Drive Node

The drive node receives Twist messages on the drive/speed topic:

• The field linear.x is the forward speed between -1 and 1, where 1 represents the maximum speed of the robot, and a negative value corresponds to moving backwards.
• The field angular.z is the turning speed between -1 and 1, where 1 represents the maximum turning speed of the robot, a positive value corresponds to a right turn, and a negative value corresponds to a left turn.

The data is then scaled between -255 and 255 and sent over serial in messages like <LINEAR:-100>, <ANGULAR:43>.

Joystick

Speed

The drive_joy node receives Joy messages and converts them to Twist messages for the drive node (described above):

• First axis = turn (left = positive, this is inverted)
• Second axis = forward (forwards = positive)
• Third axis = multiplier (-1 to 1, remapped onto 1x to 3x)

Camera

It also posts a Bool to the camera/capture topic photos when the main (index finger) trigger is pressed:

• Button 1 (1 = pressed, 0 = released)

Current limiting

The per-side current limit can be changed with the left and right thumb buttons:

• Button 3 (left) (1 = pressed, 0 = released): 10A current limit
• Button 4 (right) (1 = pressed, 0 = released): ~19A current limit (max)

Messages are sent over ROS2 in amps, and then converted to mA and sent over serial in the format <I_LIMIT:10000>.

Start

To start the joy node, run the following command:

ros2 run joy joy_node --ros-args --remap __node:=drive_joy_node -r /joy:=/drive/joy