Shop Learn
Parallax's 12V Modular Wheel and Motor Mounts - Feedback Requested! - Page 13 — Parallax Forums

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

1910111315

Comments

  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2008-11-06 18:53
    I just received a Parallax Motor mount and wheel kit with the position controllers and HB-25's. Upon opening the package I must say I am impressed with the craftsmanship that Parallax has put into this kit. The machining is first class and it is a very well thought out product that will enable many people to start building larger robots.

    I'm going to try out the kit as intended using the HB-25's for control with the included position controllers for a new robot. After that I plan on interfacing them with some other controllers which would enable these motors to be used as a base for other robot projects. When I have some news on that I'll let everyone know.

    Upon reviewing the documentation I do have a couple of things I would like to see incorporated into the next revision of the position controllers. These changes would still allow any existing programs to work just fine. According to the schematic there are a couple of unused pins on the ATiny2313 chip. These could be put to work on an upgrade. Some ideas for changes are listed below:

    - Use one of the unused pins on the ATiny2313 processor to set the initial direction of the encoder/motor assembly. This could be as simple as a 2-pin header for a jumper to ground (with a 10K pull-up). This would just preset the SREV flag. This way if power gets lost the controller won't forget what direction is set and have to be told by the host controller. I would prefer to see this as the way to setup the motors when installing them in the base. It can always be overridden by a software command but the initial state would always come up via the jumper setting.

    - Add a command to mirror SREV (perhaps called SFWD). Using either of these would override the initial setting specified by the jumper.

    - Bring the two opto-interrupter outputs to a set of pads (as well as +5v and GND) so that a person could just get the raw quadrature data for use with an existing motor controller.

    In regards to the new caster wheel kit does anyone happen to know the load capacity of those dubro 3" wheels? I've checked on the dubro site and still haven't been able to locate a rating on them. It would be nice to know the rating for each tire and also the pair as used with the caster kit.

    This is a great kit and I am excited about putting it to work.

    Robert
  • ZootZoot Posts: 2,227
    edited 2008-11-06 19:02
    I would like to add to Robert's wishlist the following ---

    Please USE AN SX INSTEAD OF THE TINY. While the firmware for the encoders is pretty decent, it would change my world to be able to put my own firmware into an SX20 or SX28. I am *most* curious -- since most Parallax peripherals are SX based, why the decision to use the Tinys on the motor encoders??

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    When the going gets weird, the weird turn pro. -- HST

    1uffakind.com/robots/povBitMapBuilder.php
    1uffakind.com/robots/resistorLadder.php
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2008-11-06 19:24
    If switching to an SX processor is an option for a future version of the position controller then I would like to see that option as well. Good suggestion Zoot! Then we could end up tweaking the code to do whatever we want.

    Otherwise I hope the existing suggestions will be considered to see if they can be working into the existing controller.

    Robert
  • WhitWhit Posts: 4,191
    edited 2008-11-06 20:52
    Tom C said...

    You might want to take a look at the spin code that Steve Norris used to control his Robostool project which use the HB-25s and the Motor Mount Position Controllers. He makes use of the MoMoctrl spin object.
    Thanks for the tip TCIII!


    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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
  • jcoloniasjcolonias Posts: 31
    edited 2008-11-06 22:08
    Whit

    Where can I find Norris's spin code using HB-25s? I am designing a robot and
    I might find some useful information in that code.

    Thank you, John
  • Tom CTom C Posts: 461
    edited 2008-11-06 23:25
    jcolonias,

    I can answer your question:

    The first link uses the HB-25s with the Position Controller.

    http://www.norrislabs.com/Projects/RoboStool/index.html

    This link just uses the HB-25s directly.

    http://www.norrislabs.com/Projects/Huey/index.html

    Hope this helps.

    Regards,
    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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: 4,191
    edited 2008-11-07 15:13
    jcolonias,

    TCIII beat me in getting back to you. Norris' site is fun to chech out all the way around.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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
  • jcoloniasjcolonias Posts: 31
    edited 2008-11-07 16:45
    Thank you TCIII and Whit. A appreciate your quick response and I will
    navigate in that site.

    John
  • Tom CTom C Posts: 461
    edited 2008-11-07 22:59
    Whit/John,

    I have several robotic platforms in work one of which uses the Modular Wheel and Motor Mounts. The other two use either a pair of HB-25s or a Sabertooth 2X10 motor controller. Given that I have three different motor control systems to deal with, I decided to make the central MCU the same for all three robots and have it interface serially with each different motor control system using a common command set.

    The MCU will take care of obstacle avoidance, navigation and other functions like speech or voice recognition. I very much like the way that Steve Norris has organized the functions in his robots and have learned alot about Propeller spin code generation from his robot control programs.

    I was hoping that Parallax might come out with·common motor driver code in PBasic and spin for control of the·Position Controllers/HB-25s to provide a jumping off point for beginner and intermediate robot enthusiasts. Also they might throw in some obstacle·avoidance and navigation code. It is not that I am lazy as I have quite a collection of PBasic/spin·code for motor control, obstacle avoidance and navigation, but if we can start with code that works, we can then customize it work as we want it to work without the frustration of trying to get the code to work in the first place.

    Just a thought.

    Regards,

    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!
  • Tom CTom C Posts: 461
    edited 2008-11-08 21:32
    Hi all,

    I have found that one of the 6 X 1 1/4 tires from the Modular Wheel and Motor Mounts kit is substantially out of round.cry.gif

    Trimming the bead of the tire helped to reduce the tire precession, but not enough to satisify me.

    I have found this scooter store in CA that sells the exact same tire and replacement inner tube: http://www.electricscooterparts.com/tires.html·smile.gif

    There are other scooter stores on-line that sell 6 X 1 1/4 tires, but they are either solid or must be inflated to 85psi.

    I plan to buy a new tire and a spare inner tube incase the existing ones start to leak.

    I emailed Parallax about the out of round tire and they provided me with an RMA to send it back for an exchange. You can always count on Parallax to guarantee their products!smile.gif


    Regards,
    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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) : 11/11/2008 3:00:51 AM GMT
  • Tom CTom C Posts: 461
    edited 2008-11-10 01:24
    Hi all,

    I managed to push my Modular Wheel and Motor Mounts equipped robot along somewhat this weekend.

    I mounted the 12vdc 7AHr battery under the chassis like Ken did. However, I left room for a bigger battery. It seems that up until a certain size, most of the SLA batteries are of the same length and width and and very the height depending on the current rating. I set up my battery mount so that I can add an SLA battery of up to 14AHr without changing the mounting arrangement.

    I also mounted the HB25s to the chassis along with an European style barrier strip to distribute power and ground and other various signals.

    I will probably temporarily mount a BS2 on the chassis to check out the HB-25s and then the Position Controllers next week end.

    I will have some pics of the updated chassis as soon as my photographer, my wife, gets over a 24hr flu bug.

    Regards,
    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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: 4,191
    edited 2008-11-10 20:31
    TCIII, John and Ken,

    I just received the Caster Wheel Kit today! It is absolutely beautiful. I have to be honest that I am now tempted a to order another and go for circular zero turning radius platform. Did any of you consider that with your design? Is a three wheel design more versitile?

    The Caster Wheel Set truly matches the quaility of the 12 volt wheel set. Thanks for another great product Parallax!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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) : 11/10/2008 8:48:34 PM GMT
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2008-11-10 20:35
    The Castor kit is very well done and the machining is fantastic. I would like to get the weight ratings for the tires though. I haven't been able to find any specs yet and don't want to overload them.

    Robert
  • ercoerco Posts: 20,139
    edited 2008-11-11 00:00
    Tom:

    Another source for tires and general electric scooter parts is http://tncscooters.com/partsdb.php?type=ES in Tennesee. They have great prices and very quick service. Also on ebay at http://stores.ebay.com/TNC-Scooters

    erco

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·"If you build it, they will come."
  • Tom CTom C Posts: 461
    edited 2008-11-11 00:57
    erco,

    Thanks for the lead, but unless I missed them, tncscooters does not appear to stock 6 X 1 1/4 tires.

    Regards,
    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!
  • Tom CTom C Posts: 461
    edited 2008-11-17 00:12
    Hi all,

    Since there has not been a contribution to this thread other than this one in the last week, I guess that enthusiasm is kind of waining in regard to the Modular Motor Mount and Position Controller.

    Anyway, I have moved my robot project along this weekend. I added an upper deck made out of 1/2" birch plywood and supported by four 3/8" dia threaded rods.

    I spotted the holes on the top deck necessary to add a motorized turret mount. I have a heavily geared down motor drive that has a 5/16" dia output shaft that I will use to pan the turret when mounted to the top deck.

    I think that I will use a 12" dia concrete form tube as the body of the turret and add a head and arms to the top of the turret.

    More next weekend.

    Regards,
    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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) : 11/17/2008 5:49:23 PM GMT
    375 x 500 - 179K
    500 x 375 - 175K
  • Chuck RiceChuck Rice Posts: 210
    edited 2008-11-18 05:04
    My MMWK is scheduled to arrive in 3 days. Looking forward to it. I could not find an object for it in OBEX, so I have already coded a spin object to drive it. (Then I discovered that the MoMo driver existed!). Mine looks pretty much the same, except it is using Simple-H H-Bridges which I already had on hand.

    My question is, what is the True Stall Current. i.e. Locked-wheels current, and what is the Stall Torque. I do not understand why datasheets list the no load current, as that is just the minimum current required to turn the driveshaft. It would be helpful to get that info in the datasheet.
  • DgswanerDgswaner Posts: 795
    edited 2008-11-18 15:29
    Chuck, back on page 13 I wrote:

    no load starting peak was 5 amps
    with load the peak was 8 amps
    if I tried to stop the wheel I could get it up to 10 amps or even higher, but I didn't want to try too hard. hope that helps, oh and that was only one motor.

    this was measured with an analog ammeter so your millage may vary

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    DGSwaner

    "When in doubt, use C4" - Jamie Hyneman, Myth Buster
  • Chuck RiceChuck Rice Posts: 210
    edited 2008-11-18 16:03
    Dgswaner said...
    Chuck, back on page 13 I wrote:

    no load starting peak was 5 amps
    with load the peak was 8 amps
    if I tried to stop the wheel I could get it up to 10 amps or even higher, but I didn't want to try too hard. hope that helps, oh and that was only one motor.

    this was measured with an analog ammeter so your millage may vary

    Thanks Dgswaner! I did read that, but I did not think that that was the max continuos stall current. I can go up to 20 amps (with no fan), but I would hate to blow the bridges because I get a stick caught in the spokes.
  • DgswanerDgswaner Posts: 795
    edited 2008-11-18 16:15
    If I recall correctly, I could get it to spike higher than 10, up to about 14 if I stopped really quickly, I didn't want to ruin by HB-25s so I didn't do too much messing around with it.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    DGSwaner

    "When in doubt, use C4" - Jamie Hyneman, Myth Buster
  • Chuck RiceChuck Rice Posts: 210
    edited 2008-11-21 02:54
    I got my MMWK today and have them mounted on my bot. not wired yet, but they look nice. They are a bit smaller than the 7 inchers that I had before, but I think that will be ok. I could not mount them exactly where I wanted them because my frame got in the way of the motors. I wish there were two more mounting holes on then end away from the motors. That would give the option to mount them vertical. I have more room vertically than horizontally.

    I had not noticed that they did not come with 1/4-20 mounting bolts and I did not have any in stock, so I had to make a quick run to the Hardware Store. A tool list would have been handy, but all in all, they are pretty nice!
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2008-11-21 14:28
    The black tires are pretty cool but I just found some non-marking gray tires that look like they will fit these rims. Check out the link below:

    http://www.quickie-wheelchairs.com/Wheelchair_Parts/Wheelchair_Tires/6_x_1_14_Pneumatic_Tire_Light_Gray/2270p0

    I may order a pair of these to try out myself.

    They seem to have a decent selection of other tires too:

    http://www.quickie-wheelchairs.com/Wheelchair_Parts/Wheelchair_Tires/521c0

    If anyone buys a set before I can order them please let us know how they work out.

    Robert
  • Beau SchwabeBeau Schwabe Posts: 6,487
    edited 2008-11-21 15:11
    RobotWorkshop,

    If the inner diameter is about 3.5 inches with a rim diameter of about 4.0 inches those wheels should work, but it's hard to tell from that link you provided if the inner diameter is within the necessary·range.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2008-11-21 16:01
    Hello Beau,

    I guess I'll ask them if they take returns before ordering a pair just in case they don't fit. Hopefully they will since that opens up another option for a replacement tire and one that should be easy on the floors. They also have a molded foam insert too avoid using tubes. That may be a desirable option for some people. It would be worth trying both the tires and foam inserts with the Parallax motor set.

    Robert
  • Beau SchwabeBeau Schwabe Posts: 6,487
    edited 2008-11-22 05:49
    RobotWorkshop,

    I would try contacting them and asking someone to take an inner diameter tire and rim measurement. Be polite, just tell them that you are interested in purchasing one of their tires. Be sure and mention which tire model you want to use. I don't think that this would be an unreasonable request.


    http://www.quickie-wheelchairs.com/contact_us/

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • StampNut2StampNut2 Posts: 224
    edited 2008-11-26 18:04
    Ken: Great looking robot platform, keep up the good work. I have not posted for some time, Have been building a highly modded J5 with 5990 digital servos and a T-1 from rise of the machines.. Hey Whit how's it going, Any progress on your 12v modular system?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Never give up when things go wrong, Just work them out.

    robosapienv2-4mem8.page.tl/
  • bulkheadbulkhead Posts: 405
    edited 2008-12-05 07:04
    "The included Position Controllers use a quadrature encoder system to reliably track the position and speed of each wheel and report the data on demand. They can also be interfaced with HB-25 motor controllers (#29144; sold separately) to automatically provide smooth speed ramping and accurate position control. "

    I searched but couldn't find any info on the position control part. Can the encoders on the motors connect directly to the HB-25 for position control? Or does the statement imply that a microcontroller must be used to take encoder data and control the output signal to the HB-25? If this is the case, is there any code written for the Propeller that will do this? I'm looking for a complete, ready to use position/speed controller solution.
  • SRLMSRLM Posts: 5,045
    edited 2008-12-05 07:14
    I believe the wheel control computers do all the talking to the HB-25. You just send the wheel computers the serial data as specified in the data sheet, and you don't have to worry about counting revolutions or any of that.
  • Tom CTom C Posts: 461
    edited 2008-12-05 12:36
    SRLM,

    Your statement is correct about the wheel control computers and the way that they interface with the HB-25s or any motor controller that can accept servo style PWM.

    Regards,

    TCIII

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!
  • bulkheadbulkhead Posts: 405
    edited 2008-12-05 19:03
    Where exactly is the wheel control computer? On the HB-25?
Sign In or Register to comment.