Both robots share the same body size and drive down the same winding passage lined with fragile pottery shards and bones, seen here from directly above. A rigid position-controlled body has no way to yield: whatever force is needed to keep tracking the driven path is the force it applies, so the instant its body brushes an artifact it keeps pushing — the artifact cracks, and the damage counter climbs.
A compliant, force-limited body continuously monitors contact distance at its own skin. The moment that distance crosses the fragility threshold, it zeroes its drive thrust, retracts a short distance along its own back-track, then re-plans a route around the obstacle before resuming toward the goal.
if contact_dist < threshold:
thrust = 0
retract(Δt_retreat)
heading += side * turnRate # re-route around contact
resume drive toward path
- Rigid mode — the body ignores contact and keeps its commanded trajectory; every touch on an artifact counts as damage.
- Compliant mode — the body treats close contact as a stop signal, retracting and steering clear before it can apply real force.
- Re-route maneuvers — counts how many times the compliant controller had to yield and detour; each one costs a little time but saves an artifact.
- Fragility threshold — the sensing radius that triggers a yield; a low threshold acts only on genuine contact, a high one gives wide berth to every artifact.