
Proactive Opinion-Driven Robot Navigation around Human Movers
Charlotte Cathcart, Mar´
ıa Santos, Shinkyu Park, and Naomi Ehrich Leonard
Abstract— We propose, analyze, and experimentally verify
a new proactive approach for robot social navigation driven
by the robot’s “opinion” for which way and by how much
to pass human movers crossing its path. The robot forms
an opinion over time according to nonlinear dynamics that
depend on the robot’s observations of human movers and its
level of attention to these social cues. For these dynamics, it
is guaranteed that when the robot’s attention is greater than
a critical value, deadlock in decision making is broken, and
the robot rapidly forms a strong opinion, passing each human
mover even if the robot has no bias nor evidence for which way
to pass. We enable proactive rapid and reliable social navigation
by having the robot grow its attention across the critical
value when a human mover approaches. With human-robot
experiments we demonstrate the flexibility of our approach and
validate our analytical results on deadlock-breaking. We also
show that a single design parameter can tune the trade-off
between efficiency and reliability in human-robot passing. The
new approach has the additional advantage that it does not rely
on a predictive model of human behavior.
I. INTRODUCTION
Autonomous mobile robots are increasingly being used
for tasks in settings such as warehouses and open public
spaces where they will encounter human movers. In order
to accomplish their tasks in these settings, the robots need
to reliably and gracefully navigate around human movers. In
this paper, we propose, analyze, and experimentally verify
a new approach for the social navigation of a mobile robot.
Fig. 1 shows experimental results of a mobile robot navigat-
ing around two human movers using the new approach.
We build on the nonlinear opinion dynamics model pre-
sented in [1] and propose an approach that allows a robot
to rapidly form an opinion that represents the strength of its
preference for which direction—left or right—it will use to
pass each human mover crossing its path. This opinion, in
turn, drives the robot’s motion, modifying its nominal path
to reliably pass the human. A key to the opinion dynamics
is that when the robot’s attention to social cues grows above
a critical value, the neutral opinion to stay the course is
destabilized and the robot rapidly forms a strong and stable
opinion for moving in one of the two passing directions.
Our approach is therefore to design dynamics for the robot’s
Cathcart, Santos, and Leonard are with the Department of Mechanical and
Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA.
{cathcart, maria.santos, naomi}@princeton.edu. Park is
with the Electrical and Computer Engineering program, King Abdullah
University of Science and Technology, Thuwal 23955, Saudi Arabia.
shinkyu.park@kaust.edu.sa.
This research has been supported by ONR grant N00014-19-1-2556,
funding from KAUST, and Princeton University through the generosity of
Lydia and William Addy ’82.
Study #14788 has been approved by the International Review Board
(IRB) of Princeton University.
(a) (b)
Fig. 1. A robot using opinion-driven navigation to pass two humans. (a)
Time-lapse of the experimental trial. (b) The full trajectories of the robot
(red line) and two humans (blue and green lines) with temporal markers.
attention that drive it above this critical value when the
robot senses a human mover approaching its path. The active
control of attention yields a rapid and reliable passing motion
in response to an approaching human mover; this renders our
approach “proactive” rather than merely “reactive.”
Once the robot passes a human, its opinion with respect to
that human is no longer relevant; the opinion quickly returns
to its neutral value, allowing the robot to continue towards
its destination. Likewise, the robot’s attention also goes to
zero, making the robot ready for new potential conflicts with
other movers. Figs. 1 and 2 provide experimental results of
the robot navigating different encounters when traveling to a
goal destination that is diagonally across an open space with
two humans moving and pausing in a variety of scenarios.
Opinion dynamics are used to enable decision making in
multi-agent systems in a range of tasks [2]–[4]. In the nonlin-
ear opinion dynamics of [1], an agent’s opinion is influenced
by the opinions of others when its attention exceeds a critical
level. At this point the agents are guaranteed to form strong
opinions (e.g., to agree on or coordinate among options),
hence avoiding indecision, i.e., deadlock in their decision
making. In the robot social navigation problem, we leverage
the deadlock breaking guarantees of the coupled attention-
opinion dynamics to ensure that, when necessary to avoid an
approaching human mover, the robot will rapidly select and
move in one of the two passing directions even if there is
no indication from the human or the environment that one
direction is better than the other, or if the robot’s bias for
one direction or the other, if it has one, conflicts with the
human’s chosen passing direction.
Of relevance to our work is the literature on robot social
navigation (see recent survey articles [5]–[9] and references
therein), where a common theme is in investigating the de-
sign of navigation algorithms for autonomous robots to safely
and comfortably interact with the humans they encounter.
arXiv:2210.01642v4 [cs.RO] 11 Sep 2023