Rear Steering Research Articles

Reconfigurable Integrated Stability Control for Four- and Three-wheeled Urban Vehicles With Flexible Combinations of Actuation Systems

Small electric vehicles, also known as urban vehicles, have been introduced to alleviate traffic congestion, energy consumption, and pollution due to their smaller sizes, higher maneuverability, and lower fuel consumption. The main objective of this study is to develop a unified control structure that can be reconfigured for stability control of different configurations of urban vehicles with flexible combinations of control actuation. The reconfigurable controller can be readily adjusted for Tadpole and Delta three-wheeled vehicles as well as four-wheeled vehicles without reformulating the problem. Different types and combinations of actuators can be selected for the control design including differential braking, torque vectoring, active front and rear steering, and active camber system. The proposed structure integrates the lateral stability control, the rollover prevention, and the longitudinal slip control in traction/braking. The reconfigurable controller is developed using the model predictive control approach. Simulation results show that the introduced controller can be effectively used for stability control of different configurations of urban vehicles, and facilitates their control design.

Explicit controller of a single truck stability and rollover mitigation

This study’s aim was to enhance the maneuverability safety in the coordination of active rear steering and differential braking control for untripped rollover prevention, which performs a panic lane change maneuver to bypass the obstacle encountered in the path. In avoiding rollover accidents, there are several guidance preventions, such as to secure the vehicle from the intention of the driver and to position the vehicle in the actual lane. A crosswind effect is also found to be a crucial factor since this may cause other accidents. Therefore, there is a need to monitor the driver’s actual path and maintaining the stability of the vehicle along the desired path in order to avoid rollover accidents. We extended the analysis of Yakub and Mori (2015) [1], by suggesting an explicit model of predictive control, which includes an active rear steering and braking control for each wheel. Our main focus was on the general trade-off between rollover prevention and path tracking. The effectiveness of the explicit control model invented for this study was measured and validated by the simulation results for a heavy vehicle proposed in this research.

Interactive Control Paradigm-Based Robust Lateral Stability Controller Design for Autonomous Automobile Path Tracking With Uncertain Disturbance: A Dynamic Game Approach

Stability as well as robustness is the major concerns in the design of a trajectory tracking controller for an autonomous vehicle. In this paper, a novel lateral stability controller design for vehicle path tracking is developed. First, using dynamic game theory as a general framework, vehicle lateral stability can be viewed as a dynamic difference game so that its two players, namely, the active front steering (AFS) system and active rear steering (ARS) system can work together to provide more stability for vehicle path tracking control. The interactive steering control strategies between AFS and ARS are obtained by noncooperative closed-loop feedback Stackelberg game theory to ensure optimal performance for vehicle path tracking. Then, based on the proposed path-following shared control paradigm, by applying the method of zero-sum game theory, a finite-time robust regulator is developed to make the interaction model more robust to uncertain lateral disturbances. Finally, double-lane change and serpentine driving condition with and without uncertain time-varying lateral disturbance are used to evaluate the proposed control algorithm. Simulation and hardware-in-loop implementation results show that the proposed shared control paradigm based robust path-tracking controller can robustly provide better lateral stability when time-varying lateral disturbances are bounded.

Numerical Simulation of the Airflow Characteristics of Drying by Ground Air Film

According to the interference and coupling characteristics among sub-systems of the chassis of the forklift truck, the the neutral network inverse system method of the non-linear system is applied for the decoupling control of the active rear steering (ARS) and the direct yaw moment control (DYC) of the forklift truck. Based on the analysis of the reversibility of the chassis system, a back propagation neutral network reverse system model is set to decouple the chassis system into two independent pseudo-linear system; A PD closed loop controller is designed to comprise a composite controller with the neutral network reverse system and the simulation is performed for verification. The simulation result shows that the decoupling control strategy with the neutral network reverse system can eliminate the interference and coupling among sub-systems of the chassis and thus enhances the status tracking and operating stability of forklift trucks.

The Decoupling Control of ARS and DYC Based on the Neutral Network Inverse System Method

According to the interference and coupling characteristics among sub-systems of the chassis of the forklift truck, the the neutral network inverse system method of the non-linear system is applied for the decoupling control of the active rear steering (ARS) and the direct yaw moment control (DYC) of the forklift truck. Based on the analysis of the reversibility of the chassis system, a back propagation neutral network reverse system model is set to decouple the chassis system into two independent pseudo-linear system; A PD closed loop controller is designed to comprise a composite controller with the neutral network reverse system and the simulation is performed for verification. The simulation result shows that the decoupling control strategy with the neutral network reverse system can eliminate the interference and coupling among sub-systems of the chassis and thus enhances the status tracking and operating stability of forklift trucks.

Vehicle Stability Control through Optimized Coordination of Active Rear Steering and Differential Driving/Braking

Vehicle Stability Control through Optimized Coordination of Active Rear Steering and Differential Driving/Braking

Modular design and analysis of the x-by-wire center point steering independent suspension for in-wheel electric vehicle

In this article, a new design scheme of x-by-wire steering suspension system is proposed, which aims to solve the adaptation problem of the traditional steering system, suspension system, and the electric wheel. It meets the requirement of four-wheel independent steering function with large scale. The design keeps wheel steering center axis to coincide with the virtual wheel kingpin, thereby realizing the application of the center point steering independent suspension system in electric wheels. In addition, modular design is adopted to reduce the coupling between the system and the car body, thereby realizing the generalization of the front and rear steering suspension system, and it also decreases the number of components. Furthermore, the theoretical analysis and parameter design of the self-aligning torque of the suspension are carried out. The multi-body dynamics model of system is established, and the performance is simulated in both time domain and frequency domain. The comparison test shows that the center point steering independent suspension has higher feasibility. Finally, a prototype of the system is developed, which provides a new idea for the designing of chassis for electric vehicles.

A Novel Reconfigurable Integrated Vehicle Stability Control With Omni Actuation Systems

This paper introduces a novel control structure for integrated vehicle stability control that can be reconfigured for a wide range of vehicles with different types and combinations of control actuation. The proposed structure can be easily adjusted for a specific vehicle as it enables any actuator to be readily added or removed without reformulating the control problem. Different types and combinations of control actuation can be selected for the control design including differential braking and torque vectoring on all or selected wheels as well as active front or rear steering. To develop this model-based reconfigurable control structure, vehicle modeling is provided in a matrix form and an actuator reconfiguration matrix is defined. The proposed structure realizes integrated lateral stability control and slip control in traction/braking. The Model Predictive Control (MPC) approach is used to develop the controller. By employing the reconfigurable structure, optimal control solutions can be achieved with respect to only available control actuations. Simulation results show that the proposed control structure can facilitate the design of stability control regardless of the actuators configuration.

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.

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.

Integrated vehicle dynamic controls using active rear wheel steering and four wheel braking

This paper describes and compares two integrated dynamic controller systems (IDCs; IDCB, IDCR) and one active rear wheel steering system (ARS), developed to stabilise lateral dynamics and maintain steerability on a slippery road. The IDCs make use of a brake system and rear steering system. A fuzzy logic control method and a sliding mode control method were employed to design the three systems. The performance of the ARS and IDCs was tested under a variety of road and driving conditions. The results show that ARS and IDCs systems tracked the reference yaw rate under all tested conditions. Two IDCs reduced the body slip angle also. When a vehicle ran on a split-μ road and brake input was applied, IDCB and IDCR virtually eliminated the lateral dynamics. These results indicate that two IDCs enhanced lateral stability and preserved steerability.

Control Allocation of Active Rear Steering and Vehicle Dynamics Control Using a New Tire Model

Control Allocation of Active Rear Steering and Vehicle Dynamics Control Using a New Tire Model

Numerical comparison of two methods for integration of active rear steering, torque vectoring and hydraulically interconnected suspension

This paper proposes the integration of three chassis control systems. In the first part, three chassis control systems including hydraulically interconnected suspension, torque vectoring system and active rear steering are introduced then these subsystems are evaluated by ramp steer and step steer manoeuvres; effectiveness and limits of subsystems are also reviewed. Then, two methods (optimal control and rule-based method) are proposed for integrated vehicle dynamics system. Both methods are evaluated with various manoeuvres to understand the advantages and disadvantages of each method.

Numerical comparison of two methods for integration of active rear steering, torque vectoring and hydraulically interconnected suspension

This paper proposes the integration of three chassis control systems. In the first part, three chassis control systems including hydraulically interconnected suspension, torque vectoring system and active rear steering are introduced then these subsystems are evaluated by ramp steer and step steer manoeuvres; effectiveness and limits of subsystems are also reviewed. Then, two methods (optimal control and rule-based method) are proposed for integrated vehicle dynamics system. Both methods are evaluated with various manoeuvres to understand the advantages and disadvantages of each method.

Integrated vehicle dynamic controls using active rear wheel steering and four wheel braking

This paper describes and compares two integrated dynamic controller systems (IDCs; IDCB, IDCR) and one active rear wheel steering system (ARS), developed to stabilise lateral dynamics and maintain steerability on a slippery road. The IDCs make use of a brake system and rear steering system. A fuzzy logic control method and a sliding mode control method were employed to design the three systems. The performance of the ARS and IDCs was tested under a variety of road and driving conditions. The results show that ARS and IDCs systems tracked the reference yaw rate under all tested conditions. Two IDCs reduced the body slip angle also. When a vehicle ran on a split-μ road and brake input was applied, IDCB and IDCR virtually eliminated the lateral dynamics. These results indicate that two IDCs enhanced lateral stability and preserved steerability.

A New Approach for Vehicle Lateral Velocity and Yaw Rate Control with Uncertainty

AbstractIn order to attain excellent stability and maneuverability to ensure safety and ride‐comfort, the lateral velocity and yaw rate of a vehicle are expected to be controlled at any desired values simultaneously. A basic manipulation model of a vehicle with two degrees of freedom which requires two independent control inputs (front and rear steering angle) is constructed. In this model, we consider the mass and the moment of inertia of the vehicle are the uncertain parameters which are (possibly) fast‐varying. However, no further information, except that the uncertainties are bounded, is assumed. Furthermore, the bound is unknown. An adaptive robust control methodology based on the Udwadia and Kalaba approach which guarantees uniform boundedness and uniform ultimate boundedness is proposed to drive the system to follow the pre‐specified constraints approximately. The adaptive law is of leakage type which can adjust itself based on the tracking error. The numerical simulation results conducted by MATLAB demonstrate the ease and effectiveness of implementation.

Integrated chassis control for a three-axle electric bus with distributed driving motors and active rear steering system

ABSTRACTThis paper describes an integrated chassis control framework for a novel three-axle electric bus with active rear steering (ARS) axle and four motors at the middle and rear wheels. The proposed integrated framework consists of four parts: (1) an active speed limiting controller is designed for anti-body slip control and rollover prevention; (2) an ARS controller is designed for coordinating the tyre wear between the driving wheels; (3) an inter-axle torque distribution controller is designed for optimal torque distribution between the axles, considering anti-wheel slip and battery power limitations and (4) a data acquisition and estimation module for collecting the measured and estimated vehicle states. To verify the performances, a simulation platform is established in Trucksim software combined with Simulink. Three test cases are particularly designed to show the performances. The proposed algorithm is compared with a simple even control algorithm. The test results show satisfactory lateral stability and rollover prevention performances under severe steering conditions. The desired tyre wear coordinating performance is also realised, and the wheel slip ratios are restricted within stable region during intensive driving and emergency braking with complicated road conditions.

Vehicle yaw stability control using active rear steering: Development and experimental validation

In this paper, a novel pulse active steering system for improving vehicle yaw stability is developed. In the proposed method, pulses are sent to the steerable rear wheels whenever the error between the expected and actual yaw rate is outside a predetermined range. The proposed method and its performance are verified experimentally by full vehicle testing. For this purpose, a simplified vehicle model and a rear suspension model are developed. Vehicle stability is investigated and the steering pulse parameters on the vehicle’s stability are studied. A control system is designed and numerical simulations are performed. Moreover, the active rear steering system is implemented on a Lexus for performing road experiments. Results from simulations and experiments indicate that considerable improvement in the yaw stability performance can be achieved by the proposed system. The proposed method is more cost effective and simpler for vehicle stability control.

Comparative study of MPC and LQC with disturbance rejection control for heavy vehicle rollover prevention in an inclement environment

This paper compares the Model predictive control (MPC) and Linear quadratic control (LQC) of heavy vehicles via active front steering for rollover prevention in inclement environments. In both control methods, a Disturbance rejection control (DRC) that negates the effects of wind and road bank acting on the vehicle is designed. Load transfer ratio (LTR) is applied to judge rollover by mitigating the absolute value of LTR as much as possible. We tested and compared two different controllers, i) MPC with DRC and ii) LQC with DRC. Two types of environmental conditions were considered, i) typhoon and ii) typhoon on a bumpy road. The simulation results demonstrate that MPC was more successfully implemented than LQC during LTR suppression. This paper also proposes an MPC for coordination of active rear steering and differential braking control maneuvers to prevent rollover in inclement environments. For a feasible comparison, the LQC controller was designed using the same approach adopted for the MPC controller. Results show the proposed coordinated control yields better performance for rollover prevention than LQC.

Enhancing the yaw stability and the manoeuvrability of a heavy vehicle in difficult scenarios by an emergency threat avoidance manoeuvre

This study aims to investigate the switching model predictive control strategy for a heavy-vehicle system in order to coordinate the actuator between active rear steering and differential braking control manoeuvres for emergency threat avoidance in difficult environments. We present the controller performances for the lateral dynamic behaviour, the yaw stability and the manoeuvrability of a vehicle when subjected to a sudden threat or disturbance such as a gust of wind, a road bank angle or a split- μ road surface in order to enable a fast safe lane-change trajectory to be followed. The vehicle was driven at a medium forward speed and a high forward speed in order to investigate the effectiveness of the proposed approach in avoiding the threat, maintaining the stability and enablinge a fast safe lane-change trajectory to be followed. We compared two different controllers (a model predictive controller and a switching model predictive controller) for two different control manoeuvres (active rear steering with differential braking control and active rear steering with direct yaw moment control). The simulation results demonstrate that the proposed switching model predictive control method provides an improved fast safe lane-change manoeuvre in a threat avoidance scenario for both control manoeuvres. It also demonstrated that the proposed active rear steering with differential braking control is more useful for maintaining the stability of the vehicle in a threat avoidance scenario with disturbance effects than is active rear steering with direct yaw moment control.