Hi Robotis, I’d like to ask questions about heat issues with XM430-W350-R motors.
We are developing legged robots using these motors and the performance of the motors drops (controller starts throttling the current, the motor cannot read the encoder super frequently any more…) when we run the motors quickly to make the robot walk. So, we would like to know if you have some test results (e.g., at what temperature the controller start throttling the current, ), it would be appreciated.
Currently, we are interested in using pairs of XM430-W350-R motors to increase the torque density. Our concern is that still, heat will be a problem. We wonder if heat issues would be relaxed with the XH540-W270-R motors since these motors consume less current. In other words, which options (a pair of XM430-W350-R motors vs a single XH540-W270-R) are your recommendation that can have less probability of having heat issues?
Based on your description of the issue, can you clarify what your current controller in use is? If your controller is throttling the current based on its maximum limit, it’s possible the DYNAMIXELs may be browning out.
DYNAMIXELs will shutdown if the temperature reaches a level over the defined Temperature Limit in the firmware: XM430-W350-T/R
Have you had the opportunity to check the Present Temperature of the units when these issues are observed?
Regarding the recommendation between one larger XH540-W270 model or two XM430-W350, it is difficult for our team to provide a specific recommendation, however I would expect two units sharing the load to experience less overall heat as the lower load experienced by each servo should result in lower current draw compared to a single model supporting the same load.
For some additional advice and recommendations regarding the heat issues, let me tag in @Tech_Support
So, we are using this controller with value 3 (default). The velocity profile (112) is 0. The acceleration profile is 500.
Would this information be enough for you to figure out my question (controller starts throttling the current, the motor cannot read the encoder super frequently any more)
Hi there @legged_robot_love, thanks for providing the additional info. Sorry for the delayed response as I’ve unexpectedly been out of the office recently.
Regarding the controller in use, I was hoping you could provide more information about the control environment / control source - is the DYNAMIXEL currently being controlled by a specific board, or by your computer using U2D2 or another interface? In addition, can you share how they are currently being powered and specs of the power supply if possible? If the issue is related to insufficient current, the power supply or control board may have an influence.
On the DYNAMIXEL side, have you had the opportunity to attempt changing the Return Delay Time setting of your DYNAMIXELs to increase feedback frequency?
I’ll also refer @Tech_Support and for some additional guidance to assist.
Could you explain how much torque is consumed when the robot move its joints? 20% higher of stall torque may cause the gear worn out which may give an affection to the encoder read error I guess. (But I am nor really sure it affects the speed of feedback. You can increase the feedback speed between controller and DYNAMIXEL by adjusting the Return Delay time and Baudrate to higher)
Generally speaking, the cause of heat quite vary in various situation such as the consuming torque as mentioned, overdrawn current (drawn to motor), gear friction.
Possible way to level down the heat generation in quick way is to decrease the stress between gears by adjusting the Profile velocity and Profile Acceleration value - The default is the Infinite Acc, Infinite Vel, normally thought as the maximum acc/vel.
The XH series uses the Maxon motor which guarantees the longer longevity and durability than other motors. However, it does not mean that it can make a phenomenal improvement in your application.
Also DYNAMIXELs are consumable, so that the longer you use, the lower performance you will get. In this case, you may need to make gear replacement.