What Is the MIT Protocol?

The MIT protocol (MIT Mode) is a CAN-bus motor control protocol originating from the MIT Mini Cheetah open-source legged robot. Its core idea: compress a full control command into one CAN frame carrying five quantities — target position p, target velocity v, position gain Kp, velocity gain Kd, and feed-forward torque τ.

Hybrid Force-Position Control

The motor computes output torque as τ_out = Kp·(p − p_actual) + Kd·(v − v_actual) + τ. By tuning the gains, one protocol covers three control modes:

• Pure torque control: Kp = Kd = 0, feed-forward torque only — the basis of high-dynamic force control;
• Position control: normal Kp/Kd values track position like a servo;
• Impedance control: intermediate gains make the joint behave as a spring-damper for compliant contact.

Why It Became a De Facto Standard

The protocol is open, compact (one frame per command), and force-control-native. Many joint motor vendors now support it, creating a cross-brand control interface. All BXI 85/70/50-series joint motors support MIT-protocol CAN/CANFD, and paired with the PCIE-CAN control module achieve >1000 Hz whole-robot control loops.