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I'm currently in the process of rebuilding my model of the droid, mainly so all components are in the same file, to minimize the impact of Fusion's editable file limit.
In the meantime, I've put some more thought into the neck design.
This meant revisiting the ambiguity that I mentioned in the last paragraph of Post #1. The more I looked at the two images of the droid we have, the more it became clear that they are actually showing two different designs for the neck "hinge" joint and the upper stalk arrangement. Have a look at this closeup:
![[Image: KkY9UQl.png]](https://i.imgur.com/KkY9UQl.png)
In the retracted version of the droid on the left, the larger stalk is pretty obviously attached to the center section of the joint, which is somewhat inset from the two round sections on the outside.
In the lifted version of the droid on the right, that same stalk is instead attached to the outer section of the joint. Also, the center segment of the joint is not inset at all. Indeed, you could read the joint as having only two sections (possibly with a very thin disc in between), with the larger stalk attached to a sleeve rotating around its section.
It's not clear exactly how the thinner stalk is attached in either image. On the lifted version it could be on the outer section of the joint opposite the thick stalk, or it could be attached to a thin disc between that section and whatever passes as the middle segment. I'm not going to try to model the latter idea, but let's call the former one interpretation A:
![[Image: MO2sHR1.png]](https://i.imgur.com/MO2sHR1.png)
On the retracted version of the droid, the thinner stalk's positioning is very ambiguous due to the shadowing that conceals its attachment. It could be beside the larger one, behind it, or both (diagonal from it). I think I can disregard the diagonal option; mechanically it doesn't seem to make much sense. The remaining two interpretations, I'm going to call B (Beside) and C (Centered).
![[Image: H6Kd9N3.png]](https://i.imgur.com/H6Kd9N3.png)
![[Image: Z7ulbOx.png]](https://i.imgur.com/Z7ulbOx.png)
What does all of this mean for my droid? Well, mostly that I have no compelling artistic reason to choose one over another, so I feel free to pick whichever interpretation I think works best.
From a purely practical standpoint, any of A, B, or C are probably workable. A or B could let one use a linear actuator as the thinner stalk (if you could fit one there) to control the bank of the droid's head. Putting the thinner stalk directly behind the larger one (Interpretation C) would make it easier to create a parallelogram for making the droid's visible neck lean forward/back, if I wanted to go that route. Or for stabilizing the head when the droid starts driving. Or making a nodding mechanism instead of a banking one.
For awhile I waffled on whether I should design a mechanism that would allow the droid's visible "neck" to lean forward and back. However, this isn't shown in the art and would be a more complex mechanism with additional motors needed, potentially more weight in the neck, etc. Maybe I'll look at that for V2.
For now, I've settled on keeping the neck vertical and simply allowing it to lift higher as shown in the art and in my earlier diagram. This is a dummy version of the neck that I've got in mind:
![[Image: 5PshjmMl.png]](http://i.imgur.com/5PshjmMl.png)
Essentially it's a basic parallelogram mechanism, but you might notice that there's no fourth bar between pivot B and pivot C.
I realized that the actual shape of the four linkages doesn't matter (within reason) as long as they are rigid, don't interfere, and their four pivot points form the vertices of a parallelogram. In this case, the entire rear half of the droid's body shell rotates around C. B ties the neck "hinge" to that. Effectively, there is a "virtual" link between B and C.
If the link CD is kept horizontal, then the link AB also remains horizontal to compensate as AD and BC tilt upwards. And since the droid's neck is perpendicular to AB, it remains vertical.
The two "pistons" shown as AD are really just decorative and do not actually change length. The lift mechanism is likely to be a small linear actuator of some sort that directly lifts the rear shell of the droid (indeed, there's a small piston-like part visible in the lifted image of the droid, just behind the orange wire).
Because the shape of the linkages in this setup doesn't much matter, the details will likely change (particularly the bit tying A to B). But this is the basic principle.
In the meantime, I've put some more thought into the neck design.
This meant revisiting the ambiguity that I mentioned in the last paragraph of Post #1. The more I looked at the two images of the droid we have, the more it became clear that they are actually showing two different designs for the neck "hinge" joint and the upper stalk arrangement. Have a look at this closeup:
In the retracted version of the droid on the left, the larger stalk is pretty obviously attached to the center section of the joint, which is somewhat inset from the two round sections on the outside.
In the lifted version of the droid on the right, that same stalk is instead attached to the outer section of the joint. Also, the center segment of the joint is not inset at all. Indeed, you could read the joint as having only two sections (possibly with a very thin disc in between), with the larger stalk attached to a sleeve rotating around its section.
It's not clear exactly how the thinner stalk is attached in either image. On the lifted version it could be on the outer section of the joint opposite the thick stalk, or it could be attached to a thin disc between that section and whatever passes as the middle segment. I'm not going to try to model the latter idea, but let's call the former one interpretation A:
On the retracted version of the droid, the thinner stalk's positioning is very ambiguous due to the shadowing that conceals its attachment. It could be beside the larger one, behind it, or both (diagonal from it). I think I can disregard the diagonal option; mechanically it doesn't seem to make much sense. The remaining two interpretations, I'm going to call B (Beside) and C (Centered).
What does all of this mean for my droid? Well, mostly that I have no compelling artistic reason to choose one over another, so I feel free to pick whichever interpretation I think works best.
From a purely practical standpoint, any of A, B, or C are probably workable. A or B could let one use a linear actuator as the thinner stalk (if you could fit one there) to control the bank of the droid's head. Putting the thinner stalk directly behind the larger one (Interpretation C) would make it easier to create a parallelogram for making the droid's visible neck lean forward/back, if I wanted to go that route. Or for stabilizing the head when the droid starts driving. Or making a nodding mechanism instead of a banking one.
For awhile I waffled on whether I should design a mechanism that would allow the droid's visible "neck" to lean forward and back. However, this isn't shown in the art and would be a more complex mechanism with additional motors needed, potentially more weight in the neck, etc. Maybe I'll look at that for V2.
For now, I've settled on keeping the neck vertical and simply allowing it to lift higher as shown in the art and in my earlier diagram. This is a dummy version of the neck that I've got in mind:
Essentially it's a basic parallelogram mechanism, but you might notice that there's no fourth bar between pivot B and pivot C.
I realized that the actual shape of the four linkages doesn't matter (within reason) as long as they are rigid, don't interfere, and their four pivot points form the vertices of a parallelogram. In this case, the entire rear half of the droid's body shell rotates around C. B ties the neck "hinge" to that. Effectively, there is a "virtual" link between B and C.
If the link CD is kept horizontal, then the link AB also remains horizontal to compensate as AD and BC tilt upwards. And since the droid's neck is perpendicular to AB, it remains vertical.
The two "pistons" shown as AD are really just decorative and do not actually change length. The lift mechanism is likely to be a small linear actuator of some sort that directly lifts the rear shell of the droid (indeed, there's a small piston-like part visible in the lifted image of the droid, just behind the orange wire).
Because the shape of the linkages in this setup doesn't much matter, the details will likely change (particularly the bit tying A to B). But this is the basic principle.