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Ted Revisited — Parallax Forums

Ted Revisited

ajwardajward Posts: 1,130
edited 2013-11-29 14:42 in Robotics
I finally got around to filming Ted with the new motors. At first I used the motors and mounts from the Parallax 7.2 volt motor and wheel package. Two problems: a) The motors (310 rpm) were just too darned fast. and b) The brackets were a little too thick to allow enough clearance for the tracks. To solve the problems I went to Pololu for their 37D, 130:1, 80 rpm motors and their thinner motor brackets.

To be sure Ted is slow, but tracked vehicles don't have to be setting world speed records. Below is a short video of Ted climbing an approximate 45 degree slope.

[video]http://www.flickr.com/photos/81065424@N00/9824791856/[/video]

Although I didn't film it, he can now do pivot turns on carpet... something the 310 and 200 rpm motors couldn't deliver. Now... on to more tinkering! ;-)

Amanda

Comments

  • mindrobotsmindrobots Posts: 6,506
    edited 2013-09-19 14:01
    Wow! Slow is ok. Being able to climb a 45 degree ramp? That's awesome!!

    Way to go and show!!
  • ajwardajward Posts: 1,130
    edited 2013-09-24 13:37
    Since I started building Ted, my goal was to make a surveillance vehicle. Been a lot of obstacles, but I have a "very" rudimentary critter working. I haven't figured out how to do live video with wireless control, tho' I can record about 30 minutes on an old digicam while running predetermined course. I've attached some video Ted captured while wandering around... on a sidewalk, climbing a slope and driving across some landscaping chips. Focus is poor, but it's an old camera.
    There is a lot of vibration on flat surfaces, but that's because of the small sprockets.

    Along the sidewalk...
    [video]http://www.flickr.com/photos/81065424@N00/9921518196/[/video]

    Climbing a slope...
    [video]http://www.flickr.com/photos/81065424@N00/9921488665/[/video]

    Driving over the wood chips...
    [video]http://www.flickr.com/photos/81065424@N00/9921655153/[/video]
    In this one, he managed to climb over a small brick border and get into the neighbor's yard. :-)

    Lastly, Ted's current configuration...
    101_0006.jpg
    101_0006.jpg
    1024 x 768 - 109K
  • NWCCTVNWCCTV Posts: 3,629
    edited 2013-09-25 20:15
    I haven't figured out how to do live video with wireless control,
    Would this work? They are quite nifty devices and can be plugged to a capture card on a pc or direct to any RCA monitor. I have used the 2.4Ghz version in the past with good results, for the price any ways.
    http://www.ebay.com/itm/5-8Ghz-Smallest-color-wireless-camera-55-90-deg-0-008lux-8g-weight-spy-gadget-/281046721393?pt=US_Security_Cameras&hash=item416fb0a371


    EDIT: I am in the CCTV business and have access to some very high end equipment if you want to go that route. But. it is VERY expensive stuff. Law Enforcement/ Military grade.
  • ajwardajward Posts: 1,130
    edited 2013-09-28 17:23
    NWCCTV wrote: »
    Would this work? They are quite nifty devices and can be plugged to a capture card on a pc or direct to any RCA monitor. I have used the 2.4Ghz version in the past with good results, for the price any ways.
    http://www.ebay.com/itm/5-8Ghz-Smallest-color-wireless-camera-55-90-deg-0-008lux-8g-weight-spy-gadget-/281046721393?pt=US_Security_Cameras&hash=item416fb0a371


    EDIT: I am in the CCTV business and have access to some very high end equipment if you want to go that route. But. it is VERY expensive stuff. Law Enforcement/ Military grade.

    Interesting... What kind of receiver does it require? What sort of power input? I've tried a 2.4 GHz unit, but with the 2.4 GHz xBee, 2.4 GHz Camera, 2.4GHz wireless network and 2.4 GHz wireless phone, things get mucked up rather quickly. I can do the 2.4 wireless camera if I use a preprogrammed route, but that's =not=quite= where I want to go.

    Heh... Law enforcement/Military grade... that would be great. Of course, =way outside= my finances, but something to day-dream about. Actually, I'm happy if my critters can wander around for half an hour without something getting loose or falling off!!!!!

    Thanks for your response Andy! Much appreciated!!

    Amanda
  • NWCCTVNWCCTV Posts: 3,629
    edited 2013-09-28 17:38
    The same company sells receivers to go with them. Any 5.8 GHz receiver would work as long as you know what channel to have the seller set the camera at. They are pretty much all the same. There is also one that is a monitor/receiver in one. Pretty nifty I think. I have used 2.4 GHz also. Problem is, when the microwave gets turned on everything goes haywire!!!

    EDIT: You can change the channel your wireless network is on to alleviate a portion of the interference problems.
  • jazzedjazzed Posts: 11,803
    edited 2013-09-28 17:47
    Cool Flicker stream. Loved your dancing Penguin too!
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-09-30 11:05
    I tried a cheap 2.4GHz system on my RC helicopter. It worked while the helicopter was on the ground with the motor off but once the 'copter was airborne, the video was nothing but static. Make sure and check your system's reception with motors powered up.

    I had better results with a 900MHz system on my ELEV-8.

    Low frequency transmitters generally have better range than higher frequency transmitters when using the same amount of power (something to do with the physics of radio/electromagnetic radiation).

    If you can get a transmitter that will also transmit sound you could use a text to speech chip to transmit data over the audio line.

    I'm also working on a treaded robot. I just posted some pictures here.
  • xanaduxanadu Posts: 3,347
    edited 2013-09-30 16:00
    Very nice, where did you get those tracks?

    For video I think 1.2ghz works best. I've used them all over the years and stopped at 1.2. It is very well rounded in power management and also antenna size, not to mention way less interference from other devices.
  • doggiedocdoggiedoc Posts: 2,243
    edited 2013-09-30 17:54
    Cool... really like that track base.
  • George SuttonGeorge Sutton Posts: 180
    edited 2013-09-30 19:20
    ajward wrote: »
    I finally got around to filming Ted with the new motors. At first I used the motors and mounts from the Parallax 7.2 volt motor and wheel package. Two problems: a) The motors (310 rpm) were just too darned fast. and b) The brackets were a little too thick to allow enough clearance for the tracks. To solve the problems I went to Pololu for their 37D, 130:1, 80 rpm motors and their thinner motor brackets.

    To be sure Ted is slow, but tracked vehicles don't have to be setting world speed records. Below is a short video of Ted climbing an approximate 45 degree slope.

    [video]http://www.flickr.com/photos/81065424@N00/9824791856/[/video]

    Although I didn't film it, he can now do pivot turns on carpet... something the 310 and 200 rpm motors couldn't deliver. Now... on to more tinkering! ;-)

    Amanda
    Your tracked platform is great. Do you have a link to a site for more construction details? Also, can you tell me what video camera you are using, and how the video is being transmitted? I am looking for a low-cost video camera to use on my mobile (wheeled) robotic inspection platform, and your video would work for me. Thank you,
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-09-30 21:49
    xanadu wrote: »
    Very nice, where did you get those tracks?

    Aren't those nice? I'm envious of her Lynxmotion tracks. I've come close, many times, to purchasing some myself.
  • photomankcphotomankc Posts: 943
    edited 2013-10-01 07:12
    Slow and highly capable is better than fast barely capable. You have lots of time to gather sensor data and react, you have enough power to get past obstacles when you need to. Nice I'd say. Pretty good litmus test I would say in doing diff-turns on carpet.
  • ajwardajward Posts: 1,130
    edited 2013-10-01 09:20
    George Sutton wrote: »
    Your tracked platform is great. Do you have a link to a site for more construction details? Also, can you tell me what video camera you are using, and how the video is being transmitted? I am looking for a low-cost video camera to use on my mobile (wheeled) robotic inspection platform, and your video would work for me. Thank you,

    Hi George! Construction was pretty straightforward... for me anyhow. There was a thread for the original build, but I can't seem to find it. So... a few photos:

    Idler.jpg

    Front idler: Could've been a lot better, but there are budget concerns and I wanted to use as many parts I already had on hand. (Hub and sprocket from Lynxmotion)

    Motor.jpg

    Motor and mount: Both from Pololu. The motor is a 37D with a 131:1 gear ratio (80 RPM). I tried 310 and 200 RPM motors, but the torque was just too low.

    Side.jpg

    Complete side with the tracks connected. 1 Lynxmotion 2-inch track set per side.

    Top.jpg

    Top view: Using the defunct MSR1 robot controller board.

    The deck is 1/4 inch expanded PVC. I'd like to use aluminum but, I really don't have the equipment to work with it. 'Sides the scrap bin at Tap Plastics is hard to beat for price! :-)

    The video above was taken with an old Vivitar digital camera. For wireless, I use a Wisecomm camera and receiver. Of course it operates at 2.4 GHz as does most everything else around here.

    Anyway, that's pretty much the process. HTH

    Amanda
    Idler.jpg
    1024 x 769 - 47K
    Motor.jpg
    1024 x 769 - 67K
    Side.jpg
    1024 x 769 - 97K
    Top.jpg
    1024 x 769 - 107K
  • George SuttonGeorge Sutton Posts: 180
    edited 2013-10-01 18:44
    ajward wrote: »
    The video above was taken with an old Vivitar digital camera. For wireless, I use a Wisecomm camera and receiver. Of course it operates at 2.4 GHz as does most everything else around here.

    Anyway, that's pretty much the process. HTH

    Amanda
    Thank you for the information! I appreciate you providing the parts info. I may have to use some of your ideas in the future. You have a really inventive design that works very well according to the videos you provided earlier. I checked out the camera (thanks for the link). With the internal rechargeable batteries, it may be something for me to consider. I found your video quality to be sufficient for my anticipated needs, and I may have to invest in one of these. Thank you for the reply.
  • xanaduxanadu Posts: 3,347
    edited 2013-11-26 13:09
    Amanda,

    I've been trying to get something going with these tracks in this thread - http://forums.parallax.com/showthread.php/151774-Project-XI-AR1

    Do the center of your tracks ride on the sprockets or is the whole track off one notch to the side for clearance?

    Also are you using the hubs that Lynx sells or did you get them somewhere else?

    I think I am coming to the conclusion I should not have shopped for hardware at Lynx (other then the track itself) because it looks like all of their stuff is designed to be used on their "Tri-Track System" robot.

    Thanks!
  • ajwardajward Posts: 1,130
    edited 2013-11-29 14:42
    xanadu wrote: »
    Amanda,

    I've been trying to get something going with these tracks in this thread - http://forums.parallax.com/showthread.php/151774-Project-XI-AR1

    Do the center of your tracks ride on the sprockets or is the whole track off one notch to the side for clearance?

    Also are you using the hubs that Lynx sells or did you get them somewhere else?

    I think I am coming to the conclusion I should not have shopped for hardware at Lynx (other then the track itself) because it looks like all of their stuff is designed to be used on their "Tri-Track System" robot.

    Thanks!

    Hi There...

    Yeah, I had to offset the tracks. I found that with any of the motor mounts I could find, the tracks had to be offset to keep the track from catching the corner of the mount. I did make mounts out of PVC pipe that eliminated the clearance problem, but when I upgraded the motors, they didn't fit in the PVC. (Some machining on the available brackets would 'probably' fix the clearance issue, I don't have the equipment to verify that. :-< )

    I used the Lynxmotion hubs and sprockets cuz' I didn't see any alternatives. While a lot of those parts are oriented toward the tri-track chassis, I don't think they're required to develop a decent chassis. (I think the only thing Ted needs is some decent road wheels)

    HTH,

    Amanda
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