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Forum Member
 
Group: Forum Members
Last Login: Saturday, August 14, 2010 12:06 PM
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I have never been successful with the Traxster II on smooth, flat surfaces such as cement, linoleum, tile, etc. The links work great on thick carpet and perfect on short grass, but on the kitchen floor or the floors at the university, I get a strong bouncing/vibration and ultimately have link breakages.
I've since taken the Traxster II apart and am leveraging the motors and Serializer for my final university project (some sort of higher-order control system). The robot was a lot of fun to learn on, and was robust and sexy, except for the plastic links; I hope to be able to revisit the hardware platform at some point in the future.
Has anyone modified the Traxster II to use RC tires (monster truck-type wheels) with two additional motors or an alternate drive train? Or, has anyone used metal links (like a bike chain) on the Traxster so that it can be used in outdoor environments, such as concrete without bouncing or slipping?
Thanks,
--Scott Thompson
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Forum Member
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Last Login: Saturday, August 14, 2010 12:06 PM
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Follow-up to changes in use:
Purchased two more of the gear motors from RC. Total of four gear motors + encoders will go into a Lynxmotion 4WD chassis w/ wheels.
Will use original Traxster II as a "trailer" for the 4WD leader and it will help me to house some of the power management systems--too much to put on one device, so the trailer idea is really singing to me right now. The Traxster II will have normal hobby-style "wheels" put on it instead of the links and will be free to move (unpowered).
Drive of the four motors will likely be through two RC Serializer boards--one V2 and the other V3. I will likely leverage the dual h-bridges from these boards (external connection). The V3 board's MCU will be utilized to connect with the computer/feedback controller and will handle the servo movement. Question: Is it overkill to have four separately controlled motors? The connections that I'm seeing on the 'net are for the two left side motors to be connected in parallel and the same for the right.
The main processor is undetermined at this time--could be a ATMega1280, Freescale 9SHC12, dsPIC, or Propeller. This processor will take control of the drive-train and will interface with the quadrature encoders from the four motors.
I am planning on incorporating dynamic fiducial markers made from 8x8 RGB matrix cells (Rainbowduino). Similar to the Playstation Move controller, I expect to be able to perform better machine image recognition (due to my limited knowledge of the subject) by having an active light source that will help with background removal. Plus, an active fiducial on the Traxster II or Lynxmotion will help me track it from the remotely mounted camera.
FWIW, I checked into creating rolling-chain type chains for the Traxster II but it wasn't really what I wanted to focus my energies on.
I hope to post my results in the users section at the end of the year when I have my project complete.
Thanks for your time and input.
--Scott Thompson
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Supreme Being
Group: Administrators
Last Login: Monday, October 31, 2011 9:18 PM
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| Hi Scott, If you want to control 4 motors via the Serializer, you can always add an external i2c h-bridges. You use the two onboard h-bridges to drive two motors, and the external i2c h-bridges to drive 2 more motors. This might be easier than controlling two separate Serializers. For proper control, you'll probably have to have four motors on all four wheels, at least for rotating. So no, I don't think it's overkill. The Traxster is designed for classroom lab use, and not intended for outdoor use. The max payload that they are designed for is about 4 pounds. Yes on hard surfaces you do get a little bit of bumping. We've discussed rolling chain as tracks, but the problem with those are that you'll get grease on your floor/carpet, and we don't want to be responsible for that. :/ Look forward to seeing your results! Best Regards,
Jason Summerour
President,
Summerour Robotics Corporation
www.roboticsconnection.com
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Forum Member
Group: Forum Members
Last Login: Saturday, August 14, 2010 12:06 PM
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Awesome info, Jason. An external h-bridge would be less space--I have the 'old' v2 board that I wanted to leverage *something* from 
Looking forward to start connecting it all; should be very fun with the Rainbowduinos.
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