive control (NMPC) method integrating active front steering and an additional yaw moment is proposed. It adopts the tire sideslip angle to express vehicle lateral stability, and addresses the actuator and security constraints and the nonlinear properties of the tire-road force effectively. Moreover, the hardware implementation, based on the field programmable gate array (FPGA), is presented to satisfy miniaturization and to discuss the computational efficiency of the proposed NMPC method. To verify the effectiveness of the presented NMPC method, offline simulations comparing the NMPC method with the direct yaw moment control (DYC) method under various running conditions and a real-time implementation experiment are carried out. The results indicate that the proposed NMPC method controls better than the DYC-based method. In addition, the presented NMPC method exhibits good robustness when the longitudinal velocity and tire-road friction coefficient vary within a suitable range. Moreover, the computational time of the proposed NMPC controller, implemented using the FPGA, is only 4.994 ms during one sampling period, which can satisfy the real-time requirement of active chassis lateral stability control.

A Novel Observer Design for Simultaneous Estimation of Vehicle Steering Angle and Sideslip Angle

Abstract: Both steering angle and sideslip angle are important states for vehicle handling and stability control. Instead of directly measuring these angles, indirect estimation of these states will provide a cost-effective way for the implementation of vehicle control systems. In the past, model-based methods have been proposed to estimate the sideslip angle with the measured steering angle. In this paper, a novel observer design is presented for simultaneous estimation of vehicle steering angle and sideslip angle so that the estimation of sideslip angle does not require the measurement of steering angle and the estimate of steering angle can also be used for other purposes, such as automatic steering control, steering system fault diagnosis, and driving performance monitoring. To enable this observer design, the Takagi–Sugeno (T–S) fuzzy modeling technique is applied to represent the vehicle lateral dynamics model with nonlinear Dugoff tyre model and time-varying vehicle speed. A T-S observer is then designed to simultaneously estimate the steering angle and sideslip angle with the measurements of yaw rate and vehicle speed, and is designed to be robust against parameter uncertainties and unknown inputs. The conditions for designing such an observer are derived in terms of linear matrix inequalities (LMIs). Experimental results are used to validate the effectiveness of the proposed approach. The results show that the designed observer can effectively estimate steering angle and sideslip angle despite the variation of vehicle longitudinal speed.

RBF Neural Network-Based Supervisor Control for Maglev Vehicles on an Elastic Track With Network Time Delay

Abstract: When the electromagnetic suspension (EMS) type maglev vehicle is traveling over a track, the airgap must be maintained between the electromagnet and the track to prevent contact with that track. Because of the open-loop instability of the EMS system, the current must be actively controlled to maintain the target airgap. However, the maglev system suffers from the strong nonlinearity, force saturation, track flexibility, and feedback signals with network time-delay, hence making the controller design even more difficult. In this article, the minimum levitation unit of the maglev vehicle system has been established. An amplitude saturation controller (ASC), which can ensure the generation of only saturated unidirectional attractive force, is thus proposed. The stability and convergence of the closed-loop signals are proven based on the Lyapunov method. Subsequently, ASC is improved based on the radial basis function neural networks, and a neural network-based supervisor controller (NNBSC) is thus designed. The ASC plays the main role in the initial stage. As the neural network learns the control trend, it will gradually transition to the neural network controller. Simulation results are provided to illustrate the specific merit of the NNBSC. The hardware experimental results of a full-scale IoT EMS maglev train are included to validate the effectiveness and robustness of the presented control method as regards to time delay.

Integral-Sliding-Mode Braking Control for a Connected Vehicle Platoon: Theory and Application

Abstract: This paper proposes a distributed integral-sliding-mode (ISM) control strategy for cooperative braking control of a connected vehicle platoon with a focus on the car-following interactions between vehicles. In particular, a linear controller considering the position and velocity of the lead vehicle as well as the braking force is proposed for the leader, while a constant-time-headway-policy-based ISM controller incorporating the car-following interactions, the spacing error, velocity difference, and external disturbances is developed for the followers. In addition, the convergence for the ISM controller is rigorously analyzed using the Lyapunov technique. Furthermore, the string stability of the platoon is analyzed using the transfer function method. Finally, extensive analyses are conducted using numerical and field experiments. Results verify the effectiveness of the proposed control strategy with respect to the position, velocity, deceleration, and spacing error profiles.