Christopher J. Harper

Towards the Development of International Safety Standards for Human Robot Interaction

This paper is an overview of the work being performed by the ISO committee TC184/SC2 “Robots and Robotic Devices”. SC2 is developing safety standards for robotic applications in personal and medical care, as well as revising existing industrial robot standards with requirements for new applications. A key driver of the new standards is the need for safety guidelines for human robot interaction, as the new applications involve much more extensive HRI behavior than previous generations of industrial robots. The paper summarizes the content of a revision to ISO 10218 for industrial robots, the development of a new standard ISO/NP 13482 for service robots in personal care, and discusses future work in standards for medical care robots and other areas.

Building safer robots: Safety driven control

In recent years there has been a concerted effort to address many of the safety issues associated with physical human–robot interaction (pHRI). However, a number of challenges remain. For personal robots, and those intended to operate in unstructured environments, the problem of safety is compounded. In this paper we argue that traditional system design techniques fail to capture the complexities associated with dynamic environments. We present an overview of our safety-driven control system and its implementation methodology. The methodology builds on traditional functional hazard analysis, with the addition of processes aimed at improving the safety of autonomous personal robots. This will be achieved with the use of a safety system developed during the hazard analysis stage. This safety system, called the safety protection system, will initially be used to verify that safety constraints, identified during hazard analysis, have been implemented appropriately. Subsequently it will serve as a high-level safety enforcer, by governing the actions of the robot and preventing the control layer from performing unsafe operations. To demonstrate the effectiveness of the design, a series of experiments have been conducted using a MobileRobots PeopleBot. Finally, results are presented demonstrating how faults injected into a controller can be consistently identified and handled by the safety protection system.

Environmental Hazard Analysis - a Variant of Preliminary Hazard Analysis for Autonomous Mobile Robots

Robot manufacturers will be required to demonstrate objectively that all reasonably foreseeable hazards have been identified in any robotic product design that is to be marketed commercially. This is problematic for autonomous mobile robots because conventional methods, which have been developed for automatic systems do not assist safety analysts in identifying non-mission interactions with environmental features that are not directly associated with the robot’s design mission, and which may comprise the majority of the required tasks of autonomous robots. In this paper we develop a new variant of preliminary hazard analysis that is explicitly aimed at identifying non-mission interactions by means of new sets of guidewords not normally found in existing variants. We develop the required features of the method and describe its application to several small trials conducted at Bristol Robotics Laboratory in the 2011–2012 period.

A methodology for provably stable behaviour-based intelligent control

This paper presents a design methodology for a class of behaviour-based control systems, arguing its potential for application to safety critical systems. We propose a formal basis for subsumption architecture design based on two extensions to Lyapunov stability theory, the Second Order Stability Theorems, and interpretations of system safety and liveness in Lyapunov stability terms. The subsumption of the new theorems by the classical stability theorems serves as a model of dynamical subsumption, forming the basis of the design methodology. Behaviour-based control also offers the potential for using simple computational mechanisms, which will simplify the safety assurance process.

Developments in vocabulary standardisation for robots and robotic devices

With the emergence of mobile robots, including service robots for use in public, domestic and industrial environments, a more comprehensive standard to cover the new robots and associated technologies is needed. New scopes of the robots applications involve almost in every case an autonomous system that can potentially cause harm to the environment, including people or malfunction and fail the mission completely. ISO has developed a set of standards supporting aspects of robot design such as performance measurement, safety assurance, user interfaces and similar for industrial robots manipulators. Evolving robot applications require the standards to be revised to incorporate requirements for new robotic domains. This prompted a group of international robotics experts in 2007 to initiate a development of new terms and regulations and modify the current robotics standard, ISO 8373, to include terms that are applicable to the new generation of robots. This paper provides an outline of the progress of the working group and the associated challenges in updating the international robotics vocabulary standard.

Service robot ethics

The area of robotics is moving from its traditional roots in the industrial sector as the entire robotic community is keen to develop new types of robots for new environments. This change is emphasis is being driven by many factors and it is now widely accepted that robots must become mass market products in order that they may fulfil their full potential in providing assistive capabilities to humans in a wide range of applications. This shift has been noticed and ISO has set up new standardization groups to investigate the robot standardization activities that need to be encouraged to facilitate the commercialisation of new types of robots throughout the world. The robotic community has been developing prototype robotic systems for a variety of new applications and many new sectors are causing concern and if they should be encouraged or not. This has started an ethical debate on what should be encouraged and if there are robot applications that should be discouraged. It is accepted that robot applications that generically improve the quality of life for humans should be encouraged but areas which promote unethical areas of human activities should be looked at more closely to determine of robots should be allowed to enter these sector or not; this includes applications such as military applications, sex robots, fully autonomous robots, etc. In view of these developments, discussions have commenced within ISO so that internationally accepted views can be formulated and accepted. This paper presents the start of these deliberations and raises some of the important issues that need to be debated so that internationally accepted views can be agreed at the ISO level so that commercialisation of only the accepted systems is permitted across international boundaries.

Direct Lyapunov design - a synthesis procedure for motor schema using a second-order Lyapunov stability theorem

In this paper we propose a new procedure for construction of motor schema typically used in behaviour-based robotics. The procedure reverses the standard stability analysis approach by searching for a control function to fit a pre-defined Lyapunov function. In order to improve the applicability of this procedure, a new second-order extension to Lyapunovs second method is proposed, allowing a stable schema to be defined directly in terms of actuator force demands. We propose a synthesis procedure called direct Lyapunov design, which searches for motor schema maps whose set points satisfy the second-order theorem. The procedure has been applied to a simple subsumption architecture controller for an inverted pendulum simulation, yielding stable behaviour.

Online hazard analysis for autonomous robots

Robotic systems require rigorous analysis at all stages of development to ensure system safety. The manufacturing industry has developed many of the robotic design methods used today. These methods were adapted from design practices taken from other industrial sectors [3]. Incorporated into the design process are proven techniques such as hazard analysis, failure analysis and testing. In addition a number of robotic safety standards have been developed; most notably ISO 10218-1 [4]. As discussed by [1], these methods are not appropriate for designing safe robots operating in unstructured environments, due to the high complexity associated with a system that must adapt to a changing environment.