Control method for preventing excessive scraping caused by sudden water splashing during dry scraping of windscreen wiper

Abstract

The invention discloses a control method for preventing excessive wiping caused by sudden water splashing during dry wiping of a windscreen wiper, which comprises the following steps of: continuously monitoring an operation load indication value of a windscreen wiper motor in the upward wiping process of the windscreen wiper; when it is monitored that the load value suddenly changes and exceeds a preset threshold value, it is judged that the windscreen wiper is in a friction load suddenly-changing state; and in the remaining upward turning process of the windscreen wiper, the upward turning limit position angle of the windscreen wiper is gradually reduced so as to avoid overshoot of the wiper blade. According to the control method for preventing excessive wiping caused by sudden water splashing during dry wiping of the windscreen wiper, the operation state of the windscreen wiper motor is continuously monitored, and the overturning limit position angle of the windscreen wiper is dynamically adjusted when the sudden change of the load is detected, so that edge beating and abnormal sound are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic wipers, and in particular to a control method for preventing over-wiping caused by sudden water splashing during dry wiping by the wiper. Background Art

[0002] During normal operation, existing automotive wiper systems control the wiper motor based on driver commands or automatic sensing signals, spraying detergent and then wiping the windshield to remove water stains. However, when the windshield is dry (dry wiping), the friction between the wiper blade and the glass increases significantly. Research has shown that the coefficient of friction between the wiper blade and the glass is much higher in dry conditions than in wet conditions and tends to be constant. In wet conditions, the Stribeck effect occurs, where the friction coefficient drops sharply as the relative sliding speed decreases. This sudden change in the friction coefficient can lead to unstable wiper blade motion, causing the wiper to overshoot and "edge" at the upper limit of the upper flip position.

[0003] However, existing technologies fail to effectively address the problem of abnormal wiper movement caused by sudden changes in friction when encountering water during wiping. Specifically, when the edge of the windshield suddenly encounters water stains, the edge of the glass becomes wet, and the friction between the wiper blade and the glass suddenly decreases. If the control strategy is not adjusted in a timely manner, the wiper blade is prone to overshooting at the upper limit of the upward tilt position, causing the wiper blade to hit the windshield frame and produce an abnormal noise. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a control method to prevent over-wiping caused by sudden splashing of water when the wiper is dry wiping. It solves the problem that when the edge of the windshield suddenly encounters water stains, the edge of the glass surface is wet, and the friction between the wiper blade and the glass drops sharply instantly. If the control strategy is not adjusted in time, the wiper is prone to overshoot and "hitting the edge" at the upper flip limit position, causing the wiper blade to hit the windshield frame and produce abnormal noise.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a control method to prevent over-wiping caused by sudden splashing of water during dry wiping by the wiper. This method is applied to the vehicle's front windshield wiper system, and includes the following steps: during the upward wiping process of the wiper, continuously monitoring the operating load indication value of the wiper motor; when a sudden change in the load value is detected and exceeds a preset threshold, judging that the wiper is in a friction load sudden change state; and during the remaining upward flipping process of the wiper, gradually reducing the upward flip limit position angle of the wiper to avoid overshoot of the wiper blade.

[0006] Preferably, the load mutation identification is achieved by monitoring the change amount or change rate of the current signal at the input end of the wiper motor.

[0007] Preferably, after identifying the load mutation, the controller obtains the current position θ of the wiper and the preset upward flip angle α_orig, and calculates the remaining flip time T; determines the total angle reduction Δα according to the load mutation amplitude, and calculates the angle Δα_per_cycle=Δα / (T / Δt) to be reduced in each control cycle; the controller dynamically reduces the target upward flip angle by Δα_per_cycle in each subsequent scheduling cycle.

[0008] Preferably, the control period Δt is the position loop scheduling period of the motor controller, and the scraper arm angle is fed back in real time by the position sensor, combined with PWM drive to control the motor movement, so that the scraper blade can achieve angle adjustment in each cycle.

[0009] Preferably, the method further comprises: when no sudden load change is detected, the wiper wipes to the originally set limit position according to the conventional control strategy; when a sudden load change is detected, avoiding edge hitting is achieved by the above-mentioned method of gradually reducing the angle.

[0010] Preferably, the method is applicable to different vehicle models and different wiper motors, and can be compatible with wiper systems of various specifications through software logic without adjusting the hardware.

[0011] Preferably, the adjustment range of the wiper upper flip angle can be determined based on preset parameters or an online self-learning method to adapt to changes in friction characteristics caused by factors such as wiper blade aging and ambient temperature.

[0012] Preferably, the control strategy is implemented by a computer-readable storage medium stored in an on-board control unit, and the control unit automatically executes the above-mentioned identification and angle adjustment steps according to the stored program.

[0013] The present invention provides a control method for preventing over-wiping caused by sudden splashing of water during dry wiping by wipers. Compared with the prior art, it has the following advantages:

[0014] This control method, which prevents overwiping caused by sudden splashing of water during dry wiping, uses software control to identify sudden changes in wiper load and dynamically reduce the limit angle during the upward flipping process of the wiper blade. This effectively prevents the wiper from overshooting and "hitting the edge" when the glass edge contacts water during dry wiping, and the resulting abnormal noise. This control method does not require changes to the existing hardware structure and only achieves functional improvements through optimization of the motor control strategy. Compared with replacing wiper components or installing hardware protection devices, the cost is lower. By reducing the limit angle, the impact force and recoil energy during the upward flipping process are significantly reduced, thereby preventing overshooting and "hitting the edge" caused by sudden splashing of water during dry wiping. In addition, reducing the control jump caused by sudden friction changes can improve the NVH performance of the entire vehicle and enhance passenger comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of load mutation of the present invention. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] See also Figure 1 An embodiment of the present invention provides a technical solution: a control method for preventing over-wiping caused by sudden splashing of water when the wiper is dry wiping. The method is applied to the vehicle's front windshield wiper system and includes the following steps: during the upward wiping process of the wiper, continuously monitoring the operating load indication value of the wiper motor; when a sudden change in the load value is detected and exceeds a preset threshold, judging that the wiper is in a friction load sudden change state; and during the remaining upward flipping process of the wiper, gradually reducing the upward flip limit position angle of the wiper to avoid overshoot of the wiper blade.

[0018] Furthermore, the load mutation identification is achieved by monitoring the change amount or change rate of the current signal at the input end of the wiper motor.

[0019] Furthermore, after identifying the load mutation, the controller obtains the current position θ of the wiper and the preset upward flip angle α_orig, and calculates the remaining flip time T; determines the total angle reduction Δα based on the load mutation amplitude, and calculates the angle to be reduced in each control cycle Δα_per_cycle=Δα / (T / Δt); the controller dynamically reduces the target upward flip angle by Δα_per_cycle in each subsequent scheduling cycle.

[0020] Furthermore, the control period Δt is the position loop scheduling period of the motor controller. The scraper arm angle is fed back in real time by the position sensor, and the motor movement is controlled by PWM drive, so that the scraper blade can achieve angle adjustment in each cycle.

[0021] Furthermore, the method further includes: when no sudden load change is detected, the wiper wipes to the original set limit position according to the conventional control strategy; when a sudden load change is detected, avoiding edge hitting is achieved by the above-mentioned method of gradually reducing the angle.

[0022] Furthermore, the method is applicable to different vehicle models and different wiper motors, and can be compatible with wiper systems of various specifications through software logic without adjusting the hardware.

[0023] Furthermore, the adjustment range of the wiper upper flip angle can be determined based on preset parameters or an online self-learning method to adapt to changes in friction characteristics caused by factors such as wiper blade aging and ambient temperature.

[0024] Furthermore, the control strategy is implemented by a computer-readable storage medium stored in the vehicle-mounted control unit, and the control unit automatically executes the above-mentioned identification and angle adjustment steps according to the stored program.

[0025] This method continuously monitors the operating status of the wiper motor and dynamically adjusts the wiper's upper flip limit angle when a sudden load change is detected, thereby avoiding edge slapping and abnormal noise. Specifically, the present invention adopts the following technical solutions:

[0026] 1. Load Sudden Change Identification: Current / torque feedback values, derived from the motor current sensor or an algorithm, are used as indicators of wiper load. During upward wiper operation, the controller compares the current wiper load value with the normal range in real time. A load sudden change occurs when the load change or rate of change exceeds a preset threshold (indicating a sudden change in friction characteristics with the glass). The controller also incorporates the current wiper angle information obtained by the position sensor for subsequent angle adjustment calculations. At this point, the system determines that the wiper has encountered water, resulting in a sudden change in friction, and triggers a switch in control strategy.

[0027] 2. Angle Adjustment Calculation: When a sudden load change is detected that exceeds a threshold, the controller calculates the remaining tilting time based on the wiper's current position and the set upward tilt angle. Specifically, it estimates the tilting time T required to reach the original planned limit angle from the current angle. Based on actual application experience or the magnitude of load variation within a sliding window, a total angle reduction, Δα, can be determined. For example, if the original limit angle is α_orig, it needs to be reduced to α_new = α_orig - Δα to mitigate the risk of overshoot caused by the load reduction. The controller distributes this total angle reduction, Δα, across each control cycle within the remaining tilting time, T. Assuming the controller scheduling period is Δt, the target tilting angle for each control cycle is reduced by Δα_per_cycle = Δα / (T / Δt). The controller uses a position sensor to precisely control the motor's angle increment per cycle, achieving dynamic adjustment with gradual convergence. In other words, with each subsequent control cycle, the wiper's upward tilt limit angle is slightly reduced relative to the original plan until the tilt is complete or the load returns to normal.

[0028] 3. Dynamic execution adjustment: During the controller scheduling cycle, the control program continuously updates the target angle based on the above calculations so that the wiper no longer extends excessively when entering the upper limit position. For example, if the remaining time is T and a total of N scheduling cycles need to be executed, the target limit angle will be cumulatively reduced by Δα_per_cycle per cycle. The motor controller drives the motor movement through the position loop and current loop closed-loop control instructions based on the updated target of each cycle to ensure that the wiper blade reaches the new flip position smoothly without exceeding it. This process is a continuous dynamic adjustment until the wiper moves to the new flip position

[0029] Example

[0030] 1. System composition and working principle

[0031] Hardware foundation:

[0032] Wiper motor (with current sensor), position sensor (such as TMR sensor), control unit (ECU), PWM drive circuit.

[0033] The current sensor monitors the motor load in real time, and the position sensor feeds back the scraper arm angle (e.g., in the range of 0° to 120°).

[0034] Control logic:

[0035] Normal mode: The wiper moves at a preset angle α orig (such as 110°) to perform an upward flip.

[0036] Mutation response mode:

[0037] When the current change rate is greater than the threshold (e.g. 50mA / ms), it is determined to be a sudden change due to friction with water;

[0038] Dynamically calculate the remaining time T (for example: current position θ = 80°, target α orig =110°, T=0.5s); set Δα according to the mutation amplitude (e.g. 10°), and distribute Δα according to the Δt=10ms period per_cycle =0.2°; target angle updated every cycle: α new =α orig -ΣΔα per_cycle .

[0039] Key Steps

[0040] Step 1: Identification of load changes

[0041] The motor no-load current reference value is I0=2A, and the current during dry scraping is I dry =3.5A±0.2A;

[0042] When water is suddenly encountered, the current drops to I within 20ms. wet =2.3A, change>threshold ΔI th =1A→trigger control strategy switching.

[0043] Step 2: Dynamic Angle Adjustment

[0044] The current position of the wiper is θ=90°, α orig =110°, remaining time T=0.3s (Δt=10ms, 30 cycles in total);

[0045] Assuming Δα=8°, then Δα per_cycle =8 / (0.3 / 0.01)≈2.67°;

[0046] The target angle is reduced by 0.267° every 10ms, and the final flip angle converges to 102°.

[0047] Step 3: Motor Execution

[0048] Position loop control: adjusts the PWM duty cycle based on real-time angle feedback (e.g. 90°→90.2°→90.4°...);

[0049] Make sure the wiper blade reaches its new limit position (102°) smoothly to avoid hitting the windshield frame.

[0050] 3. Adaptive Optimization

[0051] Online self-learning mechanism:

[0052] Record the Δα values ​​in historical load mutation events and establish a friction coefficient-Δα mapping table;

[0053] When the wiper blade ages and the dry wiping current rises to 4.0A, Δα is automatically increased to 12° to compensate for the change in friction characteristics.

[0054] 4. Verification of work results

[0055] index General Control This method Improvement Overshoot occurrence rate 92% 4% ↓95% Impact noise (dBA) 68-72 42-45 ↓35% Loss of wiper coverage - <2% Acceptable Response delay - <30ms Real-time

[0056] Note: The measured data is based on an ambient temperature of -30°C to 85°C and 50,000 aging cycle tests.

[0057] This working principle fundamentally solves the overshoot problem caused by dry scraping encountering water through the triple mechanisms of current-friction state mapping, dynamic trajectory planning, and closed-loop position control.

[0058] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A control method for preventing over-wiping caused by sudden splashing of water during dry wiping by wipers, the method being applied to a vehicle windshield wiper system, comprising the following steps: During the upward wiping process of the wiper, the operating load indication value of the wiper motor is continuously monitored; When a sudden change in the load value is detected and exceeds a preset threshold, the wiper is judged to be in a friction load sudden change state; During the remaining upward turning process of the wiper, the upward turning limit position angle of the wiper is gradually reduced to avoid overshoot of the wiper blade.

2. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: The load mutation identification is achieved by monitoring the change amount or change rate of the current signal at the input end of the wiper motor.

3. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: After identifying the load mutation, the controller obtains the current wiper position θ and the preset upward flip angle α_orig, and calculates the remaining flip time T; determines the total angle reduction Δα based on the load mutation amplitude, and calculates the angle to be reduced in each control cycle Δα_per_cycle = Δα / (T / Δt); the controller dynamically reduces the target upward flip angle by Δα_per_cycle in each subsequent scheduling cycle.

4. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: The control period Δt is the position loop scheduling period of the motor controller. The scraper arm angle is fed back in real time by the position sensor, and the motor movement is controlled by PWM drive, so that the scraper blade can achieve angle adjustment in each cycle.

5. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: The method further includes: when no sudden load change is detected, the wiper wipes to the originally set limit position according to the conventional control strategy; when a sudden load change is detected, avoiding edge hitting by the above-mentioned method of gradually reducing the angle.

6. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: The method is applicable to different vehicle models and different wiper motors, and can be compatible with wiper systems of various specifications through software logic without adjusting the hardware.

7. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: The adjustment range of the wiper upper flip angle can be determined based on preset parameters or an online self-learning method to adapt to changes in friction characteristics caused by aging of the wiper blade and ambient temperature factors.

8. The control method for preventing over-wiping caused by sudden splashing of water during dry wiping according to claim 1, characterized in that: The control strategy is implemented by a computer-readable storage medium stored in the vehicle-mounted control unit, and the control unit automatically executes the above-mentioned identification and angle adjustment steps according to the stored program.

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