Revised: 09 July 2021
tải về 1.13 Mb. Chế độ xem pdf
|
| III.
T HE L INE F OLLOWER A LGORITHM Figure 4 shows the mechanism of line follower for the AMR. The current location of the mobile robot to the respect to the center black line is recognized and calculated by the reading of IR sensors to compute the error between the current location and the desired path. Then the computed error is used as input to the digital PID controller. The Pulse Width Modulated (PWM) control signals are generated to control and drive the motors connected to the Motor Board of AMR to adjust the steering angle of the robot and to bring it back to the center of the black line. The Multiplexer logic circuit is used to interface between ATmega32u4 Microcontroller of the Arduino board and the five IR sensors to read just one data that come from IR sensors set according to command signal sent from ATmega32u4 controller. Figure 5 shows the connection of the IR sensors and ATmega32u4 microcontroller via multiplexer. The five IR sensors (IR0-IR4) are connected to the inputs of multiplexer. The selectors of the multiplexer named (SA, SB and SC) are connected to digital output pins of the ATmega32u4 microcontroller. Therefore, microcontroller is read just one IR sensor at a time that is applied to analog input pin INA. Table 1 shows the selected IR sensor reading according to the selectors command. TABLE (1) The selected IR sensor reading according to the selectors command The connection of ATmega32u4 microcontroller with two wheel motor via Motor Driver is shown in Figure (6). The speed and direction of the left and right wheel are adjusted by the motor drive. Four digital output pins (OA1, OA2, OB1 and OB2) of the microcontroller are connected to inputs of motor driver (INA1, INA2, INB1 and INB2). The inputs INA1 and INB1 of the motor driver corresponds to the forward movement of the left and right motor respectively. INA2 and INB2 corresponds to the reverse movement of the left and right motor respectively. A pulse width modulated (PWM) signals are used to control the motors. A positive input to the motor driver from the microcontroller corresponds to forward movement of the motors, whereas a negative input corresponds to reverse movement of the motors. For forward movement of both the motors, you have to apply the PWM signals to INA1 and INB1 and zero values to INA2 and INB2. Similarly for reverse movement, you have to apply the PWM signals only to INA2 and INB2 and zero values to INA1 and INB1. The line follower algorithm is constructed as closed loop controlled system with PID controller. The parameters of tải về 1.13 Mb. Chia sẻ với bạn bè của bạn:
|