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Homebuilt Robotic Platform AKA Retrobot

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  • ercoerco Posts: 20,157
    edited 2010-02-06 19:46
    Highlandtinker: Just curious if you're rolling yet. I know you're using the 24V gearmotors I recommended, driven by HB-25s with a big 12V battery. I also originally thought 12V was powerful enough, but it wasn't, after I tested it. I ended up using 18V, only using 12 V just for low-speed maneuvering. My platform weighs 14 lbs alone, and 18V is fine for the platform itself. But when I load it up with 13 more lbs of cargo (no snickering, Whit) I wish it was more powerful, maybe even 24V. I just mention this since I know those HB-25s max out at 16V. Sure, they handle 25 Amps, but we only need 1 amp or less! [noparse]:)[/noparse]

    erco

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    ·"If you build it, they will come."
  • HighlandtinkerHighlandtinker Posts: 50
    edited 2010-02-06 22:37
    erco: Yes I got my Bot rolling today. I hope to have some video as soon as it is on Youtube.
    You have some very valid points about the use of the HB-25 controllers with these motors. I· will most likely change to a different form of motor control on this Bot. I do have the 7.2V motors that Parallax sells, on order. (Tax $$ for more toys and cool Parallax stuff!!)
    I am learning alot about the HB-25 controller code and about Robot building in general. I will keep working with this Bot as a test bed and learning tool. I am not to concerned about speed as I am quit slow myself. I enjoy building the bots as much as seeing them run. As soon as I get some Pictures and video I will post.

    here is my video, sorry for the poor quility but this is my first youtube video.
    http://www.youtube.com/watch?v=wFvUnLMusos

    also some new pictures

    Post Edited (Highlandtinker) : 2/6/2010 11:15:50 PM GMT
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  • agfaagfa Posts: 295
    edited 2010-02-06 23:04
    erco said...
    I just mention this since I know those HB-25s max out at 16V. Sure, they handle 25 Amps, but we only need 1 amp or less! [noparse]:)[/noparse]
    Have you considered one of the Hbridge ICs 754410 or the L293.· They can handle up to 36v / 1amp.· You could·generate PWM with a prop, and loose the relays.· You could get a proto board and a few of these ICs for less than one HB-25.

    agfa
  • ercoerco Posts: 20,157
    edited 2010-02-07 00:15
    Highlandtinker: Great start! You're on the right track, a first bot should be a fun learning testbed. Congrats, you're a roboticist now!

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    ·"If you build it, they will come."
  • WhitWhit Posts: 4,191
    edited 2010-02-09 03:02
    Great job Highlandtinker! Your video came out great - I think! You are officially off and running.

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • ercoerco Posts: 20,157
    edited 2010-02-09 06:29
    Project Update: Check out the next issue of ROBOT magazine for a how-to article on my "poor cousin" robot, AKA Retrobot in the article. I had to rush, and barely made the cutoff date, but I'm quite pleased how the article turned out. I'm working on·my new Pathfinder software that allows you to easily teach the robot to follow any path you like. It's working quite well so far. Per my agreement with ROBOT magazine, my code will be posted on their website once it's ready. I'll get some video up when I can.

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    ·"If you build it, they will come."
  • EverQuriousEverQurious Posts: 48
    edited 2010-02-10 08:55
    I am not so patiently waiting for my teenage kid to find what he has done with the cameraphone uplink cord. So until such time as I can get a photo up I will submit the following PAINT images depicting how I constructed the robot. As you can see it is a triple decker with a OWI 007 trainer arm and a custom built controler. Please bear with me and I'll post a photo shortly. Works really well as decribed in the attachments

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    EverQurious

    Try not to fret and worry bout the things that you have not...
    Just remember to be thankful for the things you've got !!!
  • WhitWhit Posts: 4,191
    edited 2010-02-10 16:20
    Looks great EverQurious! Very well documented. Can't wait to see the pictures.

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • ercoerco Posts: 20,157
    edited 2010-02-10 17:24
    EQ: Very nicely done. You've been quiet for a while, and now we know exactly what you've been up to! I love your matter-of-fact·development documentation style: "... and we were up in a flash!"

    Nice use of MS Paint to show your design, I still use Paint a lot, too. Definitely post some pics and videos when you can. I love the OWI arm on the bot idea. In fact,·I put two OWI Edge arms on my bot for a photo in my upcoming article. Not wired in, just sitting there to inspire. Are you getting any feedback from your arm joints, or is it all open loop control?

    erco



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    ·"If you build it, they will come."
  • EverQuriousEverQurious Posts: 48
    edited 2010-02-11 05:28
    Right now have just open loop , but hope to change that soon.
    Will get pics up ASAP

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    EverQurious

    Try not to fret and worry bout the things that you have not...
    Just remember to be thankful for the things you've got !!!
  • ercoerco Posts: 20,157
    edited 2010-02-17 05:34
    The Retrobot article I rushed to ROBOT magazine bore unexpected fruit.·I had some time after submitting my print article before the editor needed my software to post on his website. My original plan was to simply clean up and submit my code·for the 3 routines I posted on Youtube: straight-line, square, and circle. But instead, I·forced myself to·finish·the software I had·always envisioned coming later, Pathfinder V1.0, and I am·amazed at the robot's repeatability. The software will be·available from the ROBOT website whenever they can get it posted.

    Long story short, you·teach the robot a path by simply driving it with an IR remote control once. It saves the encoder feedback in EEPROM, then it follows·the path·accurately on playback. I·posted·tonight's video at http://www.youtube.com/watch?v=PX0IhUqnwrk·, which shows Retrobot (a bit sleeker now, no longer·PC's simple rectangular chassis)·driving a circuit over carpet, tile, and several throw rugs.·The·total distance travelled is·about 45 feet, so it ends up within one inch of where it·started. What I didn't explain in the video is that I caused that inch "error"·when I manually drove·the robot·and programmed it. It accurately repeated my 1" mistake when·it played back·the stored path sequence.

    This video was achieved on the first take; it's not the best of 10 attempts. This bodes very well for Retrobot 2 and Pathfinder V2.0. The adventure continues!

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    ·"If you build it, they will come."
  • Roy ElthamRoy Eltham Posts: 2,995
    edited 2010-02-17 06:58
    erco,
    That's really excellent. Nice work!

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    Check out the Propeller Wiki·and contribute if you can.
  • WhitWhit Posts: 4,191
    edited 2010-02-17 23:26
    erco,

    Absolutely amazing! Can't wait for the article and the code to be posted. Not counting the labor, this about a $99 robot isn't it?

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • ercoerco Posts: 20,157
    edited 2010-02-18 01:54
    Thanks. Probably even less than a $99 robot , since that's one of the $12 BS2Es from a Parallax blowout sale two years ago.

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    ·"If you build it, they will come."
  • EverQuriousEverQurious Posts: 48
    edited 2010-02-18 02:34
    Here are the pictures of my 3 story bot with fully functional OWI-007 arm.
    Construction details can be found earlier in this link.
    He can find his way around the house pretty well avoiding objects quite well. As of yet I have not sat down and written any useful software for the arm, other than just running the joints through the motions and returning to the "HOME" position.
    I want to replace the OWI arm with someone's servo arm/controller, but the state of the economy has me having to be a bit more resourceful than I would like to be.

    Hey TOM C, Can't help but notice a few design similarities. GREAT MINDS THINK ALIKE

    AND erco thanks for all the heads up on parts and your interest

    Thanks to all who replied

    SORRY ALSO FOR THE POOR QUALITY IMAGES, but maybe you can get the idea.

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    EverQurious

    Try not to fret and worry bout the things that you have not...
    Just remember to be thankful for the things you've got !!!
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  • ercoerco Posts: 20,157
    edited 2010-02-19 01:40
    An experimental observation that surprised me: in all my dead reckoning testing, the particular caster I used worked better than I expected. Initially, I thought that a hard, slick plastic caster would offer the least rolling resistance, and would exert minimal undesirable steering forces of its own. As such, it wouldn't "fight" the two differentially steered wheels. But for reasons like noise and floor protection, I started out using a 3" diameter rubber wheel (~3/4 inch wide) ball bearing caster from Lowes. I figured I could change it if it didn't work right.

    In watching the robot drive over bumps, rug edges and thresholds (carpet/tile transition), the rubber wheel does not get deflected undesirably. Even when it catches the edge of long carpet runner at a small oblique angle, it is not deflected and tracks very straight. Its grippy surface actually improves stability and overall accuracy. In the same situation, I suspect a same-width slick plastic caster would have caught the carpet edge and easily deflected the robot's path. At Lowes, I also saw much wider barrel-shaped plastic casters that might work OK.

    My robot has ~90% of its weight on its two drive wheels, and ~10% on the front single caster.

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    ·"If you build it, they will come."
  • EverQuriousEverQurious Posts: 48
    edited 2010-02-19 05:31
    I ordered pair of full roller casters from ACME for about $4.00 a piece. They do great in all directions and over carpet ect very well! Part # is 710A-3/4
    They can be ordered from http://www.acmecaster.com/. They are very rugged and fit the height of my base using the the motor/wheels you recommended.
    Keep me posted as to your progress and I will do the same (including, er er some decent pictures)

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    EverQurious

    Try not to fret and worry bout the things that you have not...
    Just remember to be thankful for the things you've got !!!
  • TritonTriton Posts: 9
    edited 2010-02-20 19:06
    Hi there.

    There is a copy of a platform.

    I have added the G-code file too.
  • jcoloniasjcolonias Posts: 31
    edited 2010-02-20 22:38
    Hi everyone,

    I have been tempted to show my "wooden" robotic platform, but it has so many wires that need to be properly attached that I hesitated to do so. But, anyway,I thought I would share it with all those that have contributed thus far for their comments. I have two 12v motors controlled by two HB25s that work incredibly well. I just installed 3 IRs at 90 degrees apart to work with 2 or 3 ping))) sensors for navigation and obstacle avoidance. My primitive programs just make the robot go around but· have not seriously programmed the robot.I do all my hardware testing on a separate Boe-bot, and once the hardware work·I put them on the robot. Thus far everything works fine.

    I would appreciate any comments.

    Thanks, John
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  • ScribblerKartScribblerKart Posts: 45
    edited 2010-02-20 22:47
    @ jcolonias

    That's looking good so far! smilewinkgrin.gif

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    ScribblerKart


    Uh oh, ScribblerKart time!
  • ercoerco Posts: 20,157
    edited 2010-02-21 22:33
    John: Stop apologizing already! You can never have too many wires. Future expansion, right?

    That's a great-looking robot, stand, and bench you have there. Nice window view. Quite the man-cave to work in!

    Finished cabinets & molding? Check.
    Soldering iron? Check.
    Kleenex? Check.
    Anvil? Check.
    WD-40? Check.

    Full speed ahead! Post some pics & vids when you can.

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    ·"If you build it, they will come."
  • Ken GraceyKen Gracey Posts: 7,365
    edited 2010-02-22 00:33
    These are the Poor Cousin's close relatives, checking in for a visit. They're sporting a shiny set of hardware recently acquired from the local Parallax shop. But be not intimidated by their perceived beauty; the programming about to be imparted upon these sorry Rich Cousins will prove the point that "beauty is only skin deep"!

    It's taking me some time to move these robots to the next phase, but I'll have them rolling pretty soon.

    Carry on with this great thread. There's a lot of enthusiasm in these projects!

    Ken Gracey
    Parallax Inc.

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  • jcoloniasjcolonias Posts: 31
    edited 2010-02-22 14:45
    Wow! I look at Ken's workmaship and mine, and I can see that I have a ...long way to go. Thanks, erco, I will keep on. I wish I had more time to do all the things I·want to do!

    John
  • Ken GraceyKen Gracey Posts: 7,365
    edited 2010-02-22 14:55
    John, absolutely not - we're working with different resources and tools. For example, I don't have to buy any Parallax parts - I can check out any inventory I need for a project (anybody in the company can do that). And for tools I have a wide selection: mills, routers, bandsaws, etc. I'm not even skilled with the various processes we have at Parallax, but it certainly helps build a robot. Your work with your wooden robot platform involves skill building, pride, and helps you gain a lot of experience for the next project. If you feel like you are improving with each project, you are!

    You should see what I made on my first manual milling machine: a Toddler robot 15 revisions ago. It looks like a real hack-job and it's tucked away on a shelf in my garage. When I look at it I have really mixed feelings. On one hand I think "wow, I've really learned to do better workmanship" yet on the other I think "oh my, I hope nobody ever sees this thing!".

    Carry on and keep sharing!

    Ken Gracey
  • WhitWhit Posts: 4,191
    edited 2010-02-23 01:41
    erco said...
    Finished cabinets & molding? Check.
    Soldering iron? Check.
    Kleenex? Check.
    Anvil? Check.
    WD-40? Check.

    You left out...
    Sledge Hammer? and most importantly of all - Duct Tape?·These are two essentials for my sort of craftsmanship.
    erco said...
    John: Stop apologizing already! You can never have too many wires. Future expansion, right?
    @John - I am with erco -·your bot looks great!

    @Ken - Any sort of work represents your best at that time (with the limits of your knowledge, tools and resouces). I know just what you are saying - but the only way to avoid looking back on old projects and not having to think how you could do better is to never build anything.

    Unfortunately smilewinkgrin.gif - the only way to learn is to build things!


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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

    Post Edited (Whit) : 2/23/2010 1:51:33 AM GMT
  • ScopeScope Posts: 417
    edited 2010-02-23 02:34
    Whit said...
    Unfortunately smilewinkgrin.gif - the only way to learn is to build things!

    +1
  • ManetherenManetheren Posts: 117
    edited 2010-02-23 16:38
    @ken It is either to never look back at the old projects or to take what you know now and rework the old projects. THough this looses some nostalgia in the past.

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    Tia'Shar Manetheren
  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2010-02-23 17:00
    @Ken: Anything with CNC machined wheels, a polished wood body and about 10 PING sensors for full range detection is NOT a "poor cousin". If that is a poor cousin robot, then my 4 foot "junk bot" (powering forward at a breath catching 1 MPH by 2 parallax contenuous rotation servos) is a half-dead-beat-up-tossed-out-a-window poor cousin!!

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    Post Edited (microcontrolled) : 2/23/2010 5:12:07 PM GMT
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  • Ken GraceyKen Gracey Posts: 7,365
    edited 2010-02-23 17:49
    @microcontrolled: "Poor Cousin" is erco's reference to his design featured at the beginning of this thread. You'd need to read back a ways to get the history.

    Your "Junk Bot" is an important step in the right direction, BTW. You already know this, but a good effort is what it's all about - especially if you're cobbling together bits and pieces from electronic surplus stuff. That's a highly respectable ability and it shows that motivation trumps resources. In fact, one of our top engineers (Kevin) came to Parallax as a result of his Junk Bot - a fire-shooting contraption comprised of various bits of steel, aluminum and motors all put together with manual milling machines, drill press, etc. It was his robot effort that got him the job. This robot sits in our office, wondering if he'll be reincarnated as a future being. But the problem [noparse][[/noparse]as I see it] is that Kevin has developed so many skills that his junk bot now seems more like a stepping stone than something he'll put more time into. His design skills have increased, he has far more tools to use at Parallax, and he'd probably start over with an entirely new design.

    Ken Gracey
  • Ken GraceyKen Gracey Posts: 7,365
    edited 2010-02-23 17:51
    @Whit, I hear ya loud and clear on that point. It's this kind of thing that educators do so well to inspire students in their projects. Works for me, too. . .if you do nothing, you learn nothing!

    Ken Gracey

    Post Edited (Ken Gracey (Parallax)) : 2/23/2010 6:21:51 PM GMT
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