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Carl Jagt’s Rack-and-Pinion [Type] SteeringCarl Jagt, from Ontario, Canada, has made improvements on my
design. As someone who feels sometimes like a very junior member of the
Lego-Robotics mailing list (“Look what Mario’s
doing this week: He's got a robot prototype that not only climbs glass, but it
will measure the relative dirtiness of the window and clean it at the same time,
if necessary ...), it was thrilling to be the inspiration for someone else. An animated GIF of his assembly (about 294K) is available here. Carl’s Letter/NotesJust to let you know that you’ve unwittingly been my source of Lego inspiration! ;-) What I mean is, I came upon your Rack and Pinion Steering page and was almost beside myself with glee! I, too, have been fighting to design a strong, one-motor-rotation-sensorless design but, seeing as I was having little success all these weeks, I'm glad to see that you have done it!
I began building a model based upon the pic you posted; and evolved it a bit. Two key differences: the first is that I have access to a number of non-standard RCX bricks which allowed the unit’s profile to be smaller (the one brick came with Technic 8445 race car: It’s 3x1 and can take an axle on the right and left holes and the middle hole, perpendicular to the two axle holes, has a clean bore (for swiveling).
But the most interesting (I think anyways!) is that I added two more cams to your design: they are butted up against each other with a 2x1 axle and bushings to widen their leading edges. What this does is give the mechanism three opportunities to hit the touch sensor: 1) left, 2) center and 3) right!
I haven’t written any code up for this yet (NQC) but I imagine that I could use a global variable/semaphore to keep track of the cam count. The only drawback is that it's likely to not be “self-aligning”—unless I find a way of adding elastics to it to pull it back to a default position. Rather than email you all the pics right now, I've attached one and see if you're interested in the rest. I plan to post them when I have the opportunity but there are a number of server issues that need to be taken care of first. So let me know if you'd like a look-see! I also made a rather rough GIF “movie” which shows some of the motion of the steering unit. Unfortunately, it's almost 300k in size ... Again, Doug, thanks for the inspiration! The cam idea is brilliant! Cheers, |
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