Walking Robot - Models

This is the foam core model of the froggy. While making this we realized that the placing of the joints between the legs is extremely important to the function of the legs. We would have to be very careful about where the joints go and what the joints are made out of.

This is the final lego model. We went through several lego models before we were able to make the four legged model. However, we kept making the iterations on the previous lego models before we took pictures of the failed models. Each side is the same thing only flipped around and the two sides are offset so that the legs move opposite to each other. The motion of the legs mimics the motion of a four legged animal. However, the lego model horse-bot doesn't balance very well.

Some solutions to the balance problems that we came up with is adding feet to the legs which actually did help. However, another solution might be to add a tail of some sort that helps the robot to balance when it is in unstable positions.

Walking Robot - Initial Sketches

These are our initial designs for the walking robot. This is our horse-bot, we had initially looked at a six legged robot. First, we made the six-legged model on legos. We then modified it enough to come up with a design for the four legged horse-bot. It will use a DC motor to turn an axle which moves the entire robot.

This next design is aquatic and is dubbed the froggy. We it makes use of a servo motor that moves the legs back and forth. The legs are designed so that they bend in one direction but straighten in the other direction. This way as the legs go out, they bend and as they come back in, they straighten and push the water out.

This design is the spiral tail. It is a number of plates along a teflon rod. The plates would be placed so that they create a spiral pattern down and along the teflon rod. Hopefully, as the wheel turns, the spiral pattern will push the water out.
This is the scuttle bot. It was inspired by a crab. We were trying to figure out how to make a side walking robot. The bet we could do is this. We would have two squares on top of each other and the top one would be connected to a servo motor. The feet would only move in one direction and the robot would "scuttle" back and forth.
This is a simple rower, thus it is called the rower. It uses a DC motor to turn two circles and it turns the oars in a circular motion. The one concern that we had was whether or not the teflon would float on the water and whether or not we would actually be able to make a "boat" out of teflon.

Motion Module - Final Iteration

So, we are finally done with the motion module chomper. Due to my partner's awesomeness at computers making the iteration was fast and painless. We changed the size of the bushings and the offset circle from a 6.26 mm hole to a 6.2 mm hole which worked wonders. The washer/bushings and the offset circle no longer slip on the rod and stay in place so that the circle efficiently pushes the arm up. We did not change the size of the arm because while the arm was designated as a tight fit piece it doesn't have to function as a tight fit piece. It just has to move freely about the rod in order to move up and down. Since we tightened the bushings around the arm, it stays in place and functions just fine as the arm. The motion module looks the same as it did before the iterations, the holes around the rod are just slightly smaller. On to the next project!

Motion Module - Printing it Out

Our next step was to actually print out our motion module. To do this we had to put all of the pieces into a drawing consolidate it so it would print out well. We tried to do this but the laser cutter was having some problems and we had to wait a long time before we got to cut out our pieces.

Having printed out our next step was to put it all together. It was all going pretty smooth until we took one of the wrong pieces of rod which is apparently smaller than the ones we are actually using and as we tried to fit all the pieces in... they were way too loose. So we proceeded to get extremely frustrated and redid all of the dimensioning for a much smaller hole. As we were waiting for our turn on the laser cutter we cut out pieces from the correct rod and found that, hey it actually fits.... all of that re-dimensioning for nothing.

Here is our fully put together motion module. Simple and working.

One iteration that we might have to do is make our tight fit parts tighter because some of the parts and slipping now. We shall see how it looks tomorrow!

Motion Module - SolidWorks Assembly

Now we had to take all of the solidworks parts and combine them into an assembly, which we had no idea how to do. So we fiddled around with the solid works and eventually figured out how to get the parts onto the assembly. Yay!

Then we stared at the screen a little bit wondering what to do with these parts. One thing we did figure out on our own was that we had to make the rods as a part in solidworks so that we would have the rods to stick the pieces into. So we did that and then stared at the screen again.

We tried all of the usual things like trying to line them up my hand and hoping against all odds that the parts would stay like that when we started to rotate it, which of course it didn't. Then we overheard the ninja saying "..something something MATE something something..".

So clicked on the mate button, which worked wonders. We started to mate them to together using the concentric function. We made all of the holes that the rod went through, concentric with the rods. Now we had the parts onto the rod but the kept sliding back and forth and overlapping on each other.

At this point, the class tutorial on mating started and we discovered the coincident function. We then made all of the pieces that need to be next to each other coincident so that all of the pieces were now stuck together.

Our last problem was that the arm and the offset circle were overlapping in the assembly. We solved this by making the two surfaces that touched tangent to each other. We ended up with this assembly after a lot of tinkering and a lot of mating.

We then happened to see the simulation button and decided to try that one. We clicked simulation rotation and then chose the offset circle to be the one that rotated. And it worked wonderfully!

The most wonderful thing about this process was that it told us that the arm piece was too tall so there was a "collision" and it wouldn't work. So we went back and made that piece shorter so that it would work! Solidworks told us that out initial design wouldn't work and we were able to make the iteration before we printed out the pieces!!

Motion Module - SolidWorks Parts

When we partners finally met we got our bearing and looked through the sketches that I had made and the foam core model. Having agreed on the model we did measurements and determined that our loose fit would be a 6.35 mm diameter and our tight fit would be a 6.26 mm diameter. The two holes on the large base piece would be loose fits while the hole in the offset circle and the arm would be tight fits. Getting the sketches into solidworks is always harder than I anticipate. The first step was to get all of the individual parts sketched into solidworks.

Turned into this....

And this

Becomes this

And finally the last piece, the arm

Becomes a solidworks piece

At this point, we decided we needed an iteration. Lyn brought up that having washers are a good idea and we do need the washers to hold the loose fit pieces in place. We decided to draw up four washers as a tight fit.

And with that all of our solid works parts were done. The next section will be on how we made these parts into an assembly!

Motion Module - Design Process

Unfortunately, my partner was not present for the first day of designing so I was working with the ninja. I wasn't sure of what kind of motion I wanted to make so the ninja mentioned a clapping motion. I thought about it and tried to make it on the legos. After tinkling on the legos I ended up with a chomping motion instead of a clapping motion. I couldn't figure out how to get the "hands" of a clapper to come back together after separating. I liked the simple design of the chomper that I mad on the legos.

The next step was to sketch the design onto paper. I thought that all designs started on paper and then became physical. This time, I made the physical lego model of the chomper first and then started to sketch it. Using the legos to come up with designs proved to be much easier than trying to imagine how to make a 3D model my sketching it on paper.

I then made the foam core model which consisted of three pieces.

That was all for the first day of designing and making the foam core model. Now, I had to communicate with my partner make any necessary iterations, take measurements and make the solid works model.