WSN application – networked solar lamps
I live in Bangalore. We have been suffering frequent power cuts this week. I have couple of solar table lamps from Ikea . They have a detachable solar panel, led light source and 3 rechargeable batteries (NiMH / NiCD). I leave the panels in the sun and they are good to go after a full day’s charge. You can place these lamps anywhere since they don’t have a power cord. On the flip side, if a power cut leaves you in the dark, how do you switch these on ?
I would like these lamps to be intelligent. Whenever power goes in the evening, the lamp should switch on automatically and switch off when power is restored. This can be done by adding a low power wireless node to the lamp (call it L). Another wireless node (call it M) can monitor the mains. M can be battery backed or have a large enough capacitor which can power the node while it broadcasts a “power failure” message to the mesh network before shutting down. Any “L” node which receives this message can switch on it’s lamp. “L” can use time of day information and/or ambient light sensing to decide whether to switch on the lamp or not. Similarly, when mains power supply is restored, the “M” node will broadcast a ” power restored” message. Any “L” node which receives this message can switch off it’s lamp. The mesh network mentioned above is a network of wireless nodes covering the whole house. Once a lamp has a radio interface, it can be switched on/off through a smart phone provided there is a Wi-Fi <-> low power sensor network gateway in the residence.
Such requirements are common to developing countries such as India where public infrastructure such as the electricity grid and roads are not in good shape. Fortunately, there is technology to compensate (to some extent) for bad governance.