Driving DC Motors for Tracks
CAMROBO has 130-type DC-motor to drive the tracks. Raspberry Pi can control these motors with H-bridge motor drivers and PWM signals from the pi's gpio. In this section, you learn about two motor drivers.
Following wirings are examples. You can change wirings of GPIO and yaml files.
Cytron Maker Drive is a good choice for beginners. You can drive the motors without microcontrollers with pushing buttons to check wiring. Indicators in this drive show status of output signals for the DC-motors.
| Driver | Other Device |
|---|---|
| M1A (IN) | Raspi-17 |
| M1B (IN) | Raspi-18 |
| M2A (IN) | Raspi-27 |
| M2B (IN) | Raspi-22 |
| M1A (OUT) | RMotor-YELLOW |
| M2A (OUT) | RMotor-BLUE |
| M1B (OUT) | LMotor-BLUE |
| M2B (OUT) | LMotor-YELLOW |
| VM | Alkaline-V+ |
| 5V0 | Raspi-5V |
| GND | Raspi-GND, Alkaline-V- |
Sparkfun TB6612 module is smaller module to drive DC-motors. You can put this module on breadboards and proto-boards
| TB6612 | Other Device |
|---|---|
| A_IN1 | Raspi-22 |
| A_IN2 | Raspi-27 |
| A_PWM | Raspi-17 |
| B_IN1 | Raspi-13 |
| B_IN2 | Raspi-19 |
| B_PWM | Raspi-26 |
| A01 | RMotor-YELLOW |
| A02 | RMotor-BLUE |
| B01 | LMotor-BLUE |
| B02 | LMotor-YELLOW |
| VM | Alkaline-V+ |
| VCC | Raspi-3V3 |
| STBY | Raspi-3V3 |
| GND | Raspi-GND, Alkaline-V- |
tamiya_cam_robot/wheels_listener is a ROS node controlling DC motors for wheels (tracks) with H-bridge drivers. This node is L298N mode, having no PWMA and PWMB parameter. On the other hand, the node is TB6612 mode when it reserves PWMA and PWMB parameters.
- Maker Drive (L298N)
rosrun tamiya_cam_robot wheels_listener
When you add no parameters, wheels_listener sets default values ( _AIN1:=17 _AIN2:=18 _BIN1:=27 _BIN2:=22).
When you changed a wiring, you need to remap the pin assignment.
rosrun tamiya_cam_robot wheels_listener _AIN1:=17 _AIN2:=18 _BIN1:=27 _BIN2:=21
- TB6612
Inputing PWMA and PWMB set tamiya_cam_robot/wheels_listener on TB6612 mode.
rosrun tamiya_cam_robot wheels_listener _AIN1:=22 _AIN2:=27 _PWMA:=17 _BIN1:=13 _BIN2:=19 _PWMB:=26
tamiya_cam_robot/wheels_listener subscribes /tamiya1/cmd_vel (geometry_msgs/Twist) which is rostopic representing wheels efforts (-1.0 -- 1.0). You can drive the motors with publishing topics to the listener.
- Forward
rostopic pub -1 /tamiya1/cmd_vel geometry_msgs/Twist '{linear: {x: 0.5, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.0}}'
- Backward
rostopic pub -1 /tamiya1/cmd_vel geometry_msgs/Twist '{linear: {x: -0.5, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.0}}'
- Turn Right (Clockwise)
rostopic pub -1 /tamiya1/cmd_vel geometry_msgs/Twist '{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: -0.5}}'
- Turn Left (Counterclockwise)
rostopic pub -1 /tamiya1/cmd_vel geometry_msgs/Twist '{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.5}}'
- Stop
rostopic pub -1 /tamiya1/cmd_vel geometry_msgs/Twist '{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.0}}'