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Technical Paper

Allocation Control of the Distributed Steering System

2016-09-27
2016-01-8034
Distributed steering vehicle uses four steering motors to achieve four wheel independent steering. The steering angle of each wheel can be distributed respectively. The tire cornering characteristics are added to traditional steering model to study the angle allocation control algorithm. Using the constraint relation between tire slip angle, vehicle speed, yaw rate and front steering angle, and connecting with the ideal ackermann steering relationship, steering angle allocation of front wheel independent steering and four wheel independent steering is derived. Then simulated analysis is carried out to demonstrate the efficiency of the algorithm. Improvements in tire wear condition are determined by evaluating the optimization in tire lateral force, and the vehicle stability is determined by vehicle slip angle. The simulation results show that the angle allocation control algorithm has a good effect on improving tire wear condition and enhancing the stability of vehicle.
Technical Paper

Study on Controller of Electronically Controlled Air Suspension for Bus

2016-09-27
2016-01-8033
According to the vehicle’s driving conditions, electronically controlled air suspension (ECAS) systems can actively adjust the height of vehicle body, so that better ride comfort and handling stability will be achieved, which can’t be realized by traditional passive suspension. This paper presents a design and implementation of ECAS controller for vehicle. The controller is aimed at adjusting the static and dynamic height of the vehicle. To exactly track the height of the vehicle and satisfy the control demand of air suspension, a height sensor decoding circuit based on the inductance sensor is designed. Based on it, a new height control algorithm is adopted to achieve rapid and precise control of vehicle height. To verify the function of the designed controller and the proposed height control algorithm, an air spring loading test bench and an ECU-in-loop simulation test bench are respectively established.
Journal Article

Fault-Tolerant Control for 4WID/4WIS Electric Vehicle Based on EKF and SMC

2015-09-29
2015-01-2846
This paper presents a fault-tolerant control (FTC) algorithm for four-wheel independently driven and steered (4WID/4WIS) electric vehicle. The Extended Kalman Filter (EKF) algorithm is utilized in the fault detection (FD) module so as to estimate the in-wheel motor parameters, which could detect parameter variations caused by in-wheel motor fault. A motion controller based on sliding mode control (SMC) is able to compute the generalized forces/moments to follow the desired vehicle motion. By considering the tire adhesive limits, a reconfigurable control allocator optimally distributes the generalized forces/moments among healthy actuators so as to minimize the tire workloads once the actuator fault is detected. An actuator controller calculates the driving torques of the in-wheel motors and steering angles of the wheels in order to finally achieve the distributed tire forces. If one or more in-wheel motors lose efficacy, the FD module diagnoses the actuator failures first.
Technical Paper

An Active Return-to-Middle Control Method without Angle Sensor for EPS

2015-09-29
2015-01-2724
Electric Power Steering System (EPS) can directly provide auxiliary steering torque via a motor. The motor and the reducer in mechanical system will make the friction torque in steering system larger, as a result, the ability of steering returning will be reduced. Therefore, during the design of EPS system control strategy, an extra active return-to-middle control strategy is needed. For the fact that most of the low-end vehicles equipped with EPS system do not have a steering wheel angle sensor, a control strategy has to work without the datum of steering wheel angle. This paper proposes an active return-to-middle control method without steering wheel angle sensor, based on the estimated aligning torque which is converted to the pinion, and expounds how to determine the steering system current motion state in detail. This control method will work just during the turning condition, so it has no effect on the EPS basic assist characteristics.
Technical Paper

Driving and Steering Coordination Control for 4WID/4WIS Electric Vehicle

2015-09-29
2015-01-2762
This paper presents an integrated chassis controller with multiple hierarchical layers for 4WID/4WIS electric vehicle. The proposed systematic design consists of the following four parts: 1) a reference model is in the driver control layer, which maps the relationship between the driver's inputs and the desired vehicle motion. 2) a sliding mode controller is in the vehicle motion control layer, whose objective is to keep the vehicle following the desired motion commands generated in the driver control layer. 3) By considering the tire adhesive limits, a tire force allocator is in the control allocation layer, which optimally distributes the generalized forces/moments to the four wheels so as to minimize the tire workloads during normal driving. 4) an actuator controller is in the executive layer, which calculates the driving torques of the in-wheel motors and steering angles of the four wheels in order to finally achieve the distributed tire forces.
Journal Article

Based on the Unscented Kalman Filter to Estimate the State of Four-Wheel-Independent Electric Vehicle with X-by-Wire

2015-09-29
2015-01-2731
As a new form of electric vehicle, Four-wheel-independent electric vehicle with X-By-Wire (XBW) inherits all the advantages of in-wheel motor drive electric vehicles. The vehicle steering system is liberated from traditional mechanical steering mechanism and forms an advanced vehicle with all- wheel independent driving, braking and steering. Compared with conventional vehicles, it has more controllable degrees of freedom. The design of the integrated vehicle dynamics control systems helps to achieve the steering, driving and braking coordinated control and improves the vehicle's handling stability. In order to solve the problem of lacking of vehicle state information in the integrated control, some methods are used to estimate the vehicle state of four-wheel-independent electric vehicles with XBW. In order to improve the estimation accuracy, unscented Kalman filter (UKF) is used to estimate the vehicle state variables in this paper.
Technical Paper

An Active Return-to-Center Control Strategy with Steering Wheel Sensor for Electric Power Steering System

2015-09-29
2015-01-2729
For the vehicles equipped with Electric Power Steering (EPS) system, the friction and damping effect brought by assisted motor and worm gear mechanism influence the return ability and handing stability. In order to eliminate the impacts, it is necessary to add return-to-center control in EPS control strategy. This paper proposes a practical active return-to-center control strategy with steering wheel angle signals based on return state identification. In the strategy, the return state of the steering system is identified quickly according to the two signals steering wheel angle velocity and steering wheel torque. Only under return state, a double closed-loop PID control strategy is carried out to calculate a compensation current to improve the return ability. For validating the proposed strategy, a fine EPS model including BLDC assisted motor is built based on carsim and simulink co-simulation platform.
Technical Paper

Development and Research on Control Strategy of Advanced Electronic Braking Systems for Commercial Vehicle

2014-09-30
2014-01-2285
Electronic braking system (EBS) of commercial vehicle is developed based on Anti-lock Braking System (ABS), for the purpose of enhancing the braking performance. Based on the previous study, this paper aims at the development and research on the control strategy of advanced electronic braking system for commercial vehicle, which mainly includes braking force distribution and multiple targets control strategy. In the study of braking force distribution control strategy, the mass of vehicle and the axle loads will be calculated dynamically and the braking force of each wheel will be distributed regarding to the axle loads. The braking intention recognition takes the brake pad wear into account when braking uncritically, so it can detect a difference in the pads between the front and the rear axles. The brake assist strategy supports the driver during emergency braking and the braking distance is shortened by the reduction of the braking system response time.
Technical Paper

Development of Simulation Platform and Control Strategy of Electronic Braking System for Commercial Vehicles

2014-09-30
2014-01-2286
Pneumatic Electric Braking System (EBS) is getting widely spread for commercial vehicles. Pneumatic EBS improves the problem of slow response of traditional pneumatic braking system by implementing brake-by-wire. However, the time-delay response and hysteresis of some electro-pneumatic components and some other issues decrease the response and control accuracy of the pneumatic EBS.
Technical Paper

Research on Integrated Chassis Control Strategy for Four-Wheel Independent Control Electric Vehicle

2014-09-30
2014-01-2290
Four-wheel independent control electric vehicle is a new type of x-by-wire EV with four wheels independent steering and four wheels independent drive/brake systems. In order to take full advantage of the vehicle's performance potential, this paper presents a novel integrated chassis control strategy. In the paper, the strategy is designed by the hierarchical control structure and divided into integrated control layer and allocation layer. By this method, the control logical can be modularized and simplified. In the integrated control layer, Model Prediction Control (MPC) is adopted to design the integrated control unit, which belongs to be a kind of local optimization algorithm with feedback correction features. Using this method could avoid the system performance degradation caused by the control model mismatch. The control allocation layer is to optimally distribute the vehicle control forces to the steering/driving/brake actuators on each wheel.
Technical Paper

Study on Dynamic Characteristics and Control Methods for Drive-by-Wire Electric Vehicle

2014-09-30
2014-01-2291
A full drive-by-wire electric vehicle, named Urban Future Electric Vehicle (UFEV) is developed, where the four wheels' traction and braking torques, four wheels' steering angles, and four active suspensions (in the future) are controlled independently. It is an ideal platform to realize the optimal vehicle dynamics, the marginal-stability and the energy-efficient control, it is also a platform for studying the advanced chassis control methods and their applications. A centralized control system of hierarchical structure for UFEV is proposed, which consist of Sensor Layer, Identification and Estimation Layer, Objective Control Layer, Forces and Motion Distribution Layer, Executive Layer. In the Identification and Estimation Layer, identification model is established by utilizing neural network algorithms to identify the driver characteristics. Vehicle state estimation and road identification of UFEV based on EKF and Fuzzy Logic Control methods is also conducted in this layer.
Technical Paper

Development and Verification of Electronic Braking System ECU Software for Commercial Vehicle

2013-11-27
2013-01-2736
Electronic braking system (EBS) of commercial vehicle is developed from ABS to enhance the brake performance. Based on the early development of controller hardware, this paper starts with an analysis of the definition of EBS. It aims at the software design of electronic control unit, and makes it compiled into the controller in the form of C language by the in-depth study about control strategy of EBS in different braking conditions. Designed controller software is divided into two layers. The upper control strategy includes the recognition algorithm of driver's braking intention, estimation algorithm of the vehicle state, conventional braking strategy which consists of the algorithm of deceleration control and braking force distribution, and emergency braking strategy which consists of the algorithm of brake assist control and ABS control.
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