Chassis Control Research Articles

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

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.

Skyhook and CRONE active suspensions: A comparative study

Abstract This paper presents a comparison of control methods for active suspensions in the context of Advanced Driver-Assistance Systems (ADAS) which are devised with a generic hierarchical architecture for Global Chassis Control (GCC). Such architecture is composed of a supervisory level which allows the estimation of the comfort operating domain. The rear suspension of a Citroen C4 Picasso is described by a quarter-car model. Firstly, an optimal Skyhook controller is designed taking into account suspension functions (sprung mass acceleration, deflection and tyre deformation). For comparative purposes, the Skyhook is approached from the point of view of a first generation CRONE controller (Robust Control Frequency Synthesis), which is introduced as a generalized form for the suspension. Performances in terms of suspension functions are juxtaposed to those of the degraded operation mode of the active system (failure of the control), considering disturbances such as road irregularities and load transfers. Simulation results show better performances of active suspension with the first generation CRONE controller compared to the Skyhook one.

Integrated control of AFS and DYC for in-wheel-motor electric vehicles based on operation region division

The integrated chassis control system can improve vehicle handling and stability effectively. This paper proposes an integrated control system based on operation region division of active front steering (AFS) and direct yaw moment control (DYC) for in-wheel-motor electric vehicles. The control system adopts a two-layer hierarchical control structure. The decision layer employs a modified sliding mode controller to calculate the required corrective yaw moment, and determines operating regions of the two subsystems based on the driving conditions (road adhesion coefficient, tyre load and wheel slip ratio). The execution layer generates the corrective steer angle and the driving/braking torques for the AFS and DYC subsystems respectively. Simulation results show that on the high-adhesion-coefficient road, the integrated control system appropriately adopts subsystems to improve handling, while attenuating the workload of barking system; on the slippery road, the integrated control system maintains vehicle stability and provides control performance superior to those resulting from the single systems.

Hardware-in-the-Loop Simulation for a Multiaxial Suspension Test Rig with a Nonlinear Spatial Vehicle Dynamics Model

Hardware-in-the-Loop (HiL) simulations where a mechatronic system is used as the device under test (DUT), are established in the automotive sector for the design of active suspension components, e.g. roll-stabilizers. Usually, uniaxial actuator systems within the test rig are applied for the excitation of the DUT. However, in the context of mechatronic suspension systems incorporating multiple mechatronic subsystems, more sophisticated HiL test rigs / simulations with multiaxial excitation of the DUT are necessary. This contribution presents the model-based design of a HiL simulation for a multiaxial vehicle axle test rig. Within the HiL simulation a nonlinear spatial vehicle dynamics model with 36 states is used to reproduce the environment of the DUT in real-time. The implemented model and its requirements are described in detail. An appropriate HiL control framework is developed, which combines the vehicle dynamics model with the hybrid motion/force control of the manipulator systems. The primary actuator is a hydraulic hexapod. Simulation results and measurements obtained with the HiL system show the effectiveness of this approach. The potential for chassis control validation and design is highlighted in comparison to a highly detailed benchmark vehicle dynamics model.

A Global Chassis Control System Involving Active Suspensions, Direct Yaw Control and Active Front Steering

This paper aims to develop a Global Chassis Controller to coordinate the Active Front steering, Direct Yaw Control and Active Suspension controllers, in the ambition to improve the overall vehicle performance. A multilayer control architecture is adopted. It contains a local control layer and a decision layer. The local objectives for the sub-controllers in the control layer concern explicitly: maneuverability, lateral stability, rollover avoidance, and ride comfort. The sub-controllers are designed based on the super-twisting sliding mode theory. The decision layer is developed to promote/attenuate the local objectives of the sub-controllers, in order to remove the conflicts among the different objectives and extract the maximum benefit from the coordination using some evaluation criteria. This layer monitors the dynamics of the vehicle, calculates and sends scheduled gains to the sub-controllers, based on fuzzy logic rules and a stability criterion. Finally, the proposed Global Chassis Controller is validated on Matlab/Simulink using a vehicle model validated on the professional vehicle simulator “SCANeR Studio”. The results show the effectiveness of the proposed strategy.

Effect of fractional order damping control on braking performance for electric vehicles

Abstract Active suspensions are an object of interest nowadays, they have been a topic of research for decades due to their key role in Global Chassis Control (GCC). Indeed, a well-controlled active suspension system may considerably improve not only the passenger comfort by compensating the chassis dynamics but also road handling by minimizing the dynamics of the wheels normal forces. It may enhance vehicle stability by controlling the wheel load distribution, which influences the lateral and longitudinal dynamics to provide better steering performance, and safety by reducing the braking distance. The main contribution of this paper is to study the impact of fractional order (FO) control methods in the context of an active suspension system and in particular fractional order damping control. We derive two optimal damping control strategies: a comfort-oriented and a road holding oriented strategy, based on non-integer derivation of suspension deflection. The relevant benefits of both methods on vehicle response while driving on rough roads and during braking are evaluated using computer simulations applied on a two-wheel vehicle model.

Integrated state and parameter estimation for vehicle dynamics control

Most modern day automotive chassis control systems employ a feedback control structure. Therefore, a real-time estimate of the vehicle handling dynamic states and tyre-road contact parameters are invaluable for enhancing the performance of current vehicle control systems, such as anti-lock brake system (ABS) and electronic stability program (ESP). Today's production cars are equipped with onboard sensors (e.g., a 3-axis accelerometer, 3-axis gyroscope, steering wheel angle sensor, and wheel speed sensors) which when used in conjunction with certain model based observers can be used to identify relevant vehicle states for optimal control of comfort, stability and handling. However, some key variables such as the tyre forces, road bank/grade angles, and the tyre-road friction coefficient, which have a significant impact on vehicle handling performance and safety are difficult to measure using sensors already onboard vehicles. This paper introduces an integrated vehicle state estimator comprising a series of model-based and kinematic-based observers for estimating these unmeasurable states. Using an appropriate vehicle model, kinematic equations of motion and vehicle sensor data, the unknown vehicle states as well as the tyre-road contact forces are estimated by implementing a series of observers arranged in a cascade structure. Key estimated signals include the vehicle side slip angle (β), tyre longitudinal/lateral/vertical forces, and the tyre-road friction coefficient (μ). The performance of the proposed estimators has been evaluated via computer simulations conducted using the vehicle dynamics software CarSim®. An effectively designed merging scheme ensures robust estimation performance even during the vehicle manoeuvres which show highly nonlinear tyre characteristics and in the existence of road inclination or bank angle.

Literature review and fundamental approaches for vehicle and tire state estimation

ABSTRACTMost modern day automotive chassis control systems employ a feedback control structure. Therefore, real-time estimates of the vehicle dynamic states and tire-road contact parameters are invaluable for enhancing the performance of vehicle control systems, such as anti-lock brake system (ABS) and electronic stability program (ESP). Today's production vehicles are equipped with onboard sensors (e.g. a 3-axis accelerometer, 3-axis gyroscope, steering wheel angle sensor, and wheel speed sensors), which when used in conjunction with certain model-based or kinematics-based observers can be used to identify relevant tire and vehicle states for optimal control of comfort, stability and handling. Vehicle state estimation is becoming ever more relevant with the increased sophistication of chassis control systems. This paper presents a comprehensive overview of the state-of-the-art in the field of vehicle and tire state estimation. It is expected to serve as a resource for researchers interested in developing vehicle state estimation algorithms for usage in advanced vehicle control and safety systems.

Cooperative chassis control system of electric vehicles for agility and stability improvements

This study describes a cooperative chassis control system that controls longitudinal motion in accordance with the yaw movement for electric vehicles. This system can be used to improve vehicle agility and stability using the integration of torque distribution unit and electronic stability control (ESC). Moreover, this system can assist drivers smoothly navigate through a curve before ESC intervention. The structure of the proposed control system is fundamentally a model following controller, thereby making the vehicle follow the desired instantaneous handling characteristics by regulating the feedforward of the cornering stiffness, state feedback of longitudinal acceleration, and front and rear drive ratios. Experiments are performed to demonstrate the effectiveness of the proposed control system. The maximum steering angle during cornering is confirmed to be significantly reduced with proper deceleration/acceleration control and adjustment of the drive torques of the front and rear axles. Moreover, trajectory tracking can be significantly improved. The proposed control strategy can be used to assist intelligent vehicles to plan a reasonable trajectory, thereby enabling these vehicles to safely and rapidly pass corners or avoid obstacles while ensuring safety.

Integrated vehicle chassis control for active front steering and direct yaw moment control based on hierarchical structure

This paper presents an integrated vehicle chassis control (IVCC) strategy to improve vehicle handling and stability by coordinating active front steering (AFS) and direct yaw moment control (DYC) in a hierarchical way. In high-level control, the corrective yaw moment is calculated by the fast terminal sliding mode control (FTSMC) method, which may improve the transient response of the system, and a non-linear disturbance observer (NDO) is used to estimate and compensate for the model uncertainty and external disturbance to suppress the chattering of FTSMC. In low-level control, the null-space-based control reallocation method and inverse tyre model are utilized to transform the corrective yaw moment to the desired longitudinal slips and the steer angle increment of front wheels by considering the constraints of actuators and friction ellipse of each wheel. Finally, the performance of the proposed control strategy is verified through simulations of various manoeuvres based on vehicle dynamic software CarSim.

Integrated chassis control algorithm design for path tracking based on four-wheel steering and direct yaw-moment control

This article focuses on an integrated chassis control algorithm design for path tracking utilizing four-wheel steering and direct yaw-moment control. The designed integrated chassis control algorit...

Integrated Torque Vectoring Control for a Three-Axle Electric Bus Based on Holistic Cornering Control Method

An integrated chassis control framework that consists of a basic chassis controller and a torque vectoring controller is designed for a three-axle electric bus with distributed motor-driven and active rear steering subsystems. In the basic chassis controller, the active speed limiting control is integrated for antisideslip and antirollover purposes, and the interaxle torque distribution ratio is optimized for energy economy. Meanwhile, the active rear steering control is designed for the tire-wear coordinating purpose. In the torque vectoring controller, the model-based motion control algorithm based on the holistic cornering control method is designed, by which a torque increment is generated at each wheel to change the plane motion states of the vehicle. To solve the optimal torque increment vector, a real-time constrained quadratic programming problem is formulated. The constraints related to the wheel torque limits, the tire friction limits, and the anti-wheel-slip requirements are constructed and converted as the upper and lower bounds of the increments of the longitudinal tire forces. To verify the performance of the control framework, a Trucksim-Simulink cooperative test platform is established. The test results show satisfactory performances on energy economy, anti-wheel-slip, and the safety and stability of the motion control.

Real-Time Individual Tire Force Estimation for an All-Wheel Drive Vehicle

Due to demands for active control systems that can enhance driving performance, active-type all-wheel drive (AWD) systems have drawn interest recently. Equipped with an electronically actuated motor to control a wet clutch in a transfer case, the active-type AWD facilitates the variable distribution of torque from the main driveshaft to the subdriveshaft. The conventional approaches to the estimation of tire force, developed to implement chassis control, have only focused on the two-wheel drive vehicle dynamics model. In this paper, an individual tire force estimation algorithm that is particularly designed for AWD vehicles is proposed. Using the interacting multiple model filter method, the suggested algorithm can help avoid the chattering response caused by immediately switching between vehicle dynamic models. Data obtained from the controller area network of production vehicles were used for the real-time application of the proposed estimator to chassis control. Then, the proposed estimator was validated using an AWD vehicle in various driving scenarios.

Integrated observer approach using in-vehicle sensors and GPS for vehicle state estimation

This paper presents a new method for estimation of vehicle sideslip angle, which is a critical factor in some vehicle chassis control systems. Making use of easily available in-vehicle sensors and a standalone global positioning system (GPS), an integrated observer approach is developed, which includes a sensor offset compensator and two kinds of extended Kalman filters (EKFs) based on a bicycle model and a kinematic model, respectively. To properly combine the outputs of these EKFs, a weighting factor, a function of tire cornering stiffness and tire force, is designed. The observability of each EKF is checked by observability functions of nonlinear systems. As well as the sideslip angle, the longitudinal velocity, heading angle, and tire cornering stiffness are simultaneously estimated by the proposed algorithm. Finally, the performance of the entire system in various driving scenarios is verified using a test vehicle, and the superiority of the integrated observer is confirmed through a comparative study.

Selection of Actuator Combination in Integrated Chassis Control Using Taguchi Method

This paper presents a method to select the actuator combination in integrated chassis control using Taguchi method. Electronic stability control (ESC), active front and rear steering (AFS/ARS) are used as an actuator, which is needed to generate a control tire force. After computing the control yaw moment in the upper-level controller, it is distributed into the control tire forces, generated by ESC, AFS and ARS in the lower-level controller. In this paper, the weighted pseudo-inverse control allocation (WPCA) with variable weights is used to determine the control tire forces of each actuator. Taguchi method is adopted for sensitivity analysis on variable weights of WPCA in terms of the control performances such as the maneuverability and the lateral stability. For sensitivity analysis, simulation is performed on a vehicle simulation package, CarSim. From sensitivity analysis, the most effective actuator combination is selected.

Prospects of development of land driverless trucks

The paper is dedicated to the problem of creation and efficient use of driverless trucks. It also contains general analysis of foreign experience and development trends. The concept of FSUE “NAMI” for development of a platoon of driverless trucks for cargo transportation between specialized terminals on public roads is provided. A road train with virtual couplings where the lead vehicle has a driver and the rest are driverless is proposed as a base for the driverless platoon. The platoon is formed by such road trains, which ensures extended functional features, including the possibility to form platoons of road trains from different logistics centers and with different destinations, quick reforming of the platoon in the logistics centers, possibility to split the platoon when driving on public roads, higher precision of control over the platoon during driving, etc. It is also shown that in order to improve the efficiency of cargo transportation, driverless cargo platforms (trucks) shall be designed without a cabin. The paper also considers the ways to reduce the price of driverless trucks by creating a special road infrastructure, which will allow transfer of the most expensive subsystems of driverless vehicles to such infrastructure. Upon that, the following subsystems will remain within the driverless chassis: navigation, communication, chassis control and ADAS. It is noted that creation of such infrastructure will require high investments, therefore, gradual implementation of such systems is seen as rational. It is shown that the most appropriate area for these purposes is transregional cargo transportation. It is noted that the economic reasons for implementation of the proposed concept are as follows: significant reduction of the number of drivers; significant simplification of the driverless platform control system and reduction of the price of subsystems; no need for the driver’s cabin within the driverless platform; fuel economy when driving within a platoon. Power unit options for driverless cargo platforms are investigated and the reasons for selection of a particular power unit are given.

Integrated Vehicle Dynamics Control Via Torque Vectoring Differential and Electronic Stability Control to Improve Vehicle Handling and Stability Performance

This paper proposed a full vehicle state estimation and developed an integrated chassis control by coordinating electronic stability control (ESC) and torque vectoring differential (TVD) systems to improve vehicle handling and stability in all conditions without any interference. For this purpose, an integrated TVD/ESC chassis system has been modeled in Matlab/Simulink and applied into the vehicle dynamics model of the 2003 Ford Expedition in carsim software. TVD is used to improve handling in routine and steady-state driving conditions and ESC is mainly used as the stability controller for emergency maneuvers or when the TVD cannot improve vehicle handling. By the β−β˙ phase plane, vehicle stable region is determined. Inside the reference region, the handling performance and outside the region the vehicle stability has been in question. In order to control the integrated chassis system, a unified controller with three control layers based on fuzzy control strategy, β−β˙ phase plane, longitudinal slip, and road friction coefficient of each tire is designed in Matlab/Simulink. To detect the control parameters, a state estimator is developed based on unscented Kalman filter (UKF). Bees algorithm (BA) is employed to optimize the fuzzy controller. The performance and robustness of the integrated chassis system and designed controller were conformed through routine and extensive simulations. The simulation results via a co-simulation of MATLAB/Simulink and CarSim indicated that the designed integrated ESC/TVD chassis control system could effectively improve handling and stability in all conditions without any interference between subsystems.

Multi-axle/articulated bus dynamics modeling: a reconfigurable approach

ABSTRACTThis paper proposed a unified model including yaw and roll dynamics for any axle or articulation configuration of buses by using a reconfigurable approach. First, all the possible existing configurations of buses are introduced, including the axle/articulation configuration, powertrain configuration, and active chassis control configuration. Consequently, the research is motivated by a key question: how can we develop a unified model that is inclusive and configurable to all of the above bus configurations? To develop the model, three layers of the modeling process are presented step by step. The magic formula and vertical load transfer are discussed to formulate the tyre model. It is noted that the case of the articulated bus is presented in an independent section but how it is included and unified in a general form is also explained. Finally, a modeling validation of axle or articulation configuration cases is performed and the comparative results to high-fidelity models show the feasibility, efficiency, and convenience of the reconfigurable approach. As the crucial feature, the resulting model can be potentially applied to model-based controller design in any buses without reformulating the model. This will greatly benefit the vehicle dynamics control and also future autonomous buses. Although the focus of this paper is buses, the proposed approach actually covers any multi-axle/articulated vehicles, like trucks, tractor-trailers.

Internal-model control of vehicle chassis based on wavelet-network dynamic inversion method

An internal-model control strategy of vehicle chassis system is proposed based on wavelet-network dynamic inversion method, to eliminate the coupling effect among the chassis subsystems. By analysing the chassis system reversibility, the paired relationship of the input and output variables is determined. Then, a wavelet-network dynamic inversion model of vehicle chassis system is obtained and connected in series with the original system. The chassis system is decoupled into three independent pseudo-linear systems, and decoupling between the control loops of vehicle chassis system is realised. An internal-model controller is designed to improve the system response. Further, a simulation and a driver-in-loop test using LabVIEW PXI and veDYNA are conducted to verify the control strategy efficacy. The results show that the proposed control strategy can eliminate the interference and coupling between the active front-wheel steering, direct yaw-moment control, and active suspension system, and improve the vehicle handling and status tracking stability.

Internal-model control of vehicle chassis based on wavelet-network dynamic inversion method

An internal-model control strategy of vehicle chassis system is proposed based on wavelet-network dynamic inversion method, to eliminate the coupling effect among the chassis subsystems. By analysing the chassis system reversibility, the paired relationship of the input and output variables is determined. Then, a wavelet-network dynamic inversion model of vehicle chassis system is obtained and connected in series with the original system. The chassis system is decoupled into three independent pseudo-linear systems, and decoupling between the control loops of vehicle chassis system is realised. An internal-model controller is designed to improve the system response. Further, a simulation and a driver-in-loop test using LabVIEW PXI and veDYNA are conducted to verify the control strategy efficacy. The results show that the proposed control strategy can eliminate the interference and coupling between the active front-wheel steering, direct yaw-moment control, and active suspension system, and improve the vehicle handling and status tracking stability.