Variable-Radius Pulley for Non-Sinusoidal Wing Flapping
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Solution Overview
Problem
Existing flapping wing mechanisms for radio-controlled, heavier-than-air aircraft, or ornithopters, face challenges in achieving efficient and controlled wing motion due to issues with slack in drive linking members and inconsistent angular velocities, leading to suboptimal lift generation and control moments.
Innovation Solution
The implementation of a flapping wing driving apparatus with variable-radius drive pulleys and synchronization pulleys, coupled with elastic drive linking members, allows for non-sinusoidal angular rotation of the wings in response to constant crank gear rotation, reducing slack and enhancing control through synchronized opposing movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant angular rotation is used to drive the wing capstan, then the drive mechanism is simple, but the wing motion becomes sinusoidal with high accelerations and vibrations at direction changes
Solution Approach 1:
The patent applies the dynamics principle by making the drive pulley variable-radius rather than constant-radius. The drive pulley radius changes dynamically during rotation, being larger when the wing changes direction and smaller during steady flapping motion. This dynamic adjustment allows the mechanism to reduce accelerations and vibrations at critical moments while maintaining overall simplicity of the drive system.
2Ease of operation
If slack is allowed in the drive linking member, then the mechanism is more flexible, but control precision and lift generation become suboptimal
Solution Approach 1:
The patent applies parameter changes by using elastic cables instead of rigid linkages. The elastic cables can stretch and compress, allowing the mechanism to accommodate motion variations and maintain tension without becoming overly rigid. This elasticity provides flexibility while maintaining sufficient control precision for optimal lift generation.
3Productivity
If non-sinusoidal angular rotation is implemented, then lift generation and control moments improve, but the drive mechanism complexity increases
Solution Approach 1:
The patent achieves non-sinusoidal rotation through the variable-radius drive pulley that changes its effective radius during operation. This dynamic parameter change produces the desired non-sinusoidal motion profile that improves lift generation and control moments while avoiding the need for complex multi-component mechanisms.
Solution Approach 2:
The invention changes the geometric parameter of the drive pulley (its radius) to achieve non-sinusoidal wing rotation. By varying the radius parameter during the flapping cycle, the system optimizes aerodynamic performance without requiring complex control systems or multiple actuators.
4Manufacturing precision
If variable-radius drive pulleys are used, then wing motion control improves, but the manufacturing complexity of the pulleys increases
Solution Approach 1:
The variable-radius drive pulley is manufactured with a specific non-circular geometry that changes its effective radius during rotation. This geometric parameter change is built into the pulley design, allowing precise control of wing motion through a single manufacturable component rather than requiring complex assembly of multiple parts.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables more efficient wing motion with reduced accelerations and vibrations, improving lift generation and control moments, resulting in a more stable and controlled flight profile for the aircraft.
Implementation Method 1
The first drive linking member and the second drive linking member may each comprise a plurality of cables and the plurality of cables may be elastic
Data Source
AI summary
A flapping wing driving apparatus includes at least one crank gear capstan rotatably coupled to a crank gear, the at least one crank gear capstan disposed radially offset from a center of rotation of the crank gear; a first wing capstan coupled to a first wing, the first wing capstan having a first variable-radius drive pulley portion; and a first drive linking member configured to drive the first wing capstan, the first drive linking member windably coupled between the first variable-radius drive pulley portion and one of the at least one crank gear capstan; wherein the first wing capstan is configured to non-constantly, angularly rotate responsive to a constant angular rotation of the crank gear.