Sam Galison and I built a lego arm that picks up an object, rotates to a different position and drops it. Three axes of movement: up/down, rotate left/right, tweezer open/close. The only part we made from the book is shown in drawing below.
Finally getting around to some of the labs I neglected. The servo lab is certainly fun. I wanted to mount two servos on a welding hat to make the visor go up and down based on some sensory input. Further down the line I might use this as a jaw mechanism for a mask, and have the data controlling the servos come from the jaw of the person wearing it. Classic animatronics. I’m using a light detecting resistor in this video.
I made this system using both the servo library and the “pulse method” outlined on this page. To get the servos to move in opposite directions, I reversed the values of one of the servos in the map() function. For example, from the pulse method:
pulse1 = map(analogValue,890,660,minPulse,maxPulse); pulse2 = map(analogValue,660,890,minPulse,maxPulse);
I constrained the values to match the values received by the LDR. Next I will smooth the values so the servos aren’t jumping around as much.
The cigar box combo lock slash belt motor system with zoetrope is finished. At least to the point where it is presentable to class as a stupid pet trick. It’s not finished if I look at it from an aesthetic point of view. It was a good exercise, but it’s time to move on. Before that: documentation. (more…)
Last May I removed this DC motor and corresponding belt rotation systems from an old VCR. I have the photos from that day somewhere… I’ll post when I find them.
I finally got around to putting them to use. The system is mounted on masonite and other materials found on the junk shelf. I had to figure out how to mount the rotating parts in a way that caused the least friction. There was a VCR play system (where the tape ribbon gets extracted and put through the video head system) on the junk shelf that had various sized capstans and shafts– one of which fit the small black wheel perfectly. Turns out the VCR play system was the EXACT one I left on the junk shelf 4 months ago! I took off the relevant parts, adapted them to the masonite system and prest-oh change-oh the system was complete. Then I watched it revolve around and around while imagining what sort of naughty or nice things I could use it for. The first idea that stuck was a zoetrope (which is apparently “a very first year thing to do”). Well, who cares? Not me. I like doing projects where I make things I don’t know how to make.