Fig。  4。  5V supply circuit

The intelligent vehicle sensor includes speed sensor and path identifying sensor。 In order to make the vehicle move smoothly on the road marked the black line, besides controlling the front steer wheel the vehicle speed should be controlled so that the vehicle can run fast on the straight road and slow down in time on the corner。 Thus the vehicle speed can be controlled all the time and adjusted real time based on the vehicle location。 Model E6B2-CWZ6C rotary encoder, produced by Omron Corporation, is used as a speed sensor。 The hardware circuit of E6B2-CWZ6C is simple。 The resolution is 360 pulses / turn。 The rotary encoder connects with the DC drive motor by the gears with gear ratio 1:1。 Therefore the vehicles wheel turns a circle, 360 pulses can be obtained。 In a period, the pulse number entered into the controller can be employed to express the vehicle speed as the direct control parameter。

The key problem is how to identify black mark line when the intelligent vehicle runs on the given road。 Therefore, an accurate identifying mark line system is important part for intelligent vehicle design。 At present, the photoelectric sensor and CCD / CMOS image sensor are usual in path recognition。 As simple physical structure and signal process mode, the photoelectric sensor is used widely。 But the photoelectric sensor  has the  shortcoming of short detection distance     and

poor predictability。 CCD/CMOS image sensor can perceive the path information earlier。 But it has the disadvantage of complex signal output and process mode, more calculation, occupying more MCU resources and not suitable for small volume system。 Model TCRT5000 reflective infrared photoelectric sensor, which detecting distance is about 1-2cm, is employed to identify the black mark line。 See figure 5。 TCRT5000 includes light emitting diode and phototransistor in itself。 When the black mark line is detected, the triode T is cut- off and a high level is output by means of low reflectivity and small Ic。 Otherwise the white ground is detected, the triode T saturates to output low level voltage。 Thus the black mark line identification is achieved。 LM324N constitutes hysteretic comparator to form the detecting signals。

Fig。  5。 TCRT500 application circuit。

Eleven photoelectric sensors are set into "I"-shaped sensor array to identify path。 In operation, the current black mark line location is first detected by photoelectric sensor array, and then the deviation between the vehicle and the track is calculated by detecting result。 If the photoelectric sensors in the middle of the array detect the black mark line, the intelligent vehicle does not deviate from the track。 The steer gear does not turn。 If the photoelectric sensors in the left (right) of the array detect the black mark line, the intelligent vehicle deviated from the track to the right (left)。 The steer gear makes the steer wheel turn to the left (right)。 When the intelligent vehicle moves away the track, the photoelectric sensor does not detect the black mark line。 The steer gear makes the steer wheel hold the previous angle and the drive motor speed is slow down to the lowest set number。

The motor in the intelligent vehicle includes drive motor and steer motor (steer gear)。 The drive motor is a direct power source for vehicle movement。 The control effects for drive motor impacts on the vehicle speed and move stability directly。 In this design, a DC motor is chosen as drive motor。 A chip model MC33886 produced by Freescale Semiconductor Corporation is employed to drive the motor。 Figure 6 is the schedule circuit of motor drive。 In order to improve drive ability, two MC33886 are used。 The motor speed adjustment and run control can be achieved by changing the PWM waveform duty cycle output from port IN1 and IN2。

Model S3010 motor, which has large torque, good stability and accurate angle control, is employed as the steer gear。 The rotate torque of S3010 can reach 6。5kg。cm。 Therefore the torque margin can be used to improve the response speed of the steer gear。 An output arm is added between the steer gear and shift rod。 Thus in constant steer gear angle speed, the line