Flight Control Rod Sensor Coupling for Backlash-Free Angle Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flight control surface actuation systems face challenges in accurately measuring the angular displacement of connecting rods due to backlash and free play, which introduces measurement errors, particularly in aerospace applications where precise control is crucial.
Innovation Solution
A flight control surface actuation system with a connecting rod and position sensor that utilizes a conical friction surface to connect the rod to an engagement part, ensuring accurate angular displacement measurement by minimizing sliding torque and frictional forces, and integrating a load sensor to enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is mounted on the connecting rod to measure angular displacement, then the position of the flight control surface can be determined, but measurement errors occur due to backlash and free play in the connection
Solution Approach 1:
The patent introduces an engagement part with conical friction surfaces as an intermediary between the connecting rod and the position sensor. This intermediary component transmits rotational motion while maintaining firm contact through friction, eliminating backlash and free play that would otherwise occur in direct mechanical connections. The conical friction surfaces ensure accurate angular displacement measurement by providing a reliable, backlash-free interface.
Solution Approach 2:
The patent replaces traditional mechanical connection methods (which suffer from backlash and wear) with a friction-based conical surface engagement system. This substitution eliminates the problems associated with clearances and free play in conventional mechanical joints, providing continuous and accurate position sensing without the measurement errors inherent in traditional mechanical linkages.
2Device complexity
If the actuator output part is directly connected to the connecting rod, then the structure is simple, but the position sensor cannot accurately measure angular displacement due to sliding torque and frictional forces
Solution Approach 1:
The patent employs conical (curved) friction surfaces instead of flat or cylindrical contact surfaces. The conical geometry of the engagement part creates optimal frictional contact that accommodates sliding torque while maintaining firm engagement. This curved surface design allows the position sensor to accurately measure angular displacement by reducing unwanted frictional forces that would occur with simpler mechanical connections.
3Ease of operation
If the engagement part is rotatably mounted to the connection structure, then the connecting rod can rotate about the axis, but axial movement and positioning errors occur
Solution Approach 1:
The patent separates the rotational freedom function from the positioning function by using conical friction surfaces. The engagement part can rotate freely about the axis due to the friction-based connection, yet axial movement is prevented by the self-centering nature of the conical surfaces. This extraction of functions allows both rotational movement freedom and angular position accuracy to coexist without compromise.
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
The system achieves precise angular displacement measurement with reduced errors, allowing for accurate control of flight control surfaces, reducing the need for actuator size reduction and easier sensor access.
Implementation Method 1
The engagement part comprises a first conical portion which tapers in a first axial direction, wherein the first conical portion forms a first friction surface engaged with a corresponding first connecting rod friction surface
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A flight control surface actuation system (10) includes a rotary actuator (12) having an output part configured to rotate about an axis (R-R), a connecting rod (16) for connecting a flight control surface to the rotary actuator, and a connection mechanism connecting a first end (18) of the connecting rod to the output part such that rotation of the output part about the axis causes at least part of the connection rod to rotate about the axis. The connection mechanism comprises a connection structure (22) fixed to the output part and an engagement part (50) mounted for rotation about a longitudinal axis. The engagement part extends through the connecting rod and is fixed to it. A position sensor (30) is arranged to measure the angular displacement of the first end of the connecting rod about the axis. A first part of the position sensor is secured to the connection structure in a fixed position. A second part of the position sensor is rotatably mounted to the first part and is configured to rotate with the engagement part and the connecting rod. The position sensor is configured to measure the relative rotation between the first and second parts of the position sensor.