The inherent flexibility of hierarchical structure scheme with main-servo loop control structure is proposed to the problem of integrated chassis control system for the vehicle. It includes both main loop, which calculates and allocates the aim force using the optimal robust control algorithm and servo loop control systems, which track and achieve the target force using the onboard independent brake actuators. In fact, for the brake actuator, the aim friction is obtained by tracking the corresponding slip ratio of target force. For the coefficient of tire-road friction varying with different road surface, to get the nonlinear time-varying target slip ratio, the most famous quasi-static magic formula is proposed to estimate and predict real-time coefficient of different road surface and the constrained hybrid genetic algorithm (GA) is used to identify the key parameters of the magic formula on-line. Then, a self-tuning longitudinal slip ratio controller (LSC) based on the nonsingular and fast terminal sliding mode (NFTSM) control method is designed to improve the tracking accuracy and response speed of the actuators. At last, the proposed integrated chassis control strategies and the self-tuning control strategies are verified by computer simulations.

Study on Self-Tuning Tyre Friction Control for Developing Main-Servo Loop Integrated Chassis Control System

Variable time delays exist between the driver's inputs and the responses of the vehicle dynamic states during a critical steering course. And due to the delay of active brake actuators, a sideslip or a rollover may occur even to a vehicle with a traditional stability control system. In addition, the unnecessary intervention of rollover prevention controller may deteriorate yaw stability of a vehicle in these situations. To mitigate the adverse effect of time delay on vehicle stability control and to realize coordinated stability control, a novel three-dimensional dynamic stability controller (3DDSC) is designed for yaw stability control, yaw–roll stability control and rollover prevention control. The framework consists of a supervisor, an upper controller, and a lower controller. A nonlinear vehicle model is used in the supervisor to predict the vehicle's future states and to determine the control mode and the related controllable areas with active brake method. Then model predictive control is used in the upper controller to calculate the desired tire forces of four wheels under the constraints of the given controllable area; then, the desired tire forces are realized by a lower hydraulic pressure controller. The proposed 3DDSC is evaluated with a CarSim–MATLAB cosimulation and hardware-in-the-loop simulation. The results show that 3DDSC can achieve a seamless integration of lateral stability and rollover prevention in complicated steering maneuvers.

A Three-Dimensional Dynamics Control Framework of Vehicle Lateral Stability and Rollover Prevention via Active Braking With MPC

This paper investigates the path-following control problem for four-wheel independently actuated autonomous ground vehicles through integrated control of active front-wheel steering and direct yaw-moment control. A modified composite nonlinear feedback strategy is proposed to improve the transient performance and eliminate the steady-state errors in path-following control considering the tire force saturations, in the presence of the time-varying road curvature for the desired path. Path following is achieved through vehicle lateral and yaw control, i.e., the lateral velocity and yaw rate are simultaneously controlled to track their respective desired values, where the desired yaw rate is generated according to the path-following demand. CarSim–Simulink joint simulation results indicate that the proposed controller can effectively improve the transient response performance, inhibit the overshoots, and eliminate the steady-state errors in path following within the tire force saturation limits.

Composite Nonlinear Feedback Control for Path Following of Four-Wheel Independently Actuated Autonomous Ground Vehicles

Fuel consumption optimization for smart hybrid electric vehicle during a car-following process

This paper deals with the trajectory following control problem of a class of autonomous vehicles with parametric uncertainties, external disturbances, and over-actuated features. A novel adaptive hierarchical control framework is proposed to supervise the lateral motion of autonomous four-wheel independent drive electric vehicles. First, an adaptive sliding mode high-level control law with the linear matrix inequality-based switching surface is designed to produce a vector of front steering angle and external yaw moment, in which the uncertain term and the switching control gain are adaptively regulated by the fuzzy logic technique, to further moderate the chattering phenomenon, an adaptive boundary layer is introduced. Second, a pseudo-inverse low-level control allocation algorithm is presented to optimally allocate the external yaw moment via coordinating and reconstructing the tire longitudinal forces. Finally, numerical simulation and experimental results demonstrate that the proposed adaptive control approach has outstanding tracking performance.

An Adaptive Hierarchical Trajectory Following Control Approach of Autonomous Four-Wheel Independent Drive Electric Vehicles

Direct yaw moment control (DYC), which differentially brakes the wheels to produce a yaw moment for the vehicle stability in a steering process, is an important part of electric stability control system In this field, most control methods utilise the active brake pressure with a feedback controller to adjust the braked wheel However, the method might lead to a control delay or overshoot because of the lack of a quantitative project relationship between target values from the upper stability controller to the lower pressure controller Meanwhile, the stability controller usually ignores the implementing ability of the tyre forces, which might be restrained by the combined-slip dynamics of the tyre Therefore, a novel control algorithm of DYC based on the hierarchical control strategy is brought forward in this paper As for the upper controller, a correctional linear quadratic regulator, which not only contains feedback control but also contains feed forward control, is introduced to deduce the object of

A novel vehicle dynamics stability control algorithm based on the hierarchical strategy with constrain of nonlinear tyre forces

Vehicle side-slip angle is crucial for various vehicle active safety applications, but measuring it directly needs expensive measurement instruments and the vehicle nonlinear dynamics, parameters uncertainty, and sensor noise cause difficulties in its observation. Therefore, the accurate, affordable side-slip angle estimator is essential. Thus, a novel adaptive square-root cubature Kalman filter (ASCKF)-based estimator with the integral correction fusion is proposed. First, the square-root cubature Kalman filter (SCKF) parameters can be adjusted adaptively based on the vehicle dynamics states. Then, considering the unknown colored noises of sensors, the integral estimation is corrected by the damping item and zero-point-reset method and the integral value can compensate the estimation error caused by the vehicle nonlinear dynamics. Therefore, the accurate side-slip angle can be estimated by the adaptive fusion of the estimation and integral values. The simulation results and real-vehicle tests show that the proposed ASCKF-based fusion algorithm has better performance than both the traditional SCKF and ASCKF.

Fusion Algorithm Design Based on Adaptive SCKF and Integral Correction for Side-Slip Angle Observation

Knowing vehicle sideslip angle is important and useful in various vehicle active safety applications. However, equipment which could directly measure sideslip angle is usually too expensive for industrial applications, so a reliable, affordable sideslip angle observer is necessary. Model-based observer is affected by the model uncertainty, non-linearity and the road friction inaccuracy. Sensor-based observer might be easily affected by the sensor noise and the bias induced by the road micro-uneven. Thus, an unscented Kalman filter (UKF)-based adaptive variable structural observer with dynamic correction (AUKF) for vehicle body sideslip angle is brought forward in this study. First, an UKF observer with adaptive parameters is used to compensate the model uncertainty. Then, a sensor-based observer is applied to realise a variable structure observer to compensate the estimation error in the highly non-linear region. A pseudointegral method and a zero point reset method are adopted to dynamically correct the bias drift problem in the integral. Both simulations and real vehicle tests validated the proposed approach. The accurate vehicle sideslip angle is measured by a differential global positioning system. Results show that the proposed approach has better performance compared with traditional UKF method, and makes a good foundation for stability control.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-cta.2015.1030

UKF-based adaptive variable structure observer for vehicle sideslip with dynamic correction

The current research of direct yaw moment control (DYC) system focus on the design of target yaw moment and the distribution of wheel brake force. The differential braking intervention can effectively improve the lateral stability of the vehicle, however, the effect of DYC can be improved a step further by applying the control of vehicle longitudinal velocity. In this paper, the relationship between the vehicle longitudinal velocity and lateral stability is studied, and the simulation results show that a decrease of 5 km/h of longitudinal velocity at a particular situation can bring 100° increasing of stable steering upper limit. A critical stable velocity considering the effect of steering and yaw rate measurement is defined to evaluate the risk of losing steer-ability or stability. A novel velocity pre-control method is proposed by using a hierarchical pre-control logic and is integrated with the traditional DYC system. The control algorithm is verified through a hardware in-the-loop simulation system. Double lane change (DLC) test results on both high friction coefficient (μ) and low μ roads show that by using the pre-control method, the steering effort in DLC test can be reduced by 38% and 51% and the peak value of brake pressure control can be reduced by 20% and 12% respectively on high μ and low μ roads, the lateral stability is also improved. This research proposes a novel DYC system with lighter control effort and better control effect.

A novel pre-control method of vehicle dynamics stability based on critical stable velocity during transient steering maneuvering

The invention relates to an automobile brake wheel cylinder pressure real-time monitoring and collecting system. The automobile brake wheel cylinder pressure real-time monitoring and collecting system comprises a pressure collecting and launching module and a data receiving and displaying module. The pressure collecting and launching module is connected with exhaust ports of automobile brake wheel cylinders, is used for collecting pressure signals of the automobile brake wheel cylinders, and transmits the collected pressure signals to the data receiving and displaying module in a wireless mode. The data receiving and displaying module is placed inside or outside an automobile, is used for receiving, converting and storing the pressure data of the brake wheel cylinders, and displays the pressure of the wheel cylinders in real time. The pressure collecting and launching module comprises a brake bend, an exhaust bolt and a pressure collecting and launching processing unit. The data receiving and displaying module comprises an output power supply module, a wireless receiving module, a single-chip microcomputer, a liquid crystal display and a CAN module. The automobile brake wheel cylinder pressure real-time monitoring and collecting system can be widely applied to the automobile brake system manufacturing process.

Jie Chen

Papers

A novel vehicle dynamics stability control algorithm based on the hierarchical strategy with constrain of nonlinear tyre forces

Fusion Algorithm Design Based on Adaptive SCKF and Integral Correction for Side-Slip Angle Observation

UKF-based adaptive variable structure observer for vehicle sideslip with dynamic correction

A novel pre-control method of vehicle dynamics stability based on critical stable velocity during transient steering maneuvering

Automobile brake wheel cylinder pressure real-time monitoring and collecting system