DDSM115 ROS2 controller

This project is based from my previous Python DDSM115 library, and this project could make a control of DDSM115 a lot easier in ROS2 environment.

Deps

• pip3 install crcmod pyserial

Set Motor ID

You will need to connect only one motor on the RS485 bus, then run,

ros2 run ddms115_controller set_motor_id
## Then input the ID number as you want, then the node will be shutdown.

Check Online Motor ID

You can plug all of post set ID motor to the RS485 bus, then run,

ros2 run ddsm115_controller check_motor_id
## It will return a list of online ID in the bus, then the node will be shutdown.

Velocity Control

Once all the motor ID is setup and confirm, you can run

ros2 run ddsm115_controller velocity_control
## This node will check all the online ID on the bus, 
## then you can control and read data fom each motor from ROS2 topics.

Subscriber topics

• /ddsm115/rpm_cmd : as std_msgs/msg/Int16MultiArray, the node is subscribe on this command, user can publish as, e.g. [id_1_rpm, id_2_rpm, id3_rpm, ...] . If you only have 1 motor as ID 1 then just publish as [id_1_rpm], if there are two ID as 1,2 then just publish as [id_1_rpm, id_2_rpm], if you have ID 1 and 3 but no 2, then just publish as [id_1_rpm, 0, id_3_rpm]. So the rpm command of each ID must be on the correct index in the command list.

• /ddsm115/brake : as std_msgs/msg/Bool, the node is subscribe on this brake flag, if user sent True then all the motors will be braked, as default all the motors are free to rotate but with some reaction force from magnetic field. But with brake as True then it will hold the current position in place. And if publish as False to release the brake of all motors.

Publisher topics

• /ddsm115/rpm_fb : as std_msgs/msg/Int16MultiArray, the node will be publishing rpm feedback of all motors as a list, so index 1 as ID1, index 2 as ID2, and so on.

• /ddsm115/cur_fb : as std_msgs/msg/Float32MultiArray, the node will be publishing current feedback in amperes unit of all motors, the list index is similar to rpm feedback.

• /ddsm115/temp_fb : as std_msgs/msg/Int8MultiArray, the node will be publishing temperature feedback of all motors as a list.

• /ddsm115/error : as std_msgs/msg/Int8MultiArray, the node will be publishing error feedback of all motors as a list.

1 : for sensor error
2 : for over current 
4 : for phase over error
8 : for stall error
16 : for troubleshoot error

• /ddsm115/online_id : as std_msgs/msg/Int8MultiArray, the node will be publishing online motor ID of all motors as a list.

Two Wheels Robot

There is a node to make your robot quickly start as a mobile robot, so make sure to have left wheel motor setup as ID 1 and right wheel motor setup as ID 2.

ros2 run ddsm115_controller two_wheels_robot
## OR
ros2 run ddsm115_controller two_wheels_robot --ros-args -p pub_tf:=True
## if you need an odom->base_link TF published.

This node is subscribing on /cmd_vel topic then convert that to /ddsm115/rpm_cmd to drive motors, and also publishing an /odom odometry topic which calculated from /ddsm115/rpm_fb wheel's speed.

You can use rqt_robot_steering to manually drive robot OR you can use ros2 run joy joy_node to publish joystick topic to control the robot from joystick.

You can change a parameter of wheel_base to match with your robot wheel's base.