Robot arm positions affect how close people let robots get
CALM: Configuration-Aware Human Intervention Boundaries During Robot Approach
RoboticsHuman-Computer Interaction
Summary
The way a robot holds its arms changes how close people feel comfortable when it approaches them. The authors found that when the robot's arms were fully stretched out, people kept a larger distance compared to when the robot’s arms were down. They created a model called CALM that helps predict how close a group of people will allow a robot to get based on its arm position. This model can help robots plan their movements to be less intrusive or more accepted by humans. The study also showed that the size of the space around the robot affected how comfortable people felt but not the distance where people stop the robot.
robot approachhuman interventionrobot body configurationstopping distancesubjective comforteye trackingpopulation coverageplanning model
Authors
Xinting Gao, Sipu Zhu, Weimin Zhuang
Abstract
How robot body configuration shapes human intervention during approach remains underexplored. We conducted a within-participants study with 41 participants, measuring final stopping distance, subjective comfort, and exploratory eye-tracking responses across four humanoid arm configurations and two spatial scales. Full forward arm extension increased stopping distance by approximately 31-36 cm relative to arms-down. Spatial scale primarily affected comfort and pupil responses without a detectable stopping-distance shift. We introduce the Configuration-Aware Limit Model (CALM), which translates stopping-distance distributions into configuration-dependent population-coverage boundaries. Estimated boundaries at 80% coverage ranged from 0.88 to 1.47 m. In an illustrative one-dimensional planning analysis, reconfiguration enabled a 1.10 m approach goal that was unreachable with arms remaining fully extended under the same nominal pointwise 20% intervention-probability constraint. These findings support treating body configuration as a planning variable while distinguishing physical safety, behavioral intervention, and subjective cost.