Force Balance Sensor with Strain Amplification for Actuator Torque Matching
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Solution Overview
Problem
Conventional force balance sensors for flight control surfaces face challenges in accurately measuring torque differences between actuators due to installation variations and stiffness reduction caused by torque sensors, leading to potential position errors and reduced service life.
Innovation Solution
A mechanical strain amplification system is introduced, comprising a sensor torsion member with strain sensors and torsional stiffening members coupled to a torque member, which increases the mechanical strain amplitude above noise thresholds, allowing for precise measurement and adjustment of actuator positions to balance forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pressure sensors are used to sense pressure differential across actuators, then force balance error can be determined, but the force difference increases and creates counterproductive results
Solution Approach 1:
The patent extracts the sensing function from the actuator load path by placing pressure sensors in a bypass configuration. The sensors measure pressure differential across the actuator without being part of the primary force transmission path, thus avoiding the addition of sensor-induced force differences while maintaining measurement capability.
Solution Approach 2:
The patent introduces a bypass passage as an intermediary path that allows pressure sensing without direct interference with the actuator's force transmission. The bypass passage mediates between the high-pressure and low-pressure sides, enabling measurement while isolating the sensors from the main force path.
2Measurement precision
If torque sensors are placed in series between horn and torsion bar, then force balance error can be determined, but the stiffness of the torsion bar is compromised and reduced to the stiffness of the torque sensors
Solution Approach 1:
The patent extracts the torque sensing function from the torsion bar's load path. By measuring pressure differential across the actuator in a bypass configuration, the system determines force balance error without placing sensors in series with the torsion bar, thereby preserving the torsion bar's full stiffness.
Solution Approach 2:
The patent replaces direct mechanical torque sensing (which would require physical sensors in the load path) with pressure-based sensing. By measuring pressure differential across the actuator, the system infers torque information without mechanical interference, substituting a non-intrusive measurement method.
3Reliability
If triple redundant sensing with 12 individual pressure transducers is used, then force balance error can be determined with redundancy, but the device complexity increases
Solution Approach 1:
The patent merges the sensing functions by using fewer pressure sensors that can determine force balance error through pressure differential measurement across the actuator. This consolidation reduces the total number of sensors and associated electronics while maintaining the ability to detect force balance errors.
4Manufacturing precision
If actuators are commanded to the same position, then control surface positioning is adjusted, but installation variations cause torque difference and force fight between actuators
Solution Approach 1:
The patent implements feedback by continuously monitoring the pressure differential across the actuator, which indicates force balance error. The controller uses this feedback information to adjust actuator commands, compensating for installation variations and horn radius differences to minimize torque difference and force fight.
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 effectively reduces sensor complexity, error contribution, and noise interference, enabling accurate force balance measurement and improved control surface performance by amplifying torsional strain signals above noise thresholds, thus enhancing the service life and operational stability of flight control surfaces.
Implementation Method 1
at least one strain sensor coupled to the sensor torsion member between the first and second ends
Implementation Method 2
a first torsional stiffening member coupled to the first end of the sensor torsion member, and a second torsional stiffening member coupled to the second end of the sensor torsion member
Data Source
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AI summary
A force balance sensor (100) comprising a mechanical strain amplification system (130) comprising a sensor torsion member (110) having a first end (110a) and a second end (110b) spaced from one another along a longitudinal axis (110LA) of the sensor torsion member (110), at least one strain sensor (120) coupled to the sensor torsion member (110) between the first and second ends (110a/110b), a first torsional stiffening member (131) coupled to the first end (110a) of the sensor torsion member (110), and a second torsional stiffening member (132) coupled to the second end (110b) of the sensor torsion member (110), wherein the first torsional stiffening member (131) and the second torsional stiffening member (132) are coupled to a torque member (1002T).