Robot to robot communication
 

I have been looking at things on the internet and have been really interested in how to, or atleat a theory behind how to do robot to robot communication for robots to work together in a "hive" of 2 or more robots.

For a first simple project I would like to make one robot follow one another.

BTW if it helps I am working with a BASIC stamp

Re: Robot to robot communication
 

Well, you could have robot2robot communications... but for something that simple you can just have an IR receiver/transmitter.

I'm not familiar with your exact chip, but if it has RS232 you can use that to talk to the other chips. It'd be a lot cheaper to have a tether, but there are wireless RS232 adapters that would work the same way.

Re: Robot to robot communication
 

Sparks,
Many systems use a broadcast data stream with the ability to query and transmit coming from a host. One of the systems I am familiar with (an audio and video routing switcher) sends out sequential addressing and as each device's address comes up on the serial line, the device with that address sets a request to send bit. When the master asks, the device transmits it's data and then the host repeats it for all devices sitting on the line. (The serial line is called a "party line" since it is shared by all devices.) The data packet is relatively small so the system does not need to nave a high bandwidth. The party line is carried on a coax and can loop from device to device or just run all in parallel. The serial in/serial out function on the basic stamp is supposed to do this function very well.

Re: Robot to robot communication
 

I am not soley trying to make 2 robots follow each other, Like i said i am trying eventually make robots communicate so they can work in a "hive"

Making 2 robots follow eahc other si the first step, because how would they work together if they cannot follow each other.

Re: Robot to robot communication
 

the IR trans/recieve of the lego mindstorms rcx brick is quite easy to use..
and another idea would use servos and rc controllers. cimply put, both robots hold a controller. they manipulate it and the rc reciever turns those signals into motion of servos. then sensors read the movement of the servos. (Variable angles.... so pots? maybe?) and well the more channels the radio equipment, the more info each robot can send and recieve at once... so well.. kinda like a 2 way radio... using readily available items.. ($10 shipped for a simple 2 channel AM radio transmitter+reciever+crystals off ebay.)

Re: Robot to robot communication
 

I hate to disagree with you on the Lego mindstorms, an independent study in my group was programming with those and had a really hard time with loading the code on an apple mac.

Either way, I find your idea on the robots moving each others controls kinda cool. But here is another suggestion, what if you set both robots to have the same team number but then only one OI. Unless there is something in the OI that checks how many robots are connected to it it should be fine (although there may be conflict) from there on you can move both robots at the same time and turn autonomous mode on.

That leads me to my next idea, you could have the main robot painted green and then use last years CMU camera to have it follow, that would be cool.

Re: Robot to robot communication
 

bummmer..... ditch the macs! :cool:
mustve worded it weird... i didnt say exactly that... i just said one robot uses the transmitter to send signals to the other via radio>servo>potentiometer. or other rotation sensor... or you can pull it off with a touch sensor if you use a servohorn too..
so the radio is just there to give signals notreally to actually control the other robot... which is a cool idea but will give me headaches just thinking about it..
hmm... well there is that voltage display... and stuff so im guessing itll hafta just choose the stronger return signal(from the rc)... i dunno but if there was a checker thing on the OI there wiouldnt be any interference problems would there?

ahh yes.... make one robot wave flags... or send smoke signals... the possibilities are endless lol... morsecode with a lightmight work too.

Re: Robot to robot communication
 

you could also use an analog in/ out system, its much simpler but i do not know what the BASIC stamps can do, i have had very little experience with them,

Basically each robot has a cable connecting ones ana_out to the others ana_in port and that gives a large number of comands that can be sent and decoded with an if statement block or if basic allows it a case block

each one will send a signal to the other and decode the signal as it comes in via each one of their input and output tetherings, however if you get alot or robots out there this gets very complicated and messy, I would not use more than 3 robots at a time with this

Re: Robot to robot communication
 

It might be interesting to try to come up with a communication protocol using infrared. Depending on your budget (and willingness to abide by federal law), radio might not be within your reach.

If all the robots had IR transmitters and recievers, they could all talk to each other and also send out broadcast messages to everyone. It'd probably have to be designed something like ethernet though. Each robot gets an "address" and only looks at packets that are directed toward itself. I think the method of making sure that only one robot talks at a time might get funky though.

Re: Robot to robot communication
 

use the SparkFun "BlueSmIRF" which Kevin Watson advocated before. It is really nice (and fairly cheap) and abides by all FCC laws. If you want to branch out a bit, check out come of the links from the Parallax RF page, to find IC's which you can use at the heart of a radio, be warned, however, that they are not FCC certified; I believe you can still use them for "experimental" purposes, but I would check the rules on that.

Re: Robot to robot communication
 

The trick is making sure that only one robot transmits at a time. Assuming the population is known you can assign them each a unique ID. They will broadcast to the whole population a packet that includes the sender, intended recipient(s), and the data. The other robots will wait until its their turn based on their ID and the ID of the last sender. Assume robots A, B, C, and D. B can't send until A does, C can't until B, etc. If a robot transmits and doesn't hear anything from the next it will resend or send a packet to skip the next robot.

An alternative would be to promote one as the master and have it tell the others when its their turn to transmit. Assume robots A, B, C, and D, with A as the master. B, C, and D will not send anything until they receive a request from A. A will iterate through the known population and allow them to send their data in turn. Only one should ever be sending at a time so they can share the same channel. They should all listen to the broadcast packets so they know what the other units are doing.

Re: Robot to robot communication
 

basically as far as communication goes i was thinking of sumthing like a wireless bus with unique IDs, or sumthing along those lines.

I dont wanna have wires inbetween. and painting one wouldn't work because then if you have 3 the 2 that arent painted green will follow the one painted green.

I do not wanna depend on sumthing that isnt absolute like color so to speak. i wanna make it a total programming/ electrical solution. Maybe something like each robot have a IR signal unique to its ID. But then the problem is that that limits you to line of sightas far as follow or IR communication goes. It needs to be like small scale GPS I think. maybe some kind of coordinate system. like if robot A is at 2,4 but robot b is at -2,-4 and there is a wall between them. it wouldn't beable to use IR because of the line of sight problem.

I know this is difficult but any ideas?

O yea I am not using a OI or Rc hence why I said I am Using a basic stamp

Re: Robot to robot communication
 

I've gotten the BlueSMiRF to work, but it requires an additional step to form a "relationship" between the master/slave Bluetooth devices. It was a pain to setup, but it did work. It would be nice if we could buy the original SMiRF, which was pretty much plug and play.

-Kevin

Re: Robot to robot communication
 

what do you mean abide by the law? How is it illeagle to trasmit a radio signal over like 4 feet?

Re: Robot to robot communication
 

depending on frequency its illegal.. different in different countries. around here i think the 27 and 75 mhz are okay. standard groundbased hobby rc equipment. cheaper too.

Re: Robot to robot communication
 

well yea, I wouldn't go out and buy a FCC license to use a certain frequency, I dont know why someone was even thinking of that

I don't mean that in a mean way, I just don't why you would even need something like that for a hobby project, if you know then please share. Unless it is an air based frequency I know bout all that.

Re: Robot to robot communication
 

Actually, you wouldn't buy a frequency liscense, you would use an open frequency (like 900 MHz) and then need to get FCC part 15 approval by a registered lab. It isn't actually that hard, it just costs a fair amount.

Re: Robot to robot communication
 

There are various FRS frequency bands that don't require licensing as long as the power remains below a specified minimum level. Walkie Talkies are avaiable from various manufacturers for the 27, 49, 900 MHz bands, etc. Various services use these bands, i.e. modeling, experimentation etc. If you are using a n FCC type approved device to begin with you don't need to go through all the goverment paper work as long as it is in band, doesn't interfere with other services and stays below the max. power levels. For devices in an enclosed space in close proximity to each other, you should have no trouble finding transceivers to fit you needs.

Re: Robot to robot communication
 

does anyone have ideas about the actual problem I posted. It isn't a project i am working on, just something i would like to work on with a few friends

Re: Robot to robot communication
 

With the robots you could get a coded walkie talkie(the ones that have a chanel then a code on it) and rig them so that whenever a robot needs to send a signal to another it can send a series of beeps to that robot on its frequency code, you can then have a base station which uses the uncoded chanel and can "read" all input sent by all the other robots