5 ms·

I didn't say anything about the design of it, which is by the way, very cool. I don't understand the point of the triangle. The same mechanism could be used to

I didn't say anything about the design of it, which is by the way, very cool. I don't understand the point of the triangle. The same mechanism could be used to change the geometry of the wheel only at the bottom.

deleted 8y ago
[deleted]
edaemon 8y ago
I would guess that it has to do with the tread tension. A rounded top with a flat bottom may leave the tread too loose. The triangle keeps it taught.
- hsienmaneja 8y ago
  Note: taut (pulled tightly) and taught (past tense of teach) are homophones
- Amygaz 8y ago
  Considering that this is a rather a rounded triangle, I doubt it has anything to do with tightness, and more with convenience, esthetic. A symmetrical displacement is also slightly less constraining in term of keeping the overall circumference/periphery (i.e. less deformation). A better design would have been to flatten the wheel into an more oblong or even an egg shape, like snowmobiles or tanks have. However, it requires more mechanical displacement and adjustements.
  - JshWright 8y ago
    "Better" is meaningless in isolation. The design you propose is better in some aspects, but likely not in the areas the designers of this wheel are optimizing for (simplicity, reliability, etc)
tCfD 8y ago
I suspect it may apply torque from the drivetrain to the mechanism with the most optimal geometric leverage against both the mechanisms internal frame and the contact patch on the ground during transition into and out of tread mode.
egypturnash 8y ago
Changing it only at the bottom adds complexity: Which side is at the bottom right now? How can we know this; how can we know this in a way that will survive the tough conditions we expect this to be driven in? And then we need to have three separate actuator paths to transform just one part of the wheel. We would also need to deal with the fact that just flattening one side of the wheel would make for a shorter perimeter than that of the circle; the tread is a loop of a constant length, and it needs to be kept fairly taut to function in both wheel and tread mode.
- emiliobumachar 8y ago
  The triangle solution absolutely does need to keep track of which side is at the bottom, or you'll end up with all the weight on one vertice. Agree with the perimeter consideration.
fastball 8y ago
It's a symmetrical wheel -- there is no bottom.

deleted 8y ago

[deleted]

edaemon 8y ago

I would guess that it has to do with the tread tension. A rounded top with a flat bottom may leave the tread too loose. The triangle keeps it taught.

hsienmaneja 8y ago
Note: taut (pulled tightly) and taught (past tense of teach) are homophones
Amygaz 8y ago
Considering that this is a rather a rounded triangle, I doubt it has anything to do with tightness, and more with convenience, esthetic. A symmetrical displacement is also slightly less constraining in term of keeping the overall circumference/periphery (i.e. less deformation). A better design would have been to flatten the wheel into an more oblong or even an egg shape, like snowmobiles or tanks have. However, it requires more mechanical displacement and adjustements.
- JshWright 8y ago
  "Better" is meaningless in isolation. The design you propose is better in some aspects, but likely not in the areas the designers of this wheel are optimizing for (simplicity, reliability, etc)

tCfD 8y ago

I suspect it may apply torque from the drivetrain to the mechanism with the most optimal geometric leverage against both the mechanisms internal frame and the contact patch on the ground during transition into and out of tread mode.

egypturnash 8y ago

Changing it only at the bottom adds complexity: Which side is at the bottom right now? How can we know this; how can we know this in a way that will survive the tough conditions we expect this to be driven in? And then we need to have three separate actuator paths to transform just one part of the wheel. We would also need to deal with the fact that just flattening one side of the wheel would make for a shorter perimeter than that of the circle; the tread is a loop of a constant length, and it needs to be kept fairly taut to function in both wheel and tread mode.

emiliobumachar 8y ago
The triangle solution absolutely does need to keep track of which side is at the bottom, or you'll end up with all the weight on one vertice. Agree with the perimeter consideration.

fastball 8y ago

It's a symmetrical wheel -- there is no bottom.