• aditya mehrotra.

chip updates: ok we're re-designing again... [updates]

So this weekend we took some time to try to assemble the actuator we designed last week and while this was a good concept, it's going to be a real pain to get anything like this to work on a real robot. It's too bulk and it's too just like annoying to assemble. That means we need to try something different.

We thought about this a lot this morning and we want to try to make the simplest possible version of the legged robot we can think of just to start. See if we can get it to walk in a straight line, and then we'll move onto other ideas. The simplest form we can come up with is a SpaceBok kind of design, w/ the versa planetary gearboxes (100:1), and 2DoF per leg instead of the full 3, we can add the third DoF later! We want to make it walk, and possible bound and jump. We can think about reducing gear ratios more in the future too. Here's what we started with.

We started with a bracket that could connect two of the 100:1 versa-planetary motor systems together as a unit. We wanted to build a robot around the motor modules, keeping the motors a structural component of the frame to reduce weight and increase stiffness.

We assembled this into a motor module that contains four motors and is put together using Churros from Andymark. Sticking w/ that NASA white/gold color scheme b/c we think it's pretty cool like that.

The above bracket was the designed to mount two motor modules together into a single frame for the body. This doesn't finish the frame but it is one of the main structural components that connects the whole body into a single body.

Here's the frame so-far, we want to figure out how to stiffen up the frame, mount the electronics, etc etc. We need an E-Stop button and all that fun stuff as well. But a little more mechanical design first. We need cross supports inside the frame and we can develop another pair of plates for mounting purposes. You can see the two actuators providing the 2 DoF for the legs. The leg design will be very similar to SpaceBok's leg design with the CF tubes:

We will design the legs later... let's continue with the frame design. The goal is to get this design mostly done today and order the frame parts so we can assemble the frame, then figure out how to mount the electrics, and then design and mount the legs so we will be done with the robot fairly quickly so we can move to making it do things.

This is the main body of the robot without any of the electronics besides the motors mounted to it. The shafts will be used for the 2DoF legs, and "cubbies" on the side of the body will be used to house the 8x motor controllers, the center cavity will be designed around the electronics system. We are still working out the best method to attach the electronics but in the meantime we can order the stock and the parts for the rest of the body. We, once again, want 1/8" 5052 Aluminum because it is easy to form and very light. We're going to get (2x) 2ftx2ft sheets of the stuff from McMaster Carr. That'll run us ~200 dollars for stock, and then we want to order the churros from Andymark with the tapping screws.

We estimate this will already be a lot lighter than any other designs we were considering, AND the previous version of chip, especially because we now have two less DoF!!! We think we have enough #10-32 socket head screws so we will use those for now.

We're going to start prepping the files for water jetting and water jet and assemble the body before we design the leg and the mounts for the electronics system. For the AndyMark stuff we'll pay for 2-Day shipping.

Here's some ideas for the legs:

- https://dragonplate.com/Braided-Kevlar-Round-Tube-1-ID-x-24

- https://dragonplate.com/carbon-fiber-roll-wrapped-twill-tube-1-id-x-24-gloss-finish

- https://dragonplate.com/1-Female-Clevis-Connector

- https://dragonplate.com/1-Male-Clevis-Connector

All of the above could work as building blocks for a leg. We'll have to do some more research into the leg design and the RoM before deciding/designing anything.

The electrical system will also need a re-design next.

#updates #omgrobots #yay #chip2

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