Design of an inspection robot for small diameter gas distribution mains

The gas distribution network in the Netherlands has a length of roughly 100.000 km in urban areas. This network needs to be monitored constantly and segments need to be replaced when the risks of leaks increase. Since no information can be obtained from inse the network, in this thesis the design of a robot which can move (autonomously) through the gas distribution network for inspection is investigated. Three prototypes have been realised. The design of a propulsion mechanism depends strongly on the layout of the gas distribution network. The most important aspects are long stretches of pipe (tens of metres), a diameter range of 63 mm to 125 mm, (mitre) bends, T-joints and inclinations up to 30?. The design consists of a wheeled robot ?snake? consisting of a number of modules which can be used as two clamping V-shapes. The central module is a rotation joint which can be used to change the orientation of the robot in a pipe. To reduce the amount of wiring, the electronic system has been distributed over the robot segments. A master controller is added which communicates to these distributed ?slave nodes? via a serial bus. Also energy for propulsion is provided through this bus. A camera system has been developed which can be used for both pipe assessment and navigation. The camera system uses a laser projector which projects a cone (circle) on the inside of the pipe. Deformations of the pipe and obstacles such as bends and T-joints show up as deviations of the captured circle shape. The first prototype has been designed and produced in a ?conventional? way which took a long time and missed some crucial steps in integration. The second and third prototype have been designed and produced using `digital fabrication' tools (3D printing, laser cutting). The differences in design and production between the first prototype and the subsequent prototypes can be used to describe the importance of accessibility, visibility and availability of these fabrication tools as condition for fruitful usage.