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Erco's Mobile Robot/Tower of Hanoi Challenge — Parallax Forums

Erco's Mobile Robot/Tower of Hanoi Challenge

ercoerco Posts: 20,254
edited 2015-06-22 18:08 in Robotics
Who can get a mobile robot to solve a 3-disk Tower of Hanoi maneuver? Bot must roll between 3 posts (real or virtual) to move disks. It will need a gripper (or electromagnet) with one or two DOF to raise/lower and release disks.

Bonus points for solving ToH using only one servo or while doing a Figure 8.

Maybe this is the official Parallax contest for the P2 launch party.

My new tricycle bot will do it with its single 1PPR encoder. Who else will answer the call?

Martin_H, I expect you to use Forth.
Duane, your Halloween Hexapod can do this with its LED eyes closed.
Xanadu, yes you may use a drone.
Rich, time to bust out Keppler.
Whit, get the Gatorbots on the case!
Rick, it's now or never to join the fray.
Gordon, it's showtime!
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Comments

  • xanaduxanadu Posts: 3,347
    edited 2015-03-21 16:24
    Awesome idea! The hard part will be finding a name for my new drone. How about Grippy? Maybe Quadgrabber?

    I have a few parts I need. What are we looking at for a deadline?
  • mindrobotsmindrobots Posts: 6,506
    edited 2015-03-21 16:39
    How about 3 mobile posts that move in front of the stationary arm as commanded by the arm so it can remove and place disk until it is solved?
  • WhitWhit Posts: 4,191
    edited 2015-03-21 19:23
    Two weeks till Easter - is there a time limit?

    Any bonus using the S2 and GUI?
  • ercoerco Posts: 20,254
    edited 2015-03-21 19:38
    Whit wrote: »
    Two weeks till Easter - is there a time limit?

    Any bonus using the S2 and GUI?

    No time limit, I see this as a standing challenge, a rite of passage for all serious roboticists.

    Bonus for S2? Maybe, maybe not. With its million PPR wheel encoders, it comes with all of the accuracy required. That said, I don't recall seeing any grippers/servos attached to any. Just pen lifters. Get on it, Padre!
  • Martin_HMartin_H Posts: 4,051
    edited 2015-03-23 07:06
    Challenge accepted.
  • ercoerco Posts: 20,254
    edited 2015-03-23 09:30
    The venerable Martin_H was also the first to accept the Figure 8 call!
  • xanaduxanadu Posts: 3,347
    edited 2015-03-26 15:36
    I will have my top secret HXT900s Friday.

    My plan is to manually fly the copter and land it. The Propeller has to detect the landing and begin finding the towers and solve the puzzle.
  • Martin_HMartin_H Posts: 4,051
    edited 2015-06-22 18:08
    Just an FYI, my work has been crazy leaving me somewhat tapped out for robotics side projects. But I've been making slow, but steady progress on this challenge. The robot is built and now I am working on the software. I will post a picture shortly.

    Here's a link to the picture:

    http://ppl.ug/qkOSwCSuzQU/
  • Martin_HMartin_H Posts: 4,051
    edited 2015-07-11 16:02
    After four months of intermittent effort:


    This is a mobile robot arm that uses inverse kinematics to position the arm in a Y, Z plane while using a line sensor (Pololu QTR-8RC) to determine the X location. This allows of a substantially larger work envelope than a traditional revolute coordinate robot arm.

    Main robot chassis:
    • 1 RP5 chassis (about $50 online).
    • 1 Pololu RP5/Rover 5 Expansion plate RRC07B ($11.95 from Pololu).
    • 1 Parallax Board of education revision A (free from a friend).
    • 1 Baby Orangutan B-328 (~$10 on a 2 for 1 sale from Pololu).
    • 1 QTR-8RC reflectance sensor array ($9.95 from Pololu).
    • 2 1” Aluminum standoffs ($1 from Parallax)
    • 4 ½” Aluminum standoffs (~$1 from Pololu).
    • 1 1000 uF capacitor to buffer power (free salvage).
    • miscellaneous servo cables, three pin headers, 4-40 bolt, nuts, and washers.

    Robot arm:
    • 2 Power HD 1501MG servos for the shoulder and elbow joint ($40 from Pololu).
    • 1 Joinmax servo for the wrist, but any servo will work (~$10).
    • 1 GWS Mini L mini servo for the gripper ($13.95 from Pololu). These are light but have more torque than a typical mini servo.
    • 2 Parallax universal mounting brackets ($1.00)
    • 1 aluminum U channel (about $6 from the hardware store).
    • 1 sheet hobby plywood to make the gripper..
    • 1 flange-style servo bracket (2 for $1 from Budget Robotics).
    • 6 zip ties to dress the cables.
    • double sided sticky foam and sandpaper to line the gripper jaws.

    I modified the Baby Orangutan so I could host it on the BoE, but that isn’t needed as a breadboard would work just as well. The construction for the main part of the robot was bolt together, but I needed a way to front mount the line sensor. I used standoffs, popsicle sticks, and wood glue which did the trick.

    To construct the arm I cut uniform 6” lengths of u channel and drilled holes on the front and sides to enable bolting things to them. I bolted servo horns to one length of u channel to construct the humerus, and bolted universal mounting brackets to servos and u channel to construct the ulna. If you look at some of my other videos you’ll see I use this technique frequently as I often reuse parts between projects. The gripper is reused from an earlier project, but was laser cut from hobby plywood with a mini servo to actuate it.

    The hardest part of this project was the programming which I had to break down into phases. The first phase was getting the mobile base to find index marks that indicate the pickup and dropoff locations. The second phase was tweaking my existing inverse kinematics code to work on a Y, Z robot instead of an X, Y scara arm. The third and final phase was writing the tower of algorithm with callbacks to my code.
  • Outstanding Martin!
    Don't worry about the last block. It was not a fail as far as I am concered. 
  • Thanks! I had a perfect run, but technical problems with the camera made that video unusable. This was second best.
  • ercoerco Posts: 20,254
    Absolutely gorgeous! Well done and nice to see somebody doing something other than grumbling about this new forum. A well-needed call to action for all of us!

    Linear motion with cubes. Unique and first. Congrats to our new Robotic King!
  • ercoerco Posts: 20,254
    I'm thinking minimalism again for mine. One standard servo, one CR servo or DC motor with 1PPR encoder, and a permanent magnet with disks on posts. Will advise when time permits.
  • Thanks Erco. I look forward to seeing your entry as we always take the opposite approach. You use software as a glue for hardware, while I use hardware to enable my software.
    @Everyone else, come on and try this challenge.
  • NikosGNikosG Posts: 705
    edited 2017-01-05 21:45
    I decided to accept that challenge using the S3 and blockly in conjunction with a modified I2 3d printed robotic arm....
    I'm still in the very beginning but S3 seems that that is perfect for that.....
    P_all.jpg
    839 x 767 - 233K
  • PublisonPublison Posts: 12,366
    edited 2017-01-05 23:35
    Nikos, priceless!

  • Great, can't wait to see your progress!
  • ercoerco Posts: 20,254
    @Nikos: Since you're Greek, I think you should stack Olympic discuses for the towers of Hanoi. Should not be a problem with that heavy-duty arm of yours. :)
  • Here is the arm and the adapter on thingiverse:
    Changed base for the Lite Arm i2 & S3 robot adapter http://www.thingiverse.com/thing:2020071
  • NikosGNikosG Posts: 705
    edited 2017-01-19 23:25
    Taking the idea from Martin_H, I changed my aproach....
  • NikosGNikosG Posts: 705
    edited 2017-01-19 23:29
    I changed for a while my initial plans, and I made a clark arm for the S3 , making the robot's participation more active. So The S3 must move forward and backward in order to solve the task.
    S3_clark_arm.jpg
    The "clark" arm is my design using sketchup and my 3d printer, and has 7 parts.
    Is uses one mini servo and one standard servo.
    800 x 600 - 177K
  • NikosGNikosG Posts: 705
    edited 2017-01-20 00:09
    The initial design of that "clak" arm was for a continuous servo. Unfortunately I couldn't find a way to make the continuous servo rotate backward with blockly. So I replaced the continuous servo with a standard. That made the Rack's path smaller and so I reduced the number of disks. I can use only 5 disks instead of 9.
    clark_arm_sketchup3.jpg

    I made a sequential algorithm with blockly for 3 disks in order to check the arm. Improvements will coming soon....

    Here is a video from my first test.....

    https://youtu.be/kLoV7b4t-vk



    Blockly code on http://blockly.parallax.com/blockly/
    file name "Hanoi_Tower_3Disks (NikosG)"
    1058 x 835 - 70K
  • ercoerco Posts: 20,254
    BRAVO NIKOS! That is the COOLEST robot trick ever! I bow to your prowess, you are the Captain Fantastic of this challenge and @Ken_Gracey will LOVE it. I would be surprised if he didn't include your video in next week's S3/Blockly webinar on Tuesday. Seriously, well done and I think leaving the posts to float a bit is pure genius.

    Αυτό είναι όμορφο!
  • Roy ElthamRoy Eltham Posts: 2,996
    edited 2017-01-20 02:04
    Most excellent Nikos!

    I love your arm design too, I think I will have to print one out. Is it available on thingiverse or someplace?
  • I'm humbled and incapable. This is awesome!

    The continuous rotation servo might be a problem without some simple feedback (reed switches?) even if you could make it work. In Blockly you could use the "differential drive" from the Robot menu.

    Ken Gracey
  • WhitWhit Posts: 4,191
    Amazing work Nikos!
  • Great job Niko's!

    That makes you and I the only people to complete the challenge.

    Anyone else up for trying?
  • ercoerco Posts: 20,254
    Martin_H wrote: »
    That makes you and I the only people to complete the challenge.

    The only two real roboticists here. Congrats Guys!

    I'll get to this one day. Kinda buried now in other robot projects, getting ready for NYTF. Wish I could show them all to you to prove I'm not goofing off. After all, didn't me and my big mouth issue this challenge? :)

  • ercoerco Posts: 20,254
    Nikos will probably program his ELEV-8 in Blockly to solve Towers of Hanoi before I can get to it!
  • NikosGNikosG Posts: 705
    edited 2017-01-22 14:15
    Roy Eltham wrote: »
    Most excellent Nikos!

    I love your arm design too, I think I will have to print one out. Is it available on thingiverse or someplace?

    Roy, I attached the zip file (7 files for the arm& grippe,r and 2 for S3 addapter), for you and for anyone...
    You will need some sandpaper to correct the CA_4.stl in order to adapt good the mini servo
    I'll make some corrections in that part, and I'll post on thingiverse in next time .....
    Till then you can use as it is now. It is almost perfect...
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