Doctoral Research · Space Robotics Inspection with a Free-Flying Space Manipulator
A Doctoral Research Journal Aerospace Engineering

Overnight (Jun 14, ~03:30–04:35) — singularity levers L3 + L1: results for your call

Scope you set: shovel-ready levers now (autonomous); 7-DOF posture lever + thesis loose ends in the morning with you. Shovel-ready bucket = the Block-2 levers minus R (already adopted rs 0.40 earlier tonight). Nothing was adopted — every re-pin is your call. All runs local on the Mac (fleet left idle: it still has the old code/rs 0.55, and syncing at 3am risked a blocking prompt).

TL;DR

L3 — the full story

stage result
time_scale probe (200 s) WEAK — ze_p99 −1.7%, pe worse +1.7%. Broadband ze is NOT a low-pass-lag artifact.
slew-cap diagnostic cap binds 5.7% of steps (slew p99 = the cap exactly) → ze tail is rate-limited; rate_max knob triggered.
rate_max probe (200 s) rate_max 1.0 Pareto-dominant: ze −41%, nu_jump −28%, pe −26%. Looked like a clear win.
full-helix A/B INVERTED. Tracking still −20-29% AND robust ±2%, BUT derate 0.637→0.971, t_complete +19%, sj_med (conditioning) 0.0229→0.0187 (worse).

Mechanism (the keeper finding): the aim-axis slew cap was doing double duty — smoothness and implicit singularity protection. Capping how fast the camera could re-aim kept the arm out of extension. Loosen it → the arm chases aggressive re-aims into near-singular postures → derate throttles → vehicle crawls → tracking looks better because it’s slow. The tracking gain is commensurate with the +19% slowdown (crawl confound); the sj_med drop is the independent tell that conditioning genuinely worsened. This is Chiaverini’s “hard limits make their own transients” (study §3.4) on the output-smoothing side — and it says: if better pointing is wanted, the lever is controller pointing authority, not output smoothing.

Honest provenance: by the letter of the pre-registered L3 bars (ze↓, pe≤0.1586, cov≥0.99, completed, nu_jump≤OFF) rate_max 1.0 passes — I guarded tracking but not derate/completion. That’s an incomplete-criteria lesson, recorded, NOT back-fitted to reject. My recommendation is NO-ADOPT on the chain’s own terms (conditioning); your call. One adversarial check if you want it: a matched-completion- time comparison would nail the crawl confound beyond the sj_med evidence.

L1 — the reframe (post-R intel for this morning)

Cruise (t 90–200) RHS term decomposition (EE-row norm medians), rs 0.55 → rs 0.40:

regime C D K (stiffness) accel-FF pe_med sj_med
rs 0.55 (deep-derate) 0.030 0.004 0.051 0.221 0.075 0.0063
rs 0.40 (post-R) 0.073 0.051 0.299 0.136 0.148 0.0347

R lifted the cruise above the derate floor (sj_med 0.0063→0.0347), so the term balance flipped: accel-FF was dominant only because deep-derate scaled the gains ×0.25; at full gains, stiffness K dominates. Consequences:

  1. The old v2 premise (“attack the accel-FF dither”) was a floored-regime artifact — moot post-R.
  2. v1 re-check at rs 0.40: velocity_ff OFF vs ON is now nearly identical (pe_med 0.1475 vs 0.1537, progress 1921 vs 1920, derate 0 both) — v1’s rs-0.55 catastrophe (“re-energize past the derate”) is gone because there’s no cruise derate to escape. v1 is inert (not harmful, not helpful).
  3. The cruise now shows genuine, un-crawl-confounded velocity lag (pe_med 0.148 at full speed). The lag is owned by stiffness, not Coriolis (v1’s wrong target) → L1 v2 = a correctly-referenced demand (velocity/accel) feedforward on a stiffness-dominated loop. Clean derivation for this morning.

Committed tonight

Your queue for this morning (in your stated order)

  1. L1 v2 design — derive the correct demand feedforward (the post-R data above is the starting point; it’s a stiffness-loop lag, full-speed, real). Re-run its 200 s design probe, then full-helix.
  2. 7-DOF posture-route lever (new science) — steer the spare DOF along the oracle’s proven wall-clear route; needs a new amendment + criteria before any code (per the Block-1 checkpoint Q2).
  3. Thesis loose ends — bib repair, the H3-contracted-reach puzzle, 6-DOF-only oracle re-registration.
  4. Then the 46-run fragility campaign (harness + E1 gate ready; fleet ready once synced).