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Robot navigation using GPS coordinates with two ultrasonic range finders

  1. Jun 21, 2016 #1
    Ok, the reason for my absence is I have been working on a project of building a multitasking Robot. Since the connection of Robots to Physics never entered my mind I assumed I have nothing of value to add to any discussion on the PhysicsForums. If anyone is interested in the problem that I am faced with. I'm searching for a software program that will allow me to create a path of travel using GPS coordinates with two ultrasonic range finders that uses a fixed X 0.0 Y 0.0 location on a grid. Would like to hear from anyone who is interested in this kind of project.
    Last edited: Jun 21, 2016
  2. jcsd
  3. Jun 22, 2016 #2


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    Not really something I'm interested in but...

    That sounds like a very specific task. Why do you need ultrasonic range finders if you have GPS coordinates to follow?
  4. Jun 22, 2016 #3
  5. Jun 22, 2016 #4
    The ultrasonic range finders are (Kinda-Sorta but not really like) eyes for the robot to see. Just in case some silly little wabbit hops in to the path of this 300 Lbs. Robot while it is on a mission. It will stop or avoid the object ... can't overlook being O.S.H.A. approved.
  6. Jun 22, 2016 #5


    Staff: Mentor

    You omit key parameters from your question.

    What accuracy do you need, 1 mm? 100 m?

    Are there DGPS transmitters to assist?

    Do you assume that GPS reception is good every place and every time the robot operates?

    2D or 3D motion?

    How fast does the robot move?
  7. Jun 22, 2016 #6
    What accuracy do you need, 1 mm? 100 m?............. Plus or minus one inch
    Are there DGPS transmitters to assist? .................... major city heavily populated
    2D or 3D motion? ....................................................... 2D just a simple "X" or "Y" move
    How fast does the robot move?.................................. Walking, Fast Walking or jogging
  8. Jun 22, 2016 #7


    Staff: Mentor

    OK, we're getting closer. I am trying to help you understand that wise engineers always start by nailing down requirements before startting design. In other words, find out what you must do to achieve success, before beginning to ask how to do it. If your robot moves forward one inch and stops, that probably is not enough to satisfy your professor. But navigating from Seattle to New York by robot probably exceeds your requirements. Keep asking what questions until you can't think of any more. Only then should you begin design and ask how will I do this?

    I just pulled out my Android phone and started the free app "GPS Status" . It shows lat/lon coordinates. It also showed a 46 foot GPS error inside this building. The error may change significantly as I move closer to external walls or windows. It will also change hour by hour as more or fewer GPS satellites come into view. But I think you need relative GPS accuracy, not absolute. With such an app you could do a little feasibility study before making design choices. For example, walk through some samples of the course the robot will be required to go while holding your phone and record the GPS coordinates. Can you find the way point reliably to within one inch? That app allows you to set the way point (your destination target coordinates) and calculates the distance and direction to the way point, which is exactly what your robot must do. You may want to consider a smart phone as the onboard GPS sensor for your project.

    It is possible that to meet your requirements that you need a GPS with more than consumer/hobbyist quality. A better (and more expensive) GPS or adding DGPS may be needed. (google DGPS to understand what that means) That is an example of the kind of thing you need to know before design. If difficult requirements cause you to exceed your budget, perhaps you can negotiate the requirements with the professor.

    I presume that you will use a platform such as Arundino or Rasberry Pi as the platform for your robot's smarts. Google "Arundino GPS navigation" or "Rasberry Pi GPS navigation" and you may find what others have done in similar projects in terms of hardware and software.

    Good luck. You can learn a lot from such a project.
  9. Jun 22, 2016 #8
    Actually the platform or donner that I am using is a Jazzy Mobility chair with dual motor differential. Using a Sabertooth 2 X 60 regenerative dual motor driver also known as 2 X 60 H-Bridge ( www.dimensionengineering.com/products/sabertooth2x60 ). I have an Android version 5.1 phone, have not done enough research on navigation Apps . Wayz , or Verizon navigation App might have a problem with downsizing to a smaller navigation window. I have also been looking for a basic machining program the grid size I want to work in is 200' X 200' something like you would see in a CNC machine , (G code) with radius offset adjustment,
  10. Jun 22, 2016 #9


    Staff: Mentor

    By platform, I meant the computing platform for the intelligence. Searching the forums for Arduino and Rasberry Pi is likely to turn up existing projects very close to yours..

    By GPS navigation, I meant things more like your robot application than cross-country stuff like Waze. Hikers and joggers use GPS to track and to find their way to a point. Hobbyists have no doubt built lots of hobby projects to navigate a robot around a room.

    The quality of the answers you get here on PF are in proportion to the details you share about what you are trying to accomplish.

    If you compare your project with machining, then I suspect your accuracy requirements are high. You should definitely look into DGPS. For example, NASA used DGPS on an airplane in flight to measure fluttering of the wing tips.
  11. Jun 22, 2016 #10
    I used the example of machining only because that is what I do develop cutter paths for C.N.C. machines. Way-Point software would be closer to what I am thinking
    would work it is designed to work with drones. Draw a trapezoid shape that I create on a tablet or inside the program and from that shape do ( + or - ) radius offsets from the trapezoid shape and translate it to the microprocessor or Android app to make the moves smooth and fluid.
  12. Jun 22, 2016 #11
    This seems an interesting project best of luck!!
  13. Jun 22, 2016 #12
    I'm not sure I understand how you want to use the ultrasonic devices, have you looked at any specific devices? Ultrasonics are good at telling you how far away an object is, in a static environment with a constant surface, change the material type, size and angle and things get a little fuzzy. Are you thinking typical ultrasonics you would find on your car bumper? I assume you are not serious about the O.S.H.A approval.
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