Velocity control using ROS 2

[Actat]

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1. Which DYNAMIXEL SDK version do you use?

• latest foxy-devel (92f7035)

2. Which programming language/tool do you use?

• C++, ROS

3. Which operating system do you use?

• Ubuntu 20.04

3. Which USB serial converter do you use?

• U2D2

4. Which DYNAMIXEL do you use?

• XM540-W150

5. Have you searched the issue from the closed issue threads?

• Implementing velocity control  #127 implements velocity control using the older protocol.
• Do Dynamixel Servos give position feedback in velocity control mode? #221 concerns how to obtain position information while performing velocity control.
• [3.5.4][Arduino][OpenCM904] / [OpenCM 485] [MX-64] 2.0 Issue : Velocity Control Mode Code #229 is about velocity control when using an Arduino.

6. Please describe the issue in detail
   I want to use the dynamixel motor in velocity control mode. I need to get position information during control.
   I was able to run the motor in position control mode from ROS 2 using read_write_node in dynamixel_sdk_examples. However, read_write_node does not support velocity control mode. Is there another node that supports velocity control mode?

7. How can we reproduce the issue?

[shiba-8ro]

agreement +1

[Actat]

I have found an unofficial way to solve my problem.
Is there an official way?

Actat@84d759e

[anasderkaoui]

Hello @Actat !
Can you please provide us with the full modifications that you did to the code.
I am at the same page, I want to use an MX-106 servo in velocity mode but I cannot get it done. I modified the code accordingly to yours @Actat 84d759e (ADDR_GOAL_VELOCITY 104 and id 1, addresses according to my servomotor) but the motor is still in position mode !
The command lines also seem to control position mode only: ros2 run dynamixel_sdk_examples read_write_node
returns Something like "[GOAL Position: 0]"
The other command also controls position : ros2 topic pub -1 /set_position dynamixel_sdk_custom_interfaces/msg/SetPosition "{id: 12, position: 1000}"
Is there another command that you used other than these ones above ?