Wiper Position Feedback Control After Power Loss
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Solution Overview
Problem
Conventional windshield wiper systems fail to accurately determine the reference start position after a sudden power failure, leading to unintended sweeping areas due to the wiper arm assuming a random position, which causes malfunctions and shifts in the sweeping zone.
Innovation Solution
A system with a wiper arm, an angular encoder, and a controller that records and compares positions to ensure the wiper arm returns to the park position before resuming its sweep, using a motor and gear reducer to maintain the wiper within a predetermined sweep zone, and optionally utilizing a cam and Hall Effect sensor for position feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wiper arm starts sweeping from a reference start position assuming it is at the park position, then the wiper system can operate with simple control logic, but after power failure the wiper arm may assume an arbitrary position causing unintended sweeping area
Solution Approach 1:
The patent implements feedback by using an angular encoder to continuously monitor the wiper arm position and provide real-time position data to the controller. This feedback mechanism allows the system to detect when the wiper arm is at the park position and when it reaches the start position, enabling accurate positioning without complex control logic. The encoder feedback resolves the contradiction by providing simple yet reliable position detection that prevents unintended sweeping areas.
Solution Approach 2:
The patent applies preliminary action by performing a calibration sequence during system initialization or after power restoration. The controller automatically moves the wiper arm to the park position, records it as the reference zero position, then moves to the start position and records it. This preliminary calibration ensures that subsequent sweeping operations occur in the correct zone without requiring complex real-time adjustments during normal operation.
2Reliability
If the wiper arm is moved to return to park position after power failure, then sweeping zone accuracy is restored, but additional movement time is required
Solution Approach 1:
The system performs self-service by automatically executing the calibration sequence without requiring manual intervention. When power is restored or during initial startup, the controller autonomously detects the park position, moves the wiper arm to the start position, and establishes the correct reference frame. This self-calibration capability restores sweeping zone accuracy while minimizing time loss by eliminating the need for manual recalibration procedures.
3Measurement precision
If an angular encoder is used to record wiper arm position, then position accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical position sensing mechanisms with an angular encoder that provides precise electrical measurement of the wiper arm position. The encoder converts mechanical rotation into electrical signals that can be easily processed by the controller, achieving high measurement precision while reducing mechanical complexity. This substitution resolves the contradiction by providing accurate position data through a relatively simple and reliable sensing device.
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
Ensures accurate and reliable wiper arm movement within defined sweep limits, preventing zone shifts and ensuring proper operation upon power restoration, enhancing safety and reliability with precise control and reduced calibration needs.
Implementation Method 1
In certain embodiments, the position sensor can be a Hall Effect sensor
Data Source
Figure 1
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AI summary
In accordance with at least one aspect of this disclosure, a system (100) includes a wiper arm (106) configured to sweep along a sweep zone (108) defined between a start position (110) and an end sweep position (112). A wiper drive shaft (116) is operatively connected at a proximal end (118) to the wiper arm to drive the wiper arm between the start position and the end sweep position. At least an angular encoder (120) is operatively connected to a distal end (122) of the wiper drive shaft configured to record an actual position of the wiper arm. A controller (128) is operatively connected to the encoder to receive position wiper arm position data therefrom.