COMPASS: Temporally Consistent Topological Passing Decisions for Socially Aware Robot Navigation

Service robots in crowded pedestrian environments re-decide at every control cycle which side to pass a person on; when this re-decision is greedy, the passing direction can oscillate across cycles in ambiguous configurations, or the robot can freeze. Topology-aware planners bias selection toward the previously chosen class through soft costs, selection hysteresis, or consistency weights; opinion-dynamics methods make the passing side an explicit, stateful decision with deadlock-breaking guarantees; and minimum-dwell or fixed-rate selectors bound the switching rate by construction. We introduce COMPASS (COMmitment-based PASSing for Social navigation), a decision-layer planner whose commitment rule is a leaky evidence accumulator — a rectified, leaky variant of Page’s one-sided CUSUM statistic with a progress-dependent threshold — under a lexicographic safety override of the standard priority-arbitration kind. Passing classes are bound to person track IDs, a design contract that the current implementation only partly realizes. We state five properties (P1–P5); they apply standard arguments and are not new mathematics. The load-bearing one, P2, is a deterministic, pathwise lower bound on the number of control cycles between discretionary switches that follows from the accumulator rather than from a fixed dwell timer; at the default knobs its worst case is 3 cycles (0.15 s). P2 is paired with a conditional response-time bound, and P1 refines it to an exponentially small per-cycle switching probability under an i.i.d. hypothesis. In an offline harness that drives the actual decision core (5 scenarios × 50 seeds), an immediate-argmin comparator produces about 98 decision changes per encounter under ambiguous ties, whereas COMPASS produces at most one decision change in each tested encounter, as does a 0.6 s persistence (dwell) timer in that scenario; the two rules differ under transient, reversing and intermittent advantage. In a historical decision-core-only measurement, latency at K = 3 (8 classes) is p99 58.6µs and max 651.3µs (the max is about 1.30% of the 50 ms budget at 20 Hz). All comparators are internal. Closed-loop evaluation, external baselines (including a previous-class consistency-weight baseline), and user studies are not performed; they are specified as a planned-evaluation protocol. Code: https://github.com/kjungmo/compass.