System Architectures and Safety for Mobile Construction Robots

This paper describes the most recent work on the development of the autonomous robot excavator - LUCIE 2 at Lancaster. Although the LUCIE project (Lancaster University Computerised Intelligent Excavator) has been running for about five years, in recent months it has undergone a radical change in both system hardware and software. This has come about as a result of research sponsored by the UK Safety Critical Systems Programme, which has highlighted the problems of producing a well argued safety case for intelligent robots in unstructured environments. Other changes have resulted from the automation of the vehicle tracks which means that LUCIE 2 is fully mobile for the first time. Work is also progressing on the problem of linking the robot excavator to project CAD drawings, and this is briefly discussed in the paper. The new developments discussed in the paper include: the use of three individual ultra-compact PC 1 04 computer systems, communication between computers using CAN bus, the use of a new scanning laser sensor to detect possible collisions, and the use of a satellite global positioning system for excavator positioning and navigation. Recent developments in GPS technology now mean that the vehicle can be reliably positioned to an accuracy of 25 mm.