Procedia Engineering 41 ( 2012 ) 588 – 592

1877-7058 © 2012 Published by Elsevier Ltd.doi: 10.1016/j.proeng.2012.07.216

International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012)

Photoelectric Sensor Based Intelligent Track Racing Car

Shahril Shah M.G.a, Elmi A.B.b,*, Nazir A.c, Shukri S.b aSchool of Mechanical Engineering, USM Eng. Campus, 14300 Seri Empangan Nibong Tebal, Pulau Pinang, Malaysia bSchool of Aerospace Engineering, USM Eng. Campus, 14300 Seri Empangan Nibong Tebal, Pulau Pinang, Malaysia

cSchool of Electrical & Electronic Engineering, USM Eng. Campus, 14300 Seri Empangan Nibong Tebal, Pulau Pinang, Malaysia

Abstract

This paper describes research on the development of photoelectric sensor based intelligent track racing car. The main objective of the project is focusing on the design of an intelligent racing car that can recognize a racing track automatically by differentiating the background and the track in order to accomplish the route of the track in the shortest time. Ideas to develop the intelligent track racing car in small scale is to investigate the movement of given track and to achieve the require time to deliver the task. Experiment show that the system is robustness and well positioned with different speed to achieved the targeted time. © 2012 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Centre of Humanoid Robots and Bio-Sensor (HuRoBs), Faculty of Mechanical Engineering, Universiti Teknologi MARA. Keywords: intelligent track racing car; Infrared photoelectric sensor; H-bridge

1. Introduction

Mobile robot is a mechanical device that can navigate and perform task given in various way for assisting human being in doing normal task or replacing them for repetition and hazardous task. Automated Guided Vehicle (AGV) is one of mobile robot that also known as a line follower mobile robot for static and dynamic path. Nowadays, AGV become new direction for transportation and future car technology. It is developed intelligently to move from one place to another with automatic drive, path recognition and speed control, self-localizing for changing direction, barrier avoidances, moving object recognition and other advanced features by manipulating the environment information [1]. Wheel mobile robot (WMR) is one of a simple AGV that popular among researchers and can be integrate with different sensor such as CCD camera, sonar sensor, ultrasound, lasers and other approaches [1-5]. According to Chen Long [2], Laser sensor approach can extend the path information for tracing path, but the photoelectric sensor also adopted for velocity measurement due to its high sensitivity. Song [3] has used CCD camera for speed control by black line image. Fuzzy control rules have been implementing by Wang [4] in order to control speed and imitate the driving motion performance. Different approach has been established by Huang for track-line follower WMR using metal oxide semiconductor field effect transistor (MOSFET) [5] to control DC motor. The intelligent track racing car presented in this paper was using photoelectric sensor with different approach on control system. The approach will be discussed further in this paper. It has improved the racing car speed control and tracing track-line rules.

* Corresponding author. Tel.: +604-599-6391; fax: +604-594-1025 E-mail address: meelmi@eng.usm.my

Available online at www.sciencedirect.com

Open access under CC BY-NC-ND license.

Open access under CC BY-NC-ND license.

589 Shahril Shah M.G. et al. / Procedia Engineering 41 ( 2012 ) 588 – 592

2. Methodology

2.1. Aerodynamic conceptual frame design

The smart car structure concept was based on the racing car design which have good streamed line combination for better aerodynamics criteria. Due to that, the material for the casing must have the light weight, good strength and flexible aspect for better performance. Thus, fiber glass composite which has all the features of above was selected as the material for the casing. The casing making process is summarized in figure 2.

Fig. 1. (a) Racing car casing mould; (b) Mould-shaped harden fiber glass (c) final product

Fig. 2. Racing car casing process flow

2.2. Control system and sensor placement

Infrared photoelectric sensor board is mounted with board stands at the front of the car with 3.5cm above the ground for better movement during hill climbing and bumpy road as shown in figure 3. The light emitting diod (LED) are included for the purpose of lighting up the path so that the infrared photoelectric sensor can detect the contrast between the background and track-line in the absence of light.

Fig. 3. Infrared photoelectric sensor board placement

3.5cm

Fiber Glass Coating Fiber glass sheet & resin (epoxy & hardener, 5:2)

Final Finishing Add sticker for better

appearance

Surface Finishing Use abrasive paper for

smooth and fine surface

Mould Remove Use burning

method

Mould Preparation Shape design using

Polystyrene

Painting Coating with clear

yellow and black paint

(a) (b) (c)

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Both the voltage regulator and comparator board are soldered on the same board and placed at the center of the car’s body as shown in figure 4(a). This circuit board is supported by board stands and balsa wood to prevent vibration to the circuit board. Meanwhile the microcontroller and H-bridge are soldered on the other board and placed at the back of the car, on top of the DC motor as shown in figure 4(b).

(a) (b) Fig. 4. (a) The voltage regulator and comparator board placed at the center of the chassis, on top of the battery (b) Micro-controller and H-bridge board are

placed at the back, on top of the DC Motor.

2.3. Control circuit design

Microcontroller MC9S12XS128 had been used as the central processing and control unit. The infrared sensors detect the contrast between the black track-line and white background and then send the signal to the microcontroller. The microcontroller then sends a Pulse Width Modulation (PWM) signal to Speed Control Unit (DC motor) and Direction Control Unit (Servo). These two units control the movement and steering of the smart car. Lighting Unit helps to light up the track during night or dark condition. Sensing Unit circuit consists of eight infrared sensors which arrange in different location to recognize the track and is placed at the front of the smart car.

Fig. 5. Control system structure diagram

Sensing Unit (Infrared Sensor)

Speed Control Unit (DC Motor)

Direction Control Unit (Servo Motor)

Lighting Unit (LED)

MC9S12XS128

591 Shahril Shah M.G. et al. / Procedia Engineering 41 ( 2012 ) 588 – 592

(a) (b)

Fig. 6. (a) Infrared photoelectric sensor arrangement layout (b) Infrared photoelectric sensor and LED arrangement on circuit board The infrared sensors arrangement is designed for the track dimension and definition. Starting line is detected by sensors No. 1 and No. 8 while sensors No. 4 and No. 5 are located at the centre of the line for the straight motion. The remaining sensors are used to recognize the left and right turning motion of the smart car. The sensors’ output will be converted into voltage form and sent to the comparator circuit LM 324. The comparator circuit, will then compare the signal from the sensor and the threshold voltage (1.0 V). The comparator circuit will read any signal less than 1.0 V (< 1.0 V) as 0 while signal more than 1.0 V (> 1.0 V) will be read as 1. Then, the digital outputs are transmitted to the microcontroller. Five light emitting diode (LED) are used to assistance the sensor detect the track-line in dark or night condition. H-bridge MC33886VW was used in speed control unit.

3. Result and discussion

To try out the intelligent track racing car, we design a 25 m track-line as shown in figure 7(b). In order to move along the track line, the infrared photoelectric sensor detect the track line and signals from the sensor will execute corresponding command lines in the programming. Then, respective value will be set for both servo and DC motor in order to control the motors’ direction and speed. If the sensor does not detect any track line, the intelligent track racing car servo motor will make a round movement until the track-line is detected as shown in control design flowchart in figure 7(a). The developed intelligent track racing car is able to complete the track without run out of the track-line when the motor set to low speed but tend to stray from the track especially at the left cornering and straight line. Modification has been made on the programming to reduce the reaction time of the servo thus, yield more stable fast moving car.

(a) (b) Fig. 7. (a) control design flowchart (b) Racing track with calibration track

Transmitter

Receiver

LED

1

2 3

4 5

6 7

8

Start

Determine track-line

Detect Track-line

Set Servo Motor and DC Motor

End

Yes

No

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This intelligent track racing car has delivered the project’s objective by completed 7 out of 10 laps for high speed setting while with low speed setting, the percentage for car’s performance in completing the track is 25 percent higher than the high speed setting. Table 1 shows the details information of the intelligent track racing car’s performance.

Table 1. Speed, accuracy and frequency of racing track information detection.

Speed Time Taken (s)

Frequency (mHz)

Time per lap (s)

Velocity (m/s)

Accuracy (%)

Slow 45 22.22 4.74 5.28 95%

Fast 30 33.33 4.29 5.83 70%

Graph shows that the drag value increases with speed squared. The purple line indicates the maximum available thrust from the engine. The track racing car can achieve higher speed with the same engine thrust. The low drag and high drag curve will significantly diverge as the speed increased. According to the above, the LEDs enables the intelligent racing car to maintain the speed performance in the absence of light.

Fig. 8. Plot of drag against speed

4. Conclusion

The speed and stability become a major concern on this intelligent track racing car. The result had shown that the racing car can move at a high speed with high stability. The correct response to the environment can be improved through programming modification. In this research, the photoelectric sensor based intelligent track racing car had been developed in order to investigate the accuracy of the line tracking within slow speed and high speed. Thru the experiment, we achieved 7 laps out of 10 laps completed with less than half minutes while moving in high speed. In future, consideration about the current parameter setting related with its algorithm can be improved to increase the intelligent track racing car steering and tracking accuracy for both speeds.

5. Reference

[1] Liu Feng Xian; Wang Ling; Sun Bo; , "A Method of Measurement and Control about Automatically Tracing Intelligent Vehicle Based on Infrared Photoelectric Sensor,"International Conference on Intelligent Computation Technology and Automation (ICICTA), 2010, vol.1, no., pp.164-167, 11-12 May 2010

[2] Chen Long; Zhang Jin; Huang Huanhuan; , "Design and implementation of the tracing smart car system based on laser sensors," International Conference on Computer Design and Applications (ICCDA), 2010 , vol.2, no. , pp.V2-598-V2-601, 25-27 June 2010

[3] Song Zhicong; Li Xuemei; Chen Mei; Zhang Hongbin; , "The design of smart car based on Freescale processor," International Conference On Computer and Communication Technologies in Agriculture Engineering (CCTAE), 2010, vol.2, pp.508-510, 12-13 June 2010

[4] Wang Yong-ding; Nie Li-na; , "Design of Smart Car Speed Control System Based on Fuzzy Control," International Conference on Artificial Intelligence and Computational Intelligence (AICI), 2010, vol.2, no., pp.516-519, 23-24 Oct. 2010

[5] Huang Junhua; Li Li; Liang Xianlin; Zhang Hongbing; , "Creative practice based on Freescale processor smart car with photoelectric sensor," Second International Conference on Communication Systems, Networks and Applications (ICCSNA), 2010, vol.2, pp.375-378, June 29 2010-July 1 2010.