Wiper Arm Position Detection via Motor Current Analysis
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Solution Overview
Problem
Vehicle windscreen wiping systems face damage when the wiper arm is driven from its storage position to a maintenance position, as it can collide with the vehicle's bonnet, and existing methods lack a reliable way to determine the wiper arm's position before activation.
Innovation Solution
A method that estimates parameters such as electrical consumption, output torque, and friction coefficient to differentiate between the wiper arm's service and maintenance positions, using these values to control the motor and prevent damage by determining whether the blade is in contact with the window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wiper arm is driven from storage position to maintenance position, then the wiper arm becomes accessible for blade maintenance, but the wiper arm or blade can collide with the vehicle bonnet causing damage
Solution Approach 1:
The control unit performs a preliminary check by analyzing motor current consumption and torque parameters before allowing the wiper arm to be driven to maintenance position. This preliminary detection prevents collision by identifying the storage position condition in advance, blocking the maintenance position transition when the blade would collide with the bonnet.
2Measurement precision
If a sensor is added to directly detect wiper arm position, then position detection accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical position sensors with an electrical parameter-based detection system. The control unit monitors motor current consumption and torque characteristics to infer wiper arm position, eliminating the need for additional mechanical sensors while achieving sufficient detection accuracy for preventing storage position collisions.
Solution Approach 2:
The existing motor serves dual purposes: both driving the wiper arm and providing position information through its electrical characteristics. The motor's current consumption and torque parameters inherently contain position information, allowing the system to use the motor itself for detection without adding separate sensing components.
3Ease of operation
If the wiper arm is driven when in storage position, then blade maintenance can be performed, but the blade strikes the bonnet causing damage
Solution Approach 1:
The control unit continuously monitors motor electrical parameters during operation and uses this feedback to determine wiper arm position. When the blade approaches the bonnet during movement toward maintenance position, the feedback signal triggers an automatic stop command, preventing collision damage while allowing safe maintenance operations.
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
Prevents system damage by accurately determining the wiper arm's position before activation, ensuring the blade is not in contact with the window during motor operation, thereby avoiding collisions and maintaining system integrity.
Implementation Method 1
When the wiper arm is in its service position and it is driven by the motor, a friction occurs between the window and the blade which is sliding on the window
Implementation Method 2
This friction causes a friction torque which opposes the output torque of the motor
Implementation Method 3
a friction being characterized by a friction coefficient. This friction causes a friction torque which opposes the output torque of the motor
Data Source
AI summary
Method for detecting the position of a wiper arm (5) for a system (1) for wiping a vehicle window (3), comprising the steps consisting in:a) measuring or estimating (35) at least one parameter for determining the maintenance or service position,b) comparing (37) the measured or estimated value of said parameter with a reference value or a range of reference values, andc) determining, from the results of the comparison, whether the wiper arm is in maintenance or service position.