Thursday 14 March 2013

HOG getting closer...

I worked on the hog drive again last night, I made a gimbal bracket out of lego, hot glue and a servo. Ultra high quality I know, but 1, good enough for a prototype, 2, I was going to use aluminum, but lego is better for rapid prototyping (that, and my hacksaw does not have a blade right now...) 3, lego is still pretty sturdy, and 4, the rest of the frame is going to be lego anyway, so the bracket and base should fit together fine.

Some pics of the bracket:

And a frame around it:
 
The gimbal that you see is for driving, and can move 180 degrees left and right. To steer, it will rase and lower it's rear wheels in tandem, causing a tilt of the whole bot to a "nose up or nose down" attitude. I sort of struggled on how to make the whole bot run, I have seen both a straight up 2 axis gimbal, and one bot that independantly rased or lowered each wheel to drive and steer.  I chose the hybrid method because I wanted to have maximum travel latterally so that the whole hemisphere could be used for driving, and max top speed could be reached, and to do this with a regular gimbal would have been tough. I will not get max travel for steering, but really, I do not need to turn at 150 km/h, that is just a bit excessive... We will see how this system works for a first prototype.

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