4. Service expansion through energy conservation

What specific fields do you think this will develop into?

FujiokaWell, if we attach sensor nodes to products as they move through factory production lines, for example, we can implement a traceability system that lets us instantly know where the products currently are by simply looking at a Web server screen. Other possibilities include simple control with a Web server for tracking temperature changes with temperature sensors as in an ordinary sensor network, optimizing air conditioning by installing temperature sensors here and there within a building, or monitoring the temperature conditions of freight by attaching temperature sensors to freight items. Another possibility is using nodes equipped with person detectors, motion detectors or both in combination for crime prevention. While we believe such applications are important, we would like to move the technology in the direction of future sensor networks that will save users time and labor. For example, by wearing a sensor node like a badge as you work, an agent function incorporated in the sensor node can detect where you worked and how long you worked there, and perform the application process from creating the necessary documents to submitting the application in your stead.

So you see evolution toward an active sensor network?

FujiokaYes. The biggest difference between the passive sensor nodes used in ordinary sensor networks and the active sensor nodes that we have developed is having or not having batteries. Without the battery, the node can be that much more compact, but because the available power is very limited, the communication function is mainly passive. Turning that around, however, once the battery is there, it can be used for different things. In the attraction system, the battery allowed the node to have the active functions of the blinking LED and vibration according to the users behavior. The problem with that, though, is the inconvenience of frequent battery replacement. Longer battery life means keeping power consumption low. The deciding factor in energy conservation is the program implementation technology, which is to say μWirelessWeb. There are many types of microprocessors, but large, high performance processors generally consume a large amount of power, and small processors tend to have low power consumption but low performance. Our development approach is to make the program as small as possible and then select a microprocessor that can just barely accommodate it as the shortest path to energy conservation. I think using the μWirelessWeb technology allows us to overcome those problems and pave the way to using active sensor networks in the kinds of broad services that I mentioned earlier.

Figure 4: Application to society of μWirelessWeb technology