Patrick Mccabe's Posts (11)

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AGV Chassis change

Yup, it now has 2 platforms instead of that plastic truck shell.

Here is a picture to remind you what it looked like

Here are some photos of the building of the dual platform. Its made from lexan, each platform measuring 12"x5.5". Holes were drilled for the spacers and for the pegs that hold the platform to the chassis.


It is still the same old setup (compass, GPS, and my custom board), but i am trying to think of things to add. If you have any ideas, please leave a comment. The compass is mounted on the top deck with a custom bracket made of polymorph plastic.

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AGV improvements

The AGV code has been improved tons with lots of help from Bill porter, Thanks Bill. A lot of cleaning up and basic improvements were done but so were major ones. Added PD control instead of the plain P like before. The code runs faster at 10hz. The best part by far is the added functionality of storing waypoints in EEPROM and using the Ardupilot config tool to upload the points. Just today i ended up plugging the ESC into the on board receiver that the truck came with so i can control the speed manually (seen in the video above. Sorry for the shaky beginning).

As always the full story can be found here

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My New AGV

You might remember the old one, which was just a prototype, this one is much better.

The new really big difference is the vehicle (you can see the name of it on the truck every where). I am pleased with the truck, a lot better than my $20 Rc hummer i was using before. This one has plenty of power to drive up inclines and through grass even though i still would only like to drive it on concrete or asphalt.

Also i made some custom PCBs for this purpose

If your interested in a PCB, i have extras i want to get rid of for $6 and free postage in the USA. If you want one then send me a message.

Here are the parts that go on the board:

I will be working on the code for the next few days. I have ran test code and rough AGV code and my custom board is working fine.

I bought a 3"x 2" x 1" plastic project box from Radio Shack and cut a few different holes for cables to go through. My custom AGV PCB goes inside.

The ESC, servo, and UBEC wires go through a hole in the top of the truck that was meant for the antenna.

The box is attached to the bed of the truck using velcro and the GPS is attached to the box using velcro

Here it is all finished. Just like before, the compass is mounted high in the air away from any magnetic interference from the electronics and motor.

I will post some video hopefully next week.

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AGV update--- Custom Controller


Parts list:

It is programmed on the side via a FTDI cable. The lipo's charging cable comes out of the top so it can be charged without having to open up the controller.


This custom controller allows for more options and modes than a normal, off of the shelf controller.

Some modes and features might include:

  • RC mode
  • GPS waypoint mode
  • Sending new GPS cordinates
  • Return to home (back track of GPS waypionts)
  • RC mode with Compass assistance (like keep on x heading)
  • Kill switch
  • Adjustment during GPS waypoint mode
  • Speed control via sliding pot
  • And so much more....

The xbee adapter plugs into the FTDI port with a homemade male to male adapter

RC control will have the option of using the joystick on board the controller, the wii nunchuck's joystick, or the wii nunchuck's accelerometer.

When i get the money i hope to update to this rc truck as my AGV. As you may know, right now i am using a cheap hummer from Walmart.

I have also made my own AGV arduino PCBs. I just sent the gerber files off to seeedstudio yesterday and in a few weeks they will arrive. But more on this later.

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AGV update

Update 5.20.10


This idea came to me in math class when i was talking to one of my friends about this robot.

So whats new? BUTTONS!

I added 2 buttons. The one on the right is for storing waypoints. Now all i have to do is push the button and it stores the current location as a waypoint. This is done to store all the waypoints. There is also a LED that lights up to show that it is storing a waypoint. When you are done storing waypoints, then push the left button and the AGV drives the waypoint path. So no more must i lug my laptop around and read the serial monitor, write down the gps points, upload the gps points to the arduino. I now just push these little buttons which i took from a old rc controller from a cheap toy. When i am able to test this at my test site, i will add a better video of it driving in the comments below so be on the look out for it.

Here is the full post on my AGV from start to finish

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You can see my forum post here :

Here is all the information on it here :

I now have a compass module and i wrote some better code. The compass module is just a life saver. It is really accurate and just makes programming easier. You use i2c to communicate with it and just a snippet of code. Just make sure you mount it level and away from the electronics.

My new code has improved steering. I guess its proportional but i do not know if it is definition proportional drive. I came up with this little formula of delay=degree error / 180 *3000. It takes about 3 secs to turn 180 degrees so 3000 was my number i could tweak. Of course it is out of 180 because that is the most i will be turning either left or right. Our degree of error is how much we are off from our current heading to the heading we need to be at. Simply subtract the current heading from the desired heading and take the absolute value and presto! This code seems to work really well. I tested this in a parking lot plus i had 2 waypoints this time. (see video). You can see the results. the waypoints were given a radius of 2 meters but it normally gets closer than that. I will reduce the radius next time. The AGV is programmed to stop when it reaches its last GPS point. I ordered a l298 motor driver and will update this post when i have that on the AGV and i will have a more complicated path of waypoints.

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Sparkfun's AVC contest is today

Go here for all the information


  • 8 AM - Team Admission
  • 9 AM - General Public Admission
  • 9:30 AM - 1st Heat Start Time, Raffle at End of 1st Heat
  • 12 PM - 2nd Heat Start Time, Raffle at End of 2nd Heat
  • 2:30 PM - 3rd Heat Start Time, Raffle at End of 2nd Heat, and Free-For-All Race (mass start)
  • 4:30 PM-ish - Awards
  • 6 PM-ish - After party @ Dark Horse
Time is for Boulder Colorado, USA.

Make sure you watch the ustream channel for live video of the event.
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Yup i fixed it since last time. They said it was the round headers that were not making a good connection. Well i got square ones and they are now tight fitting. So why do i have a problem? Ok im using 2.0 code which loads fine no z sensor or expansion shield. 2.4ghz 6ch transmitter and receiver already bonded and i know they are. I dont i have the ESC plugged in and am using a UBEC to power the receiver and board. Ok so i believe that everything is plugged in right and the lights are right so i dont know whats the deal. I know i didnt calibrate the sensor but that shouldnt effect the manual mode. I should always be able to have manual control when switch on and i dont. I doubt that will fix UAV mode too which is also not working. I made a video like last time so the link will be below.Thanks for any help :)ok here is the video
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Video showing my problem

ok im having alot of problems.1. The UAV mode is not working2. Manual mode is not working3. so nothing is really workingI have successfully downloaded 2.1 code. And i have put one gps point in using the configuration tool. But if you watch the video you will see i have the right setup (i believe) but its not working.So please watch the video and see if you can help.Thank here to see video on youtube
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