The DC motor's LuGre bristle state must integrate the velocity of its own
transmission, so actuator ordering cannot affect it. The test places a
multi-output SO3 actuator before the DC motor, making the motor's actuator
id and output address diverge, and requires the bristle state to match the
motor-first ordering. Currently fails: the exact ZOH update in
mj_nextActivation reads actuator_velocity[actuator_id] instead of the
motor's own actuator_velocity[outadr], so the bristle integrates the SO3
actuator's velocity.
Giuseppe Sensolini
f95d50c12f