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!
Thursday, September 8, 2011
Back at the MIT + DragonBot Update
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:
At this point I decided to do some calculations in order to get an idea of how much force I'd need to lift the giant arm. To get the mass of each part I applied material properties to each model in Solidworks. The four-bar is 16 inches long (0.41 meters) and should weight about 0.94 pounds (0.43 kg) and the dragon wing pieces weight about 0.12 pounds (0.05 kg) together. The grabber should weigh about 0.77 pounds (0.35 kg) and is another 2.5 (0.06 m) inches out. Simplified, this is 0.34kg at 0.41m and 0.35kg at 0.47m. This means that all together I'll need to apply at least 0.3 kg*m of torque at the top of the box extrusions. I was planning to use a 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!
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!
Wednesday, August 24, 2011
End of Summer + DragonBot Intro
It is the end of summer, and school will be starting in less than two weeks. I recently finished working on Robocon, which was a great experience. For details on that, check out the 2.007 and Robocon link, also on the left.
Before Robocon ended I was working on 2.007 style robot I have dubbed DragonBot. It was basically a more legit remake of a demo robot I made as a 2.007 UA in the spring to pick up a toy police car for the contest. I already waterjet some parts out of ABS plastic and assembled the grabber, but it is in my room at school. I am currently at my girlfriends house so I'm not able to work on it, but I should be able to finish the robot shortly after classes start. However, I still have my cad files! Here is one of the grabber, which is a rack and pinion.
The design allows for a strong grip due to the small radius of the pinion gear, applies force only in the same direction regardless of object size, and can let go cleanly without applying any torque to the object its lifting. This is key for precise placement of objects, which was critical in the 2.007 contest. Most of it is assembled using t-nuts (as seen in the lower left corner of the picture above), which I learned about from Charles. They are really handy when waterjetting parts; all you need to do use bolts to piece things together (I can explain in more detail if anyone is interested). So why is it called DragonBot?
That's right: waterjet dragon wings on a four-bar mechanism. The grabber simply slides into the slot you see on the bottom.
Well I guess that's all for now. I am also starting to work on a new super-secret project which I will reveal in my next post (lies), so check back for that later (or subscribe)!
Before Robocon ended I was working on 2.007 style robot I have dubbed DragonBot. It was basically a more legit remake of a demo robot I made as a 2.007 UA in the spring to pick up a toy police car for the contest. I already waterjet some parts out of ABS plastic and assembled the grabber, but it is in my room at school. I am currently at my girlfriends house so I'm not able to work on it, but I should be able to finish the robot shortly after classes start. However, I still have my cad files! Here is one of the grabber, which is a rack and pinion.
The design allows for a strong grip due to the small radius of the pinion gear, applies force only in the same direction regardless of object size, and can let go cleanly without applying any torque to the object its lifting. This is key for precise placement of objects, which was critical in the 2.007 contest. Most of it is assembled using t-nuts (as seen in the lower left corner of the picture above), which I learned about from Charles. They are really handy when waterjetting parts; all you need to do use bolts to piece things together (I can explain in more detail if anyone is interested). So why is it called DragonBot?
That's right: waterjet dragon wings on a four-bar mechanism. The grabber simply slides into the slot you see on the bottom.
Well I guess that's all for now. I am also starting to work on a new super-secret project which I will reveal in my next post (lies), so check back for that later (or subscribe)!
Tuesday, August 23, 2011
First!
Hello world! Welcome to my new website. While my old website was sleek and fancy, it would be far too much work to keep it updated and iron out all of the little wrinkles that plagued it. As a result I have moved to Blogspot. My plan is to have a couple semi-static pages for my finished projects (picture links on the left) while also posting updates on projects I'm currently looking forward to. I hope you enjoy, and check back soon for updates!
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