Youqun Zhao

Generalized Internal Model Robust Control for Active Front Steering Intervention

Because of the tire nonlinearity and vehicle’s parameters’ uncertainties, robust control methods based on the worst cases, such as H∞, µ synthesis, have been widely used in active front steering control, however, in order to guarantee the stability of active front steering system (AFS) controller, the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control. In this paper, a generalized internal model robust control (GIMC) that can overcome the contradiction between performance and stability is used in the AFS control. In GIMC, the Youla parameterization is used in an improved way. And GIMC controller includes two sections: a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters’ uncertainties and some external disturbances. Simulations of double lane change (DLC) maneuver and that of braking on split-µ road are conducted to compare the performance and stability of the GIMC control, the nominal performance PID controller and the H∞ controller. Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle’s parameters variations, H∞ controller is conservative so that the performance is a little low, and only the GIMC controller overcomes the contradiction between performance and robustness, which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller. Therefore, the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system, that is, can solve the instability of PID or LQP control methods and the low performance of the standard H∞ controller.

A new robust control method for active front steering considering the intention of the driver

The influence of the active front steering system on the driver’s intention and the trade-off between the robustness and the performance of the active front steering controller have not been adequately addressed by current research studies. A new robust control method based on the normalized left coprime factorization model including uncertainty and perturbations is introduced, and the robustness of this method against high speeds and variations in the cornering stiffness without changing the intention of the driver is guaranteed by the design of the feedforward controller and the feedback controller. A single-step method is adopted to solve the feedforward robust controller and the feedback robust controller. The resulting controllers obtained by the proposed robust control method have a simple structure and do not require online optimization. Furthermore, simulations of the double-lane-change manoeuvre and of braking on a split-μ road are conducted to compare the performance and the stability of the new robust control method with those of the proportional–integral–derivative controller and the standard H∞ controller. Simulation results show that, in comparison with the other two control methods, the established new robust control method can enhance the vehicle stability and handling, and the tracking rapidity is improved by the introduction of feedforward control so that the active steering intervention does not affect the driver’s intention, regardless of the external interferences or emergency evasive manoeuvres.

Vehicle active steering control research based on two-DOF robust internal model control

Because of vehicle’s external disturbances and model uncertainties, robust control algorithms have obtained popularity in vehicle stability control. The robust control usually gives up performance in order to guarantee the robustness of the control algorithm, therefore an improved robust internal model control(IMC) algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness. The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties. In order to separate the design process of model tracking from the robustness design process, the improved 2 degree of freedom(DOF) robust internal model controller structure is given from the standard Youla parameterization. Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm, on the basis of a nonlinear vehicle simulation model with a magic tyre model. Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance, which can enhance the vehicle stability and handling, regardless of variations of the vehicle model parameters and the external crosswind interferences. Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.

Simulation of steady-state rolling non-pneumatic mechanical elastic wheel using finite element method

Abstract A three-dimensional (3D) nonlinear finite element (FE) model was established for the numerical investigation of a novel non-pneumatic mechanical elastic wheel (MEW) under the steady-state rolling conditions. The reliability and accuracy of this FE model of an MEW were validated through a comparison of the numerical simulation and experimentally measured data with regard to the radial stiffness, footprint and longitudinal slipping characteristics. The validated FE model was applied to study the dynamic characteristics of the MEW under various steady-state rolling conditions using steady-state transport technology in Abaqus/Standard. The contact pressure and friction stress distribution of an MEW were studied in detail. In addition, the stress states of the key components of an MEW, such as the elastic ring and hinge group, were also analysed based on the simulation results. The main innovation of this work is the application of steady-state transport technology to a parametric analysis of the steady-state rolling of a non-pneumatic tire, the simulation results of which can provide guidance for an optimization of an MEW and other non-pneumatic tire structures.

Surface temperature prediction of novel non-pneumatic mechanical elastic wheel based on theory analysis and experimental verification

Abstract A theory analysis procedure has been developed here to predict the steady-state surface temperature of the mechanical elastic wheel (ME-Wheel), operating under different driving conditions. Due to the unique structure of ME-Wheel, the heat generation and heat dissipation mechanisms of ME-Wheel are discussed first. Then, the mechanical model of ME-Wheel is established to obtain the heat generation energy per unit time, while the heat dissipation energy is obtained using the theory thermal analysis of ME-Wheel. Two separate sets of testing are conducted to obtain the essential parameters of the contact patch and collect the data of the steady-state surface temperature of ME-Wheel, respectively. Then the proposed theory model has been verified. The obtained results indicate that the proposed theory model is feasible, showing the great potential to be applied in predicting the thermal conditions of ME-Wheel working under practical environment.

Thermal modal analysis of novel non-pneumatic mechanical elastic wheel based on FEM and EMA

A combination of Finite Element Method (FEM) and Experiment Modal Analysis (EMA) have been employed here to characterize the structural dynamic response of mechanical elastic wheel (ME-Wheel) operating under a specific thermal environment. The influence of high thermal condition on the structural dynamic response of ME-Wheel is investigated. The obtained results indicate that the EMA results are in accordance with those obtained using the proposed Finite Element (FE) model, indicting the high reliability of this FE model applied in analyzing the modal of ME-Wheel working under practical thermal environment. It demonstrates that the structural dynamic response of ME-Wheel operating under a specific thermal condition can be predicted and evaluated using the proposed analysis method, which is beneficial for the dynamic optimization design of the wheel structure to avoid tire temperature related vibration failure and improve safety of tire.

Study on Conducted Interference and Radiated Interference of Buck-Boost Converter in Electric Automobile

Buck-boost converter is an important component of electric automobile, it is an important interference source in electric automobile, the study of the interference source is very important to restrain interference. The buck-boost converter in continuous conduction mode (CCM) is established by using circuit simulation software PSPICE. According to the request of GB18655-2002, the simulation study on common-mode conducted interference,differential-mode conducted interference and far-field radiated interference of buck-boost converter are given. The common-mode current radiation of buck-boost converter is simplified as an electric dipole radiation mode and the differential-mode current radiation is simplified as a rectangular loop antenna. In order to improve the electromagnetic compatibility of buck-boost converter in electric automobile, some measures to reduce the conducted interference and the radiated interference are proposed.