Hardware-in-loop Electronic Throttle System Based On Simulink

Ning Chen1,a ,Pinchang Zhu1,b 1Zhejiang Institute of Mechanical & Electrical Engineering, Zhejing, Hangzhou, 310053

afrank_chan@139.com ,bzhupinchang@126.com

KeyWords: Electronic throttle, Simulink, Hardware-in-loop.

Abstract: The structure and the principle of the electronic throttle control system(ETCS) is

elaborated. The electronic throttle(ET) control model is built based on Matlab/Simulink, and the

hardware-in-loop simulation on the ET model is processed. The result shows that the

hardware-in-loop electronic throttle system have significant means on the automotive electronic

teaching and design.

Introduction

The electronic control technology is widely used on automobile due to the problems of energy

saving, environment protection and vehicle safety. And the automobile electronization marks the

auto industrialization level of a country. China has already been the world's largest auto production

and marketing kingdom since 2009. At the same time some proven techniques is introduced

according to our country and the world famous auto factory's cooperation. However, because of the

relatively backward industrial base, there is still a big gap in the automobile electronic technology

development level compared with the developed countries. Therefore, it is necessary for us to focus

on the automobile electronic technology research so as to transcend the advanced world level.

For the traditional design method for the automobile electronic system, the computer algorithm is

designed firstly, and the corresponding hardware assembly experiment is made afterwards. For this

method, the design cycle is long, research and development is costly and the test is difficult.

Considering the defects above, the hardware-in-the-loop simulation of automotive electronic control

system design method is proposed which could be expressed in Figure 1. By using the

hardware-in-the-loop simulation, it can be directly access the system and the control algorithm

could be designed and validated. After the product design is finalized, it could be directly produced

by just modify hardware and software of the system which would lead to more excellent products in

relative short research time.

Figure 1. The hardware-in-the-loop simulation design method

Applied Mechanics and Materials Vols. 128-129 (2012) pp 898-903Online available since 2011/Oct/24 at www.scientific.net© (2012) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMM.128-129.898

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1. ETCS composition and principle

Throttle is an important control component for the engine. In order to improve the automobile dynamic property, ride, and reduce exhaust emission, the world's big carmakers introduced kinds of ETs and corresponding systems which have good control characteristic. The ETCS could precisely control the valve opening, this could not only improve fuel economy and reducing emissions but also obtain the satisfactory quick response and the control performance. On the other hand, the integration of the idle speed control, the cruise control and the vehicle stability control could be realized, and the system architecture is simplified.

The ETCS consists of accelerator pedal position sensor, the ET body and the control unit which can be shown in figure 2. The accelerator pedal position sensor collects the pedal position signal which could reflect the driver’s intention; the ET body is composed of the throttle positioning motor, the throttle position sensor, the throttle driver device and etc, which is the executive actuator for the throttle valve; The control unit makes the instructions for the throttle opening based on the working condition of the engine.

Figure 2. ETCS composition

When the driver controls the accelerator pedal, the position sensor produces certain voltage signal

which would input throttle control unit. The signal is filtered at first for eliminating environmental

noise, and then the basic demand of engine torque is calculated according to the current work

pattern and the pedal mobile amount for analyzing driver’s intention, later the basic expectation for

the corresponding throttle Angle is obtained. Various sensor signals such as the engine speed, the

gear position, the throttle position, the AC energy consumption are communicated with the throttle

control unit with CAN bus which could calculate all the vehicle’s torque demand. The best opening

throttle would be obtained by compensating the throttle angle opening. After the drive circuit

module receives the voltage signal, the best throttle opening position is achieved by control the

throttle driver device. The throttle open degree signal feedbacks to throttle control unit and forms

the closed loop. The electronic throttle control system diagram is shown in figure 3.

Figure 3. The electronic throttle control system diagram

The ET control strategy is mainly based on the engine torque requirements. However, it could

also be used for the purpose of demand expansions for various aspects such as the acceleration slip

regulation (ASR), the cruise control system (CCS), the idle speed control (ISC), the gear shifting

control, the altitude compensation, etc.

Applied Mechanics and Materials Vols. 128-129 899

2. The hardware-in-the-loop model

The 9S12 microcontroller from the Feescale is chosen as the ET’s ECU. All the input/output

devices and control object is connected. The electronic throttle control algorithm is generated and

downloaded to the 9S12 microcontroller by using the 9S12toolbox real-time hardware interface

library. Then the ET hardware-in-the-loop simulation can be quickly realized. The ET

hardware-in-the-loop model is shown in Figure 4. The “A to D Converter Channel 1” is the signal

from the accelerator pedal position sensor1 which is the system input signal; The “A to D Converter

Channel 0” is the signal from the Throttle position sensor1 which is the system feedback signal; The

“A to D Converter Channel 3” is the AC switch signal; The “A to D Converter Channel 2” is the

signal from the accelerator pedal position sensor2; the “PWM-A” is the signal from the No 1

position of the throttle positioning motor and the “PWM-B” is the signal from the No 2 position of

the throttle positioning motor.

Figure 4. The ET hardware-in-the-loop model

3. Control algorithm and debugging

The ETCS adopts PID control method. The proportion(P), the integration(I)and the

differentiation(D) is constituted as the control value by linear combination. The PID control system

diagram is shown in Figure 5.

Figure 5. The PID control system diagram

Control deviation e(t) is defined as:

e(t) = r(t) - y(t) (1)

900 Measuring Technology and Mechatronics Automation IV

The PID control low is defined as:

(2)

Where, Kp is the radio, Ti is the integral time constant, and Td is the differential time constant.

The Kp reflect deviation proportion of the e(t) in the control system. The control system aims to

minimize the system deviation.

Ti is mainly used to eliminate the static difference. Integral effect grade depends on the integral

time constant Ti. The bigger the Ti is, the weaker the integral role is on the whole. It's the same in

reverse.

Td reacts the deviation trend of the signal, and introduce a modified signal in order to speed up

the system action speed and reduce the system adjust cycle before the signal deviation changes too

much.

After elaborate debugging in Simulink, we established the simulation model for the ETCS system

on the basis of PID control method. The ETCS PID control model is shown in Figure 6.

Figure 6. The ETCS PID control model

Transfer function determines that the system simulation is successful or not. Establishing the

transfer function of electronic throttle needs to do a lot of assumptions, deductions, analysis and

experiment. Relevant documents are used to fix its transfer function as follows:

(3)

4. Conclusion

Using the hardware-in-the-loop simulation technology, the ET hardware-in-the-loop model is

designed which is shown in Figure 4. Transfer function does not need to be considered because the

controlled object (electronic throttle body) just in this system circuits. The controller which is

designed with Simulink directly controls the ET body, thus the actual control effect could be

Applied Mechanics and Materials Vols. 128-129 901

observed such as throttle sluggish and vibration phenomenon. If the control effect is not satisfied,

the structure and the parameters of the controller could be adjusted until the prospective control

effect is achieved. The figure 7 is the PID controller parameter adjustment interface, and the figure

8 is the system’s actual response for the step signal when a group of control parameters is inputted.

Figure 7. The PID controller parameter adjustment interface

Figure 8. The system’s actual response for certain step signal

The controller which is debugged well could be considered to a actual controller prototypes. If

the control effect is satisfied, embedded controller could be produced after certain modifications are

made and the generated code can also be used directly. The ET controller development cycle could

be greatly shorten and finally the controller’s design is finalized.

Practice shows that the hardware-in-the-loop simulation can improve efficiency and reduce the

cost for the automotive electronic control system design. Also it can be introduced into the

automobile electronic teaching, which has high application value for raising the high-skill person

for the automotive electronic control system design

Foundation item ： Technology projects of education department, Zhejiang province(NO.

Y201018374)

902 Measuring Technology and Mechatronics Automation IV

Brief introduction of authors:

1 Ning Chen（1974-），male，han ethnic，birth in Hangzhou Zhejiang，Zhejiang Institute of

Mechanical & Electrical Engineering senior engineer，master degree，major in the electronic

technology research

2 Pinchang Zhu（1981-），male，han ethnic，birth in Yiwu Zhejiang，Zhejiang Institute of

Mechanical & Electrical Engineering engineer，master degree，major in the electronic technology,

CAD/CAE research

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Applied Mechanics and Materials Vols. 128-129 903

Measuring Technology and Mechatronics Automation IV 10.4028/www.scientific.net/AMM.128-129 Hardware-in-Loop Electronic Throttle System Based on Simulink 10.4028/www.scientific.net/AMM.128-129.898