Aircraft Wiper Control via Tip Position Feedback
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Solution Overview
Problem
Traditional windshield wiper systems for aircraft lack feedback on the actual position of the wiper blade tip, leading to potential over sweep issues due to blade flexing and variable operational loading, which can result in blade failures and damage to the aircraft frame.
Innovation Solution
Incorporating sensors on the wiper blade tip and windshield to provide feedback on the blade's position, allowing the control system to adjust the wiper blade's speed and direction to prevent over sweep by generating commands based on discrete signals from these sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional software-controlled angular rotational limits are used for the wiper output shaft, then the sweep area and park position can be controlled, but the actual position of the wiper blade tip cannot be monitored, leading to over sweep incidents
Solution Approach 1:
The patent implements a feedback mechanism using sensors (e.g., optical sensors, encoders) mounted on the windshield to detect the position of the wiper blade tip. The sensor output is fed back to the control system, which adjusts the motor control signals to maintain the blade tip within the desired sweep area, preventing over sweep incidents despite blade flexing and wear.
Solution Approach 2:
The patent replaces traditional mechanical position sensing methods with electronic/optical sensing systems. Instead of relying solely on mechanical angular limits of the output shaft, the system uses optical sensors or encoders to electronically detect the actual position of the wiper blade tip, providing more accurate and adaptable position measurement.
2Reliability
If the wiper arm operates without position feedback, then the system is simpler, but the wiper blade will eventually run out of sweeping limits and hit the windshield frame due to blade flexing and variable loading
Solution Approach 1:
The control system continuously receives feedback from position sensors about the wiper blade tip location and adjusts motor commands in real-time to prevent the blade from exceeding its sweep limits, even under varying aerodynamic loads and blade flexing conditions.
Solution Approach 2:
The system dynamically adjusts the wiper motor's speed and direction based on real-time blade position feedback. The control algorithm modifies operational parameters on-the-fly to accommodate blade flexing during operation and compensates for changes in aerodynamic loading conditions.
3Duration of action of moving object
If over sweep is increased due to aerodynamic loads or aging of wiper arm, then the system continues to operate, but it leads to blade failures and potential damage to the aircraft frame
Solution Approach 1:
The control system takes preliminary action by continuously monitoring blade position and proactively adjusting motor commands to prevent the wiper blade from reaching positions that would cause over sweep. This preventive approach stops the harmful sequence before it begins, protecting both the blade and windshield frame from damage.
Solution Approach 2:
Real-time feedback from position sensors enables the control system to detect approaching sweep limits and adjust operation accordingly, preventing the conditions that lead to blade failure and frame damage even as the wiper arm ages or operates under high aerodynamic loads.
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 precise control of the wiper blade, reducing wear and extending its lifespan by avoiding over sweep incidents, ensuring consistent performance and reducing the need for unscheduled replacements.
Implementation Method 1
a transmitter disposed in the tip of the wiper blade and first and second sensors disposed proximate to first and second angle limits of the sweep pattern, respectively, whereby the first and second sensors are provided to receive signals created by the transmitter
Data Source
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AI summary
A windshield wiper system (WWS) is provided and includes a wiper blade (120), a motor assembly (130) and a control system (150). The wiper blade includes a tip (123). The motor assembly is configured to drive the wiper blade in a sweep pattern across a windshield. The control system is configured to control the driving of the wiper blade by the motor assembly in accordance with positions of the tip of the wiper blade.