R/C Control types

[ChrisH]

Originally posted by caffel
They want to add the combat robotiers to their target market.
Its that simple.
Notice that the new controller doesn't have the word 'Edubot' on it.

Actually I think the combat robotiers are a small market compared to the existing RC market. Do you have any idea how much simpler the new edubot controler could make it to sequence landing gear doors to open at the right speed and in the right order? The Scale guys will go ape once they figure it out.

I haven't actually seen one yet, but I assume it's still a little big and bulky for sailplanes yet. Otherwise you will see auto thermalling planes before too long.

[caffel]

Its less than 3" x 5" and about 5/8" thick.
It weighs nothing.

[kmcclary]

Originally posted by caffel
They want to add the combat robotiers to their target market. Its that simple.
Notice that the new controller doesn't have the word 'Edubot' on it.

Oooooh, EXCELLENT point, Charlie! I think you're right!

BTW, slightly off topic, but note that IFI has a "parallel" website to InnovationFirst.com:
- http://www.ifirobotics.com/

It's VERY instructive to explore. I was hoping to catch a glimpse of the new controller there, but they're a few years behind us in CPU tech. (Darn...) IMO, IFI is probably using FIRST to finance the development of their products, and then selling them to the BattleBot et al crowd via IFIRobotics storefront to help extend the product lifetimes, and float the company off season. (IMO a smart business move.) I don't see the EduBot's CPU there yet. The Issac32 is our controller from at least two years back (see the battery screws).

Can any old timers here tell us: Is the "Issac16" from even EARLIER FIRST contests? If so, what year(s)?

Now what *I* want is for us to have access to the IFIRobotics 120A *885* Victors (or *150A* "Thor"!) and some SERIOUS drive motors, and/or the "SC" ("Spin Controller") versions of the smaller Victors, which would be great for things like soccer ball shooters! <drool>

Back to topic...

I see on the IFIRobotics website a "PWM Signal Driver". See:
http://www.ifirobotics.com/victor-SC...ler-robots.htm

I'll bet that's the WRONG way though (standard 5V PWM R/C signals up to 12V PWM signals...)

Gee... If the only problem is the peak PWM voltage out of the Robot Controller PWM outputs, that can EASILY be handled with simple resistor-zener voltage clamps on each PWM input of the EduBot. Would only cost a couple of bucks to whip THAT up. LOTS less than even a CHEAP R/C rig!

- Keith

[Joe Ross]

The Isaac 16 is a cut down version of the Isaac 32. However, it was never used for FIRST. It was designed specifically since many battlebot teams don't need so much I/O.

[kmcclary]

I'd avoid AM radios with FIRST robots, and go *only* with FM. FM is much more noise immune, and between the microprocessors, and all the electrical noise from the motors et al, IMHO you're just asking for trouble with an AM rig.

Compare during a lightning storm how static filled an AM radio gets, to the quietness and clarity of an FM broadcast, and think about what the robot is "listening to" for its instructions.

- Keith

[sanddrag]

Innovation FIRST now has links on thier site to this
http://www.robotcombat.com/marketplace_rc-quattro.html
and this:
http://www.robotcombat.com/marketplace_rc-4yf.html

[earthchild]

Meh. It really does not matter what radio you get. Most people in the battlebots community use aircraft radio by having them retuned.
A stupid question but I am guessing that the use of programable r/c radios is bad.

Well, I do Science Olympiad and they had a new rule that said that aircraft bands(72mhz) cannot be used for ground vehicles because of FCC Regulations beginning in May 02. As far as I know, Robot Battles and Battle Bots have also disallowed it too. I doubt FIRST will be any different.

My first post

[Justin Stiltner]

If you notice, it was said that they have them retuned, it has been illegeal to use aircraft band radios on ground models for years. First and IFI would prefer that we use whatever is approprate for our uses, IE if the edu R/c was in an aircraft, use aircraft band, however they wont make a rule aginst use of it.. because the edu r/c isnt used in competition, and we wont be using the hobbie r/c ssytem in actual compeition or with the real robots.

[Joe Johnson]

From my discussions with my local hobby shop folks, it is my understanding that

#1 Any of the aircraft radios/controllers can be purchased in ground frequencies (typically local shops will not stock them but you can get them in 2-4 weeks)

#2 Most manufacturers have programs where (for a fee) you can get aircraft radios retuned to ground frequencies.

I have not verified this but it has the ring of true truth to it.

Joe J.

[kmcclary]

Originally posted by Justin Stiltner First and IFI would prefer that we use whatever is appropriate for our uses, IE if the edu R/c was in an aircraft, use aircraft band, however they wont make a rule against use of it.. because the edu r/c isnt used in competition, and we wont be using the hobby r/c system in actual competition or with the real robots.

Yes, using the aircraft band IS illegal, period. Regardless of a FIRST ruling, DON'T use the aircraft band for your robot under ANY circumstances.

From a practical point of view, remember that in some areas schools often have the only clear field, so many R/C airplane enthusiasts use local school yards after school and on weekends for their flying. If you fire up your edubot on an aircraft band while someone is flying in your school's field nearby, you'll probably crash their plane. Believe me, they'll be pissed off, and your team could even be liable for the damages to a multi-hundred dollar R/C airplane because you were illegally on their frequency.

Considering the exponential growth in the number of schools involved in FIRST these days, the constant elimination of other clear fields in communities from population growth housing/building construction, and the fact that our "hot" time includes almost two months of contiguous weekends, conflict is a non-trivial possibility that will only increase with time.

Therefore, use ONLY ground frequencies. If you crash someone's car, you were both on the band legally (and R/C car are expected to take crashes! )...

BTW, regardless of ground frequency, R/C car controls are often only two channel. Given a four or more channel radio if you skip the first two servo channels for your drivetrain you'll protect yourself from most R/C Cars that happen to be on the same frequency (though your grippers may be "jumpy", so watch out). Even if they have more channels, R/C cars normally use the first two servo channels for speed and steering and the rest for switches, which simply turns your motors on to a set value instead of making them behave wildly as they run their car.

[edit]
BTW, Another advantage of FM radios is that they tend to "lock" onto the strongest nearby transmitter. Since all are roughly equal in power (with full batteries), that means a given receiver normally listens to the closest transmitter of that frequency, which should be yours.
[/edit]

Originally posted by Joe JohnsonFrom my discussions with my local hobby shop folks, it is my understanding that
#1 Any of the aircraft radios/controllers can be purchased in ground frequencies (typically local shops will not stock them but you can get them in 2-4 weeks)
#2 Most manufacturers have programs where (for a fee) you can get aircraft radios retuned to ground frequencies.

#1: True. The problem is that most ground freq radio sales are for cars, which are typically only 2-4 channel and use the "knob/trigger" controls, so that's what they stock. Most joystick >=4 chan radios stocked locally are for planes and choppers, all on the wrong band(s). Therefore, you'll probably have to order it. Online ordering is normally the fastest and cheapest, but if you work through your hobby store, you get local sales/service assistance (and maybe a new team sponsor!!!).

#2: Depends highly on the brand, and the model. High end models/brands are often worth the changeover, as they normally have modular transmitter "bricks" which can be swapped out easily in minutes. OTOH, Cheapie rigs normally aren't worth the effort and expense for the entire guts are on one PCB. You'll either basically have to replace the entire board inside to change the transmitter's band, or incur a tech's bench time to change components and realign the radio. Either of these tasks can easily cause the retrofit to exceed the price of a new transmitter.

- Keith

[Justin Stiltner]

I posted this in another thread but its good info...

the folks over at r/c heli base have an white paper on the operation of a normal r/c controller... from this paper i found out that nearly all 3-7 channel non computer radios use the same encoder chip... so that means that your 4 channel ground radio can actually transmit 7 channels of data, all you have to do is free the extra input pins on the encoder (they are grounded) and attach your pot and voltage reference and you now have an 7 channel radio!!
here is the link
http://www.rchelibase.com/radio/index.html

btw ive looked in my radios and it seems that to retune one you would only need to replace the crystal, maby a few coils and adjust a few trimmers if i can get my hands on an frequency counter i may try it myself

[kmcclary]

Originally posted by Justin Stiltner I posted this in another thread but its good info...

http://www.rchelibase.com/radio/index.html

[...] from this paper i found out that nearly all 3-7 channel non computer radios use the same encoder chip... so that means that your 4 channel ground radio can actually transmit 7 channels of data, all you have to do is free the extra input pins on the encoder (they are grounded) and attach your pot and voltage reference and you now have an 7 channel radio!!

Be careful... If you're planning on jacking in our standard PC Joystick, watch your pot values. PC Joysticks run from 90K-100K (Flightsticks are about 93K), whereas many R/C pots are closer to 5K. That may be able to be compensated for via a capacitor change in the R/C.

It depends on how they're doing the encoding. Many radios are using a small CPU for multichannel encoding, cause they're CHEAP. But you're right. You should always peek under the hood to see if they give you more channels than are brought out to the case controls.

Originally posted by Justin Stiltner I posted this in another thread but its good info...
http://www.rchelibase.com/radio/index.htmlbtw ive looked in my radios and it seems that to retune one you would only need to replace the crystal, maby a few coils and adjust a few trimmers if i can get my hands on an frequency counter i may try it myself

Maybe, maybe not. You can't change a 27MHz rig to a 75MHz one. You may be able to shift from 72MHz to 75MHz though. However, be warned that FCC rules state that to legally modify a transmitter in the US you have to either be a Ham (be a licensed Amateur Radio Operator), or hold a First Class FCC License.

There are exceptions under Part 15 of the FCC rules for building VERY low power transmitters, but I was told at the hobby store this week that people who modify R/C transmitters are definitely regulated, even if you're only attempting to switch channels on one to another allocated frequency. That was news to me, and I haven't had time to verify it yet. (It may be an attempt to encourage business...) You USED to be able to at least switch your own crystals within a single band, but now my local shop is claiming that's true only if the radio is designed for user plug-in crystals, and to insure compliance the FCC is now taking a harder stand WRT people who take the soldering iron to transmitter circuitry.

Now home brew encoders are fair game. You can always build your own 8-channel encoder, and pipe it into the already established transmitter brick! If it's worth it to you to save a few bucks, you may be able to take a standard 2-channel car r/c transmitter and some 555 timers, and build your own 8-channel transmitter. You'll still need the receiver though, so I'm not sure it's worth the time. Great learning experience though. Back in college I built my own 8-channel R/C encoder and decoder with an Ace R/C kit. VERY simple circuits.

Hmmm... I wonder... Anyone have a source for cheap prebuilt R/C transmitter and receiver "upgrade bricks" (transmitter/receiver only modules that fit into some modular radio line) to which we can tie our own encoders and decoders? THAT may be a cheap way to go!

- Keith

[Justin Stiltner]

the low end transmitters we are probably working with (non computer radios) that i have seen don't have the transmitter brick you talk about, from what i have seen they are all single board models, no modules of any type, of course different brands may be different. Yes the pot values are different.. however in my link there is also an data sheet telling you the values and even a basic circuit diagram.

To my knowledge changing crystals is still completely legal, and as most radios have a small "shuttle" that the crystal sits in that guides it into the radio it makes it very easy to do so. Rember that some (not saying all are like this but I know some are) model shops, the employees are still amazed that the radio can do what it does, and dont have a working knowlage of the laws and regulations reguarding their modification. Not saying that your hobbie shop is like that but unless you hear it from a very very reputable source i would take most things with a grain of salt.

/edit
The encoder used in my radios(futaba conquest) is an NE5044 this is a specialized enocoder expressly made for r/c use.

[Adam Y.]

They want to add the combat robotiers to their target market.

There will be absolutely no demand for this controller by the robot combat people considering the fact that the only thing the controller had going for it was a secure radio signal. Im not sure about the other controller though. The demand for the older controller will most likely stay high though.