Control your Arduino Robot with ROS
The Arduino robot is the first Arduino on wheels, see: https://www.arduino.cc/en/guide/robot
The Arduino Robot. Copyright: arduino.cc
Unfortunately this robot is retired now, but if you might still have one, it is be fun to use it with ROS:-)
The robot consists of two boards. To control it from ROS, the original firmware for the motor board will work. For the control board a rosserial_arduino client should run for publishing and subscribing of ROS topics. The USB connector from the control board forms the serial interface and it can, for instance, be connected to a single board computer carried by the robot.
Unfortunately, the standard Robot Control library uses too much resources to leave enough free memory space to run a rosserial_arduino client. A stripped down version of the Robot Control library can be found here: https://github.com/MartinStokroos/Robot_Control_Lite
The ROS library for Arduino can be installed via the Arduino IDE library manager, or the library can be generated with a Python script from the ros-noetic-rosserial-arduino package. Modify ros.h by adding support for the Atmega32u4 MCU.
Add under namespace ros:
```
#elif defined(__AVR_ATmega32U4__)
typedef NodeHandle_<ArduinoHardware, 5, 3, 150, 150> NodeHandle;
```
The NodeHandle arguments are: number of publishers, number of subscribers, input buffer size, output buffer size. Always keep an eye on the available free memory after compiling the sketch for the robot ( use <80% for stable operation ).
- Robot_Control_ROS.ino
| Currently supported topics | publisher/subscriber | message type | function |
|---|---|---|---|
| cmd_vel | sub | twist |
Linear and radial velocity as raw PWM values (float) |
| msg_compass | pub | Int16 |
Compass heading 0...360 degrees (int16) |
| msg_irarray | pub | Adc |
5 element array of uint16 for IR sensors |
This work is under development...
Start the serial node (using direct USB cable connection to a Linux system):
rosrun rosserial_python serial_node.py /dev/ttyACM0
Check for available topics:
rostopic list
Check the data rate:
rostopic hz /msg_compass
Echo the compass heading:
rostopic echo msg_compass
Plot IR array sensor response:
rqt_plot msg_irarray
Drive the motors straight forward:
rostopic pub -r 1 /cmd_vel geometry_msgs/Twist "linear: x: 75.0 y: 0.0 z: 0.0 angular: x: 0.0 y: 0.0 z: 0.0"