MultiRobotBench

Goal. Take the red toolbox out of the cabinet and put it on top of the cabinet, then let both doors close.

west panda · east panda · south panda | toolbox_width: easy 22, hard 30 cm

Scripted reference succeeds at both levels. Agent cases: surplus, shortfall, borrow (a heavy block as a door stop: works on paper, friction margin thin, not tried in Isaac).

A double-door cabinet stands on the table, a toolbox on its shelf 22 cm up. Each door, the whole height of the front, has a soft-close spring and swings shut when let go, and the toolbox is wider than one door's opening: both doors must be held open at once while a third hand takes the toolbox out and puts it on top of the cabinet. Reference: the west and east Frankas each take a door's handle from above, pull it open and hold it; the south Franka pulls the toolbox out by its pull and lifts it onto the cabinet; then the doors are let go.

Goal. Pull the orange plug in the middle of the power strip out of its socket and hold it at least 5 cm above it. Do not move the strip.

west panda · east panda · south panda | pull_force: easy 20, hard 40 N

Changed 2026-10-19: every socket holds a plug. With three plugs, one hand pressing 15 cm from the plug held the strip and two arms did it in Isaac (found by the agent). Now one hand at an end: strip moves 1.3 cm, fails; two blocks on the ends hold it.

A power strip lies on the table with a plug in each of its seven sockets; the middle one sits so tight that it takes 20-40 N to pull out. Pulled up while nothing holds the strip, the strip comes up with it; the plugs leave room for a hand only at the strip's two ends, and pressed down at one end alone, the strip swings up about that end. Both ends must be pressed down at once while a third hand pulls the plug. Reference: the west and east Frankas each press one end down onto the table; the south Franka pulls the middle plug straight up and out.

Goal. Hold the wooden socket still in the assembly zone above the table, insert the blue peg into its hole and put the red cap on the peg.

south piper · west panda · east panda | clearance: easy 3, hard 1 mm

No scripted reference yet.

There is no vise: a socket block has to be held still in the air, in the assembly zone, while a peg is inserted into it and capped. The peg and the cap start in the west and east zones, which no other arm reaches, so the cap needs a third arm. Reference: the south Piper lifts the socket and holds it in the zone; the west Franka inserts the peg; the east Franka caps it.

Goal. Keep two separate buttons pressed at the same time while a third arm retrieves the target through the open passage.

3 Franka arms: left button holder · right button holder · retriever

Three-arm reference succeeds; the borrow recording uses a released weight on one button. Quantitative button force–displacement calibration remains open. Every video includes the overview and all available wrist cameras.

Continuous support. The passage stays open only while both buttons remain depressed. Releasing either button removes the interlock condition during retrieval.

Borrow version. Two arms: place and release a weight on one button, keep the other button pressed with one arm, and retrieve the target with the free arm.

Scripted engineering references, not autonomous agent evaluations. The two-arm failure describes the recorded strategy; it does not prove that all two-arm strategies fail. Historical baseline and control settings are not a strictly matched quantitative ablation.

Goal. Put the red ball into the white cup and stand the cup upright on the orange coaster. On its way the cup must pass through the zone in the air above the middle of the table.

east panda · west panda · south piper | cup_radius: easy 45, hard 30 mm

No scripted reference yet. IK check (validate --ik): the west arm reaches the ball, said to be the south arm's only -- to fix with the scene.

The cup stands within reach of the east arm only, the ball within reach of the south arm only, and the coaster within reach of the west arm only; the cup must pass through a handover zone in the air above the middle of the table, and end upright on the coaster with the ball in it. Reference: the east Franka picks the cup up and hands it to the west Franka in the zone; the Piper drops the ball into it while the west Franka holds it; the west Franka stands it on the coaster.

Goal. Sort the blocks in the pile by colour: each block into the bin of its own colour.

west panda · east panda · south piper | blocks_per_arm: easy 2, hard 4 blocks

No scripted reference. IK check: its reach claims hold (an earlier, looser check let the south PiPER's hand reach through the bins' walls).

Red, green and blue blocks are mixed in one pile that all three arms reach; each colour's bin stands where only one arm reaches it, so each colour needs its own arm. Reference: each arm sorts one colour, all three at once, without getting in each other's way.

Goal. Build a 3-block tower on the white square, bottom to top: red, green, blue.

west panda · east panda · south piper | tower_height: easy 3, hard 6 blocks

No scripted reference. IK audit: the south PiPER reaches the red and blue supplies, the west arm the green one. Candidate to drop.

Build one tower in front of the south arm in the colour order red, green, blue, red, ... from the bottom up. Each colour's blocks start where only one arm reaches them, so the three arms take turns at the tower. Reference: the west Franka places red, the south Piper green, the east Franka blue.

Goal. Take the lid off the box and put it on the white area, pack all the items into the box, then put the lid back on the box.

west panda · east panda · south piper | num_items: easy 2, hard 4 items

No scripted reference. IK audit: the west arm reaches the lid's rest. Candidate to drop.

A lidded box stands in front of the south arm. The items to pack lie on its west and east sides, each side within reach of one arm only, and the white area where the lid is put down is within reach of the south arm only. Reference: the Piper takes the lid off and parks it; the two Frankas each pack the items on their side; the Piper puts the lid back on.

Goal. Put the soup, the sandwich and the pudding on the tray and slide the tray along the lane to the till at the east end; it must arrive there with every dish on it.

west piper · south panda · east piper | till_tolerance: easy 6, hard 3 cm

Fixed 2026-10-21 (the east arm could take the sandwich by its corner): sandwich on a 25 cm pass shelf behind and beside the south arm, 0.86 m from the east arm; no end arm reaches it, Franka or Piper. Reference succeeds at both levels (67.3 / 67.7 s). Borrow design to revise (a pass counter for the board to slide on).

A tray slides along a lane down the counter, 1.8 m, past three stations to the till at the east end -- a cafeteria line. At each station the arm there puts its dish on the tray (soup, a sandwich, a pudding) and slides the tray on into the next arm's reach. Each dish is within reach of one arm only -- the sandwich on a pass shelf beside the south arm, well clear of the end arms (checked by IK with margins) -- so the line takes three arms (the tray alone the end arms could pass between them). The tray stays where it is let go, so no arm holds anything while another works. Reference: the west Piper adds the soup and slides the tray to the middle, the south Franka adds the sandwich and slides it on, the east Piper adds the pudding and slides it to the till.

Goal. Put the screwdriver and the wrench away, each in the tray of its colour: red in the red tray at the far west end, blue in the blue tray at the far east end.

west piper · south panda · east piper | num_tools: easy 2, hard 3 tools

New 2026-10-20: scene and scoring built; scripted reference not written yet.

A screwdriver and a wrench (and, hard, a hammer) stand in a caddy in front of the south arm; each must end in the tray of its colour, the red tray far out at the west end, the blue one far out at the east end. The caddy is within reach of the south arm only, each tray of one end arm only: the tools leave one place for two -- sorting outward by identity. Laid on a pad, a tool stays, so no arm holds anything while another works. Reference: the south Franka takes each tool out and lays it on the pad by the end arm it belongs to; that arm puts it in its tray.

Goal. Hang the string of lanterns on the three hooks: the rings at its ends over the pins of the two outer hooks, its middle over the middle hook, with every lantern clear of the table.

west piper · south panda · east piper | hook_height: easy 25, hard 30 cm

Reference succeeds at both levels (16.7 s). IK audit with margins (2026-10-21): the east arm's hand comes within 5 cm of the point over the middle hook; a cord can be draped from about 9 cm. Fix proposed: middle hook further from the east arm.

A 2 m cord with four small paper lanterns on it, and a ring at each end, lies along the table in front of the south arm; south of it three hooks stand in a row. The string must hang from them: its end rings over the pins of the two outer hooks, its middle over the middle hook, every lantern clear of the table. Each hook is within reach of one arm only -- the outer ones of the west and east arms, the middle one of the south arm -- so the string takes three arms because it is long. A ring dropped over a pin stays, and a cord laid over a hook stays: no arm holds anything while another works -- a long soft thing spanning the table. Reference: the west and east Pipers take the rings by their knobs and the south Franka pinches the cord's middle; together they lift the string, drop the rings over the pins and lay the middle over the middle hook.

Goal. Put the red block on the tray, lift the tray at least 10 cm, carry it to the yellow pad and set it down; never tilt it more than 10 degrees.

west panda · east panda · south piper | max_tilt: easy 10, hard 4 deg

Extension: no scripted reference.

The Piper puts a block on a tray. The two Frankas, facing each other, grip the two ends of the tray, lift it at least 10 cm and carry it to the target pad on the far side, keeping it level so the block does not slide off. The block starts where neither Franka reaches; the Piper does not reach the pad. One Franka holding the tray firmly by one end could carry it alone: only grip and payload say it cannot.

Goal. Take the red gate bar off the rack and lay it on the white area, then lay the long rod flat across both rack posts.

west panda · east panda · south piper | rod_mass: easy 0.4, hard 1.2 kg

Extension: no scripted reference.

A gate bar lies across a two-post rack in front of the Piper. The Piper lifts the gate off and parks it where neither Franka reaches; then the two Frankas carry a 60 cm rod together from the far side and lay it across the posts. Whether one Franka could lift the rod alone by one end is a matter of the rod's mass and the grip.