Flexible obstacle avoidance and fast tracking

The smart rescue vehicle is a machine, and it must be equipped with various sensors so that the vehicle can perceive the wonderful world outside and complete the corresponding tasks according to the control of the "brain", that is, the microcontroller. On the basis of completing the minimum system of the single-chip microcomputer of the smart rescue vehicle, the obstacle avoidance circuit and the tracking circuit are added, and the smart rescue vehicle can move as required.

1. Obstacle avoidance circuit (see Figure 1)

The obstacle avoidance circuit uses a diffuse reflection photoelectric switch for obstacle avoidance. The photoelectric switch is a detection switch that integrates a transmitter and a receiver. Its working principle is that the light beam emitted by the transmitter is reflected by the object, and the receiver determines whether there is an obstacle based on this. When there is light reflected back, the output is low level; when there is no light reflected back, the output is high level. The microcontroller makes corresponding control according to the level of the receiving head to prevent the car from hitting obstacles. Since the receiving tube outputs TTL level, it is beneficial for the microcontroller to process the signal.

The obstacle avoidance circuit consists of a bidirectional bus driver U8 (74HC245), an E-gate detection photoelectric switch U10 (E3F-DS30C4), a right obstacle avoidance photoelectric switch U11 (E3F-DS30C4), a left obstacle avoidance photoelectric switch U12 (E3F-DS30C4), and a front obstacle avoidance photoelectric switch U13 (E3F-DS30C4). The installation of the four photoelectric switches: the front photoelectric switch U13 on the bottom layer detects obstacles in front, the left photoelectric switch U12 detects obstacles on the left, the right photoelectric switch U11 detects obstacles on the right, and the upper right photoelectric switch U10 is responsible for detecting the E-gate of the site. The four photoelectric switches work together to complete the functions of obstacle avoidance and door finding. See Figure 3 for the specific installation location.

debug:

1. To ensure that the intelligent rescue vehicle travels in the middle of the road in most cases, the detection distance of the left and right obstacle avoidance photoelectric switches should be consistent. The specific method is: connect the left and right obstacle avoidance photoelectric switches to a 5V power supply before installation, adjust the fine-tuning potentiometer of the photoelectric switch, so that when the obstacle is 8cm in front of the photoelectric switch, the photoelectric switch outputs a low level, and the test points are B3 and B4, as shown in Figure 2. The test method is shown in Figure 4.

2. The front obstacle avoidance photoelectric switch is used for front obstacle detection. To ensure the reliability of front obstacle detection, corresponding debugging should be done: the debugging method is the same as point 1, and the test point is B5, as shown in Figure 2.

3. The E-door obstacle avoidance photoelectric switch is specially used for the detection of the E-door of the venue. The debugging method is the same as point 1. When the obstacle is 10 cm in front of the photoelectric switch, the photoelectric switch outputs a low level and the test point is B2, as shown in Figure 2. The detection distance of each obstacle avoidance photoelectric switch is shown in Table 1.

2. Tracking circuit (see Figure 5)

The tracking of the intelligent rescue vehicle is completed by two photoelectric switches U15 (E3F-DS30C4) and U16 (E3F-DS30C4), and the installation diagram is shown in Figure 5. When the photoelectric switch detects a light-colored object, the light reflection is strong and the output is low. When the photoelectric switch detects a dark-colored object, the light reflection is weak and the output is high. The microcontroller makes corresponding control according to the level of the two photoelectric switches to achieve tracking. Figure 7 shows the state of the intelligent rescue vehicle when the tracking is biased to the left: the LCD displays left; the right LED is on, indicating that the next step is to turn right. Figure 8 shows the state of the intelligent rescue vehicle when the tracking is biased to the right: the LCD displays right; the left LED is on, indicating that the next step is to turn left.

debug:

1. To ensure the reliability of the tracking of the intelligent rescue vehicle, the left and right tracking photoelectric switches are debugged as follows after testing: the left and right tracking photoelectric switches are connected to a 5V power supply before installation, and the fine-tuning potentiometer of the photoelectric switch is adjusted so that when the photoelectric switch is 7cm above the tracking line, the photoelectric switch outputs a low level, and the level test points are B6 and B7, as shown in Figure 2; the distance test is shown in Figure 10.

2. As the tracking line uses a 20mm wide black line, to ensure the reliability of tracking, the transmitter heads of the two photoelectric switches used for tracking should be placed on the inside, and the receiver heads on the outside. The center point spacing of the transmitter heads is 18mm, and the left and right tracking photoelectric switches are 1mm away from the edge of the black line. As shown in Figure 5.

3. The actual distance between the tracking photoelectric switch and the tracking line is 2mm, as shown in Figure 10. The test points and distances of the left and right tracking photoelectric switches are shown in Table 2. This is the obstacle avoidance and tracking circuit. As long as the diffuse reflection photoelectric switch used for the obstacle avoidance and tracking circuit is selected and the wiring is done according to Figures 1 and 6; if the debugging method is appropriate, the intelligent rescue vehicle can avoid obstacles and track.

Figure 8 Tracking to the right