Asymmetric Motor Control for Wiper Arm Speed Stability
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Solution Overview
Problem
Existing wiper device motor control systems face challenges in achieving smooth wiping operations due to uneven motor load conditions caused by windshield surface conditions and wind resistance, leading to asymmetrical target speed curves that can result in incongruous wiping speeds and difficulty in maintaining stable control, especially during deceleration.
Innovation Solution
A motor control method and device that set distinct acceleration and deceleration regions with varying speed change amounts, where the addition amount in the acceleration region is larger than the subtraction amount in the deceleration region, and include a constant speed region between them, allowing for adaptive target speed control and stable operation even when the operation angle changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If symmetric target speed curves are used for acceleration and deceleration, then the control is simple, but the wiping operation becomes incongruous due to uneven motor load conditions
Solution Approach 1:
The patent applies asymmetry by setting different addition amounts and subtraction amounts for target speed adjustment. Specifically, the addition amount (for acceleration) is set larger than the subtraction amount (for deceleration), creating an asymmetric target speed curve that compensates for the uneven motor load conditions during wiping operation, thereby achieving smooth and congruous wiping performance
Solution Approach 2:
The patent changes the parameters of target speed control by introducing different addition and subtraction amounts based on motor load conditions. The control device adjusts the target speed by adding or subtracting predetermined amounts according to the current motor load, dynamically modifying the speed profile to maintain consistent wiping performance across varying operational conditions
2Stability of the object's composition
If the addition amount equals the subtraction amount, then the target speed curve is symmetric, but the wiper blade speed becomes uneven under varying windshield conditions
Solution Approach 1:
The patent deliberately creates asymmetry in the target speed curve by setting the addition amount larger than the subtraction amount. This asymmetric design compensates for the natural unevenness in motor load during deceleration, ensuring that the wiper blade maintains consistent speed and pressure on the windshield throughout the entire wiping cycle, regardless of varying windshield conditions
Solution Approach 2:
The patent modifies the speed control parameters by introducing load-dependent addition and subtraction amounts. The control device monitors motor load and adjusts the target speed accordingly, using larger addition amounts during acceleration phases and smaller subtraction amounts during deceleration phases, thereby maintaining reliable and consistent wiping performance under varying operational conditions
Data Source
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AI summary
In a system in which an acceleration region SU and a deceleration region SD are provided between operation start and end positions of a wiper arm 1, in the acceleration region and the deceleration region, an addition amount and a subtraction amount are calculated, respectively, based on a difference between a maximum rotation speed and a current rotation speed to update a target rotation speed. The addition amount is set larger than the subtraction amount, and a constant speed region CV is provided between the acceleration region SU and the deceleration region SD. A length of the constant speed region CV can be changed. When a change amount of an operation angle of the wiper arm 1 does not exceed the constant speed region CV, the operation angle change amount is subtracted from the constant speed region. On the other hand, it maybe. Further, when the operation angle change amount exceeds the constant speed region CV, the target rotation speed is updated by the same change amount, e.g., the subtraction amount in the deceleration region both in the acceleration region and the deceleration region.