Monday, January 27, 2014

Final Eye Version (Almost)

As noted last time, I've made some changes to the eye socket assembly and this time I'm almost done with the rest of the eye itself. This time I redesigned the rear portion of the eye with the support beam in mind unlike last time where I put it in at the last minute and made everything inelegant. I've also update the pivot brackets and the way that they mount to the rear of the head to be simpler and just plain better.

Here you can see the 3 pivot brackets with a larger relief fillet than last time.

It's a little difficult to see with all the shadows but here's the inside portion

And here are some renders without most of the outer shell components.

Looks pretty cool, huh? :)

One problem that's been on my mind is that I might not have enough room to run all the wires through the rear connector. For each eye, there will be 4 servos, 1 stepper motor, 1 switch, and 1 accelerometer. I need to run all those cables through the rear connector. So if I were to run those separately, that would be 15 wires-ish (assuming the grounds are common). I might be able to combine some of the power lines if they ran on the same voltage but I don't know quite yet. Right now, I have a 1/2" ID line to play with but I was hoping for a 1/4" ID line to better fit the look.

Anyways, I was finally able to understand why my original head pivot (pitch, roll) didn't work! The original design called for the same two actuators with a center pivot to provide 2 D.o.F. but during the simulations, with both actuators locked, I still had an unrestrained D.o.F. That's why I changed it to the current design with the support spring and all that junk.

After taking another look, it was such a dumb mistake. The 2 D.o.F. design is pretty common as a simulator platform but I couldn't figure out why mine didn't work while all the ones I've seen online worked. Well, the problem was that I used a ball joint to support the weight while every was using U-joints. I totally forgot that with the shafts constrained, the U-joint doesn't allow for roll along the axis while the ball joint under the similar constraints will.... duh.

So, tomorrow I will be shopping online for a suitable U-joint (probably from SDP-SI) and continue on with the rest of the head joint. I'm just hoping that I will have enough clearance for the range of motion that I want in the head.

Alright, time to take a break!

Update: Okay, so here's the revised head pivot!

I had to reverse mount the servos due to clearance issues and I will have to create spacers to offset them even more to stick out more towards the rear of the pivot.

There are going to be some clearance issues with the linkage hitting the lower sides of the pivot.. you can already see it being pretty close. I'll either shave off part of the pivot or flip the servos such that the arms are on the outside edge. That'll also lead to some clearance issues with the eye's bottom cover but these issues can all be addressed without too much difficulty. I just have to find that sweet spot... The other issue I'm worried about are the rod ends. The website where I'll be purchasing them do not specify the maximum swivel angle and I have a feeling that I'm already pushing them beyond their limits, especially on the two located on the very bottom. I might be able to alleviate this issue a little bit by drilling the mounting holes at an angle downwards. Hmm...

And here are the final renders for tonight:



No comments:

Post a Comment