Devlog #4

Hey. This is my fourth Devlog for O.T.I.S, my personal AI desk robot. I know this is a lot of time to be putting into one Devlog, but I will try to go into as much depth as possible.

What I did

So, I started by creating a little notch for the camera module. I am going to buy an extension for the camera because it allows me to mount it separately, and because it comes with two heatsinks. Next, I made the gears that would hold the treads using a model of an SG90 attachment for dimensions. I also remodeled the top of the servo because the model had more comprehensive dimensions for the servo as well. After that, I began working on the front wheels. I created a model of a 2mm rod for the axle and made a cylindrical guide for the axle and gear. I also made a small stopper that I will attach to keep the axle from sliding out. Then I figured I should start on the assembly guide. I decided that an exploded view of the robot with a disassembly animation would suffice, but then I realized that I had not created a model for the LCD or the camera, so I began with the LCD. Once I completed that, I put the LCD on the robot and modeled holes for the screws. Lastly, I moved on to the camera module itself. I decided to model just the camera and the heatsink, since I didn’t think the extended wire would look accurate or contribute to the design. I also created models for the screws and nuts so that I could include them in the assembly guide. Lastly, I ordered the microcontroller, 22 AWG wire, and the servos.

Challenges

Modeling the gears

I had quite a bit of trouble when trying to model the gears. I wanted them to have the grooves inside similar to other common servo attachments, but I couldn’t find dimensions for the attachments that included them. I did find a 3d model online that had dimensions, so I based my design off of that. I haven’t modeled the grooves, but I will likely do so if I can find some reference. I also had a little bit of trouble finding rubber treads for the robot, since they were all too large. But I came across timing belts, which are usually used in printers or small CNC machines, and they seemed like the perfect solution. This is because they were small enough, were made of rubber, and had teeth.

Creating the screws

When looking for ways to mount the LCD to the robot, I decided that screws would work well. So I measured the size of the holes on the LCD, but they were 3mm big. This meant that a standard M3 (3mm) screw would not fit. So I looked for one slightly smaller and found M2.5. This size should work, since it is slightly smaller than the hole, but not too small. I also had a bit of trouble finding dimensions for the threads, since I thought that I would need to specify all of that when creating the screw. But I realized that Fusion only needed the size of the screw (M2.5), which I was able to provide. I did the same for the nut, using a reference I found on a listing. I will likely buy these screws from a local hardware store, so I will update my design after I buy them.

Deciding on a board

This was one of the biggest problems I had when creating this robot. Buying an unsoldered version would mean I could make stronger connections by twisting wire or soldering (I don’t have a soldering iron and don’t know how to solder). But it would make testing harder, and I would also be risking causing a short circuit if the wires shift around too much. Buying the board with presoldered pins would mean easier and more reliable testing. But jumper wires are not very secure, which means I would have to learn to solder anyway. In the end, I decided to go for the unsoldered version. My plan is to wrap the wire around the pins and to add hot glue or shrink wrap to make the connection safer while I get comfortable with soldering.

What is next

I am going to do research on the best AI for OTIS’s brain, as well as finish the 3D model and assembly guide.