Novel approaches for the safety of human-robot interaction

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. We believe that the safety issue is a primary factor in wide scale adoption of personal robots, and until these issues are addressed, commercial enterprises will be unlikely to invest heavily in their development. In this thesis we argue that traditional system design techniques fail to capture the complexities associated with dynamic environments. This is based on a careful analysis of current design processes, which looks at how effectively they identify hazards that may arise in typical environments that a personal robot may be required to operate in. Based on this investigation, we show how the adoption of a hazard check list that highlights particular hazardous areas, can be used to improve current hazard analysis techniques. A novel safety-driven control system architecture is presented, which attempts to address many of the weaknesses identified with the present designs found in the literature. The new architecture design centres around safety, and the concept of a `safety policy' is introduced. These safety policies are shown to be an effective way of describing safety systems as a set of rules that dictate how the system should behave in potentially hazardous situations. A safety analysis methodology is introduced, which integrates both our hazard analysis technique and the implementation of the safety layer of our control system. This methodology builds on traditional functional hazard analysis, with the addition of processes aimed to improve the safety of personal robots. This is achieved with the use of a safety system, developed during the hazard analysis stage. This safety system, called the safety protection system, is initially used to verify that safety constraints, identified during hazard analysis, have been implemented appropriately. Subsequently it serves 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 both simulation environments and physical hardware. These experiments demonstrate the effectiveness of the safety-driven control system for performing tasks safely, while maintaining a high level of availability.