23 Jan 2006 cschur   » (Master)

HI all,

We made some great progress this weekend on the Geobot. I installed a tilt sensor, made from a damped potentiometer with a six inch weighted pendulum. Reading it with the 10 bit A/d in the 16F877, we set it for a 12 degree uptilt for the limit forward, and a 22 degree down tilt when going down the hills. There is a lot of pea gravel sized rocks in our area, so thats why the relatively shallow uptilt. Its like driving on ball bearings! When a uptilt limit is reached, the architecture considers it as a top priority impact, and stops, reverses for 2 seconds (pendulum time constant) and turns 90d right. Then resumes. In this manner, it tends to skirt a hill to get around it.

Downtilt is another matter. Since reversing wont work since it slips too much, I cut the speed in half for up to 22 degrees , and after that a full stop is in order.

We did get the sonars and Devontech compass from Mark III robotic store very promptly. As soon as we are through with the tilt sensor algorithm, then its on to the exciting world of sonar navigation amongs giant rocks!

Ill post a page on the tilt sensor soon...


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