Developing shared rules for indoor & outdoor robots: earning public trust

Author: Francisco Javier Martin Romo

Date Published: November 22, 2025

In recent years, service robots have quietly migrated from factories and warehouses to the places where life actually happens. We may see robots gliding through hospital corridors, navigating hotel lobbies, patrolling supermarket aisles, and negotiating the bustling atriums of shopping malls.

Legally, these indoor environments may be private property and, therefore, are not subject to municipal bylaws and regulations. But in practice, they function as public squares: open to everyone, inherently unpredictable, and filled with bystanders who are untrained, uninvolved, and often distracted.

The Urban Robotics Foundation’s drafting work on ISO 4448: Intelligent transport systems — Public-area mobile robots (PMR) originally focused on developing deployment guidelines for improving safety and accessibility in outdoor pedestrian environments like sidewalks, public parks and crosswalks. Yet, the exact same challenges plague indoor hubs. The fundamental question of how machines and humans coexist in environments not built for both remains identical.

For anyone observing the evolution of public-area mobile robots (PMRs), the conclusion is unavoidable: the line between “indoor” and “outdoor” robotics is far thinner than we pretend. In practical terms, it often doesn’t exist. This highlights the critical relevance of ISO 4448 for what we might call "other public spaces" - not just publicly-owned property, but also those areas on privately-owned property that are accessible to the general public.

The Illusion of Control

A colleague recently phrased it perfectly: "The distinction isn't indoor versus outdoor. It’s controlled versus shared.”

• A warehouse is controlled. A hospital corridor is shared.

• A loading bay is controlled. A shopping mall is shared.

In shared spaces, robots face one defining constant: human unpredictability. Children dart out without warning; elderly visitors move cautiously; tourists stare at their phones. In these dynamic environments, a robot must do more than simply avoid collisions.

Robots must behave legibly. They must signal their intentions in ways humans can understand: through subtle pauses, predictable trajectories, and clear communication. Robots need a social grammar. This is one of the elements ISO 4448 aims to provide.

When Robots Need to “Speak”

Anyone who has encountered a delivery robot knows the moment of hesitation: 

Is it about to turn? Will it wait for me? Is it yielding, or is it stuck?

Humans constantly broadcast their movement intentions through eye contact, posture, and gait. Robots lack that luxury. These communication functions rely entirely on design: lighting cues, directional indicators, acoustic signals, and a “body language” expressed through motion.

Currently, a unit in an airport might chime softly, while one in a hotel flashes an LED ring. For the general public, this inconsistency is confusing. For people with disabilities, it can be dangerous.

A unified framework, one language that all robots, regardless of manufacturer or context, can use to communicate, is no longer a theoretical ambition. It is a practical necessity.

The Unspoken Etiquette Between Machines

If robots must learn to communicate with people, they must also learn to communicate with each other. As multi-robot deployments scale, with cleaning units crossing paths with delivery bots, the lack of shared etiquette becomes glaring. When two machines from different manufacturers meet in a narrow corridor, who yields? When an elevator opens, which robot enters first?

Humans handle these micro-negotiations effortlessly, drawing on the evolution of social conventions. Robots have no such background. Without shared rules, their interactions become inefficient at best and unsafe at worst.

ISO 4448 proposes a behavioural scaffold for PMRs: common priorities, right- of-way expectations, and cooperative negotiation. These concepts translate indoors almost perfectly. The architecture is already there; we just need to apply it.

Accessibility as the First Principle

Indoor environments are magnets for vulnerable groups: patients, families with strollers, and travellers with heavy luggage. Here, accessibility is not a secondary requirement; it is the defining constraint.

The URF’s approach places accessibility at the core of design. While initially conceived for urban sidewalks, this principle is perhaps even more urgent indoors. These facilities are becoming the most demanding proving grounds for human-robot interaction, and the lessons learned there will inevitably shape how robots behave on our streets.

A Convergence Already Underway

Indoor robots used for cleaning floors, delivering food, passengers and other goods, are not exceptions to the PMR ecosystem. They are its pioneers. Indoor PMRs operate in densely populated spaces and must earn public trust.

These venues are effectively living laboratories for the standards governing public-area mobile robotics. Behaviours that succeed indoors, such as clear signalling, predictable motion, and consistent etiquette, can scale outward. Those that fail provide lessons for their outdoor cousins.

The lines are already blurring. Robots in hotels use elevators and cross open plazas; hospital units exit buildings to reach adjacent wings. As their operational domains expand, the need for shared rules becomes more urgent.

A Shared Future

Whether a robot is delivering towels in a resort or transporting medication across a campus, the essentials remain unchanged: it must coexist with humans in a way that feels natural, understandable, and safe. It must make its intentions visible.

Most importantly, it must do so consistently across environments so that the public develops a common “robot literacy” over time.

This is the vision behind the PMR standardization framework. As indoor robots become more sophisticated and their presence more commonplace, they will not simply benefit from these standards; they will help accelerate them.

In that sense, indoor delivery robots are not merely part of the transition. They are the bridge.

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