A Prototype Study of an Autonomous Robot Platform for Sewerage System Maintenance

The paper describes KURT, an autonomous robot platform prototype that is able to navigate through a network of sewage pipes. KURT is a six-wheeled vehicle; it has modular, layered hardware and control architectures. Its sensor connguration consists mainly of stationary and one exible ultrasound transducers and of two inclinometers. In experiments run in a test sewerage system consisting of concrete pipes of 600mm diameter, it has proven its abilities to travel safely through straight pipes, to recognize diierent types of pipe crossings, to turn at crossings, and to navigate from a given start point to arbitrary speciied goal points. 1. Aim and Scope of the Study The public sewerage system in Germany is about 400,000km long, and it is in no good condition 7]: sewage may leak out, possibly polluting soil and ground water, and it may wash away soil, possibly eroding the foundations of buildings or the underground of streets and pavements. Consequently, considerable eeort must be taken to maintain the sewage pipes, which includes inspection and local repair. A large part of the public sewerage system consists of circular pipes of 300{ 600mm inner diameter , which is the type of pipes to that we restrict our attention here. Obviously, they are not accessible for humans. The current state of the art to maintain such pipes 13] uses tele-operated robot platforms. These platforms are connected to the outside world by a cable that gets used for energy supply, for transmission of commands from the human operator to the device, for data transmission back to the operator, as a lifeline in case the device gets stuck in the pipe, and as a measuring line for the distance traveled. However, the cable severely restricts the range of action of the platforms due to friction at the pipe inside after bends or after long straight tours, where \long" means typically 200m here. This range restriction, in turn, adds considerably to the maintenance cost, because it forces the maintenance teams frequently to haul in the device, change the location, put the device back in, and continue work. There is quite some work on optimizing the design, handling, and sensoric abilities of these tethered platforms and on tuning the use and properties of the cable, e.g., 2], 8]. However, such work does not|and does not intend to|address the question how to overcome the most fundamental physical limitation of today's sewer platforms: the cable. …