Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: My FB project, Question on MOSFETs

  1. #1
    Constant Bitrate mx270a's Avatar
    Join Date
    Aug 2003
    Location
    Iowa
    Posts
    167

    My FB project, Question on MOSFETs

    Well guys, today was the maiden voyage for the project I've been working on - steering a tractor via GPS. I'm using a fusion brain to read steering angle position, and triggering two outputs that control relays that drive an electro-hydraulic valve that steers the tractor. I was letting the software drive the tractor, which stayed within a range of about one foot of the line.


    Can I use a MOSFET instead of a relay? Would the FB outputs be alright with that? The clicky clicky of the relays was a bit louder than I prefer. I could move them somewhere else for testing, but just checking out other options? The solenoids I'm driving are 12vDC at ~3.5 amps.

    -Lance

    More info (added by greenman100)
    Here's a new video:
    http://www.youtube.com/watch?v=YFqfTlqF2NY

    The machine is a Case IH 2588 combine (~300HP) that is harvesting soybeans at 4 MPH. I'm using the FB to read a steering angle position sensor, a yaw sensor, and a tilt sensor. That is added to a GPS position to drive the machine in a straight line, with each pass parallel and at a consistent distance from the last pass. The fusion brain outputs steering commands, which go to a couple relays, which send power to solenoids on a hydraulic valve that is connected in parallel to the steering wheel orbital.


    The header (thing on the front) is 25 feet wide. As you can see in the video, the yaw sensor makes the vehicle control very smooth. It still likes to drift off the line, then slowly come back to it (it can get up to about 8" away from the line.) I'm still working on revising the yaw sensor calibration algorithm, and the method used to calculate what angle the steer axle should be at. Yaw sensors are a royal pain due to their "zero" position changing as they warm up. As slow as the machine is moving, with subtle steering inputs, getting an accurate and precise yaw reading is a challenge.

    -Lance

  2. #2
    Fusion Brain Creator 2k1Toaster's Avatar
    Join Date
    Mar 2006
    Location
    Colorado, but Canadian!
    Posts
    10,049
    The output uses the ULN2003A which outputs 400mA to 500mA
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  3. #3
    Fusion Brain Creator
    Join Date
    Mar 2005
    Posts
    2,221
    You could, of course.

    I'm not sure exactly what your question is.

  4. #4
    Constant Bitrate mx270a's Avatar
    Join Date
    Aug 2003
    Location
    Iowa
    Posts
    167
    My question was if I could use a FET in place of a relay. I'm relatively sure it will work, just thought I'd run it by you guys to confirm.

    -Lance

  5. #5
    Fusion Brain Creator
    Join Date
    Mar 2005
    Posts
    2,221
    yes, it shouldn't be a problem

  6. #6
    Fusion Brain Creator
    Join Date
    Mar 2005
    Posts
    2,221
    Also: could you post a video/writeup on what you did? It sounds really cool.

  7. #7
    Constant Bitrate mx270a's Avatar
    Join Date
    Aug 2003
    Location
    Iowa
    Posts
    167
    I'm working on putting together some details on what's going on here - will probably post it in the 'show off your project' section of the site. Still working on getting some video of the system in action.

    Still haven't tried the mosfets. We found that it's actually preferable to use the relays while the system is in development, as it allows the operator to hear that the system is working, as well as how active it is. Here's a picture of what we're doing:



    The computer is steering the tractor along a straight line, the operator turns around at the end, and the computer steers again. We end up with straight passes that are all equally spaced.

    -Lance

  8. #8
    Who am I? HiJackZX1's Avatar
    Join Date
    Jul 2007
    Location
    Miami
    Posts
    6,557
    Wow this is cool..... pretty soon Im sure someone will come up with a solution to drive a car on the streets on its own via GPS.
    Nirwana Project, the Android/Win 7 hybrid system!

    1X Ainol Novo Flame Tab
    4X MK808b
    3x Perixx Touchpads
    3x 7 inch Screens
    1X 7 inch motorized Screen
    1x Win 7 PC

  9. #9
    FLAC
    Join Date
    Oct 2006
    Location
    Las Vegas
    Posts
    1,286
    Quote Originally Posted by HiJackZX1 View Post
    Wow this is cool..... pretty soon Im sure someone will come up with a solution to drive a car on the streets on its own via GPS.
    What a scary thought.. At least this is way out in the open.

    So, did you just happen to have a guide-a-tractor-by-gps program sitting around, waiting to be taken to the next step? That's the part that intrigues me the most. It's pretty impressive, what you did right thar.

  10. #10
    Maximum Bitrate bes51659's Avatar
    Join Date
    Sep 2005
    Location
    Vasastaden, Stockholms Län, Sweden, Sweden
    Posts
    852
    Fastest way to goal is to buy solid state relays. And maybe safest...

    Quick search: http://www.ab.com/industrialcontrols...ate_relay.html

Page 1 of 2 12 LastLast

Similar Threads

  1. PROJECT ST34LTH : Project Car Purchased w/PICS
    By ST34LTH in forum General Hardware Discussion
    Replies: 69
    Last Post: 09-01-2008, 09:09 AM
  2. Complete Newbie Question.
    By DomesticImport in forum Newbie
    Replies: 15
    Last Post: 07-07-2005, 06:24 PM
  3. A Start Community Project
    By BenjaminS in forum MacCar
    Replies: 9
    Last Post: 03-25-2005, 05:46 PM
  4. Project "Ford Windstar XP"
    By Vchat20 in forum Show off your project
    Replies: 2
    Last Post: 02-14-2005, 03:47 AM
  5. New Project: Contrast Mediaplayer
    By pplante in forum Software & Software Development
    Replies: 26
    Last Post: 07-07-2004, 11:06 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •