Developments in simulating an Acceleration Slip Regulation (ASR) system for 4WD
1 like326 views
This paper presents an acceleration slip regulation (ASR) system for four-wheel drive electric vehicles, utilizing sliding mode control. The ASR includes three control modes to optimize inter-axle torque distribution based on road conditions, enhancing vehicle stability and grip. Simulation results demonstrate that the proposed system effectively adapts to varying road friction, improving overall driving performance.
![Energies 2014, 7, 3748-3763; doi:10.3390/en7063748
energies
ISSN 1996-1073
www.mdpi.com/journal/energies
Article
An Acceleration Slip Regulation Strategy for Four-Wheel Drive
Electric Vehicles Based on Sliding Mode Control
Hongwen He *, Jiankun Peng, Rui Xiong and Hao Fan
National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100081,
China; E-Mails: pengjk87@gmail.com (J.P.); rxiong6@gmail.com (R.X.); haofanbit@163.com (H.F.)
* Author to whom correspondence should be addressed; E-Mail: hwhebit@bit.edu.cn;
Tel./Fax: +86-10-6891-4842.
Received: 28 January 2014; in revised form: 15 May 2014 / Accepted: 3 June 2014 /
Published: 17 June 2014
Abstract: This paper presents an acceleration slip regulation (ASR) system for four-wheel
drive (4WD) electric vehicles, which are driven by the front and rear axles simultaneously.
The ASR control strategy includes three control modes: average distribution of inter-axle
torque, optimal distribution of inter-axle torque and independent control of optimal slip rate,
respectively, which are designed based on the torque adaptive principle of inter-axle
differential and sliding mode control theory. Furthermore, in order to accurately describe the
longitudinal tyre force characteristic, a slip rate calculation formula in the form of a state
equation was used for solving the numerical problem posed by the traditional way.
A simulation was carried out with the MATLAB/Simulink software. The simulation results
show that the proposed ASR system can fully use the road friction condition, inhibit the
drive-wheels from slipping, and improve the vehicle longitudinal driving stability.
Keywords: acceleration slip regulation (ASR); four-wheel drive (4WD); electric vehicle;
sliding mode control
1. Introduction
Although the dynamic performance of four-wheel drive (4WD) conventional vehicles is improved
compared with that of two-wheel drive vehicles, the fuel economy is relatively poor. It’s worth noting
that a purely electric vehicle can completely ignore the impact of fuel economy [1,2]. Considering the
motor has the characteristics of low speed and high torque, a pure electric vehicle that employs the 4WD
OPEN ACCESS](https://image.slidesharecdn.com/anaccelerationslipregulationstrategyforfourwheeldriveev-150527064918-lva1-app6892/85/Developments-in-simulating-an-Acceleration-Slip-Regulation-ASR-system-for-4WD-1-320.jpg)
![Energies 2014, 7 3749
scheme can not only improve the vehicle’s acceleration and climbing performance, but also have a
positive impact for reducing emissions and air pollution [3–5]. However, the chassis layout of a high
power motor is usually difficult due to its large volume, but a good distribution layout scheme can divide
one high power and large volume size motor into several small motors, thus realizing a flexible chassis
layout and improving the vehicle’s dynamic performance reliability [6–9].
Electric vehicles have several advantages such as a drive wheel torque that can be acquired easily,
sensitive motor response, and motor torque that can be controlled accurately, etc. Therefore, the advantages
of acceleration slip regulation (ASR) application in an electric vehicle are incomparable to those seen in
a conventional vehicle. Not only PID (Proportion Integration Differentiation) control, but also several
techniques based on nonlinear control have been applied to ASR research [10,11]. A fuzzy logic control
was introduced in ASR control in [12]. Nakakuki et al. [13] proposed the linearization feedback control
for the ASR function. Sliding mode control enables the system architecture having the switching
characteristics changes over time, forces the system into doing the small amplitude and high frequency
movement along a predetermined state trajectory with a certain characteristic, and the control theory was
studied by many scholars due to its good robustness [14–18]. The key technology of ASR is how to
balance the relationship between the driver demand torque, the tyre characteristics and the road friction
conditions [19]. This paper undertakes a specific analysis of these three elements, and an ASR strategy
which contains three control modes is designed for good roads, slippery roads and bad roads, and the
motor output torque is controlled based on sliding control theory. The simulation results show that the
proposed ASR system can choose the suitable control mode according to the different road friction
conditions and take full advantage of the road friction, thus improves the vehicle’s longitudinal
driving stability.
2. System Model
In this paper, the 4WD electric vehicle ASR system layout was as shown in Figure 1. The power battery
pack provides power to the two identical power and volume motors, and the ASR controller sends the
control command in the form of torque control to the two motors, thus the two motors simultaneously
output power externally by directly connecting to the differentials of the front and rear axles.
Figure 1. The four-wheel drive (4WD) electric vehicle acceleration slip regulation (ASR) system layout.
1xF
2xF
3xF
4xF
u
2w
1w 3w
4w](https://image.slidesharecdn.com/anaccelerationslipregulationstrategyforfourwheeldriveev-150527064918-lva1-app6892/85/Developments-in-simulating-an-Acceleration-Slip-Regulation-ASR-system-for-4WD-2-320.jpg)
Developments in simulating an Acceleration Slip Regulation (ASR) system for 4WD
- 1. Energies 2014, 7, 3748-3763; doi:10.3390/en7063748 energies ISSN 1996-1073 www.mdpi.com/journal/energies Article An Acceleration Slip Regulation Strategy for Four-Wheel Drive Electric Vehicles Based on Sliding Mode Control Hongwen He *, Jiankun Peng, Rui Xiong and Hao Fan National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China; E-Mails: pengjk87@gmail.com (J.P.); rxiong6@gmail.com (R.X.); haofanbit@163.com (H.F.) * Author to whom correspondence should be addressed; E-Mail: hwhebit@bit.edu.cn; Tel./Fax: +86-10-6891-4842. Received: 28 January 2014; in revised form: 15 May 2014 / Accepted: 3 June 2014 / Published: 17 June 2014 Abstract: This paper presents an acceleration slip regulation (ASR) system for four-wheel drive (4WD) electric vehicles, which are driven by the front and rear axles simultaneously. The ASR control strategy includes three control modes: average distribution of inter-axle torque, optimal distribution of inter-axle torque and independent control of optimal slip rate, respectively, which are designed based on the torque adaptive principle of inter-axle differential and sliding mode control theory. Furthermore, in order to accurately describe the longitudinal tyre force characteristic, a slip rate calculation formula in the form of a state equation was used for solving the numerical problem posed by the traditional way. A simulation was carried out with the MATLAB/Simulink software. The simulation results show that the proposed ASR system can fully use the road friction condition, inhibit the drive-wheels from slipping, and improve the vehicle longitudinal driving stability. Keywords: acceleration slip regulation (ASR); four-wheel drive (4WD); electric vehicle; sliding mode control 1. Introduction Although the dynamic performance of four-wheel drive (4WD) conventional vehicles is improved compared with that of two-wheel drive vehicles, the fuel economy is relatively poor. It’s worth noting that a purely electric vehicle can completely ignore the impact of fuel economy [1,2]. Considering the motor has the characteristics of low speed and high torque, a pure electric vehicle that employs the 4WD OPEN ACCESS
- 2. Energies 2014, 7 3749 scheme can not only improve the vehicle’s acceleration and climbing performance, but also have a positive impact for reducing emissions and air pollution [3–5]. However, the chassis layout of a high power motor is usually difficult due to its large volume, but a good distribution layout scheme can divide one high power and large volume size motor into several small motors, thus realizing a flexible chassis layout and improving the vehicle’s dynamic performance reliability [6–9]. Electric vehicles have several advantages such as a drive wheel torque that can be acquired easily, sensitive motor response, and motor torque that can be controlled accurately, etc. Therefore, the advantages of acceleration slip regulation (ASR) application in an electric vehicle are incomparable to those seen in a conventional vehicle. Not only PID (Proportion Integration Differentiation) control, but also several techniques based on nonlinear control have been applied to ASR research [10,11]. A fuzzy logic control was introduced in ASR control in [12]. Nakakuki et al. [13] proposed the linearization feedback control for the ASR function. Sliding mode control enables the system architecture having the switching characteristics changes over time, forces the system into doing the small amplitude and high frequency movement along a predetermined state trajectory with a certain characteristic, and the control theory was studied by many scholars due to its good robustness [14–18]. The key technology of ASR is how to balance the relationship between the driver demand torque, the tyre characteristics and the road friction conditions [19]. This paper undertakes a specific analysis of these three elements, and an ASR strategy which contains three control modes is designed for good roads, slippery roads and bad roads, and the motor output torque is controlled based on sliding control theory. The simulation results show that the proposed ASR system can choose the suitable control mode according to the different road friction conditions and take full advantage of the road friction, thus improves the vehicle’s longitudinal driving stability. 2. System Model In this paper, the 4WD electric vehicle ASR system layout was as shown in Figure 1. The power battery pack provides power to the two identical power and volume motors, and the ASR controller sends the control command in the form of torque control to the two motors, thus the two motors simultaneously output power externally by directly connecting to the differentials of the front and rear axles. Figure 1. The four-wheel drive (4WD) electric vehicle acceleration slip regulation (ASR) system layout. 1xF 2xF 3xF 4xF u 2w 1w 3w 4w