MIT Mini Cheetah Actuator

A quasi-direct-drive joint module MIT designed for the Mini Cheetah quadruped, later widely copied across the industry.

The MIT Cheetah actuator is a joint module designed by Ben Katz at MIT's Biomimetic Robotics Lab (Sangbae Kim's group) for the Mini Cheetah quadruped robot: a large-diameter outrunner brushless motor paired with a single-stage 6:1 planetary reducer, with an integrated driver board and magnetic encoder, communicating over CAN. The low gear ratio means low reflected inertia and the ability to be backdriven by external force, so the joint can estimate torque directly from motor current without needing a separate torque sensor — this is the core idea behind quasi-direct drive and proprioceptive actuators. Because the design files and firmware were published openly, a large number of low-cost joint motors in China and elsewhere have since copied its structure and its “MIT mode” control command format.

ExampleJoint motors such as those from DAMIAO, Xiaomi's CyberGear, and the CubeMars AK series all support MIT mode, where a single command frame carries target position, velocity, Kp, Kd, and feedforward torque together.

Also called

Mini Cheetah Motor, Mini Cheetah Joint Module

Related

MIT Mini Cheetah · Quasi-Direct Drive · Proprioceptive Actuator · MIT Mode · Planetary Gearbox · Backdrivability

Sources

Mini Cheetah: A Platform for Pushing the Limits of Dynamic Quadruped Control (ICRA 2019)
bgkatz/motorcontrol - GitHub