A force limit recomputed each step from the measured speed fought MuJoCo's
implicit solve, which linearises an actuator as its damping: pinning the force
at a bound broke that assumption and injected energy. A joint commanded along a
smooth 1.2 rad/s ramp ran away to 131 rad/s and never recovered.

A motor's speed limit is its back-EMF, which resists motion whenever the motor
is connected, so it belongs on the joint as damping of maxForce over maxVelocity.
MuJoCo integrates that implicitly. Saturated drives still settle at their rated
speed, and the same ramp now tracks to ten milliradians.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>