POST No. 2407440
CM-530 C embedded control
2019-06-07 14:57:50 MESEGUER


I'm trying to control a bioloid premium robot controlled by a CM-530 with embedded C and eclipse.

Using an external microcontroller (Beaglebone Black), my purpose is to read the servos' position and move them with the internal ST microcontroller of the CM-530, depending on a trajectory calculated with my BeagleBone Black.

This Beaglebone communicates with the CM-530 through the miniUSB, using a Serial Comunication.

Knowing my objective, I need documentation about the electric circuit between the ST microcontroller and the different ports or terminals of the CM-530 and the servos that are connected to. Also, I would like to have some type of scheme, that may describe the physical characteristics of the servos, and the structure, in order to calculate the trajectory through reverse kinematics.

I know that this is too much information, but it is for educational purpose. 

2019-06-07 14:57:50
2019-06-10 14:43:05 Will Son


Thank you for your inquiry.

The electrical connection information can be found from eManual below.


DYNAMIXELs are different from the traditional servos and there are many parameters that can be configured via digital command packets, so it is difficult to define the physical characteristics of the servo as they can be differ by configurations.

Please refer to eManual for more information about DYNAMIXEL


Thank you.

2019-06-10 14:43:05
2019-06-10 23:20:28 Andrés

Ok, thank you Wilson.

Just one more question. I'm trying to calculate trajectories through reverse kinematics but I am going to need a type of model, in order to get the correct configuration of the robot's servos. Have you got something related to this? Or I have to create my own reverse kinematics model?

Thanks for your time.

2019-06-10 23:20:28
2019-06-11 04:15:42 Kurt Eckhardt

Sounds interesting... My math skills these days are real rusty, but do play around with some robotics like stuff, like Hexapods from Trossen Robotics...  Which do use Kinematics...  But again my math skills are real rusty...

So hopefully @willson will be able to give you more what you are looking for.

If I remember correctly most all of this is calculated using the angles of the servos and the lengths of each segment...

So in the hexapod 3 or 4 DOF legs, the reverse kinematics code calculates the desired angle for each of the servos... When I am ready to tell the servos to move to the new angle, the underlying code then needs to convert the angles (in degrees or ...) to servo units.

With some of the lower end servos like the AX-12, the servos can be positioned in angles from 0 to 300 degrees using  1024  So conversion to degrees is simply: angle/300 * 1024  (plus maybe some offset for what is logically 0...

For many of the newer servos like XL430-250, the servos can be positioned over the full 360 degrees and they have a higher resolution of 4096 so again:


Again there is lots of data up on the main page, plus emanual:

Example XL servos: http://emanual.robotis.com/docs/en/dxl/x/xl430-w250/ and http://www.robotis.us/x-series/

AX Servos: http://emanual.robotis.com/docs/en/dxl/ax/ax-12a/ and http://www.robotis.us/ax-series/ 

2019-06-11 04:15:42
2019-06-11 11:35:07 Will Son

BIOLOID does not use the Inverse Kinematics for its motion, so unfortunately we don't have a specific IK model for the robot.

If you wish to use IK, you'll need to create your own with a preferred method.

Thank you very much.

2019-06-11 11:35:07
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