Servo - May 2009

OBJECT TRACKING

FIGURE 22. Screen dump image of model.

Troubleshooting

If the green LED on the CMU-01 never blinks when you run the program, you probably have the TX and RX lines reversed. So, switch the two lines and try again. Make sure you have the power switch on the CMU-01 in the on position.

If the robot turns to the left when it needs to turn to the right, you have the left and right servomotors reversed. Switch them.

CMU-Pro Program

FIGURE 23.

Standard picture of model.

The C-Bot is bundled with the CMU-Pro program. This software allows you to work with many features of the CMU camera. The CMU-01 camera is bundled with an RS-232 serial cable to connect it to the PC. It therefore requires the PC to have an available serial port.

With the C-Bot, you can get a feel for how the camera views targets. Using the CMU-Pro software, you can see exactly what the camera sees by using screen dumps from the camera. Look at Figures 22 and 23. Figure 22 is of our model Kim as she appears to the CMU-01 camera. Figure 23 is the same lighting and background shot with a standard camera.

The CMU-Pro program allows you to track on any color within the screen dump image. So, if you wanted to try to track Kim’s eye, you could select her eye for tracking. Tracking may be accomplished using simulation on the PC, if you’d like.

Going Further

C-Bot Parts and Kit available from: Images Scientific Instruments, Inc. 109 Woods of Arden Road Staten Island, NY 10312 (718) 966-3694 www.imagesco.com/c-bot.html

The C-Bot has lots of room for improvement. In its current state, C-Bot responds to only one movement of the target at a time (whether it is left, right, up, down, forward, or backward). It is possible to program C-Bot to respond to multiple target movements. This will increase the complexity and size of the program, however.

If the size of the program exceeds the 2K programming space of the 16F628, you can use a PIC16F88. The 16F88 has the same footprint as the 16F628 but twice the memory (4K). To use the 16F88, I believe the comparators are already disabled by default. Converter inputs are controlled with the ANSEL register. So, use the command: ANSEL = $00 to make all the pins digital. SV

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RESOURCES Videos of the CMU software tracking object in window: www.cmu-camera.com/cmucampro.wmv Videos of CMU Pro software controlling X-Y Bot tracking object: www.cmu-camera.com/cmucamtrk.wmv Parallax www.parallax.com HiTec www.robonova.com microEngineering Labs www.melabs.com