Bangji Zhang

A Novel Observer Design for Simultaneous Estimation of Vehicle Steering Angle and Sideslip Angle

Both steering angle and sideslip angle are important states for vehicle handling and stability control. Instead of directly measuring these angles, indirect estimation of these states will provide a cost-effective way for the implementation of vehicle control systems. In the past, model-based methods have been proposed to estimate the sideslip angle with the measured steering angle. In this paper, a novel observer design is presented for simultaneous estimation of vehicle steering angle and sideslip angle so that the estimation of sideslip angle does not require the measurement of steering angle and the estimate of steering angle can also be used for other purposes, such as automatic steering control, steering system fault diagnosis, and driving performance monitoring. To enable this observer design, the Takagi-Sugeno (T-S) fuzzy modeling technique is applied to represent the vehicle lateral dynamics model with nonlinear Dugoff tyre model and time-varying vehicle speed. A T-S observer is then designed to simultaneously estimate the steering angle and sideslip angle with the measurements of yaw rate and vehicle speed, and is designed to be robust against parameter uncertainties and unknown inputs. The conditions for designing such an observer are derived in terms of linear matrix inequalities (LMIs). Experimental results are used to validate the effectiveness of the proposed approach. The results show that the designed observer can effectively estimate steering angle and sideslip angle despite the variation of vehicle longitudinal speed.

A Condensation Method for the Dynamic Analysis of Vertical Vehicle–Track Interaction Considering Vehicle Flexibility

This paper is aimed at developing a computationally efficient approach to simulate the vertical dynamic behavior of vehicle–track coupled system. With the finite element method, the car body, bogies, and rail are modeled as Euler beams supported by springs and dashpots, which can investigate the influence of flexibility of the vehicle on structural dynamic response. By a variant of component-mode synthesis (CMS), the degrees-of-freedom (DOFs) within the substructures are condensed and the two substructures are coupled through nonlinear Hertzian theory. Although the system matrix is updated and factorized during the calculation, the total computational efficiency is significantly improved due to the much smaller size of the equations of motion and direct solution algorithm instead of iterative procedure. Compared with an existing model, the accuracy and efficiency of the method are investigated. Application of the model is shown by numerical example.

Physical parameter identification method based on modal analysis for two-axis on-road vehicles: Theory and simulation

Physical parameters are very important for vehicle dynamic modeling and analysis. However, most of physical parameter identification methods are assuming some physical parameters of vehicle are known, and the other unknown parameters can be identified. In order to identify physical parameters of vehicle in the case that all physical parameters are unknown, a methodology based on the State Variable Method(SVM) for physical parameter identification of two-axis on-road vehicle is presented. The modal parameters of the vehicle are identified by the SVM, furthermore, the physical parameters of the vehicle are estimated by least squares method. In numerical simulations, physical parameters of Ford Granada are chosen as parameters of vehicle model, and half-sine bump function is chosen to simulate tire stimulated by impulse excitation. The first numerical simulation shows that the present method can identify all of the physical parameters and the largest absolute value of percentage error of the identified physical parameter is 0.205%; and the effect of the errors of additional mass, structural parameter and measurement noise are discussed in the following simulations, the results shows that when signal contains 30 dB noise, the largest absolute value of percentage error of the identification is 3.78%. These simulations verify that the presented method is effective and accurate for physical parameter identification of two-axis on-road vehicles. The proposed methodology can identify all physical parameters of 7-DOF vehicle model by using free-decay responses of vehicle without need to assume some physical parameters are known.

Model Reduction Technique Tailored to the Dynamic Analysis of a Beam Structure under a Moving Load

This study presents a technique that uses a model reduction method for the dynamic response analysis of a beam structure to a moving load, which can be modeled either as a moving point force or as a moving body. The nature of the dedicated condensation method tailored to address the moving load case is that the master degrees of freedom are reselected, and the coefficient matrices of the condensed model are recalculated as the load travels from one element to another. Although this process increases computational burden, the overall computational time is still greatly reduced because of the small scale of motion equations. To illustrate and validate the methodology, the technique is initially applied to a simply supported beam subjected to a single-point load moving along the beam. Subsequently, the technique is applied to a practical model for wheel-rail interaction dynamic analysis in railway engineering. Numerical examples show that the condensation model can solve the moving load problem faster than an analytical model or its full finite element model. The proposed model also exhibits high computational accuracy.

Development of continuously variable transmission and multi-speed dual-clutch transmission for pure electric vehicle:

Pure electric vehicles, as a promising alternative to conventional fossil fuel–powered passenger vehicles, provide outstanding overall energy-utilizing efficiency by omitting the internal combustion engine. However, because of lower energy density in battery energy storage, the driving range per charge is limited by this electrochemical power source, leading to a so-called range phobia and presenting a major barrier for large-scale commercialization. The widely adopted single-reduction gear in pure electric vehicles typically do not achieve the diverse range of functional needs that are present in multi-speed conventional vehicles, most notably acceleration performance and top speed requirements. Consequently, special-designed multi-speed pure electric vehicle–powertrains have been compared and investigated for these applications in this article. Through the optimizing of multiple gear ratios and creating special shifting strategies, a more diverse range of functional needs is realized without increasing the practical size of the electric motor and battery. This article investigates the performance improvements of pure electric vehicle realized through utilization of multi-speed dual-clutch transmissions and continuously variable transmissions. Results reveal that there can be significant benefits attained for pure electric vehicles through multi-speed transmissions. Simulation results shows that continuously variable transmission and two-speed transmission are the two most promising transmissions for pure electric vehicle in different classes, respectively.

A Piecewise Hysteresis Model for a Damper of HIS System

A damper of the hydraulically interconnected suspension (HIS) system, as a quarter HIS, is prototyped and its damping characteristic is tested to characterize the damping property. The force-velocity characteristic of the prototype is analyzed based on a set of testing results and accordingly a piecewise hysteresis model for the damper is proposed. The proposed equivalent parametric model consists of two parts: hysteresis model in low speed region and saturation model in high speed region which are used to describe the hysteresis phenomenon in low speed and nonhysteresis phenomenon in high speed, respectively. The parameters of the model are identified based on genetic algorithm by setting the constraints of parameters according to their physical significances and the corresponding testing results. The advantages of the model are highlighted by comparing to the nonhysteresis model and the permanent hysteresis model. The numerical simulation results are compared with the testing results to validate the accuracy and effectiveness of the proposed model. Finally, to further verify the proposed model’s wide applicability under different excitation conditions, its results are compared to the testing results in three-dimensional space. The research in this paper is significant for the dynamic analysis of the HIS vehicle.

A New Physical Parameter Identification Method for Two-Axis On-Road Vehicles: Simulation and Experiment

A new physical parameter identification method for two-axis on-road vehicle is presented. The modal parameters of vehicle are identified by using the State Variable Method. To make it possible to determine the matrices , , and of the vehicle, a known mass matrix is designed to add into the vehicle in order to increase the number of equations ensuring that the number of equations is more than the one of unknowns. Therefore, the physical parameters of vehicle can be estimated by using the least square method. To validate the presented method, a numerical simulation example and an experiment example are given in this paper. The numerical simulation example shows that the largest of absolute value of percentage error is 1.493%. In the experiment example, a school bus is employed in study for the parameter identification. The simulation result from full-car model with the estimated physical parameters is compared with the test result. The agreement between the simulation and the test proves the effectiveness of the proposed estimation method.

Dynamic Characteristics Analysis of Vehicle Incorporating Hydraulically Interconnected Suspension System with Dual Accumulators

A novel roll-resistant hydraulically interconnected suspension with dual accumulators on each fluid circuit (DHIS) is proposed and dynamic characteristics of vehicle incorporating DHIS subsystem are studied in this paper. A 10-degrees-of-freedom (DOFs) vehicle model coupled with DHIS subsystem is established and validated. Four physical parameters of DHIS subsystems which are crucial to vehicle responses are selected with prescribed variation ranges to explore their relationships with the vehicle performance. Simulations of vehicle conducting sine-wave steering maneuvers are carried out to evaluate handling performance with roll angle and vertical tyre force for DHIS subsystem with the parameters varying, compared with the results for vehicle with the original spring-damper suspension and conventional hydraulically interconnected suspension (HIS). On the other hand, ride comfort performance indicated by total weighted root mean square accelerations at the center of gravity is studied when vehicle is excited by three different types of road pavements when the four parameters vary in the prescribed ranges. Simulation results are compared to investigate the special merits of DHIS subsystem, and the parameters that influence the handling performance and ride comfort most are identified. Overall, the DHIS subsystem can effectively enhance the vehicle handling performance compared with the original spring-damper suspension, and it can also benefit much to the ride comfort in contrast to the HIS subsystem.

Non-linear tyre model–based non-singular terminal sliding mode observer for vehicle velocity and side-slip angle estimation

Vehicle velocity and side-slip angle are important vehicle states for the electronic stability programme and traction control system in vehicle safety control system and for the control allocation method of electric vehicles with in-wheel motors. This paper proposes an innovative side-slip angle estimator based on the non-linear Dugoff tyre model and non-singular terminal sliding mode observer. The proposed estimation method based on the non-linear tyre model can accurately present the tyre’s non-linear characteristics and can show advantages over estimation methods based on the linear tyre model. The utilised Dugoff tyre model has a relatively simple structure with few parameters, and the proposed non-linear observer can be applied in various vehicle tyres and various road conditions. Precise determination of the Dugoff tyre model parameters is not required and the proposed observer can still perform good estimation results even though tyre parameters and the tyre–road friction coefficient are not accurate. The proposed non-singular terminal sliding mode observer can achieve fast convergence rate and better estimation performance than the traditional sliding mode observer. At the end of this paper, simulations in various conditions are presented to validate the proposed non-linear estimator.

Optimal preview position control for shifting actuators of automated manual transmission

This paper is concerned with the problem of position tracking control for the motor-driven gear-shift actuating mechanism for electro-mechanical automated manual transmissions (AMT). It is well known that torque interruption is an inherent flaw of AMT. As shift duration directly affects the torque interruption interval, shift quality can be improved by minimizing the duration of the shift. To realize rapid and precise gear-shift control, an optimal discrete-time preview position control scheme is proposed. The proposed control scheme consists of state-feedback control, a discrete integrator, and preview feed-forward control. Instead of the traditional difference method, the state transformation method is utilized to construct the augmented error system such that the augmented system can be kept in a simple form. The H∞ performance index is employed to reduce the effect of the shifting load disturbance during the gear-shifting process. The controller gains are obtained by solving a linear matrix inequality (LMI). Simulation and test bench results all show that the proposed preview control algorithm has better dynamic response and adaptability under different loads compared to the optimal linear quadratic regulator (LQR) controller and the standard PID controller.