Dynamixel tutorial

This repository includes the Dynamixel library and python sample code for position and current control. You can use most of the languages with Dynaimxel SDK. If using other Dynamixel model, you need to change addresses in my_global_variables_XL330M288T.py according to your model.

• OS: Mac OS / Windows / Linux
• Language: Python
• Dynamixel model: XL330-M288T

Quick start

1. Download this repository.
2. Set up hardware as described in Dynamixel_tutorial.pdf
3. Run dynamixel_sdk_sample_read_write.py to try position control. Or, run my_current_control.py to try current/torque control. (You might need to change DEVICENAME in my_global_variables_XL330M288T.py if not using Mac. Refer to the last page in Dynamixel_tutorial.pdf)

Sample code

dynamixel_sdk_sample_read_write.py is a sample code given by Dynamixel (modified) that you can run for position control. my_current_control.py is a sample code for current control, which uses self-defined functions in my_utils.py and parameter definitions in my_global_variables_XL330M288T.py.

Steps in code to do position or current control is:

1. Set control mode to position/current control
2. Enable torque
3. Set goal position/current
4. Read present position/current to check
5. Disable torque after the task is done

Reading and writing information

Upon a few settings at the beginning, the code to control Dynamixel is basically reading and writing information at specific addresses which are defined in control table on each model's page (for example, XL330-M288-T). Size (Bytes) of the data is also specified on the control table.

For example, use information, result, error = read4ByteTxRx(portHandler, Dynamixel_ID, Address_number) to read a 4 byte information from Address_number, use result, error = packetHandler.write2ByteTxRx(portHandler, Dynamixel_ID, Address_number, information) to write information to Address_number which has a 2 byte size.

For reference, reading or writing information takes around 15~16 milliseconds with my MacBook.

Enable torque

You need to 'enable torque' (writing TORQUE_ENABLE to ADDR_TORQUE_ENABLE) to access Dynamixel internal information.

However, after enabling torque, a lot of settings are locked (i.e. you cannot write information to change them). To see what information is locked: enable torque on DYNAMIXEL Wizard application and check the control table on the app.

Thus,

• Set operating mode and various limits etc. (all the parameters that will be locked) before enabling torque.
• You might need to disable torque at the beginning of the code, if it was not disabled properly after the last operation.

Attachment to motor

Dynamixel_attachment.stl is an attachment to Dynamixel motor. You can 3D print it and use the screws that come with the Dynamixel to attach it. Dimensions of the attachment can be found in Dynamixel_tutorial.pdf.

Tutorial

Refer to Dynamixel_tutorial.pdf for instructions on hardware setup, package download, DYNAMIXEL Wizard application and running sample code.