S.A.G.A.R. Semi-Autonomous Gps Assisted Rover

Posted in Projects by Bill
29 Dec 2009

Well, I finally have gotten around to posting about my current project, Sagar! (The name might be changed if i come up with a better one) Basically, in an effort to better understand the technology I use at my job in the Navy, I am building a robot from scratch. My hope is in the end to have a robot that can be driven remotely, or drive itself with the aid of a GPS and inertial navigation system as well as avoid obstacles and reroute around them. I want it to be able to ‘record’ a route while being driven remotely, then be able to ‘replay’ the path without any assistance.

The base chassis is a Lynx-motion 4WD rover body. I have just finished building my own motor-controller that has feedback from the motors. This allows for commands to be given in speed rather then in power and it is able to track how far the robot has traveled; something most commercial products (like the Sabertooth) cannot do. The motor controller also monitors battery voltage and current, and will override commands given to it if the battery current gets too high.

It is powered by 2 Li-Ion packs i built myself; has GPS, 3 axis compass, Xbee 900Mhz radio and an Axon as the main MCU. Eventually it will have an array of ultrasonic range finders for obstacle avoidance.

More to come.

Be sure to check out all the pictures on the Photos page.


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  1. 9 Comments.

    • BillNo Gravatar says:

      Feel free to leave comments here.

    • HemanthNo Gravatar says:

      This is cool! How do you build this? Do you have a diagram that shows how the components of the circuit are to be connected?

    • BillNo Gravatar says:

      I do not have one written up, would you like me to make one?

    • HemanthNo Gravatar says:

      yes, please. thanks in advance !

    • JeffNo Gravatar says:

      I would also love to see a tutorial for this. Also could you email me if you wouldn’t mind answering a couple questions?

    • BillNo Gravatar says:

      Well, I guess it’s time for a more in-depth post on this. Since it’s a long weekend, I will try to get one up in a few days. Also, Jeff (and anyone else) feel free to email me at bill@billporter.info with questions.

    • Sean KaurNo Gravatar says:

      GPS is very useful specially the ones that are put on the Car dashboard. it can really help you drive on unfamiliar places.`-~

    • Jimmy HuchNo Gravatar says:

      Wow this looks pretty awesome, just like that RC car in COD.

      Sorry, but I perceived your post a bit short. I didn’t quite understand how you integrated the GPS and how if it uses a channeled receiver or not. Do you mind telling me whether you used Covert GPS Tracking technology or simple technology found in Portable GPS Systems. If you can elaborate, that would be great.

    • BillNo Gravatar says:

      I am using a 50 channel GPS that sends the positional data over a UART using NMEA standard strings.

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