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Thread: W.A.L.T.E.R. v2.0

  1. #1

    Arrow W.A.L.T.E.R. v2.0

    Those who know me from the Lynxmotion forums have probably seen more than they ever wanted to see about W.A.L.T.E.R. I started working on W.A.L.T.E.R. (the Wheeled Autonomous Learning Terrain Exploring Rover) in August of 2006 as my very first robot project. W.A.L.T.E.R. started out as an Octabot II kit from Budget Robotics. To put it mildly, W.A.L.T.E.R. is receiving a MAJOR make over now. I designed a set of brand new and larger octagonal shaped decks based somewhat on the original kit, and fixing what I saw as problems with that kit (wheels not properly centered in the body, all decks were not perfect octagons, etc). So, I designed four decks I believe to be perfect for two wheeled rovers like W.A.L.T.E.R.

    I use Alibre Design Expert for 3D CAD and I model every robot in full 3D before I even consider ordering parts and starting a build. So far, I have designed many more robots than I can ever probably hope to build, but I also enjoy the design and CAD process very much too. I got together with KM6VV (another Lynxmotion forum user and friend) who has a small Sherline setup. Alan (KM6VV) is a cool fellow and helped me learn what he needed to make stuff from my designs. This is the very first time I have actually seen a design of mine become real and I got a real rush when I saw the first pictures of the new decks. As it turned out, the ONLY problem with my design is that the mounting holes for the Lynxmotion MMT-02 motor mounts are spaced too far apart. I've only been working with 3D CAD since starting work on W.A.L.T.E.R. I'm really happy the way this came out!

    W.A.L.T.E.R. started out using continuous rotation servos for locomotion, but gained so much weight the poor servos failed under the load. I have since converted him to roll around on a pair of 5" off road tires on two Lynxmotion GHM-04 (now discontinued) gear head motors controlled by a Dimension Engineering Sabertooth 2x5 motor controller. I also have a Lynxmotion SSC-32 servo controller for servo control and have the Sabertooth 2x5 (bottom deck with the motors) connected to it for PWM based control at present. This is what the software for W.A.L.T.E.R. is setup for right now. I also have a pair of QME-01 shaft encoders for the GHM-04 motors, I2C compass and RTC modules, and a 3-Axis accelerometer to eventually install on W.A.L.T.E.R.

    As for sensors, there are currently 5 consisting of 3 Sharp IR Rangers (one on the end of the arm), an IRPD (rear mounted, for sneaky kitty detection), and a PING mounted above the Sharp IR Ranger on the end of the arm. I've been controlling all this and obstacle avoidance so far with a Basic Atom microcontroller made by Basic Micro, but have run out of space for much needed code additions (currently 79 bytes free).

    I have decided that I no longer want to use microcontrollers or modules that do not have decent Linux based development tools or are closed and proprietary. I want to do all development I can under Linux from now on and only really need Windows for working with Microchip PICs/dsPICs, Renesas Highspeed Embedded Workshop (which I really do like, and I have four Renesas starter kits), and of course Alibre Design Expert for 3D CAD. Well, OK, I also need Windows for when I want to play WoW (Silver Hand for Alliance and Bronzbeard for Horde) but I have not been able to play for almost 3 months now.

    Right now I am tinkering with the Hammer Board module from TinCanTools, which will be W.A.L.T.E.R.'s next main controller. I could wish for more RAM and Flash on Hammer, but I believe it will work out very good for a new main controller. I already have the Hammer Carrier board mounted on W.A.L.T.E.R. and also have the components I need to modify that for dual power (battery or wall wart). I can pretty easily convert the current software that runs W.A.L.T.E.R. over to a language such as Python since I have not used any microcontroller specific features. I have been tinkering with a Subsumption architecture, based heavily on work by members of the DPRG, for the new control software. I hope to also create a version of software for W.A.L.T.E.R. in Smalltalk (Squeak).

    My first real project with Hammer is going to be interfacing two Microchip dsPIC30F4012's to it, using I2C, which will each handle the tasks of reading and processing data from the shaft encoders (one quadrature encoder module per 4012), providing five 10-bit ADCs, more GPIOs, and perhaps other things in the future. The 4012's also have a 6 channel motor control PWM module I might eventually implement.

    These are my current plans for W.A.L.T.E.R. v2.0. I believe I can accomplish all of this in bits and pieces over a very long time. You can see some early development videos, and some current pictures, of W.A.L.T.E.R. on my website.

    8-Dale
    Last edited by LinuxGuy; 03-13-2008 at 04:07 AM. Reason: Added info about videos and pictures.
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  2. #2
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    Re: W.A.L.T.E.R. v2.0

    Very cool, Awesome project. I cant wait to see more videos.

  3. #3

    Re: W.A.L.T.E.R. v2.0

    Quote Originally Posted by Droid Works View Post
    Very cool, Awesome project. I cant wait to see more videos.
    I probably will not be posting any more new pictures or videos because all I have is a cheap $50.00 webcam. I can't get the resolution I want to show the real detail I need to show.

    However, I am almost finished with the new 3D model of W.A.L.T.E.R. 2.0, so can post a 3D PDF of that, which you will be able to rotate and zoom to see whatever you want to see from any angle.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  4. #4

    Arrow Re: W.A.L.T.E.R. v2.0

    OK, I posted a few grainy and otherwise bad pictures of the new decks for W.A.L.T.E.R.

    I am also working on an IRC bot to integrate with the rest of the software for W.A.L.T.E.R. to provide an IRC interface.

    Since the rest of the control software will also be written in Python, this should work well.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  5. #5

    Re: W.A.L.T.E.R. v2.0

    I have uploaded two images of the front arm I have designed for W.A.L.T.E.R.

    The end effector is the wrist rotate for a Lynxmotion
    Little Grip Kit.

    8-Dale

    Last edited by LinuxGuy; 07-11-2008 at 05:23 PM.
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  6. #6

    Re: W.A.L.T.E.R. v2.0: Servos

    I finally did it - broke down and ordered five servos for the front arm on W.A.L.T.E.R. I should have them early next week. I am getting 5 Hitech servos, 3 HS-645MG and 2 HS-475MG. I'll use at least two HS-645MG servos in the arm itself, with the third (pan servo) being an HS-475MG. The Gripper, which I need to add to the order, will have an HS-475MG for wrist rotation and an HS-645MG for the actual gripper. I'll shuffle servos around as required.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  7. #7

    Re: W.A.L.T.E.R. v2.0

    I've been doing some tinkering with the front mounted arm, deck spacing, etc. I'm trying to get the arm and decks working where the arm can actually reach in and pick objects (which could be RSRs) from the cargo deck and put them on the floor, as well as retrieve them from the floor and put them back on the cargo deck. I got my inspiration for this from a comment Sienna made on IRC one evening after I mentioned I also want to build a Really Small Robot. I am very close now, and may just have to raise the second deck another 1/2" or so to make it possible.

    Right now, I have the arm mounted on the front of the top deck. which does not allow it to reach all the way to the floor. I am trying to coordinate the deck spacing with the arm design, and this is proving to be quite a challenge. I've already redesigned the arm completely once and have another idea for it. The arm is made of SES brackets, so my spacing options are pretty limited.

    Update 04/21/2008: I think I have found a deck spacing, 3" between the bottom/second and second/third decks that will indeed allow W.A.L.T.E.R. to load/unload from his new cargo deck. I am also tinkering with a different way to mount the end effector sensors. I have an idea..

    I love tinkering!

    8-Dale
    Last edited by LinuxGuy; 04-21-2008 at 02:08 PM.
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  8. #8

    Arrow Re: W.A.L.T.E.R. v2.0

    Here are a few new pictures of W.A.L.T.E.R., taken at the March meeting of PARTS. All photos were done by Tyberius J5 Productions. I pulled this from my blog in case some had not had a chance to see them.

    Top Deck:

    This shows the new top deck, with all the SES compatible hole mounts for brackets, sensors, and much more.

    Left side of the arm:

    This shows the left side of W.A.L.T.E.R. with the new front mounted 3DOF arm and sensor/gripper head.

    The Electronics (Third) Deck:

    Here is a view of the electronics on the third deck. You can see the Hammer Carrier Board near the center and the Lynxmotion SSC-32 at the rear. Nothing is connected at present.

    Closer view of the electronics:


    IR Sensor Mount:

    Here you see the way I can mount sensors without interfering with the deck standoffs. The standoff just does go through the sensor mount.

    Another view of the sensor mounts:



    Fully exposed bottom:


    View of the new arm:

    I think I am going to move the arm to an upper deck. I don't think it can have full function where it is now.

    Detail of the sensor/gripper head:

    I finally figured out a way to mount two sensors together without needing an additional bracket.

    Here's lookin' at you kid:


    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  9. #9

    Re: W.A.L.T.E.R. v2.0

    Here is a small update: I've solved the problem of how to get the entire sensor/gripper assembly to rotate the way I want it to. I only need a Little Grip Attachment kit to attach the Little Grip and gripper servo. I don't know if the end effector assembly is too heavy for an HS-475HB servo to rotate, but will be finding out very soon.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  10. #10

    Re: W.A.L.T.E.R. v2.0

    I've switched to using Gentoo Embedded Linux for software development on W.A.L.T.E.R. This gives me access to much more software. I've caught the interest of the lead developer for Gentoo Embedded, and we are discussing various ideas. He wants to see W.A.L.T.E.R. operational.

    I've now got a web server (Cherokee, configured and working), SQL Database (SQLite, configured and works), web framework (DJango), and an IRC Bot (Phenny, configured and working) SSH (Dropbear), plus supporting dependency packages stuffed into the 16 MB of Flash on the Hammer. I just need two more packages (pysqlite and python imaging) to complete the software components for W.A.L.T.E.R. These last to components will allow images to be processed and connection between DJango and SQLite to be made. PySQLite will, of course, also allow SQLite to be accessed from any Python program.

    I'm doing software development using a TinCanTools Nail Board, which has built in JTAG. There are just two USB connectors protruding from the case, one for the USB Client connection to the PC and the other for USB Host to connect other devices. The USB Client provides up to three devices - JTAG, Console port, and one Gadget device. The Gadget device can be Ethernet, serial, mass storage, etc. I have it configured for Gadget Ethernet.

    I am also working on a tutorial for Gentoo Embedded Linux, but it will be awhile before I can post it here. If you want to see the progress on this tutorial, check it out on my Wiki. I also have a Blog and Forums (not setup yet).

    As you can see, I have not been idle.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

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