Content in “Input devices and sensors”

SM125-IC/M1 RFID reader/writer

Tgeahre — Thu, 17 Jul 2008 05:46:25 +0200

There are a few models of this but the SM125-IC is an RFID Interigator with read/write capabilities and I2C connection capabilities. I have been looking for a chip to base my RFID interigator after for a while and this one in my humble opinion takes the cake.

Quadrature Encoders

BaseOverApex — Sat, 12 Jul 2008 11:20:36 +0200

Isn't that just a pot?

You are forgiven for thinking you are looking at a photo of a potentiometer AKA variable resistor. That's what this looks like. However, if you were to rotate the shaft, you'd very quickly find out that there are no endstops. It just keeps going round and round.

PC Ball Mouse = Rotary Position Sensor

BaseOverApex — Sat, 12 Jul 2008 11:20:02 +0200

Computer mice with balls contain two (or sometimes three, if the have a scroll wheel) rotary position sensors. These are not mechanical switches, but optical ones. (Just to confuse you, this is why "ball mice" are "optical mice".) A pair of receivers is placed on the opposite side of a slotted wheel from a transmitter. As the ball rotates, it spins the wheel and the sensors detect the direction and speed. Two such arrangements are placed perpendicual to one another.

PIR (Passive Infrared Sensor)

fritsl — Fri, 13 Jun 2008 22:56:02 +0200

PIR's are cheap little things that combined with a little chip (PIR Sensor Control IC) and possible a Fresnel Lens will tell you if there is motion in font of it. Especially that of a human body, as it is reacting on Infra Red.

No, you can not use a PIR for anything but on something that stands still, to detect something else that moves.

No, you cannot use a PIR to make a robot follow you. The PIR only detects changes. A moving robot (even turning it's head) would be one constant "alarm" of "changes" - not possible to tell what is what.

Tilt sensor

fritsl — Thu, 28 Feb 2008 09:46:44 +0100

I bought some small tilt-sensors. basicly they where a small metal capsule with a ball inside. When tilted, the contact was switched on/off.

I thought this was smart, as the robot would then know for instance if a caterpillar-driven robot was on it´s way to flip backwards due to too steep terrain etc.

I also thought I could use them for balance, a robot would stick out a foot or something if it was too tilted to one side.

In practice I never made them do much good; The ball inside is constantly shaken by what ever else the robot is doing.

Accelerometer

fritsl — Mon, 18 Feb 2008 13:53:12 +0100

Accelerometers are very exciting little things. When I say "little", I mean it, as they usuallyfits 4 or more on a finger nail! And each typically has some 7-20 points so solder. This makes them quite hard to work with, and so I recomend that you also buy a board of some sort, so that you end up with something that you can hook up to your Microcontroller easily.

What you get from the thing is a signal. The signal can be analouge, I2C, or anything else, depending on the thing you get.

SRF05 Ultra Sonic Range finder

fritsl — Wed, 13 Feb 2008 16:12:32 +0100

IMHO the best way to have your robot measure distance to objects. Fast and accurate.

If you are using Picaxe, you may find this info useful: http://letsmakerobots.com/node/66