1 Mar 2008 motters   » (Master)

Over the last few weekends I've been stuck with a microcontroller problem. Basically I'm just trying to use a couple of interrupts to count encoder pulses, then pass that back to a PC via RS232. The programming on this stuff is fairly archaic and requires proprietary software tools which are flaky and no longer supported (the classic proprietary "software death"). I don't really want to spend weeks or months on this so as a plan B I've opted for using a couple of phidget encoder counter boards instead.

http://www.active-robots.com/products/phidgets/encoder-1057-details.shtml

This is a slightly more expensive solution, but it will allow me to use full quadrature rather than just single ended pulses and the rate of communication with the PC will be far higher than is the case for RS232 at 9600 baud.

I've also noticed that the servo which I'm using to pan the stereo cameras is underpowered, resulting in some laggy control. At the moment I'm just using bog standard 3kg/cm RC servos for pan and tilt, which you can get from any hobby store. I've ordered a couple of 13kg/cm RC servos with the same physical dimensions and metal gears which should give better controlled movement. Good control of the stereo cameras will be essential for 3D mapping performance.

If all goes well and there are no further holdups I'm hoping to be able to begin some dead reckoning tests in maybe a month.

Of course all of this hoo-haar is symptomatic of the fact that at present there is no reasonably sized PC based robot platform which you can buy on a hobbyists budget as an "off the shelf" package.

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