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However, valve gear mechanisms have been modified to be used as steering mechanisms for ornithopters, where the mechanism is used to modulate the wing stroke on both sides of the ornithopter much in the same way we intend to steer. A mechanism designed by Valentine is shown below.[1] While this mechanism has the advantage that it directly outputs an oscillating rotary motion of a link with a decent mechanical advantage, it is very complicated and requires linear actuators for stroke adjustment.
Another mechanism we considered was the
After doing further research on ornithopter turning mechanisms, we found a hypocycloid gear mechanism for stroke control. It consists of a ring gear with a rotating planet gear inside with a pin that connects to a scotch yoke. By rotating the ring gear one can adjust the stroke that the scotch yoke moves through. This mechanism is nearly ideal, however, it requires a complex arrangement of gears that would be difficult for us to manufacturer.
The next one is a variable piston stroke mechanism used in automobile engines and uses a linear actuator to move a pivot point along a circular path to modify the stroke of a piston.
Sources:
- A Variable Stroke Mechanism for Ornithopters
- Fixed Frequency, Variable Amplitude (FiFVA) Actuation Systems for Micro Air Vehicles
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