imp_stiff_low — cocarry_partners@v2

Set. cocarry_partners@v2 (task cocarry@v1) · Stratum. scripted · Split. public · Role. partner_arm

Identity. partner_id 2551311d47ba8e57 · parameter digest a5d61ee76a1a7a8a7f9241d25fca8db825215da0babb8fcda096e2bec36073a0 · weights_uri member://cocarry_impedance/a5d61ee76a1a7a8a7f9241d25fca8db825215da0babb8fcda096e2bec36073a0

What this partner does

A deterministic end-effector-space PI impedance controller for one co-carry arm (ADR-026 §Decision 1): it drives its bar-end toward the cooperative goal along a straight Cartesian path through a damped pseudo-inverse Jacobian, sharing the bar load compliantly with the ego arm. kp/ki set the Cartesian PI gains, step_max the per-step command clip (response speed), damping the pseudo-inverse regularisation, and lag_steps a bounded transport delay (a sluggish-but-competent member: delayed but convergent tracking).

Construction provenance

Built from registry class cocarry_impedance (PartnerSpec(seed=0, checkpoint_step=None)). Public member: the exact values below were drawn from the committed box under the maintainer-held derivation seed and are committed next to their digest.

parameter	committed box	value
damping	[0.035, 0.045]	0.0442
ki	[0.5, 0.7]	0.6616
kp	[1.1, 1.6]	1.1991
lag_steps	[0, 0] (int)	0
step_max	[0.028, 0.032]	0.0286

Behavioural fingerprint

Committed probe suite: seeds [7000, 7001, 7002, 7003] x 5 episodes against the task's reference ego (archive: spikes/results/partner-fingerprints/cocarry_partners-v2/imp_stiff_low/, an ADR-028 v3 bundle). Summary statistics of the member's action distribution and the dyad's stress channel — enough to tell members apart without policy access (ADR-018/I3).

statistic	value
action_abs_mean	0.313
action_abs_p90	1
action_std	0.4232
n_episodes	20
stress_max	103.9
stress_mean	81.57
stress_p50	80.36
stress_p90	97.9
success_rate	1

Competence floor. floor probe fingerprint — success 1 vs committed floor 0.75 → PASS