Institute for Personal Robots in Education Blog

SRV-1 comments

Thu, 2007-07-12 11:50
Howard Gordon (not verified)

It's fairly simple to add a battery level detector - take a look at the Panasonic MN13812 chip. It has an internal voltage reference, and only needs a couple of external resisters in a bridge to measure the battery voltage. There's a digital output that can drive an LED circuit of feed back into the processor. We're building a motor speed detection circuit board that will include the battery level detector, and hope to have prototypes in a few weeks.

With regard to the occasional pauses, that's just something in the robot firmware that can be easily fixed by commenting out a single line of code in main.c. Just after the restart: label, comment out the following line. We'll correct this in the next firmware update ...

restart:
// setPwmDutyPercent(0, 0);

Finally, with regard to image processing speed, the onboard processor captures images at 5-10 frames per second because there's a 921kbps interface between the camera and processor, but the Zigbee radio operates at a bit less than 100kbps, so there is a delay from the time that the image is transferred from camera to processor, and then from processor to host via radio at the lower data rate. The onboard image processing actually occurs pretty quickly, but you'll see delays on the host display.

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