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Cooperatively avoiding collision is a critical functionality
for robots navigating in dense human crowds, failure
of which could lead to either overaggressive or overcautious
behavior. A necessary condition for cooperative collision avoidance
is to couple the prediction of the agents’ trajectories with
the planning of the robot’s trajectory. However, it is unclear
that trajectory based cooperative collision avoidance captures the
correct agent attributes. In this work we migrate from trajectory
based coupling to a formalism that couples agent preference
distributions. In particular, we show that preference distributions
(probability density functions representing agents’ intentions)
can capture higher order statistics of agent behaviors, such as
willingness to cooperate. Thus, coupling in distribution space
exploits more information about inter-agent cooperation than
coupling in trajectory space. We thus introduce a general objective
for coupled prediction and planning in distribution space,
and propose an iterative best response optimization method
based on variational analysis with guaranteed sufficient decrease.
Based on this analysis, we develop a sampling-based motion
planning framework called DistNav1 that runs in real time on a
laptop CPU. We evaluate our approach on challenging scenarios
from both real world datasets and simulation environments, and
benchmark against a wide variety of model based and machine
learning based approaches. The safety and efficiency statistics
of our approach outperform all other models. Finally, we find
that DistNav is competitive with human safety and efficiency
performance.
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