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Author Topic: Possible to make wheeled robot travel to transmitter 50 feet away?  (Read 1916 times)
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I am trying to build a robot that will follow a transmitter up to 50 feet away.  Possible a radio controlled transmitter.  My knowledge on robotics is not very much so please bear with me.

Would anyone mind please telling me what kind of parts I would need to create such a thing?  Or if this is even possible with an Arduino chip set.

Thank You
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First off - what do you mean by "follow a transmitter"? Are you wanting the robot to be controlled by the transmitter, or are you wanting it to "home in" on the transmitter, or something else?
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A radio-controlled transmitter of what?
IR?

What is controlling the radio-control?

Is the 50 feet a horizontal distance, or a vertical distance?

What sort of responsiveness do you expect?

How big is the wheeled device?

What is your budget (hobby, domestic, industrial, defence...)?
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If you could accept the limitation that the robot must be able to "see" the beacon, a simple bright light, IR would be my choice, as beacon and a Wiimote "camera" on the robot as sensor would be a very "do-able" answer. Use Google on "wiimote pixart"...

http://letsmakerobots.com/node/7752

... is good, for instance
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I'm trying to make a three wheeled robot travel horizontally to a transmitter.  I was thinking about having it follow a radio signal (transmitter).  Meaning that if I had the radio signal on my person, it would be able to follow me as long as I was on fairly flat ground.  I would also like it to keep a good distance from the transmitter.  As you may already know, I do not know much about robotics but I would like to know what books/sites/parts I can use to make this a possibility.

I was reading a good deal about Directional Finding (DF) hardware.  Though I am still not sure how to code or do anything with the parts.  I have found this website so far:

http://www.robotshop.com/general-rf-data-telemetry.html

Can someone please steer me in the right direction?
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Can someone please steer me in the right direction?
That's cheating - it's the robot that's supposed to steer.

Your problem isn't really one of telemetry (unless both you and your robot are equipped with GPS), but of knowing what the strength of the radio signal is.
Few cheap radio modules provide this information.
« Last Edit: April 26, 2011, 02:22:04 pm by AWOL » Logged

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I think trying to home in on a RF signal is pretty much a non-starter as the needed antenna directionality and required precision of receive signal strength would not be cost or size efficient. IR or ultrasonic detection on a scanning head of the robot would probably be a more practical method.

Lefty

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I'm trying to make a robot that can keep up with a person who is running.  Will an IR Sensors/Ultrasonic sensors be able to do that?  Does that mean the person running should be carrying something that emits ultrasonic sounds?
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I'm trying to make a robot that can keep up with a person who is running.  Will an IR Sensors/Ultrasonic sensors be able to do that?
This is a very difficult problem.
I don't think a microcontroller has sufficent "poke".


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Exactly.  I apologize for not being so clear.  I would think RF Signals would be the way to go.  However, I have no idea how to go about using them.  Are there any books out there that can teach me?
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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.
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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.
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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?
« Last Edit: April 26, 2011, 04:25:13 pm by Sickopuppie » Logged

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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....
« Last Edit: April 27, 2011, 02:47:42 am by tkbyd » Logged

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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.

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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).
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