Since this was the week of our COGS 344 presentation, I spent most of it collecting past robot designs and preparing to present. The currently printed body is not able to display the behaviors I had hoped, so I’m planning on bringing it in without the motors and relying on my video of the wood-block prototype to illustrate the intended range of motion. I also spent a lot of time leading up to the presentation trying to finish a better 3D model to demonstrate in my presentation and hopefully use in the future.

The “ears” in this image are there just to illustrate what this would look like if printed with attached ears.

Despite the fact that most people I have asked have seen my prototypes as heads rather than bodies, I have chosen to commit to creating a body instead for several reasons. First, this design is more mechanically consistent with the wood-block prototype i created earlier. The strings that control the ears full backward rather than down as they did in my previous print. That downward motion meant that the ears did not behave as expected. Beyond that, using a head as a model presents difficulties in terms of later testing. A disembodied head on a table is weird, and would need to be incorporated into a body of some kind. Designing an entire body instead eliminates this problem.

At the time of my COGS 402 final deliverable, this is the most recent prototype I have, and the result of many weeks of constant sketching, prototyping, and failing across a number of physical and digital mediums. More than anything, I would say this experience has illustrated to me how important the “rapid” part of rapid prototyping is. The amount of time I spent struggling to learn to use 3D modelling tools to realize my ideas dramatically slowed my progress toward creating a usable robot. One of my personal goals for this project was to learn how to 3D model, and in that way I was successful, but I probably should have spent more time on lower fidelity prototypes before devoting so much time to learning an entirely new tool from scratch. Regardless, my time in SPIN Lab was an amazing and fun learning experience, and one which I would highly recommend to future 402 students.

The temporary wooden base I was using to hold my model ear to the screw attaching it to the body has finally broken. This means I need to quickly build a new model so that I can continue making sure that my current model is viable before designing behaviors and potentially printing a final body. The new ears are built around a hollow aluminum tube attached to a screw. The fact that it’s hollow makes it much easier to achieve the flat shape i need than the wood, which I had to sand down by hand.

Reconstructing the ears has also given me the opportunity to reconsider the mechanism I’ve been using to attach them to my past body designs. Previous designs relied on a tightened bolt to hold the ears in place inside a channel along the top of the body. This worked at the start, but the constant rotation of the ears meant that the bolts would eventually loosen, relying instead on the tautness of my control strings to hold the ear in place. Crimping aluminum directly onto the screws means that the rotation shouldn’t have any effect on the tightness of their attachment to the body, which should make the ears more reliable. As always, I’m still working on body redesigns in my free time.

At this point, I’ve printed the body and the internal case which will hold my servos in place. As a result, I’ve spent this week finally attaching the ears and their mechanism to the body. If I had it to do over again, I would have removed the rear wall of the body as well as the bottom. It’s been difficult to attach the servos to the strings that connect to the ears while inside the head, making sure that all of the strings are tight enough that the ear motion will be fully realized when the servos move.

I’m still not especially happy with the design of my head, and have been working on a redesign in my free time. I’m not sure that I will have enough time to to this before my 344 presentation, but for the future study, it would be nice to have a more complete and compelling model.

For these two weeks, I’ve been working on incorporating the servos directly into the body of my robot. The servos will fit inside the larger rounded end of the body and control the ears through strings running through channels to the surface of the body. I started by quickly creating a model of the rear structure of the body to make sure that I leave enough space to accommodate the servos.

Based on this model’s measurements, I’m planning on creating an internal box that will hold the servos in place. The future body will have the bottom face of the body missing to allow me to put the servos in. Time and Solidworks abilities permitting, I will try to create a bottom that I can attach to the body which will make the body robust enough to be carried rather than only resting on the table.

Outside of body design, I’m starting to think about ways to redesign the ears to make them more robust, since the current version relies on barbecue skewers for attachment.

The new model had some serious problems around measurements. The slots which the ears would have attached to were printed too small, either as a result of poor measurement or lower than expected printing resolution, probably a combination of the two. To fix this, I printed several variants of the ear slots to help me determine what size they will need to be in the final version.

In doing this, I also realized that the structure I created was not as reliable as I expected. The very circular internal chamber which the screw head rotates within makes it difficult  to lock the ears into place. Future versions of the body will incorporate a different attachment mechanism that should let the ears lock into place better.