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Re: [SeattleRobotics] Chassis for Magellan like robot.

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  • Tom Saxton
    Our Robo-Magellan entry, Scout, is based on the Tamiya Super Clod Buster R/C Monster Truck. It s a bit spendy (about $250 from Tower Hobbies), but it is four
    Message 1 of 10 , Oct 1, 2004
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      Our Robo-Magellan entry, Scout, is based on the Tamiya Super Clod Buster R/C
      Monster Truck. It's a bit spendy (about $250 from Tower Hobbies), but it is
      four wheel drive, four wheel steer, and gets you an all terrain chassis with
      motors, gear box and wheels very quickly. You'll also need to buy a 7.2 V RC
      car battery and charger.

      We threw out the three-speed motor controller (a complicated switch with
      some big resistors to take part of the load at lower speeds) and replaced it
      with a IFI Victor 884 ($100?). (An H-Bridge that can handle a few amps would
      probably work fine and cost less.) The motors will take 10+ amps if you wire
      them in parallel and stall them at full throttle. We wired them in series,
      run them at a fraction of full speed, and draw between 1 and 2 amps.

      We used Larry Barello's ARC board with an ATmega32 for the CPU. We also
      stacked an auxiliary board to interface with the sensors and drive an LCD
      for menus and debugging.

      Our kill switch is based on a $5 Sharp solid state relay (DigiKey) between
      the Victor output and the motors, wired to a Cat5 cable with a simple
      contact switch. Note that the relay is really intended for switching AC, so
      it doesn't work if you put it between the battery and motor controller -- it
      won't ever turn off. (That was a rude little last minute discovery.)
      Fortunately, the PWM output from the Victor looks enough like AC that it
      does switch off correctly.

      Our sensors are a CMUcam v1.1 ($100), an Analog Devices digital rate sensor
      evaluation board ($50), encoders mounted inside two of the hubs (Hamamatsu
      sensors with laser cut acrylic discs) and simple contact sensors (cheap)
      mounted between the "chrome" bumper and the chassis.

      Our next hardware upgrade will be to put on a sonar sensor for obstacle
      avoidance.

      I can dig up actual part numbers if anyone cares. I should put it on a web
      site. Someday...

      --
      Tom Saxton
      tomsax@...


      on 9/30/04 5:36 PM, Ben Greear wrote:

      >
      > Hello!
      >
      > I was inspired by the Robo fest to attempt to build a robot that could
      > compete in the Magellan challenge. I feel that I will have a good chance
      > at doing clever things with software, but at hardware I am much more
      > a newbie. So, I was hoping to get a mostly pre-built chassis with drive
      > train and then spend my main effort interfacing a small PC motherboard
      > with motor controllers, GPS, cameras, compass's etc....
      >
      > Any suggestions for such a chassis?
      >
      > Thanks,
      > Ben
    • jay_c_beavers
      I m with you. I like the software but pretty hardware challenged. I followed the pattern of the UPenn s GRASP project and used a Tamiya TXT-1 monster truck as
      Message 2 of 10 , Oct 1, 2004
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        I'm with you. I like the software but pretty hardware challenged.

        I followed the pattern of the UPenn's GRASP project and used a
        Tamiya TXT-1 monster truck as the chassis
        (http://www.cis.upenn.edu/mars/site/platforms.htm).

        I have a pretty detailed description of the parts I assembled and
        the changes you have to make to the stock TXT-1 chassis on
        http://cylonrobot.blotspot.com The GRASP site also has a changes
        list that talk about how to "robot-ize" the TXT-1 chassis.

        - jcb

        --- In SeattleRobotics@yahoogroups.com, Ben Greear <greearb@c...>
        wrote:
        > Hello!
        >
        > I was inspired by the Robo fest to attempt to build a robot that
        could
        > compete in the Magellan challenge. I feel that I will have a good
        chance
        > at doing clever things with software, but at hardware I am much
        more
        > a newbie. So, I was hoping to get a mostly pre-built chassis with
        drive
        > train and then spend my main effort interfacing a small PC
        motherboard
        > with motor controllers, GPS, cameras, compass's etc....
        >
        > Any suggestions for such a chassis?
        >
        > Thanks,
        > Ben
        >
        > --
        > Ben Greear <greearb@c...>
        > Candela Technologies Inc http://www.candelatech.com
      • John McIvor
        You might want to consider looking for a Rolling Chassis of RC truck or buggy on eBay. Many of these have been pounded on pretty hard before they are sold,
        Message 3 of 10 , Oct 1, 2004
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          You might want to consider looking for a "Rolling Chassis" of RC truck
          or buggy on eBay. Many of these have been pounded on pretty hard before
          they are sold, but the basic chassis components are very tough, and
          parts are easy to get. I bought a really nice 1/8 scale gas buggy this
          way. I did have to put in my own electric motor, but it's not too hard
          to do that conversion. There are either none, or very few electrics in
          1/8 scale. Be careful when selecting an RC chassis if you choose to go
          this way, I looked at quite a few lower end RC vehicles and the problem
          with many of them is they are made from a lot of molded plastic
          components that are not meant to be taken apart. The higher end hobby
          vehicles are completely disassembleable and made from steel and
          aluminum, making them much more flexible to build onto.

          ...John


          >>>>>>>>>>>
          .... So, I was hoping to get a mostly pre-built chassis with drive
          train and then spend my main effort interfacing a small PC motherboard
          with motor controllers, GPS, cameras, compass's etc....

          Any suggestions for such a chassis?

          Thanks,
          Ben
        • Ben Greear
          ... Looks promising. That cylonrobot.blogspot.com just takes me to the main blog creation page. Do you have a different link maybe? Ben -- Ben Greear
          Message 4 of 10 , Oct 1, 2004
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            jay_c_beavers wrote:
            > I'm with you. I like the software but pretty hardware challenged.
            >
            > I followed the pattern of the UPenn's GRASP project and used a
            > Tamiya TXT-1 monster truck as the chassis
            > (http://www.cis.upenn.edu/mars/site/platforms.htm).
            >
            > I have a pretty detailed description of the parts I assembled and
            > the changes you have to make to the stock TXT-1 chassis on
            > http://cylonrobot.blotspot.com The GRASP site also has a changes
            > list that talk about how to "robot-ize" the TXT-1 chassis.
            >
            > - jcb

            Looks promising. That cylonrobot.blogspot.com just takes me to
            the main blog creation page. Do you have a different link maybe?

            Ben

            --
            Ben Greear <greearb@...>
            Candela Technologies Inc http://www.candelatech.com
          • Jay Beavers
            They seem to be having a problem with the redirection of that root page the last day or two. It works about 90% of the time I ve tried it. I ve just seen
            Message 5 of 10 , Oct 1, 2004
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              They seem to be having a problem with the redirection of that root page the last day or two. It works about 90% of the time I've tried it. I've just seen this happen 2-3 times over the past day or two.
              ----- Original Message -----
              From: Ben Greear<mailto:greearb@...>
              To: SeattleRobotics@yahoogroups.com<mailto:SeattleRobotics@yahoogroups.com>
              Sent: Friday, October 01, 2004 2:53 PM
              Subject: Re: [SeattleRobotics] Re: Chassis for Magellan like robot.



              jay_c_beavers wrote:
              > I'm with you. I like the software but pretty hardware challenged.
              >
              > I followed the pattern of the UPenn's GRASP project and used a
              > Tamiya TXT-1 monster truck as the chassis
              > (http://www.cis.upenn.edu/mars/site/platforms.htm<http://www.cis.upenn.edu/mars/site/platforms.htm>).
              >
              > I have a pretty detailed description of the parts I assembled and
              > the changes you have to make to the stock TXT-1 chassis on
              > http://cylonrobot.blotspot.com<http://cylonrobot.blotspot.com/>. The GRASP site also has a changes
              > list that talk about how to "robot-ize" the TXT-1 chassis.
              >
              > - jcb

              Looks promising. That cylonrobot.blogspot.com just takes me to
              the main blog creation page. Do you have a different link maybe?

              Ben

              --
              Ben Greear <greearb@...<mailto:greearb@...>>
              Candela Technologies Inc http://www.candelatech.com<http://www.candelatech.com/>



              Visit the SRS Website at http://www.seattlerobotics.org<http://www.seattlerobotics.org/>
              Yahoo! Groups Links









              [Non-text portions of this message have been removed]
            • Ben Greear
              ... I did manage to find your blog, but I wasn t able to find any details on how you interfaced a computer with the TXT-1 s drive train. I assume I would need
              Message 6 of 10 , Oct 18, 2004
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                jay_c_beavers wrote:
                > I'm with you. I like the software but pretty hardware challenged.
                >
                > I followed the pattern of the UPenn's GRASP project and used a
                > Tamiya TXT-1 monster truck as the chassis
                > (http://www.cis.upenn.edu/mars/site/platforms.htm).
                >
                > I have a pretty detailed description of the parts I assembled and
                > the changes you have to make to the stock TXT-1 chassis on
                > http://cylonrobot.blotspot.com The GRASP site also has a changes
                > list that talk about how to "robot-ize" the TXT-1 chassis.

                I did manage to find your blog, but I wasn't able to find any
                details on how you interfaced a computer with the TXT-1's drive
                train.

                I assume I would need some sort of servo-control hardware to
                replace the standard RC control interface? Any pointers to
                such a thing and/or general information on the topic would
                be very welcome!

                Thanks,
                Ben

                --
                Ben Greear <greearb@...>
                Candela Technologies Inc http://www.candelatech.com
              • Tom Saxton
                ... We used a Tamiya Super Clod Buster chassis and just replaced the switch/resistor setup with a Victor 884. The details with part numbers and links are on
                Message 7 of 10 , Oct 20, 2004
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                  on 10/18/04 9:01 PM, Ben Greear wrote:

                  > I did manage to find your blog, but I wasn't able to find any
                  > details on how you interfaced a computer with the TXT-1's drive
                  > train.
                  >
                  > I assume I would need some sort of servo-control hardware to
                  > replace the standard RC control interface? Any pointers to
                  > such a thing and/or general information on the topic would
                  > be very welcome!

                  We used a Tamiya Super Clod Buster chassis and just replaced the
                  switch/resistor setup with a Victor 884. The details with part numbers and
                  links are on our web page:

                  http://www.idleloop.com/robotics/Scout/

                  You could probably also use any H-Bridge capable of handling a few amps.

                  --
                  Tom Saxton
                  tomsax@...
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