Control strategy for clutch engagement during mode change of plug-in hybrid electric vehicle

The plug-in hybrid electric vehicle (PHEV) has various driving modes used in both internal combustion engine and electric motors. The EV mode uses only an electric motor and the HEV mode uses both an engine and an electric motor. Specifically, when the PHEV of a pre-transmission parallel hybrid structure performs mode changing, its engine clutch is either engaged or disengaged, which is important in terms of ride comfort. In this paper, to enhance the mode changing process for the clutch engagement, a PHEV performance simulator is developed using MATLAB/Simulink based on system dynamics and experiment data. Vehicle driving analysis is carried out of the control logic and properties of the mode changing. A compensated torque is applied during the mode change. This results in the rapid speed synchronization with the clutch although the trade-off relationship of the mode change. In addition, the mode changing is conducted through the transmission shifting process to rapidly synchronize with speed. The control strategy implemented in this study is shown to improve the drivability and energy efficiency of a PHEV.     

Model referenced adaptive control to compensate slip-stick transition during clutch engagement

Clutches are widely used in various vehicle powertrains. The engagement process of a friction clutch has three phases, i.e., open, slipping, and sticking. Transitions between different phases introduce a discontinuity to the powertrain dynamics, which has been neglected in previous research. A model referenced adaptive controller (MRAC), based on Popov hyper-stability criterion, is designed to compensate the discontinuity. MRAC adjusts the frictional torque along with the errors of the state variables compared with those of a referenced model. The designed MRAC is applied to a clutch in a bus. Simulation and experimental results under fast and slow startup cases show that MRAC can simultaneously reduce vehicle jerk and frictional dissipation when compared with the conventional controller.     

Shifting control of an automated mechanical transmission without using the clutch

The automated mechanical transmission (AMT) is gaining popularity in the automotive industry, due to its combination of the advantages of mechanical transmissions (MT) and automatic transmissions (AT) in terms of fuel consumption, low cost, improved driving comfort and shifting quality. However, the inherent structural characteristics of the AMT lead to disadvantages, including excessive wear of the clutch plates and jerk and traction interruption during the shift process, that severely affect its popularity in the automatic transmission industry. The emerging technology of shifting control without the use of the clutch is a promising way to improve the shifting transients of AMTs. This paper proposes a control algorithm that combines speed and torque control of the AMT vehicle powertrain to achieve shifting control without using the clutch. The key technologies of accurate engine torque and speed control and rapid position control of the shift actuators are described in detail. To realize accurate engine speed control, a combined control algorithm based on feed-forward, bang-bang and PID control is adopted. Additionally, an optimized closed-loop position control algorithm based on LQR is proposed for the shift actuators. The coordinated control algorithm based on engine and shift actuator control is described in detail and validated on a test vehicle equipped with an AMT. The results show that the coordinated control algorithm can achieve shifting control without the use of the clutch to improve driving comfort significantly, reduce shift transients and extend the service life of the clutch.     

Observer-based clutch disengagement control during gear shift process of automated manual transmission

A clutch disengagement strategy is proposed for the shift control of automated manual transmissions. The control strategy is based on a drive shaft torque observer. With the estimated drive shaft torque, the clutch can be disengaged as fast as possible without large driveline oscillations, which contributes to the reduction of total shift time and shift shock. The proposed control strategy is tested on a complete powertrain simulation model. It is verified that the system is robust to the variations of driving conditions, such as vehicle mass and road grade. It is also demonstrated that the revised system with switched gain can provide satisfactory performance even under large estimation error of the engine torque.     

Multi-state control strategy of starting for a wet friction clutch via a fuzzy logic algorithm

Wet multi-plate friction clutches are used in automotive drivelines to transfer torque, change gears, and prevent motion by locking-up components in the transmission. The control strategy of starting is a crucial technology for the application of a wet multi-plate friction clutch in the automotive industry. In this paper, a multi-state fuzzy control strategy for starting is presented and applied to a continuously variably transmission (CVT) powertrain for the validation of this strategy. The operation of the clutch was divided into four states: parking, starting, riding and emergency. The starting state was investigated in detail. A fuzzy algorithm was employed to control the pressure of the hydraulic cylinder acting on the clutch. A distinguishing feature is that the pressure does not increase but decreases to implement smooth starting during the initial period of starting. The rapid-control prototype (RCP) of the wet friction clutch was developed to validate the new control strategy onboard a test vehicle. Based on the experimental results, the multi-state control strategy for a wet friction clutch is a viable candidate for engineering applications.     

An adaptive fuzzy-sliding lateral control strategy of automated vehicles based on vision navigation

Lateral control is considered to be one of the toughest challenges in the development of automated vehicles due to their features of nonlinearities, parametric uncertainties and external disturbances. In order to overcome these difficulties, an adaptive fuzzy-sliding mode control strategy used for lateral control of vision-based automated vehicles is proposed in this paper. First, a vision algorithm is designed to provide accurate location information of vehicle relative to reference path. Then, an adaptive fuzzy-sliding mode lateral controller is proposed to counteract parametric uncertainties and strong nonlinearities, and the asymptotic stability of the closed-loop lateral control system is proven by the Lyapunov theory. Finally, experimental results indicate that the proposed algorithm can achieve favourable tracking performance, and it has strong robustness.     

重型卡车离合操纵系统优化设计

本文以某重卡的离合系统操纵机构为研究对象,计算分析该机构匹配的合理性,并对该车离合操纵机构进行优化,使其满足踏板行程及踏板力要求.     

DCT起步离合器滑磨控制策略制定及验证

结合离合器的工作原理,对DCT起步时离合器的动作过程进行了分析,并提出起步时离合器的控制方案。为了实现车辆的平稳起步,在离合器的滑磨控制中引入模糊控制理论,从而延长离合器的使用寿命。利用Matlab建立起步控制模型,通过仿真实验验证所建立的控制模型是可行的。     

Combined longitudinal and lateral control for automated vehicle guidance

This paper deals with the longitudinal and lateral control of an automotive vehicle within the framework of fully automated guidance. The automotive vehicle is a complex system characterised by highly nonlinear longitudinal and lateral coupled dynamics. Consequently, automated guidance must be simultaneously performed with longitudinal and lateral control. This work presents an automated steering strategy based on nonlinear model predictive control. A nonlinear longitudinal control strategy considering powertrain dynamics is also proposed to cope with the longitudinal speed tracking problem. Finally, a simultaneous longitudinal and lateral control strategy helps to improve the combined control performance. This whole control strategy is tested through simulations showing the effectiveness of the present approach.     

混合动力轿车控制策略的仿真

介绍了国家“863”计划中“十五”重大专项电动汽车项目,采用的电动汽车仿真软件ADVISOR2002,并对国内某一混合动力轿车样车的控制策略进行建模与仿真的研究工作。该车与本田公司的混合动力轿车Insight的动力系统结构相同,但是采用了不同的控制策略,因此在分析ADVISOR的Insight模型的基础上,重新设计控制策略模块并进行仿真,给出了结果和改进方案。     

并联混合动力电动汽车的转矩控制策略

讨论了并联混合动力电动汽车的能量管理策略,阐述了一种基于规则转矩的控制策略,并在ADVISOR2002仿真软件上结合模型作了仿真分析。仿真试验证明这种转矩控制策略是一种合理的能量优化管理策略,提高了并联式混合动力电动汽车系统效率,获得了整车最大的燃油经济性、最低的排放以及平稳的驾驶性能。     

Trends in vehicle motion control for automated driving on public roads

ABSTRACT

In this paper, we describe how vehicle systems and the vehicle motion control are affected by automated driving on public roads. We describe the redundancy needed for a road vehicle to meet certain safety goals. The concept of system safety as well as system solutions to fault tolerant actuation of steering and braking and the associated fault tolerant power supply is described. Notably restriction of the operational domain in case of reduced capability of the driving automation system is discussed. Further we consider path tracking, state estimation of vehicle motion control required for automated driving as well as an example of a minimum risk manoeuver and redundant steering by means of differential braking. The steering by differential braking could offer heterogeneous or dissimilar redundancy that complements the redundancy of described fault tolerant steering systems for driving automation equipped vehicles. Finally, the important topic of verification of driving automation systems is addressed.     

Torque coordinating robust control of shifting process for dry dual clutch transmission equipped in a hybrid car

For a hybrid car equipped with dual clutch transmission (DCT), the coordination control problems of clutches and power sources are investigated while taking full advantage of the integrated starter generator motor's fast response speed and high accuracy (speed and torque). First, a dynamic model of the shifting process is established, the vehicle acceleration is quantified according to the intentions of the driver, and the torque transmitted by clutches is calculated based on the designed disengaging principle during the torque phase. Next, a robust H_∞ controller is designed to ensure speed synchronisation despite the existence of model uncertainties, measurement noise, and engine torque lag. The engine torque lag and measurement noise are used as external disturbances to initially modify the output torque of the power source. Additionally, during the torque switch phase, the torque of the power sources is smoothly transitioned to the driver's demanded torque. Finally, the torque of the power sources is further distributed based on the optimisation of system efficiency, and the throttle opening of the engine is constrained to avoid sharp torque variations. The simulation results verify that the proposed control strategies effectively address the problem of coordinating control of clutches and power sources, establishing a foundation for the application of DCT in hybrid cars.     

Optimized fuzzy control strategy for a spa hybrid truck

In this paper, an optimized control strategy is proposed for a split parallel hydraulic hybrid truck. The model of the vehicle was simulated in Simulink. According to a global optimization technique, a fuzzy control strategy is developed for the vehicle. This strategy shows flexibility for different drive cycles and a desirable fuel consumption reduction, especially for a low speed drive cycle, which is extracted according to an urban utility vehicle mission.     

A driver-adaptive stability control strategy for sport utility vehicles

Conventional vehicle stability control (VSC) systems are designed for average drivers. For a driver with a good driving skill, the VSC systems may be redundant; for a driver with a poor driving skill, the VSC intervention may be inadequate. To increase safety of sport utility vehicles (SUVs), this paper proposes a novel driver-adaptive VSC (DAVSC) strategy based on scaling the target yaw rate commanded by the driver. The DAVSC system is adaptive to drivers’ driving skills. More control effort would be exerted for drivers with poor driving skills, and vice versa. A sliding mode control (SMC)-based differential braking (DB) controller is designed using a three degrees of freedom (DOF) yaw-plane model. An eight DOF nonlinear yaw-roll model is used to simulate the SUV dynamics. Two driver models, namely longitudinal and lateral, are used to ‘drive’ the virtual SUV. By integrating the virtual SUV, the DB controller, and the driver models, the performance of the DAVSC system is investigated. The simulations demonstrate the effectiveness of the DAVSC strategy.     

混合动力电动汽车控制策略的研究

主要讨论了并联式混合动力电动汽车的控制策略,详细阐述了控制策略的依据以及控制过程,并给出了控制策略的仿真结果。     

Optimal control of motorsport differentials

Modern motorsport limited slip differentials (LSD) have evolved to become highly adjustable, allowing the torque bias that they generate to be tuned in the corner entry, apex and corner exit phases of typical on-track manoeuvres. The task of finding the optimal torque bias profile under such varied vehicle conditions is complex. This paper presents a nonlinear optimal control method which is used to find the minimum time optimal torque bias profile through a lane change manoeuvre. The results are compared to traditional open and fully locked differential strategies, in addition to considering related vehicle stability and agility metrics. An investigation into how the optimal torque bias profile changes with reduced track-tyre friction is also included in the analysis. The optimal LSD profile was shown to give a performance gain over its locked differential counterpart in key areas of the manoeuvre where a quick direction change is required. The methodology proposed can be used to find both optimal passive LSD characteristics and as the basis of a semi-active LSD control algorithm.     

Research on automated lane tracking using linear quadratic control:: control procedure for a curved path

When an automated vehicle is travelling along a curved path, the yaw rate and yaw angle do not have values of zero. This means that it is impossible to apply a simple regulator that converges the values of all state variables to zero. This paper describes the use of a set point regulator, which applies linear quadratic control theory while shifting the equilibrium point in a situation where the road curvature is given as feed-forward information. It also proposes a control method that enables an automated vehicle to navigate curves without feed-forward information by estimating the road curvature as it proceeds.     

Hierarchical distributed coordination strategy of connected and automated vehicles at multiple intersections

In this paper, we present a hierarchical distributed coordination strategy for connected and automated vehicles (CAVs) that are travelling through multiple unsignalized intersections. The control strategy focuses on the improvement of vehicle fuel efficiency and system mobility. In presence of wireless communication among the involved CAVs and the intersection controllers, our coordination strategy focuses on leading the CAVs travel through a road network without conventional traffic light control and ensuring collision avoidance at the intersection areas. We propose a three-layered coordination strategy in this paper. First, we evaluate the road desired average velocity considering both upstream and downstream traffic to speed up the traffic density balance. Second, the intersection controllers optimally assign reference velocity to each vehicle based on the minimization of velocity deviation from its current velocity and collision avoidance at the intersections. Finally, fast model predictive control (F-MPC) is applied for each vehicle to track their reference velocity in a computationally efficient manner. Two simulation scenarios with different difficulty levels have been implemented on a two-interconnected intersection network. Simulation results indicate the feasibility and scalability of the proposed method, as well as vehicle fuel efficiency and system mobility improvement.     

线控系统中相位差优化模型的研究

以使沿干线双向行驶的车辆延误最小为目标，以最优化理论为基础，通过对上、下行车辆在交叉口的延误规律进行分析研究，建立起线控系统相位差调节的优化模型，为干线交通流畅通提供了一种优化控制方法。