Saturday, October 18, 2008

CMUcam KIT - boe-bot accessories

Track images with the Boe-Bot® Robot CMUcam! The Boe-Bot CMUcam ships with printed documentation, cd-rom with demo programs, and mounting directions. The Boe-Bot CMUcam (#30051) is designed specifically for the Parallax Boe-Bot robot. Download the complete manual and video at the bottom of the page for more detailed information.

The board communicates using a TTL level serial port and has the following functionality:

* Track user defined color blobs at 17 frames per second, find the centroid of the blob
* Gather mean color and variance data Arbitrary image windowing
* 80x143 resolution
* 9600 baud serial communication
* Automatically detect a color and drive a servo to track an object
* Slave parallel image processing mode off a single camera bus - advance function
* Ability to control 1 servo or have 1 digital I/O pin - advanced function
* Adjust the camera's image properties - advanced function.

The Boe-Bot CMUcam includes a printed user manual, cd-rom with sample code, and a pre-installed custom mounting bracket with two screws. There are other CMUcam kits available which may have different parts, features, and documentation that aren't designed to work specifically with the Boe-Bot robot.

1) The Boe-Bot Robot version of the CMUcam as shipped by Parallax cannot use the CMU PC Java code directly without modifications (and voiding the Parallax warranty)
The Boe-Bot CMUcam uses the same PCB as the general purpose package (described below) but does not include the parts that convert the serial port to RS232C levels compatible with a PC serial port. It also doesn't include the voltage regulator and jumper headers since they aren't required when using the BASIC Stamp microcontroller. This version can be modified for use with a PC by adding the parts that were left off the board, although the Parallax warranty is voided if you modify the board. While you cannot directly view a picture from the camera on your PC with the Boe-Bot CMUcam setup, a demo program is included that allows you to display the tracking data packets from the CMUcam on the PC debug screen. In some ways this is better than viewing a raw camera picture because you are seeing the data your robot will be using to "see" its world.

2) The regular version (non Boe-Bot robot specific version/not offered by Parallax) of the CMUcam directly supports the Java app on the PC.

A general purpose CMUcam PC evaluation package doesn't include the mounting brackets for the Boe-Bot robot. If you wanted to use this package with the Boe-Bot robot you would need to build a mounting bracket and remove the Max232 chip. Then you would have to add wires from the TTL level serial port to the Boe-Bot robot's BASIC Stamp module. You would also need to add wires to connect the CMUcam to the Boe-Bot robot's battery pack. One potential problem with this is that you can damage the CMUcam or BASIC Stamp module when using the TTL level serial port connection if the power to both is not turned on and off at the same time. The Boe-Bot robot version of the CMUcam can be modified to be the same as the non Boe-Bot robot version of the CMUcam then it will work with the CMU Java program (but voids Parallax warranty).

Technical summary of the above information:

In order to use the Java PC program the CMUcam needs to operate at 115,200 baud. The Boe-Bot robot version of the CMUcam is strapped to operate at 9600 baud only. You also would need to translate the TTL level serial port to standard RS232C levels for connection to a PC serial port.