pub const FADE_BAND: f64 = 0.15;Expand description
The narrowest band, as a fraction of a joint’s velocity limit, over which the law’s push along the joint’s motion fades out under the barrier’s onset: the fade starts at the cap or this far under the onset, whichever is lower, and never below rest.
Away from a position limit the band is this wide and the fade adds up to
|law| / (FADE_BAND × limit) Nm per rad/s to the loop’s gain, about 30 on an FER’s wrist at
its 11.5 Nm clamp, which the loop settles on 0.03 kg m² and more; a fade from a cap of 0.8
rings there. Inside the position margin the cap is 0 – the braking envelope is 0 at and past
the margin – so the start is 0 and the band is [0, onset]. Where the arm’s limit toward
that side is flat, as the FER’s is, that is the narrower band and the figure above is not the
bound; what bounds the gain is the position fade
(POSITION_FADE_BAND) tapering the same push to nothing over
the same rad. Both vanish linearly, so the product is finite, and it peaks at the margin at
|law| / (velocity_barrier_fraction × E(POSITION_FADE_BAND)): on the FER 1.16 to 1.61 times
the figure above (tests/torque_position.rs). The FR3’s limit is position-dependent and has
itself come down by the margin, so its band is wider there and the figure above does bound
it.