When autonomous robots begin to share the human living and working spaces, safety becomes paramount. It is legally required that the safety of such systems is ensured, e.g. by certification according to relevant standards such as IEC 61508. However, such safety considerations are usually not addressed in academic robotics. In this paper we report on one such successful endeavor, which is concerned with designing, implementing, and certifying a collision avoidance safety function for autonomous vehicles and static obstacles. The safety function calculates a safety zone for the vehicle, depending on its current motion, which Electronic supplementary material The online version of this article (is as large as required but as small as feasible, thus ensuring safety against collision with static obstacles. We outline the algorithm which was specifically designed with safety in mind, and present our verification methodology which is based on formal proof and verification using the theorem prover Isabelle. The implementation and our methodology have been certified for use in applications up to SIL 3 of IEC 61508 by a certification authority (TÜV Süd Rail GmbH, Germany). Throughout, issues we recognized as being important for a successful application of formal methods in robotics are highlighted. Moreover, we argue that formal analysis deepens the understanding of the algorithm, and hence is valuable even outside the safety context.

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Abstract. This paper introduces Proof General Kit, a framework for software components tailored to interactive proof development. The goal of the framework is to enable flexible environments for managing formal proofs across their life-cycle: creation, maintenance and exploitation. The framework connects together different kinds of component, exchanging messages using a common communication infrastructure and protocol called PGIP. The main channel connects provers to displays. Provers are the back-end interactive proof engines and displays are components for interacting with the user, allowing browsing or editing of proofs. At the core of the framework is a broker middleware component which manages proof-in-progress and mediates between components.

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