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Designing Interactions With Shared AVs in Complex Urban Mobility Scenarios

Marius Hoggenmueller, Martin Tomitsch, Stewart Worrall

TL;DR

This paper addresses how to design external communication for shared autonomous vehicles operating in pedestrianized urban spaces. It combines human-centered design with tangible prototyping and immersive VR evaluation to study how eHMIs convey vehicle identity, intent, and awareness while riders and pedestrians share space. The findings show that people rely heavily on color cues to identify their vehicle, but need additional explicit and implicit signals to support correct interactions, especially in multi-vehicle contexts. The work highlights a holistic design approach that couples light-based eHMIs with vehicle motion cues and multi-touchpoints, offering practical guidance for SAV deployment in complex urban environments.

Abstract

In this article, we report on the design and evaluation of an external human-machine interface (eHMI) for a real autonomous vehicle (AV), developed to operate as a shared transport pod in a pedestrianized urban space. We present insights about our human-centered design process, which included testing initial concepts through a tangible toolkit and evaluating 360-degree recordings of a staged pick-up scenario in virtual reality. Our results indicate that in complex mobility scenarios, participants filter for critical eHMI messages; further, we found that implicit cues (i.e., pick-up manoeuvre and proximity to the rider) influence participants' experience and trust, while at the same time more explicit interaction modes are desired. This highlights the importance of considering interactions with shared AVs as a service more holistically, in order to develop knowledge about AV-pedestrian interactions in complex mobility scenarios that complements more targeted eHMI evaluations.

Designing Interactions With Shared AVs in Complex Urban Mobility Scenarios

TL;DR

This paper addresses how to design external communication for shared autonomous vehicles operating in pedestrianized urban spaces. It combines human-centered design with tangible prototyping and immersive VR evaluation to study how eHMIs convey vehicle identity, intent, and awareness while riders and pedestrians share space. The findings show that people rely heavily on color cues to identify their vehicle, but need additional explicit and implicit signals to support correct interactions, especially in multi-vehicle contexts. The work highlights a holistic design approach that couples light-based eHMIs with vehicle motion cues and multi-touchpoints, offering practical guidance for SAV deployment in complex urban environments.

Abstract

In this article, we report on the design and evaluation of an external human-machine interface (eHMI) for a real autonomous vehicle (AV), developed to operate as a shared transport pod in a pedestrianized urban space. We present insights about our human-centered design process, which included testing initial concepts through a tangible toolkit and evaluating 360-degree recordings of a staged pick-up scenario in virtual reality. Our results indicate that in complex mobility scenarios, participants filter for critical eHMI messages; further, we found that implicit cues (i.e., pick-up manoeuvre and proximity to the rider) influence participants' experience and trust, while at the same time more explicit interaction modes are desired. This highlights the importance of considering interactions with shared AVs as a service more holistically, in order to develop knowledge about AV-pedestrian interactions in complex mobility scenarios that complements more targeted eHMI evaluations.
Paper Structure (29 sections, 4 figures)

This paper contains 29 sections, 4 figures.

Table of Contents

  1. Introduction
  2. Related Work
  3. AV-Pedestrian Interfaces
  4. Shared Autonomous Vehicles
  5. Design Process
  6. Urban Context, Scenario and Situations
  7. Passenger Transport Pod and eHMI Hardware
  8. Designing eHMI Light Patterns
  9. Tangible Multi-Display Toolkit
  10. Expert Workshops
  11. Final Set of Light Patterns
  12. Virtual Reality Prototype
  13. Evaluation Study
  14. Materials and Setup
  15. Participants and Procedure
  16. ...and 14 more sections

Figures (4)

  • Figure 1: Passenger transport pod with "U"-shaped low-res lighting display.
  • Figure 2: The tangible multi-display toolkit used to inform the eHMI visualisation design via computer simulations across multiple displays to capture different viewing angles, tangible objects to interact with the simulated environment and to depict the eHMI’s behaviour through an integrated miniature LED display.
  • Figure 3: Overview of the encoded eHMI messages and light patterns linked to the previously identified situations. Light pattern L1-L3 are in purple colour which we used in the VR study for participants to indicate their vehicle.
  • Figure 4: Recording plan of the three scenes, vehicle trajectories and eHMI light patterns (left); screenshot taken from the 360-degree video prototype representing the second scene with an actor entering the SAV (right).