This paper introduces in detail the working principle of the reflective photoelectric sensor tracing module, the circuit diagram of the tracing module and how to realize the automatic tracing driving of the intelligent tracing car based on the MSP430 microcontroller as the control core. The circuit diagram of the system is briefly introduced. This technology can be used in unmanned production lines, service robots, warehouses and other fields.

0 Preface

The smart car, also known as the wheeled mobile robot, can automatically move in a specific environment according to a preset mode, without manual intervention, and can be used for scientific surveying, modern logistics and the like. Reflective photoelectric sensors are commonly used path recognition sensors for applications where black marking lines are used as path guides. Reflective photoelectric sensors are widely used in structured environments and low-cost products due to their simple signal processing and physical structure. Although there are weak points with close detection distance and poor predictability, reasonable design and selection of reflective photoelectric sensors Combined with appropriate information processing software, it can meet the above simple environmental applications. With the development of electronic control of automotive ECUs, telematics, sensors and receivers are equipped on the car, and the uncontrolled driving of the car can be achieved through coordinated control of these devices. This paper proposes a control device based on MSP430 single-chip microcomputer. Through the reflective photoelectric sensor tracing, the MSP430 MCU processes the signal detected by the reflective photoelectric sensor, thereby controlling the steering of the smart car and realizing the automatic tracing of the smart car.

1 system overall design

Four sets of tracing modules are installed in the vicinity of the front end of the car body. As shown in Figure 1, the MCU automatically marks the signals sent by the four tracing modules. The tracing module sends a low-level signal when it encounters a black line, and sends a high-level signal when it encounters a blank space. The MCU can make a corresponding operation by judging the high and low levels. Through the combination of signals sent by the four sets of tracing modules, the driving state of the trolley can be divided into seven states as shown in Table 1.

Figure 1 Schematic diagram of the tracking module

The MCU determines the current operating state and then operates the L298 driver module accordingly. When it is normal, no adjustment is made; when the left side is biased, the L298 drive module is adjusted to make the car's left wheel speed greater than the right wheel speed, so that the car can be adjusted to the right. There are three cases due to the left side, but each case only has different PWM parameters for the enable side. When right-biased, the processing flow is similar to the left-handedness.

2 hardware design of the tracing module

The circuit diagram of the completed reflective photoelectric sensor is shown in Figure 2. The working principle of the circuit is as follows: When the optocoupler TCRT5000 reflects light back, that is, it encounters a white runway with strong reflective power, the output of the output of the amplifier LM324AD is high, and vice versa, the output is low. The microcontroller can control the output voltage of the LM324AD by controlling the output voltage of the LM324AD. The four identical modules are connected to the P41, P42, P43, and P44 pins of the microcontroller. The MCU module is shown in Figure 3.

Figure 3 MSP430 microcontroller master chip

Table 1 Car driving status

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