Go Down

Topic: Possible to make wheeled robot travel to transmitter 50 feet away? (Read 2 times) previous topic - next topic

AWOL

Quote
I would think RF Signals would be the way to go

Why?
RF direction finding is very difficulty.

Even Kevin Warwick went for IR when he was going to run a half marathon with one of his robots.
Unfortunately, on the morning of the race, the robot locked on the strongest source of IR and set out for it.
It didn't manage to achieve escape velocity (I don't think the batteries would have lasted until it reached the Sun anyway) and crashed on the other side of the car park.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

jraskell

Don't take this the wrong way, but your goal is well beyond the means of an admitted robotics novice.

That's not to say it's a goal you shouldn't have, but it may be better if it was a long term with a series of intermediate goals leading up to it.

For example, just getting a three wheeled robot fully controlled by a microcontroller is a substantial task for a novice.  You're asking for a list of parts to perform RF location, but what parts are you using to drive the bot?  You have motors and a motor controller picked out?  Will you be using encoders or an IMU for tracking bot movement (or even better, both)?  What method of steering will you be employing?  There are a whole slew of questions and issues that will need to be answered and resolved just accomplishing this relatively basic robotic goal.

Your original post was analogous to a high school biology student asking his teacher how to do major surgery.

I'm not trying to discourage you, just trying to get you to understand the scope of your goal.

Sickopuppie

#12
Apr 26, 2011, 11:14 pm Last Edit: Apr 26, 2011, 11:25 pm by Sickopuppie Reason: 1
I understand the scope of my goal.  I have about 5/6's of a year to complete it.  Does that mean there are no books pertaining to the specific manipulation of RF signals to have a robot follow a transmitter?

tkbyd

While I agree with the "this may be a bridge too far" remarks above, I also know the feeling of wanting to do something I "can't", and have spent happy hours not getting where I wanted to go.

And so, in that spirit...

Maybe "the answer", if you really want to go the RF route, is a highly directional RF receiving antenna (do they exist?) mounted to rotate, a bit like a radar dish... hmm **R**adar.... and use a combination of signal strength and antenna's direction to generate the wanted info?

But all of that from someone who knows nothing about radio, it must be said.

Of course that approach depends on the receiver giving a signal STRENGTH indicatoin, which previous posters have said will be difficult.

The little "RF link" modules which might be tempting aren't tri-state... the receiver can't tell you "sender sending 1"/ "sender sending 0"/ "no signal seen".

To use one of those would entail yet more complexity (=ways to go wrong, be slow)

You'd set the sender to send a square wave of a set frequency. And then "ask" the receiver: "Are you seeing that frequency, or not?" If seeing frequency, antenna is pointed towards sender. If not, not.

Of course, that "solution" assumes that there will be no reflections of the sender's signal off of, say, a wall....

Grumpy_Mike

Quote
I understand the scope of my goal.  I have about 5/6's of a year to complete it.

So if you have less than a year to complete it I would suggest to you that you do not understand the scope of what is involved.

Quote
Does that mean there are no books pertaining to the specific manipulation of RF signals to have a robot follow a transmitter?

I suspect you are right here.

Direction finding with RF is tricky with a skilled operator and practically imposable for a hobby style robot. The RF receiver needed is quite complex, requiring multiple antenna and a phased array. I did see a circuit that used 16 quarter wave dipoles arranged in a circle and switched rapidly round each of them. Then it used a Doppler shift measurement to determine which of the 16 antennas was pointing closest to the transmitter. The circle need to be at least a quarter wavelength in diameter. That makes it a big robot for a simple RF transmitter (450MHz).

Go Up