Erco's Figure Eight Challenge

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  • zappmanzappman Posts: 417
    edited 2015-01-01 - 14:39:39
    FrankenBot accepts the Figure Eight challenge on 1/1/2015
    [video=youtube_share;0PgDEv8_bMk]
  • ercoerco Posts: 19,736
    edited 2015-01-01 - 14:54:33
    Winner! Nicely done in record turnaround (pun intended) time. A promising start to 2015. Bravo!
  • ercoerco Posts: 19,736
    edited 2015-03-19 - 00:48:36
    Here is today's uber-simple bot, an ugly but quite functional duckling. We're probably going to 3D print an improved version of this chassis to use in a robot camp. Two 9g servos, one continuous rotation drives, one steers. And a 1 PPR mechanical encoder. Easy peezy, works every time. Just have to calibrate servo turning radius to match up to a 360 degree turn with an integer multiple of my wheel circumference. In this case, 12 wheel revolutions per circle. Accelerates & decelerates. First test was this figure 8 course. Bot will soon have IR and ultrasonic sensors and audio output. Maybe light tracking too.

    Video thumbnail shows bare chassis before the electronics were added. So hideous that it's beautiful.
  • zappmanzappman Posts: 417
    edited 2015-03-19 - 05:17:15
    erco wrote: »
    Here is today's uber-simple bot, an ugly but quite functional duckling. .... So hideous that it's beautiful.

    Nicely done. Love the rear wheels and tires.
  • ercoerco Posts: 19,736
    edited 2015-03-19 - 08:39:32
    All my wheels are hacked out of thin sheet styrene, hand-turned on a shaft against a belt sander. Rubber band tire is a slit of road bike innertube stretched around the disk. Crude, quick, works great!
  • PublisonPublison Posts: 11,506
    edited 2015-03-19 - 09:11:42
    erco wrote: »
    All my wheels are hacked out of thin sheet styrene, hand-turned on a shaft against a belt sander. Rubber band tire is a slit of road bike innertube stretched around the disk. Crude, quick, works great!

    No glue on the rubber? I guess if you cut it short enough to stretch, it will hold.

    Looks nice man.
  • ercoerco Posts: 19,736
    edited 2015-03-19 - 09:22:16
    Videos show wheel encoder (Oh Mr. Demille, I'm ready for my closeup) and bare chassis with both servos being driven by a servo tester in oscillate mode. A random pattern, but delightfully fluid.
  • mindrobotsmindrobots Posts: 6,506
    edited 2015-03-19 - 09:34:53
    erco,

    I love your robot reports! They amuse and amaze me! That's a very impressive figure eight for such an unorthodox configuration. The simple and elegant encoder is great!!

    I'm almost inspired to actually do something!! :D There must be some excuse I can come up with that I haven't used yet.........
  • ercoerco Posts: 19,736
    edited 2015-03-19 - 10:02:21
    Excellent feedback, Rick! Come on in, the water's fine... Here's a table top-sized figure 8 for my presentation today. Didn't even use the encoder, it's quick & easy to use timing commands and calibrate for consistent 90 degree turns. This simple little trike bot is actually a lot of fun to use.
  • mindrobotsmindrobots Posts: 6,506
    edited 2015-03-19 - 11:38:29
    It's fun to watch! I really like how well the outside rear wheel sticks on a turn. It looks like your success with accuracy comes from how well you have center of the front wheel aligned with the center of the pivot attaching it to the body.

    If I jump in the water now, I'd have to shove a bunch of other neglected projects off the bench to make room. Of course, I am supposed to have a 3D printer coming and something like this would be post-justification for that purchase! Hmmmm, maybe I can rationalize it that way!!
  • ercoerco Posts: 19,736
    edited 2015-03-19 - 14:40:25
    IMO the best thing is that you can go straight just by steering the servo to a certain location. You don't have to monitor two wheel/motor encoders and synchronize wheels as required by differential steering. Freedom at last!
  • WhitWhit Posts: 4,130
    edited 2015-03-19 - 19:24:25
    This is so great erco!
  • ercoerco Posts: 19,736
    edited 2015-03-20 - 07:56:24
    This older related video is a little hard to watch, as it sounds like fingernails on a chalkboard, but it eventually does do an 8 around 2 IR beacons after some dramatic pauses. :)

    Same bot does "slalom" course faster: https://www.youtube.com/watch?v=9152JjyRkJE
  • Martin_HMartin_H Posts: 4,050
    edited 2015-03-21 - 04:08:47
    Nice little bot. Tricycle drive definitely has its place in robotics. You lose the ability to turn in place, but can go straight or turn in arcs easily.
  • ercoerco Posts: 19,736
    edited 2015-03-21 - 08:34:41
    This Mindstorms robot gets extra point for entering & exiting the course.
  • JasonDorieJasonDorie Posts: 1,930
    edited 2015-04-01 - 11:44:36
    Does this count? :)
  • PublisonPublison Posts: 11,506
    edited 2015-04-01 - 12:38:07
    JasonDorie wrote: »
    Does this count? :)

    Oh yes, it does! Well done Jason.

    !0 Points!

    Jim
  • WhitWhit Posts: 4,130
    edited 2015-04-01 - 13:31:55
    Jason - I think you are the winner! Unbelievable!

    It's not an April Fool's CGI creation is it? The dog looked a little fake... :-)
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2015-04-01 - 15:17:19
    New requirement: All contest videos posted this point on must contain either at least one adorable kid, or one cute dog or cat. Extra credit if you can get in at least two of the three!

    So Jason, what was the huge package you bought from Amazon?
  • JasonDorieJasonDorie Posts: 1,930
    edited 2015-04-01 - 15:23:26
    Pretty sure that was a whiteboard. The box has a huge surface area, but it's only 4" thick. And Whit, this isn't an April Fool's joke - The thing (and the dog) exists, though I'm steering it with a joystick and moving it with balance, so it probably violates some of the rules of the contest. :)
  • NikosGNikosG Posts: 702
    edited 2015-04-01 - 17:11:17
    I echo Whit! Jason's project is super!!!!!
  • Martin_HMartin_H Posts: 4,050
    edited 2015-04-01 - 17:20:33
    Jason, it's still a pretty cool gizmo, even if you are controlling it.
  • TtailspinTtailspin Posts: 1,326
    edited 2015-04-01 - 19:11:50
    Rules?, What Rules? All the rules went out the window after Amanda went crazy and started running over Teddy Bears...

    That looks really cool Jason, is it almost ready for production? :)




    -Tommy
  • WhitWhit Posts: 4,130
    edited 2015-04-01 - 21:43:15
    Ttailspin wrote: »
    Rules?, What Rules?

    I am with Tommy!

    Great project - who, or whatever is driving it!
  • JasonDorieJasonDorie Posts: 1,930
    edited 2015-04-01 - 23:12:58
    This is V1, so it's still got a ways to go. It's rideable as is, but I need to change the form factor, and hopefully add wheel encoders so I can improve the control loop and adjust the PIDs for different speeds. Currently I'm using the gyro to keep it going in the intended direction, which works surprisingly well. :)

    There's another video of it in the Projects forum, under "SideWay".
  • ercoerco Posts: 19,736
    edited 2015-04-02 - 01:10:37
    Fabulous as always, Jason. Once again you raise the bar!
  • cruXiblecruXible Posts: 78
    edited 2015-04-02 - 02:05:50
    New requirement: All contest videos posted this point on must contain either at least one adorable kid, or one cute dog or cat. Extra credit if you can get in at least two of the three!

    I have an image in my head of my baby and the cat in the seat of a cute babyblue hexapod and my wife screaming at me. Would the angry screaming detract points?
  • mindrobotsmindrobots Posts: 6,506
    edited 2015-04-02 - 09:47:03
    I see Thurber is still rockin' his green mohawk! Extra points for that too!!

    Well done, as always!!
  • ercoerco Posts: 19,736
    edited 2015-04-04 - 15:32:22
    Martin_H wrote: »
    [Trikes] lose the ability to turn in place....

    I hear that argument often, but of course it depends on how you view your chassis. Many diff steered chasses are circular, so it's easier to visualize. But if I put a circular body on a trike chassis (and keep the CG forward of the two trailing wheels), the two behave very similarly. The trike's powered wheel becomes the caster on the DS robot.

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  • WhitWhit Posts: 4,130
    edited 2015-04-11 - 06:48:39
    @erco - agreed and a very different movement from the old ARobot with exactly the opposite arrangement - that is - one drive wheel and two wheels that steer - all located at the perimeter.

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