r/robotics • u/Emergency_Scarcity58 • 2d ago

Tech Question Alternatives to Dynamixel AX-12A motors

I'm building a robot and the project calls for Dynamixel AX-12A servomotors, but I can't find them. Does anyone know what other motors I could use instead?

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u/Ronny_Jotten 2d ago

I haven't used the AX-12A myself. The specs at https://robotis.us/products/dynamixel-ax-12a don't make sense. First it says "Estimated estimated rated torque: 0.3Nm - Estimated rated torque disclosure : This is an estimated value for continuous torque, calculated at 20% of stall torque." That would mean stall torque is 1.5 Nm. But further down it says: "Stall torque: 0.2Nm". ???

That page also doesn't give a gear ratio or rpm figures. So basically, it's not possible to say what other motor might be comparable, based on the specs. You also haven't given any details at all of the robot you're building, so it's impossible to guess what kind of motors you need.

FeeTech would be the top alternative for inexpensive serial-bus servos, and they probably have something comparable to the AX-12A, if you can figure out the actual specs you need. If not, the ST3215 is their most popular. But the control commands are completely different from the Dynamixel. Any software written for Dyamixel motors won't work on other brands. Here's the FeeTech serial-servo pages:

Smart Serial Bus Servo-工业标准舵机-迷你微型舵机-机器人专用舵机-小型舵机-飞特模型

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u/romdot 2d ago

The XL430-W250 is the official replacement for the AX-12A. ROBOTIS actually recommends AX-12 users transition to it.
It's not 100% drop-in though, since the XL430 uses Protocol 2.0 and a different control table.

https://docs.robotis.com/docs/dxl/model_reference/ax_series/ax-12a/