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Parallax's 12V Modular Wheel and Motor Mounts - Feedback Requested!

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Comments

  • SRLMSRLM Posts: 5,045
    edited 2008-12-05 19:29
    It comes with the wheel kits. The HB-25 simply takes in a pulse, and has no idea at what speed the wheel actually rotates. Read through the HB-25 datasheet and the Wheel Kit datasheet for all the details (or at least most of them).
  • WhitWhit Posts: 4,190
    edited 2008-12-18 18:06
    I have a break after Christmas. I hope to make some progress then. I am going to go with a round design - zero turning radius.

    I am planing on using something unconventional for the platform - if I can make it work. I have been doing a bit searching lately - If it works, it will look really good.

    I also found a good local source for battery and charger.

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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
  • Ken GraceyKen Gracey Posts: 7,366
    edited 2008-12-19 20:10
    Hey guys,

    I've been working on regular business-related projects as of late, so I haven't had a chance to work on this robot. But over the last week I picked it up again and was able to mount the Ping))) sensors and GPS module. During my absence Phil Pilgrim even wrote a two-way modem protocol for use with 2-meter handheld radios, so I'll be able to put that to use too!

    I get really caught up in details. Sometimes so much that I forget about my objective and where I was headed with·the project. Such was the case with my custom Ping))) Mounting Brackets! These turned out to be a small·yet fun project all on their own for a few evenings.

    I'm now heading into the programming stage. I'll be developing the Propeller code one subsystem at a time - not faster than I can learn it though. I'll start with the individual sensors, then I'll work towards·using them for robot control, and finally I'll integrate the·2-meter radios for communication. The·goal is to navigate around the Parallax building while I sit·on my laurels in the office, monitoring sensor data on a display. The Human Resources manager has an expensive car, so I'll need to be sure to program this robot to avoid such obstacles.

    Parallax will essentially be shut down for the next·two weeks (yeah!), giving me time to work on this project and hopefully see others make some similar progress.

    Ken Gracey
    Parallax, Inc.

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  • WhitWhit Posts: 4,190
    edited 2008-12-19 21:16
    Looks great Ken! I love the Ping))) brackets too. You are making us all look bad.

    If mine turns out half this good, I will be very happy.

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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
  • Tom CTom C Posts: 461
    edited 2008-12-25 17:27
    Ken,

    Why not use a Propeller Control Board in place of the Propeller Protoboard (I bagged one when they were initially on sale)? I know that it is substantially more expensive than the Protoboard, but its use will save a lot of time building and testing individual circuits to manage sensor inputs and provide command outputs.

    The PCB has the same O&M as the Protoboard and has mounting points for the GPS, Compass, and Triaxial Accelerometer.

    Also, you can control eight servos with just two Propeller pins!

    Regards,
    TCIII

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    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!

    Post Edited (Tom C) : 12/26/2008 3:57:37 PM GMT
  • WhitWhit Posts: 4,190
    edited 2008-12-31 15:40
    Well, I ran into some problems. I wanted to use Corian for my platform. It would have been heavier than plywood, but not bad in the size we are are talking about. I wanted solid black or black with speckles (they had multi-color or gray speckles - see - http://www2.dupont.com/Surfaces/en_US/products/corian/pr_corian_colors.html Nocturne (black), Mardi Gras (black with multi-color speckles and Black Quartz or Cobalt (black with gray speckles)). I think it would have looked great with the milled aluminum and it would have been non-conductive. It is 1/2 inch thick and very stiff (agian in this size).

    Anyway, you can't actually buy the material! It is not that hard to work with -·cuts and drills easily, but the seams are·tricky (butt·joints, like for counters). That is why it is only supplied throught liscensed installers. The only way to get it is in scrap pieces from a local installer. I still may try, though I may have to wait a while to find the color in the size I need. I wanted two pieces (one extra for a future second platform).

    I am also re-thinking the two caster, zero turning radius design. On uneven surfaces I guess there is the chance of the drive wheels being raised. This is obviously not a problem with a three wheeled design. Any thoughts?

    I may just go ahead and build a more simple design and work out some of the other kinks.

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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) : 12/31/2008 3:49:57 PM GMT
  • John AbshierJohn Abshier Posts: 1,115
    edited 2008-12-31 21:08
    Some people put springs on the casters when they use two casters. It doesn't completely solve the problem of raising the drive wheels.

    John Abshier
  • Ken GraceyKen Gracey Posts: 7,366
    edited 2009-01-01 23:25
    Whit,

    When you initially proposed the round, dual-caster design I thought "that's great - it won't hit anything when it turns - a real ZTR". For some reason it took a day or three to click that the design has some problems. I've seen these designs on uneven surfaces - they kinda clunk across flooring transitions as one caster raises and the other hits the ground. It works great if everything is more or less flat. It has one huge advantage of making a zero-radius turn, of course.

    You could still make a ZTR with a round platform and one caster. Just move the weight around so that it doesn't send the rear into the air, and use speed ramping to avoid jerky movements.

    Ken Gracey
    Parallax, Inc.
  • WhitWhit Posts: 4,190
    edited 2009-01-02 03:12
    Ken and John,

    Thanks for the comments. I had thought about a three wheel design. The SLA battery certainly adds enough weight that could keep it weighted toward the tail wheel.

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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
  • WhitWhit Posts: 4,190
    edited 2009-01-08 20:55
    Ken,

    On your Hybrid Robot, I believe you had a ground wire under the bot to discharge static electricity. Will you do this with this robot? Why or why not.? Is this something that is required?

    Any body else speak to this if you have opinions (ha, ha!)

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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
  • Ken GraceyKen Gracey Posts: 7,366
    edited 2009-01-08 21:02
    Hey Whit+

    Hmm. No, just all grounds are connected together regardless of whether or not I have seperate power supplies (I'm using one 7AH/12V battery). I haven't had any issues with static, this time or on any of my larger robots. I know I'll have other problems than static, like running into parked cars. . . what starts out as a pretty robot really gets ugly as time passes.

    Ken Gracey
  • WhitWhit Posts: 4,190
    edited 2009-01-08 22:00
    Was there a ground wire under the hybrid?

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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
  • Ken GraceyKen Gracey Posts: 7,366
    edited 2009-01-08 23:03
    Nope. No ground wire on that either.

    Ken
  • WhitWhit Posts: 4,190
    edited 2009-01-08 23:23
    Ken,

    I guess I was thinking about this picture. I assumed the wire was a ground wire to discharge static electricity as the robot rolled. Don't some people do this or am I going crazy.

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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
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  • Beau SchwabeBeau Schwabe Posts: 6,488
    edited 2009-01-09 05:15
    Whit,

    The only time that I've heard of a grounding wire or chain is in the use of a Helicopter or Plane, as the rotating blades can cause a Wimhurst or Van de graff generator effect.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • WhitWhit Posts: 4,190
    edited 2009-01-09 19:13
    Thanks Beau!

    Now, I have to figure how where I saw ground wire reference. I'll probably drive myself nuts.

    Edit - Found it - I am starting a new thread on this.

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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) : 1/9/2009 7:28:43 PM GMT
  • ryan1985ryan1985 Posts: 8
    edited 2009-01-12 04:51
    @ Ken: Do you have a cad drawing of the platform you made to test the motor kit. I have a set and want to test them.


    @Whit: What's the purpose of the robot whose pic you attached 3 posts above?

    Thanks
  • Tom CTom C Posts: 461
    edited 2009-01-12 23:18
    ryan1985,

    This was Ken's last response, on 11/3/08, to my request for a cad drawing of his platform:
    "Tom,

    You got it! I haven't replied because I still haven't produced a drawing, but I can see that you've leap-frogged that problem anyway. Nice work, good chassis, and you're now caught up with me.

    Carry on!

    Ken Gracey"

    Regards,
    TCIII

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    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!
  • WhitWhit Posts: 4,190
    edited 2009-01-13 01:21
    ryan1985,

    I was asking a question about a grounding wire. The photo was Ken Gracey's Hybrid Robot. I thought the wire dangling underneath it was ground wire. It is not though.

    All,

    There is an advertisement in the March/April 2009 Robot Magazine for the 12 Volt Motor Mount and Wheel Set and the Caster Wheel Kit. The ad says, "Download 3D models of each kit and a 2D template to make your own robot base! Find them on the kit product pages at parallax.com"

    I have seen the 3D models, but I have not found the 2D template yet. Any ideas where this might be?

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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
  • Ken GraceyKen Gracey Posts: 7,366
    edited 2009-01-13 02:02
    ryan1985, Tom C, Whit,

    I'll promise you the requested drawing by Friday. The reason it didn't get finished is because I spent the rest of Christmas break programming Propellers. . .and it was so much fun!

    I'm working in the Parallax office today, but I'll be working at home the second half of the week. That's when I can get some real work done. The office is a bit too much fun to be productive.

    Ken Gracey
    Parallax, Inc.
  • Tom CTom C Posts: 461
    edited 2009-01-13 02:22
    Ken,

    Any of the Propeller programming have to do with your PropBot?

    Regards,
    TCIII

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    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!
  • WhitWhit Posts: 4,190
    edited 2009-01-13 03:04
    Thanks Ken! I was afriad it was somewhere that I couldn't find - and believe me, I really know my way around the Parallax site! turn.gif

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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
  • Ken GraceyKen Gracey Posts: 7,366
    edited 2009-01-13 03:25
    Hey Whit+, TCIII,

    I spent the first part of the break programming the Prop for a very Stamp-like project, as shown here:

    http://forums.parallax.com/forums/default.aspx?f=25&m=317563

    I wanted to do something that's really easy on the BASIC Stamp, just to get a feeling for the Propeller. As I mentioned in that thread, I've not really programmed it prior to that project (tisk tisk, I know). Now I'm programming it on the PropBot (you know which one: the wooden skateboard-looking thing). And I must say, it's an absolute pleasure to use this chip [noparse][[/noparse]no marketing here, honest]. Take the Ping))) for example. . . all of them are stuffed into an object instance that you run when you want. To get the value back from a Ping))) you simply put in your code:

    distance := ping.inches(pingPin)

    And shazamm! The result is stuffed into the distance variable. It just doesn't get any easier than this - no Ping))) communication in your main program except to get the result. With the Prop you get to sort out the working blocks of your code into nice little objects that are packed away and called upon when you need them, minimizing the complexity of your main program.

    I don't know if you have already programmed the Prop or not. You are likely miles ahead of me. But if not. . .I'd be pleased to help you get started.

    Ken Gracey
    Parallax, Inc.
  • WhitWhit Posts: 4,190
    edited 2009-01-14 02:02
    TCIII,

    You are well ahead of me on this. Sorry I can't provide any help at this time. I am still just barely "Spinning" and keep getting side tracked on other projects. One of my resolutions is to try one project at a time.

    Ken,

    Thanks for the offer of help and the update on the drawing. Glad you've been having some time to play and learn!

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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
  • VGVG Posts: 32
    edited 2009-01-15 22:28
    Hi All,
    ··· I am having trouble making Motor Mount Wheel Kit work.

    I tried the BS2 PositionControllerTestcode downloaded from Motor Mount Wheel Kit page:
    http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/Level/a/ProductID/507/Default.aspx?SortField=ProductName%2cProductName

    After executing the code I see the wheels rocking back and forth for about 3 or 4 times then stop about 5 seconds and then repeat the same.

    I tried BS2 stamp (with the above sample code) as well as Propeller (using code from Robostool). After receiving the TRVL command the controller keep on rocking the wheels until I power down/reset the Prop or BS2.

    The connections and jumpers are correct and both motors move fine with HB25. It seems the problem is only when I route control through the position controller.
    Did you see/know of·similar problem or how to solve this?

    Sincerely,
    VG.
  • DgswanerDgswaner Posts: 795
    edited 2009-01-15 22:40
    are you powering up the HB25's a few seconds after the prop/bs2?

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    DGSwaner

    "When in doubt, use C4" - Jamie Hyneman, Myth Buster
  • Kevin McCulloughKevin McCullough Posts: 62
    edited 2009-01-16 00:11
    Hi VG,

    If you are running the example code on the BS2 and still having problems, then it is likely that either the ID jumper settings are not quite right, or the motors are not wired properly to the HB-25s. The Yellow motor wire should go to M1 on the HB-25 and the Blue motor wire should go to M2. If these happened to be reversed, the motors will still run when controlling the HB-25's directly, but will not be controlled properly by the Position Controller. The Position Controller assumes that when it sends pulses to go forward to the HB-25, that the motor will actually go forward (rather than reverse).

    Here is an excerpt from the product documentation (pg. 11):
    "When using the Motor Mount and Wheel Kit in the standard mirrored left motor and right motor
    configuration, connect the yellow lead of each motor to “M1” and the blue lead of each motor to “M2” on
    each respective HB-25. In this configuration, the orientation of the Position Controller on the right-hand
    motor must be reversed in software (see the SREV command). When wired and programmed this way,
    the motors will rotate in opposite directions, but the direction of rotation will be interpreted as “positive”
    by both Position Controllers. The result is a straight path of the vehicle (rather than rotating on center).

    After wiring both leads identically, and setting the Position Controller on the right to be reversed
    orientation, both Position Controllers can be given a command to travel forward and will correctly travel
    in the same direction. If one of the motors starts traveling away uncontrollably (when they should
    otherwise be holding a position), it is likely an indication that the motor wiring is incorrect, or that the
    command to reverse the Position Controller’s orientation was sent to the wrong Position Controller, or not
    sent at all."

    After setting everything up this way, your robot should work with the supplied BS2 test code. However, it is also important to make sure that the ID jumpers on the Right and Left Position Controllers physically correspond to the test code: Right = 1; Left = 2.

    Hopefully this helps! smilewinkgrin.gif
    -Kevin McCullough
  • VGVG Posts: 32
    edited 2009-01-16 03:10
    Hi Kevin,

    ··· Thanks a lot for that reply.· I realized I was cross connecting the motor power cables (following the directions from Robostool.) M1 -> Yellow and M2 -> Blue·resolved the problem.·What is the logic behind??? I am glad you explained the logic. It makes sense.

    Thanks again.

    Venkata.
  • Tom CTom C Posts: 461
    edited 2009-01-25 20:55
    Whit, Ken,

    It has been too cold (32 F) during the day here in North Texas to do much in my unheated garage workshop. However I was able to wire up the Motor Controllers to the HB-25s and a BOE I had lying around.

    I double checked all of the wiring polarities and then ran a smoke test. I am happy to report that there was no smoke and the Motor Controllers performed as expected. Ramped the wheels up both in the same direction and then ramped them down.

    In the meantime I have been workinging on·updating my·Propeller Spin based Motor Controller program that will accept serial commands to·halt, emergency halt, go forward, go backward, and spin CW and CCW. The program also allows the user to set the distance to travel and the speed.

    The program is an adaption of Steve Norris' RoboStool Mission and MoMoCtrl spin code. I will try the Propeller spin code next weekend.

    The·program requires the following objects: FullDuplexSerial.spin and MoMoCtrl.spin.

    It compiles correctly and I get the proper feedback from each command. Each command starts with a ! and ends with a CR. Example for "go forward": !FWCR

    When using the speed and distance commands, send the command followed by a CR and then send the new speed or distance value followed by a CR. Example to set a new distance of 2500 counts: !SDCR 2500CR

    I am presently using the Parallax Simple Terminal to commuicate with the Propeller at 9600 baud, but the baud rate can be set much higher. Serial input to the Propeller is on pin 21 and output from the Propeller is on pin 22.

    Update:

    While I was reviewing the V2 code, I noticed that the commands "Left More (L2)" and "Right More (R2)" did not result in an action that was any different than the commands "Left (LF)" or "Right (RT)". I noticed that the·methods called by the LF, RT, L2, R2, commands, had an identical delay of 500ms. So I created a local variable called·"delay" that is initially set to 500ms and added it to the·VeerLeft and VeerRight·method calls, but not before setting the delay to 1000ms for the "Left More" and "Right More" commands.·Upon completion of the VeerLeft or VeerRight methods, the delay variable is set back to the default value of 500ms. The new object is called BaseMtrCtrl V3.spin.

    Regards,
    TCIII

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    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!

    Post Edited (Tom C) : 1/28/2009 2:06:42 AM GMT
  • ercoerco Posts: 20,180
    edited 2009-01-26 17:05
    Tom et al: I am very interested in these big robots you guys are building with these Parallax motors. Other than a battlebot for TLC's Robotica show, I have only build 5-pounders or less. Are your big robots intended for indoor or outdoor use, and are they evolving testbeds or do you have a specific objective in mind? If you can share any info and tests through Youtube videos, please post them and let us know.

    Tom: BTW, it's cold back here in southern California, too. It only got up to 70 degrees in Torrance yesterday! Gotta love those Santa Ana winds.

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    ·"If you build it, they will come."
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