i-Que's sensors are all infrared sensors. Infrared is like that in your remote control for your TV, stereo and other devices. It relies on a transmitter/receiver where one sends an invisible beam of light and the other end recieves it and acts on the pulses of that light. It also pulses so fast you can't really catch it. It works in only short range, and must have a bee-line from the transmitter to receiver. This is one type of infrared and is what i-Que uses for homing into his charging bay.

The other type of infrared sensor i-Que uses is for his navigation. This type is kinda like your optical mouse. When you move the mouse, the cursor moves to show the location of the mouse. When i-Que moves, he scans to see what is there. He has them on the underside to detect whether he's still on a flat surface or not, and also in the front and back to see what is in front or behind him. He can not see objects or shapes. This type of infrared depends on getting a signal reflected back to it. It too runs in pulses. If the beam isn't reflected back, then no action is taken. Or it doesn't 'see' anything. Let's think of it as if the light is reflected back then it's '1', and if no light is reflected back it's '0'.

Now how does this help i-Que to see where he's going, find his charging bay and dock, and to not fall off tables? And why doesn't it always work? Infrared (also abbreviated as "IR") is not foolproof technology. But it gets the job done. It's also cheaper to produce circuitry for and keeps the cost of electronics within affordable levels.

Let's take a look at i-Que's docking station seek mechanism. When i-Que needs to charge, he'll put his head down and keep some red lights lit on his 'face'. He'll announce he's going to recharge. In this mode, he's using the little nub on his head to send/recieve beams to and from the docking station. He keeps doing this until he picks up the IR response beam from the charging station. Once he does that, he keeps using that as a means to try and align himself for docking. You'll notice a clear square-like area under the white nub on top of the docking station tower. This is probably how he aligns himself. If there is anything in between the robot and the docking station, then the signal could be lost, causing the robot to not be able to dock. i-Que may wonder a little in an effort to relocate the beacon. If he can't after a little bit longer he'll ask for help. Roombas use a similar technology as well. However, i-Que seems to also map out the area on the way to the docking station, so he is less likely to bump into things if you keep the docking station in the same place. Since there is limited range, he has to be within range as well. He may rely on previously stored mapping data to find the charger but also may just roam until he picks up the beam. If he gives up, he might have not had any 'clues' from mapping the area or got close enough to the charger to pick it up.

When he's roaming around, he may bump into some things that his sensors don't detect. He may even go off the edge of a flat surface. Never rely on him to stay on a table or chair! Even though he's supposed to avoid drops, the technology still is not that reliable and things can happen, possibly causing damage to the robot unit. The reason why he's bumping into things and falling off stuff is because the IR sensor needs a reflected beam. In other words, as stated above, he's recieving a '0' and not a '1' so he doesn't change direction because his sensors didn't indicate anything changed! His IR sensors work best on areas that will reflect back the beam. Dark areas and surfaces may not work well. You're probably thinking 'Now wait a minute! My optical mouse is on a black mouse pad and it works fine!' Take a good look at that mousepad. I bet if you look closely you'll see things like ridges and maybe slight 'sparklies'. Anything that can create a surface that will change from one spot to another. Take that mouse on a smooth glossy surface or a dark surface that doesn't have all that on it and I bet you won't be moving the mouse pointer too well. i-Que has this same problem.

There's more to infrared that meets the eye (no pun intended). To get a good idea exactly how infrared works, check out these links:

• What is IR wireless?
• An Introduction to Infrared Technology
• Infrared Wiki article