The Gigabot Project


Building up an inexpensive high resolution panoramic robot from LEGO NXT parts

Part 1: Building and assembly

Shopping List:
  • a camera with a tele lens, cable release (something cabled where you can press a button) and a solid tripod
  • LEGO NXT controller unit, 2 motors and some Lego technic bricks
  • Panoramic head (can be self made), single-row or multi-row
  • a large disk, wooden, metal or pastic, whatever you have
  • nylon string
  • 2 adapter screws from your local camera shop (see below)
  • Some DIY-parts and tools

 

The central part of the robot is a large disk where the motor will travel around. This disk doesn't necessarily have to be built with high precision. The diameter of the disk should be chosen as large as possible but  smaller than the "arm" of your panorama head (watch the photos to see why).
The important feature of the disk is a notch that will act as a guide for the nylon string that will later span around the disk. In my case, I have used 3 thin plywood pieces left over from some broken photo frames.
The radius of the middle disk is a few millimeters smaller than the outer ones. This notch is half-filled with some heat bonding plastic, so our string  can neither slip nor slump.
To be able to firmly mount disk and head on the tripod, I bought an adapter screw from a  local camera shop. This adapter screw sits in between tripod mount and panohead.
The thickness of the disk is chosen a few 1/10th millimeters less than the "thickness" of the adapter screw. This will squeeze the disk between tripod and panohead and therefore provide a self-fastening mount for the disk.
Now we can start building the actuator responsible for rotating the panohead. On the right you can see this motor with some sort of simple gear to reduce speed and increase accurateness.
Wrap the nylon string around the axle several times and knot both ends together to build a loop that you can later wrap around our disk.
See detailed building instructions for the "motor" part.
To be able to fasten the motor on the arm of the panohead, I bought a second adapter screw (with a little longer thread than the first one). A small piece of plywood acts as a mounting plate, holding the motor as well as the adapter screw.
As you can see, I used another simple screw to fasten the motor on this plate.
Ensure that the axle with the nylon string will later align with the notch of the disk, otherwise the string will tend to slip off.
Now we can attach the mounting plate on the arm of the panohead.
Now we have to actuate the cable release. This is the task of the second motor. Build a fixture for the cable and use the motor with an attached LEGO brick to press the button.
See detailed building instructions for the "shutter" part.
The panohead I'm using is big enough to simply pile the NXT controller on its arm. To prevent the controller slipping off, I use some detachable DIY gum.
You are free to use adhesive tape or an even more professional solution...
You may now attach the shutter to the controller brick...
See detailed instructions on assembling the robot and the panohead.
Seen from the bottom...
That's all folks. We are finished. If you don't have 2 left hands, you should end up with something like this:


 

Part 2: programming the robot

I assume you are familiar with the NXT-G programming environment (that's the one delivered with the NXT Robot), so I'm including only basic instructions.

This is Version 2 beta:

  • You can either download the Compiled Binary or the Source Files.
    Binary: Ver. 0.3c (older Ver. 0.2.b)
    Source: Ver. 0.2b

  • Open the readme in the zip file. It contains the instructions how to install und use the software.

  • For your convenience, here's a copy of the included "operation manual":

Usage:
------

The robot assumes you are working from left to right: Right button should move the view to the right, left button vice versa.

First step: Define the left and right border of your panorama

Second step: Define the FOV. This is done by learning the robot the angle between 2 shots.
The angle can be defined at any position inside the panorama's FOV limits.

Third step: Shoot a single row.
If you experience any problems, you can press the "enter" (orange) button.
The robot will stop and ask you to either:
- continue shooting
- go back to repeat last shot (you can go back more than one shot if you like)

Fourth step:
Tilt the camera and repeat the row.

Feedback, questions?
Please mail me at salzamt@dativ.at