Controller design for vehicle stability enhancement

Aiming to maximize not only stability limit but also vehicle responsiveness combined yaw moment and lateral force control as a cooperative control is presented. The total lateral force for front and rear wheels as well as direct yaw moment are introduced using the models response of side-slip angle and yaw rate. The side-slip response is the 2DOF vehicle response while the yaw rate response is a suggested first order lag to prevent oscillation in relation to steering input. Three different cases of combining lateral force and direct yaw moment control have been investigated using computer simulations. In order to show the effect of the cooperative control on vehicle stability and responsiveness, a direct yaw moment control to follow the yaw rate response is taken as comparison case. The effect of cooperative control is proved by computer simulations of the vehicle response to a single sine wave steer input with braking.

<div class="section abstract"><div class="htmlview paragraph">Aiming at the problems of ineffective collision avoidance and vehicle instability in the process of vehicle emergency braking in road conditions with low adhesion and sudden change in adhesion coefficient, a stability-coordinated emergency braking and collision avoidance control system SEBCACS) is proposed. First, according to the motion of the ego vehicle and the target vehicle as well as the road adhesion conditions, a collision time model is proposed for evaluating the vehicle collision risk, and the expected deceleration required to avoid the collision is calculated. Then, the MPC method is used to calculate the yaw moment generated by the four-wheel braking force required to maintain vehicle stability according to the actual and reference yaw rate and side slip angle deviation. Then it is decided whether to implement additional yaw moment control according to the body stability evaluation results. Finally, the required four-wheel braking force is calculated according to the expected deceleration and the expected additional yaw moment (produced by differential braking). The simulation results show that the control system designed in this paper can effectively ensure the vehicle’s longitudinal collision avoidance safety and vehicle stability in the face of harsh environments, compared with the traditional AEB method.</div></div>

Vehicle dynamics control (VDC) systems require information about system variables, which cannot be directly measured, e.g. the wheel slip or the vehicle side-slip angle. This paper presents a new concept for the vehicle state estimation under the assumption that the vehicle is equipped with the standard VDC sensors. It is proposed to utilise an unscented Kalman filter for estimation purposes, since it is based on a numerically efficient nonlinear stochastic estimation technique. A planar two-track model is combined with the empiric Magic Formula in order to describe the vehicle and tyre behaviour. Moreover, an advanced vertical tyre load calculation method is developed that additionally considers the vertical tyre stiffness and increases the estimation accuracy. Experimental tests show good accuracy and robustness of the designed vehicle state estimation concept.

Direct yaw moment control is a key technology to improve vehicle stability and driving comfort, and its performance has a great impact on vehicle active safety control. For solving the problems of model uncertainty and system robustness in vehicle active safety control, a direct yaw moment control formwork based on sliding robust control is proposed. It makes the state of the control system slide along the sliding surface by switching the control quantity, which can ensure the invariance of the control system under external disturbance and parameter perturbation. To describe the drivability of the vehicle under the tire nonlinear conditions, a vehicle dynamics model based on the Fiala method is established in the controller design. Meanwhile, a correction model of the reference yaw rate and reference sideslip angle based on the road adhesion coefficient is designed to ensure the tracking accuracy of the vehicle to the stability index. We established the control model of Simulink for co-simulation with Carsim. Meanwhile, a hardware simulation-in-the-loop(HIL) platform for yaw moment based on the NI-Lab VIEW system is established. The experiment shows that the formwork can further ensure the vehicle's stability by providing yaw moment when the vehicle is driving, and improving the vehicle's handling performance.

This study presents an approach to develop a controller for stabilization of a apping wing micro-air vehicle (MAV) operating in gusty environments. The rigid-wing MAV is modeled as a nonlinear periodic system and the periodic-shooting method is used to nd a trimmed periodic orbit. A linearized discrete-time representation of the system is created about this trimmed periodic orbit. This linearized representation is used for control synthesis based on linear quadratic regulator (LQR) theory. The kinematic variables controlling the wing motion are used as control inputs. The controller is implemented on the nonlinear system model to stabilize the system in the presence of external disturbances, both longitudinal and lateral, modeled as discrete gusts in this study. The performance of the controller, in terms of the gust speed tolerance, is studied on the nonlinear system for various controller designs. The studies show that the LQR based controller is able to stabilize the system under both longitudinal and lateral gust disturbances, although the maximum gust speed tolerated by each controller is inuenced by a variety of parameters discussed in this paper. The numerical simulations show that the gust tolerance under the longitudinal gust is far superior to the lateral gust tolerance. The study also shows that lateral control of the MAV can be achieved using only the wing-stroke magnitude and wing-stroke oset as the control inputs for each wing.

The direct yaw moment control system is able to greatly enhance the vehicle stability when driving on challenging road surfaces. This paper introduces a direct control approach for managing the vehicle yaw moment, utilizing terminal sliding mode control and a square root cubature Kalman filter (SRCKF). Initially, the longitudinal and lateral forces acting on the vehicle’s tires are estimated through a sliding mode observer. Subsequently, the SRCKF algorithm and the four-wheel tire force are employed to accurately estimate the yaw rate and sideslip angle. Based on these estimations, additional yaw moments are determined using the terminal sliding mode control algorithm, and a combined control of yaw rate and sideslip angle is achieved through a threshold method. A rule-based braking force distribution strategy is then implemented to ensure vehicle stability control. Simulation results demonstrate that the tire force estimations from the sliding mode observer and the vehicle yaw rate and sideslip angle estimations from the SRCKF algorithm closely align with the output results from Carsim, with an error margin of less than 15%. The braking force distribution strategy, based on the direct yaw moment control using the terminal sliding mode algorithm, effectively tracks the desired yaw rate and sideslip angle.

With the rapid development of intelligent transportation system, the research on vehicle stability can be a theoretical basis for realizing autonomous driving technology. The previous stability control strategies have not taken into account the tire force saturation factor, the slip rate, and the robustness of the control system sufficiency. According to the characteristic that the torque of each wheel can be distributed independently, a torque distribution algorithm under emergency conditions is proposed. The proposed torque distribution algorithm is constructed using three hierarchical controllers. The upper controller attempts to judge whether the vehicle is in stable state using the phase plane method. Also, it judges whether the wheels are slipping. The middle controller aims to calculate the demands for the desired traction force and yaw moment, whereas the lower controller is designed to translate those virtual signals into actual actuator commands. When designing the middle controller, a sliding mode control method is utilized to guarantee system stability and robustness by taking into account various factors, including lateral wind, and sensor noise. For the lower controller, the control allocation optimization method is utilized to determine an appropriate control input for each in-wheel motor by considering the road conditions, adhesion utilization, and maximum output torque of the motor. The numerical simulation studies are conducted to evaluate the performance of the torque distribution algorithm. Comparison results indicate that the proposed algorithm presents better performance to distribute the appropriate torque for each wheel and ensure the stability of the vehicle under emergency conditions.

This publication describes a process to develop and calibrate a physics-based model for vehicle stability control. The approach consists of two phases. In the first phase, a baseline vehicle dynamics model was established using the commercially available simulation tool CarSim. The model was calibrated and validated for a variety of steady state, transient state and brake intervention handling manoeuvres using experimental test data. In the second phase, a simplified stability control model was developed in Matlab/Simulink based on representative control strategies. Subsequently, the vehicle dynamics model and stability control model developed were coupled using co-simulation and calibrated such that the closed-loop system behaviour approximated the real world test behaviour as best as possible. Finally, two case studies were developed to showcase the application of the closed-loop mathematical model in simulation-based studies addressing aftermarket vehicle modifications and their implication on vehicle stability control behaviour.

A novel control scheme is proposed to improve the vehicle stability by coordinating the slips of the two wheels on the same side simultaneously. This scheme is a three-level structure that includes the first level of yaw moment controller, the second level of brake force distributor and the third level of wheel slip regulator. Brake force distributor distributes the desired brake forces to the two wheels on the same side properly and the wheel slip regulator is designed to track the desired slips from the brake force distributor. Simulation results of the proposed control scheme are rather satisfying.

A study of the effectiveness of Electronic Stability Control in Canada

In this paper, we propose a new yaw moment control based on fuzzy logic to improve vehicle handling and stability. The advantages of fuzzy methods are their simplicity and their good performance in controlling non-linear systems. The developed controller generates the suitable yaw moment which is obtained from the difference of the brake forces between the front wheels so that the vehicle follows the target values of the yaw rate and the sideslip angle. The simulation results show the effectiveness of the proposed control method when the vehicle is subjected to different cornering steering manoeuvres such as change line and J-turn under different driving conditions (dry road and snow-covered).

This thesis is concerned with electronic stability of an all-wheel drive electric vehicle with independent motors mounted in each wheel. The additional controllability and speed permitted using independent motors can be exploited to improve the handling and stability of electric vehicles. In this thesis, these improvements arise from employing a direct yaw moment control (DYC) system that seeks to adapt the understeer gradient of the vehicle and achieve neutral steer by employing a supervisory controller and simultaneously tracking an ideal yaw rate and ideal sideslip angle. DYC enhances vehicle stability by generating a corrective yaw moment realized by a torque vectoring controller which generates an optimal torque distribution among the four wheels. The torque allocation at each instant is computed by finding a solution to an optimization problem using gradient descent, a well-known algorithm that seeks the minimum cost employing the gradient of the cost function. A cost function seeking to minimize excessive wheel slip is proposed as the basis of the optimization problem, while the constraints come from the physical limitations of the motors and friction limits between the tires and road. The DYC system requires information about the tire forces in real-time, so this study presents a framework for estimating the tire force in all three coordinate directions. The sideslip angle is also a crucial quantity that must be measured or estimated but is outside the scope of this study. A comparative analysis of three different formulations of sliding mode control used for computation of the corrective yaw moment and an evaluation of how successfully they achieve neutral steer is presented. IPG Automotive’s CarMaker software, a high-fidelity vehicle simulator, was used as the plant model. A custom electric powertrain model was developed to enable any CarMaker vehicle to be reconfigured for independent control of the motors. This custom powertrain, called TVC_OpenXWD uses the torque/speed map of a Protean Pd18 implemented with lookup tables for each of the four motors. The TVC_OpenXWD powertrain model and controller were designed in MATLAB and Simulink and exported as C code to run them as plug-ins in CarMaker. Simulations of some common maneuvers, including the J-turn, sinusoidal steer, skid pad, and mu-split, indicate that employing DYC can achieve neutral steer. Additionally, it simultaneously tracks the ideal yaw rate and sideslip angle, while maximizing the traction on each tire[CB1] . The control system performance is evaluated based on its ability to achieve neutral steer

Suspension system plays most significant role in supporting the vehicle weight and isolating vehicle body from road shocks and vibrations. The aim of suspension system is to suppress uncomforting situations from road unevenness to driver and passengers and to provide road handling and stability of vehicles. The aim of this research work is to design efficient active controller for active suspension system for improving ride quality and road holding that can tackle different types of road input conditions. By using mathematical modeling 2 Degree Of Freedom (DOF) Quarter Car Model is designed. Linear Quadratic Regulator (LQR) and Fuzzy logic controller which are capable of considering disturbances have been designed. Three different road profiles such as Step, Sine and Band limited white noise are taken as input disturbances. In this work, MATLAB/SIMULINK software is used for simulation purpose and simulation result demonstrate that proposed active suspension system shows excellent performance by improving road holding, ride comfort, reduced peak overshoot and reduced settling time in comparison to passive suspension system for all the road profiles. LQR controller gives extremely good performance improving up to 96%.

Essential principles of the vehicle electronic stability control (ESC) operation are analyzed. Mathematical model employed for the performance investigation of vehicles equipped with ESC is described. Modeling results are presented, simulating the actual road test, in which ESC-equipped vehicle performed an emergency maneuver at the surface covered with packed snow. Modeling allowed identifying ESC interventions occurred in the road test. Also, modeling results are presented, simulating the same road test with disabled ESC and with replacement of the original ESC by an experimental yaw stability controller. Conclusions are drawn about performance of both original ESC and the experimental controller. Analysis of the simulation results allowed disclosing changes of the vehicle steering behavior during the maneuver, as well as stability loss factors emerging at particular points of the maneuver. Variation of controller’s parameters allowed defining conditions in which ESC should intervene to prevent the vehicle from a skid.

Rotational Motion Control by Feedback with Minimum L1-Norm