View Full Version : [Question(s)] Controling Dynamixal torque?

06-27-2015, 03:19 PM
Hello everyone

I have a project for school and all I need is a way to control a Dynamixal torque?
To be more clear what I am trying to do is have some kind of interface that you input a number and the Dynamixal will turn and stop to that certin torque.
I now that this can be done using a current, but how I am going to control it? current sonsor?
I am not good with writing Arduino programs, so an example code that can get me started would be great.
I will be having a torque sensor as well to conform the toqure readings of the motor.

Thank you

06-27-2015, 10:22 PM
None of the AX/RX/EX/MX/XL dynamixel servos have a torque sensor and only the MX-64/106 have basic current sensing capability. The 'MAX_TORQUE' (absolute maximum) and 'TORQUE_LIMIT' ('easily modified' / 'temporary' limit that defaults to 'MAX_TORQUE' value at boot) registers simply determine the maximum PWM-value used to drive the H-bridge controlling the motor. The 'PRESENT_LOAD' register is simply the PWM-value currently being used to drive the H-bridge.

So, there is not really much you can do to actually control the dynamixel's torque other than frequently updating the 'GOAL_POSITION' and 'TORQUE_LIMIT' registers several times each second using your own algorithm based on sensor feedback running on an external microcontroller. You might be able to use an external current sensor and external microcontroller to approximate the torque produced by the motor as a function of the current, but will not be too accurate since the dynamixel servo's microcontroller contributes to the current consumption of the servo. Another method would be using the actual torque values retrieved by the torque sensor to adjust the 'GOAL_POSITION' and 'TORQUE_LIMIT' values.

06-28-2015, 01:41 PM
Thank you, the only thing that I need right now is the arduino code?