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Miniature Autonomous Forklift

   
I organized and led a team of three to design this forklift that broke all previous competition records to place second in the BYU Mechatronics Competition 1999.  My team, comprised of only mechanical engineers, finished second out of nine other multidisciplinary teams.  Even though this was my teams first time programming a microcontroller and designing a mechatronic system, we were able to finish ahead of almost all other more experienced teams.
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The competition was simple.  Autonomously navigate a miniature factor floor, scanning and delivering packages to their proper locations.  Do this the fastest with the fewest mistakes and you win.  In order to accomplish this a forklift must be able to:
  • Follow the white line on the factory floor while navigating all turns, pickup and drop-off locations
  • Use a barcode scanner to properly identify packages
  • Pickup and drop off packages at varying heights
  • Sense when a package is properly positioned on the forks
  • Receive an infrared signal from the factory IR tower that tells the forklift to move clockwise or counterclockwise around the circle at the center of the factory floor
 

Video of Forklift

   
Click here or on the icon to the right to download and play a video of the forklift in action.  This file is 5.9 MB in size so please be patient.

   
The video begins with the forklift calibration.  This consists of driving the forklift over the white line on the factory floor.  The forklift is then positioned at the starting line and set in motion.  It scans a package, identifies the contents and delivers it.  It then moves to the next package, identifies the contents and delivers it to the proper location.  The forklift returns to the center of the factory floor, picks-up and identifies the contents of the next package and then waits for information from the factory IR tower to know if it should travel clockwise or counterclockwise around the circle.  The package is then delivered and the forklift returns to the starting line.  
   

Detail Pictures of the Forklift

   
Click any of the thumbnails below for a larger view of the image.
   
Line sensor array used white LEDs and photo resistors purchased at our local Radio Shack to read the line on the factory floor.  The microcontroller (The Handy Board) was programmed to use PID control to follow the line.

   
The gear train consisted of two DC gear motors wired directly to the microcontroller.

   
Rear swivel wheel that made it possible to steer the forklift by controlling the speed of each drive wheel independently.

   
The barcode scanner used to scan and identify packages on the factory floor.

   
The hall effect sensor used to detect if a package was positioned properly on the forks.

   
The drive motor (DC geared) and sensor (single turn potentiometer) used to move the forks and keep track of their position.

   
The infrared sensor positioned at the top of the fork lift tower.  The upper pulley of the forklift drive belt can also be seen here.  The belt and pulley were taken from an old dot matrix printer.

   
The entire fork lifting mechanism.

   
This mechanism, using a standard hobby servo and a custom servo horn, was used to lock our rear swiveling wheel in place so that the forklift would backup in straight line.  This ingenious mechanism saved several hundred lines of code that would have been otherwise necessary for backing up in a straight line.