## 3 Methodology and Results  
### The Smart Pipe Demonstrator Unit  
For the development of a smart pipe system, issues related to communication, sensor development and integration within and around the pipe as well as the power requirements of such a system need to be investigated. A range of sensors and communication elements were incorporated into a smart pipe demonstrator unit utilising mainly off-the-shelf MEMS components. The aim was to demonstrate the concept and show how the individual elements could work together. Different modes of communication were investigated, with the signals travelling through the ground, along the pipe and to a so called Smart Server capable of amplifying the signal. Figure 1 shows the schematic of the smart pipe demonstrator unit. It is expected that any sensor system for water pipes will require a combination of sensors to detect a range of potential problems. This demonstrator unit comprised a number of communication systems, which are described later and a range of sensors including piezoelectric transducers, force sensors, light detection circuits,two-axis accelerometers and randomly distributed temperature sensors (all hard wired to the Smart Server). The data gathered from these sensors were transmitted from the Smart Server via a Bluetooth module situated on the ground surface. Figure 2 shows the smart pipe demonstrator unit before burial in the laboratory. The unit consisted of lengths of PVC pipe with an internal diameter of 150 mm. A smart sensing system which can collect sensor signals and transmit these to a Smart Server (Figure 3) was developed. The idea behind the Smart Server is that the individual sensors (due to their small size and power requirements) would only be capable of transmitting information over a short distance, while the Smart Server could house a system capable of storing and transmitting the data a longer distance along the pipe or through the ground. This function could be utilised in a practical  
Figure 1: Schematic arrangement of the smart pipe demonstrator unit [29]. Figure 2: Smart pipe demonstrator unit before burial. smart pipe system, where units with more power could be located at certain intervals along the pipe capable of storing and then transmitting data as required. It is envisaged that this could be developed so that the Smart Server transmits the data on a regular basis, possibly once a month, but it would also have on-board analysis software that could recognise a change in data and, if it is outside a set range of trigger values, would transmit these data immediately and thus highlighting a problem. An alternative approach was the use of a Smart Pig, which incorporated sensors, electronics and signal tranmission components. It could traverse along a pipe and collect, store and transmit data from the randomly distributed sensors within and around the pipe. This could either be used on its own or in combination with the Smart Servers. The Smart Pig, for example, could collect data from the sensors and then upload these data to the Smart Server as it passes where upon these data could be transmitted from the Smart Server out of the pipe network. Figure 4 shows the Smart Pig used in the demonstrator unit. The Smart Pig was made from a plastic container with a diameter of 50 mm and a length of 150 mm. It contained an inductor loop connected to a function generator on the surface. This was used in order to produce signals for low frequency communication. It also contained a microcontroller and RS232 system for high frequency communication. The Smart Pig was connected to a wire in order to feed it through the pipe and to supply the signal from the surface based function generator. Although feeding a pig through a real pipe network is not ideal, it showed the principle of using such a system. Figure 4: Smart Pig device **(a)** prior to insertion into the smart pipe demonstrator unit and **(b)** inside the pipe [29]. Figure 3: Prototype Smart Server [29].