The effect of appearance features of sidewalk autonomous delivery robot on perception of pedestrian

Sidewalk autonomous delivery robots (SADRs) are increasingly appearing on urban sidewalks and sharing public space with pedestrians. This study aims to investigate how different appearance features of SADRs influence four dimensions of human perception: Likeability, Competence, Perceived Safety, and Existence Acceptance. In Study 1, an affinity diagram method was used to classify the appearance features of existing SADRs into four categories—contour, proportion, facial features, and color scheme—which were then used as the design variables in Study 2. In Study 2, 100 participants completed an online questionnaire after viewing AI-generated videos of SADRs and evaluated the robots on the four perceptual dimensions. The statistical results showed that rounded contours and the presence of facial features significantly increased Likeability, Perceived Safety, and Existence Acceptance. White–black and yellow color schemes generally received higher ratings for Likeability, Perceived Safety, and Existence Acceptance than black–gray and red color schemes. In addition, a tall proportion significantly reduced Likeability. Study 3 used online semi-structured interviews to further examine the reasons underlying these evaluations and to explore participants’ subjective perceptions of SADRs. The findings provide practical guidance for designing SADR appearances that can foster more positive pedestrian perceptions and acceptance.