As the title mentions, I'm back on campus! I've been very busy with my fraternity's rush, so not much work has gotten done, but I have at least made it through my first day of class! Hopefully I'll have time to go into Pappelardo to make the rest of DragonBot before the end of the week. Since the grabber is done I just need to make a four bar mechanism and a base with wheels and aluminum box extrusion uprights. Oh, and I also need to figure out how to lift the massive grabber. To cut back on weight the four-bar will be made out of steel sheet metal which I'll bend to make more rigid. I'm hoping this will be strong and very lightweight. The base will be made out of ABS and will have standard 2.007 continuous rotation servos and wheels for front wheel drive, with a caster wheel or two in the back. To stabilize the tall aluminum box extrusions I plan on bolting on aluminum brackets to attach it to the base. Here's what it will probably look like:
Vigor VS-11 servo which applies about 0.16 kg*m of torque at 5V, so I'll need to at least get a mechanical advantage of 2x; 4x would probably be ideal. If I use a 1/4" diameter pulley attached directly to the VS-11, I'll be able to pull with a force of 25.2N. To get 4*0.16= 0.64 kg*m of torque I'll need to extend the four bar mechanism to stick out 1 inch the other way and attach it to the pulley with a string.
Well, that's about it for now (I am le tired). And don't think I forgot about my other not-so-secret project, I promise I will reveal the details in my next post!