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Radio conrol? — Parallax Forums

Radio conrol?

egertegert Posts: 10
edited 2005-01-28 18:19 in BASIC Stamp
Hey! I was wonderin if it was at all to retrofit a 72 mhz radio controller to control the boe bot? It is just a plain old futaba 4 channel radio. Is THis at all possible?
Thnks!
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A CHAIN IS ONLY AS STRONG AS ITS WEAKEST LINK
GENIUS IS 1% INSPIRATION AND 99% PERSPIRATION
THERE IS ALWAYS GOING TO BE ONE PERSON RICHER THAN YOU, UNLESS YOUR NAME IS BILL GATES
What is is, what is not is not, isn't it?
It is.

Comments

  • SPENCESPENCE Posts: 204
    edited 2005-01-25 04:32
    Possible but as far as i know it is absolutly illegal.

    72 mhz is for aircraft, helicopters blimps and the like which are airborn.

    It is not legal to modify it yourself uness you have a fcc general commercial radio license.

    75 mhs is the only band for unlicensed operation for ground or water..

    73
    spence
    k4kep
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-01-25 14:19
    OK, so if you use a 75 Mhz R/C control reciever, whose outputs would normally go to servos, then if you wire those outputs to the BS2, the BS2 can determine the size of the pulses. You can then control the BS2 with your R/C control hand-set, yes.

    And, as Spence says, you don't do this by hacking the RC reciever, merely by using what the R/C reciever already gives you.
  • SPENCESPENCE Posts: 204
    edited 2005-01-25 20:17
    THE WAY I READ THE SPEC'S ON THE FUTABA 9C 75 MHZ IS THE YOU CAN RUN THE
    RECEIVER SERVO TO A MICRO OR DIRECT SAY TO A MC-7 MOTOR CONTROLLER
    USED BY KADTRONICS ON THE WORKMAN II OR III.

    QUOTE FROM MC-7 MOTOR CONTROLLER BY "DIVERSIFIED"
    Control it from your microprocessor by applying a PWM control signal between the
    "pot wiper" (PW) terminal and ground to control speed, and a +5V signal on either
    the forward or reverse connectors to control direction. Enable it with +5V on the
    enable terminal. END QUOTE

    I THINK THEY ARE SAYING THE PCM RECEIVER OUT PUT IS THE SAME AS PWM.
    COMMENTS?????

    YOU HAVE TO USE SEPERATE MOTOR CONTROLLERS FOR LEFT AND RIGHT SIDE.
    BTW I AM TRYING TO DECIDE BETWEEN THE KADTRONICS OR A 16" SQUARE
    ZAGROS.

    https://www.zagrosrobotics.com/shop/item.asp?itemid=517&catid=1

    AND THE KADTRONICS 4 WHEELER

    73
    SPENCE
    K4KEP
  • HimszyHimszy Posts: 28
    edited 2005-01-25 20:57
    Is it possible to change a 35mhz·transmitter/receiver·to a 40mhz?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-01-25 22:11
    There are devices (Circuits), called frequency converters, that could do what you're talking about.· However, I'm not sure I want to give an answer, since in my experience, they've been used for things like obtaining frquencies not normally allowed on scanners, etc.· Perhaps Google?


    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • egertegert Posts: 10
    edited 2005-01-26 03:26
    It is possible since alot of the futaba radios you can change the crystals. That way you can change it to wat ever

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    A CHAIN IS ONLY AS STRONG AS ITS WEAKEST LINK
    GENIUS IS 1% INSPIRATION AND 99% PERSPIRATION
    THERE IS ALWAYS GOING TO BE ONE PERSON RICHER THAN YOU, UNLESS YOUR NAME IS BILL GATES
    What is is, what is not is not, isn't it?
    It is.
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-01-26 14:00
    No, Spence, the output from the reciever SHOULD be a 'Servo Control Signal'. That's a low idle, 1 to 2 mSec pulse high (1.5 mSec is 'centered') repeated every 20 to 50 mSec signal. I believe the purpose in life of the MC-7 is to convert the 'Servo Control Signal' into a PWM signal you would use to control a DC motor.

    The quote you presented sounds as if there is an interface so a Microprocessor generated PWM signal could interface with the MC-7 drive electronics -- but PWM is NOT a 'Servo Control Signal', and is MUCH harder to generate with a BS2. I don't think the two signals are the same.
  • steve_bsteve_b Posts: 1,563
    edited 2005-01-26 14:04
    Most newer radio's are frequency synthesized.·

    But true, some do still use modern components with old methods, so you might find crystals.· But they may not work with all the filters that are in the radio.· Especially today with the 'bands' being so congested, there's a push for manufacturers to keep things tighter so they don't interfere with their 'neighbors'.

    We had a radio transmitter who's filter had let out the smoke, but the radio kept chugging along.· But instead of transmitting at 164Mhz with whatever bandwidth, we were on every multiple of 800kHz above and below our frequency.· Just so happens we were interfereing with the railways radio comm lines (emergency lines?).· Well, they promptly kicked in the door to our shack (remote area, nobody to call) and shut off our gear and called Industry Canada.

    If you go about modifying radio gear that's near aircraft bands or other 'priority' bands, then you need to know if you are 'bleeding across' the band.· A Spectrum Analyzer is nice for this....but if you can afford one of these, then you can afford to have a company custom build you a transmitter or 100!

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    ·

    Steve
    http://members.rogers.com/steve.brady
    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • HimszyHimszy Posts: 28
    edited 2005-01-26 22:12
    Thing is that crystals are used to change frequency like 35.2 to 35.4 or what ever. I want to convert my 35nhz to 40mhz
  • egertegert Posts: 10
    edited 2005-01-27 01:44
    yah, I do have a nice old crystal radio for planes, but the crystal is easily accessible (on the front plate)...would this work?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    A CHAIN IS ONLY AS STRONG AS ITS WEAKEST LINK
    GENIUS IS 1% INSPIRATION AND 99% PERSPIRATION
    THERE IS ALWAYS GOING TO BE ONE PERSON RICHER THAN YOU, UNLESS YOUR NAME IS BILL GATES
    What is is, what is not is not, isn't it?
    It is.
  • blink13blink13 Posts: 65
    edited 2005-01-28 00:39
    i dont know but if you go to this website···http://geocities.com/SiliconValley/Orchard/6633/rfremote.html······································ it will tell you how to make a rmote controll that would operate multiple relays from up to 300 feet

    ps i know basically nothing about remote controlls but i found this intersting
  • Andy Lindsay (Parallax)Andy Lindsay (Parallax) Posts: 1,919
    edited 2005-01-28 01:24
    Your old 4 channel radio must have controlled an RC plane/boat/car that had a receiver that converted the RF signals to pulses that controlled the plane/boat/car's servos. If you connect that receiver to a Boe-Bot, it should work pretty well.

    It's true that you can connect the receiver outputs directly to the Boe-Bot's servos, but in doing so, you would loose the ability to programmatically fine tune the handling, check sensors and override the remote control, and other cool projects.

    I think it would be way better to have the BASIC Stamp measure the pulses the receiver sends and use those measurements to control its servos. Make sure the receiver's ground is connected to the Boe-Bot's ground (Vss). Then, the connections on the receiver that used to send the pulses to the plane/boat/car's servos can send pulses to BASIC Stamp I/O pins instead. The BASIC Stamp can monitor these signals with the PULSIN commands, then control its servos (connected to different I/O pins) with the PULSOUT commands.

    If you don't have the receiver any more, one option would be to take your radio control down to a hobby shop and see if they can set you up with a compatible one.· Given the choice between that and blink13's link, I'd definately opt for blink13's link.·

    As an aside, here's a link to an article with an RF controller that you tilt to control the Boe-Bot: A Tilt Radio Controller for Your Boe-Bot



    Post Edited (Andy Lindsay (Parallax)) : 1/28/2005 1:29:26 AM GMT
  • Joe FishbackJoe Fishback Posts: 99
    edited 2005-01-28 03:00
    I have just got my robot be controled by a RC unit and at the same time have the Stamp BOE detect for objects.
    What I tried to get the Stamp to read the RC pulses with PULSIN and PULSOUT commands and also check sensors for objects, the servos did not run smoothly. While the program was checking the sensors, no signal pulses are being sent to to servos. To get around this I used two SPDT relays to switch control between the RC and the Basic Stamp program that checked for objects. Nornally the RC receiver controls the robot drive wheel servos directly. The Basic Stamp program runs all the time checking the sensors for objects. The relay coil is controled (thru a transistor) by toggling pin 6 from low to high. If no object is detected pin 6 is LOW and the relay allows RC control. If an object is detected pin 6 goes HIGH and relays switch the servos control to the Basic Stamp navigation routines. When the object is no longer detected pin 6 is toggled back to LOW and the RC takes back control.

    This seems to give nice smooth running servos. Does anybody have any other ideas? I would like to do away with the relays, but they give good clean isolation of the RC pulses from the pulses sent by the Basic Stamp program.

    Joe Fishback
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-01-28 18:19
    The BS2 should be able to do this. What you want to do is insure that no matter what path your code takes through the main loop, your servo's get refreshed each 20 mSec.

    You could arrange this so you check the left sensor, refresh servos, check right sensor, refresh servos, etc.

    You're going to wear out the reed relays pretty quickly using them this way, I would think. They're only rated for like 100,000 operations, no?

    You could also use a multi-plexor chip, so when the signal is high the RC control gets the servo, when low the BS2 gets the servos.

    Note also the BS2 should refresh BOTH servos, THEN wait 20 mSec.· It's NOT refresh one, wait 20, refresh two, wait 20.· It's more like Refresh one, refresh two, wait 20, refresh one, refresh two, wait 20.

    ·
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