4.6 Card Recognition

4.6.1 Algorithm

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It can identify whether there are corresponding traffic cards in the image. If yes, it will return information including the coordinates, size, and label values of the cards.

4.6.2 Classification Label

Label

Definition

Pic

1

go forward

007

2

turn left

001

3

turn right

002

4

turn around

004

5

stop

003

6

green light

009

7

red light

005

8

speed 40

008

9

speed 60

010

10

speed 80

006

Note: The algorithm can recognize multiple cards simultaneously. The card can still be recognized within a certain rotation, deflection and pitch angle. When using, please make the card face the camera as directly as possible for better recognition effect.

4.6.3 Test Code

  1. In the code start-up, set the serial port baud rate to 9600, and then set the communication mode of the AI vision module to I2C, and finally set it to run in Card mode.

a54

  1. The if block determines the number of detections. Only when the number of detections is greater than 0 will the data be output. Note to choose Card.

  2. Loop through the result quantity. When multiple cards are detected, it will loop multiple times and then use a variable on the parameter group. After each loop print, the variable adds by one. In this way, the information of cards can be printed (Note: Set the mode of the returned data to “Card”).

Complete code:

a55

4.6.4 Test Result

After uploading the code, the AI vision module will scan the area captured by the camera. If there is a card, it will recognize the card and print its coordinates(x,y), width(w) and height(h) in the serial monitor.

4.6.5 Extension Gameplay

Color picker

  • Game rule: Rotate the card (to the right/left) to change WS2812 light colors. For example, the normal sequence of lights is: red > green > blue > yellow > purple, etc., yet we can adjust them by turning the card. Suppose the current color is red, and we rotate the card to the right to change it to green; rotate to the left to make it purple; in a loop.

  • Practice: After identifying the card, control the light by performing addition or subtraction on a variable.