Vehicle rain detector using psycho-acoustic indicators

Abstract

An automatic wiper control system for a vehicle window determines the presence of rain based on vehicle window vibrations. During a vehicle drive cycle, a controller measures window vibrations using an accelerometer attached to the window. The controller calculates a psychoacoustic index based on the measured vibrations, where the index may include a clarity index, sharpness, or roughness. The calculated index is compared to a threshold value indicating rain hitting the window. A wiper system is activated based on the comparison result.

Description

Technical Field

[0001] The present invention generally relates to detecting the presence of rain on vehicle windows to automatically activate a wiper system, and more particularly to rain detection accomplished by mechanical sensing and digital processing of acoustic indicators of sensed vibration signals. Background Art

[0002] Automatic windshield wiper control systems that adjust wiper operation / speed based on the presence of moisture on the windshield or the intensity of rainfall are known in the art. Such systems typically include an electronic control module that is connected to a wiper arm drive motor. The control module adjusts the operation and speed of the wiper arm drive motor in response to the sensed input. Optical sensors are the most common choice for detecting moisture. Placement on the window (e.g., near the rearview mirror) allows the sensor to detect moisture based on changes in light reflection when water is present. However, the moisture must be precisely concentrated in a small area of ​​the optical sensor for the optical sensor to work properly. Dirt or other matter on the windshield is sometimes interpreted as moisture, erroneously triggering the wipers. In addition, the sensors are relatively expensive and are used only for rain detection. It is desirable to improve rain detection performance, reduce sensor costs, reduce package size, and adopt sensor technology that supports other types of functions. Summary of the invention

[0003] In one aspect of the invention, a rain detector for a vehicle window includes an accelerometer mounted on the window to generate a vibration signal. A processor uses the vibration signal to calculate a predetermined psychoacoustic index. A discriminator compares the calculated psychoacoustic index to a threshold value indicating rain hitting the window.

[0004] By using an ultra-thin accelerometer on the windshield to pick up the sound vibrations, a wide range of interior and exterior events can be continuously monitored. The windshield or other window acts as a baffle, allowing the accelerometer to act as a microphone. Digital signal processing is applied to the resulting sound to distinguish the signature of rain hitting the windshield from other types of interior and exterior sounds that the vehicle will encounter. Mass-produced accelerometers can be obtained at a very low cost, yet the resulting rain detection performance is robust and reliable. These devices have a small size and can be easily placed on a rearview mirror assembly or other convenient location. Rain falling on a windshield creates a very distinct sound wave profile, which can be used to detect raining conditions. Additionally, the vibration signature can also be used to detect other events, such as sirens from emergency vehicles.

[0005] According to the present invention, there is provided a rain detector for a vehicle window, comprising:

[0006] an accelerometer mounted on the window to generate a vibration signal;

[0007] a processor that calculates a predetermined psychoacoustic index using the vibration signal; and

[0008] A discriminator compares the calculated psychoacoustic indicator to a threshold value indicative of rain impinging on the window.

[0009] According to an embodiment of the present invention, the psychoacoustic indicator comprises an articulation index, and the threshold is selected within a range of 5% to 10%.

[0010] According to another embodiment of the present invention, wherein the psychoacoustic indicator comprises sharpness, and wherein the threshold is selected within the range of 3.8 to 4.3 acum.

[0011] According to another embodiment of the present invention, wherein the psychoacoustic indicator comprises roughness, and wherein the threshold is selected within the range of 4 to 5.2 asper.

[0012] According to another embodiment of the present invention, the processor comprises a DSP audio processor.

[0013] According to another embodiment of the present invention, the discriminator comprises a comparator.

[0014] According to the present invention, there is also provided a vehicle wiper system for a vehicle window, comprising:

[0015] a wiper assembly, the wiper assembly comprising a wiper motor driving a wiper arm;

[0016] a wiper controller, the wiper controller selectively activating the wiper motor;

[0017] an accelerometer mounted on the window to generate a vibration signal;

[0018] a processor that calculates a predetermined psychoacoustic index using the vibration signal; and

[0019] A discriminator compares the calculated psychoacoustic index to a threshold value indicative of rain impinging on the window and provides a command signal to the wiper controller to activate the wiper motor.

[0020] According to an embodiment of the present invention, the psychoacoustic indicator comprises an intelligibility index, and the threshold is selected within the range of 5% to 10%.

[0021] According to another embodiment of the present invention, wherein the psychoacoustic indicator comprises sharpness, and wherein the threshold is selected within the range of 3.8 to 4.3 acum.

[0022] According to another embodiment of the present invention, wherein the psychoacoustic indicator comprises roughness, and wherein the threshold is selected within the range of 4 to 5.2 asper.

[0023] According to another embodiment of the present invention, the processor comprises a DSP audio processor.

[0024] According to another embodiment of the present invention, the discriminator comprises a comparator.

[0025] According to the present invention, there is also provided a method for operating a vehicle window wiper system, comprising:

[0026] measuring window vibrations with an accelerometer attached to the window;

[0027] Calculating psychoacoustic indices from the measured vibrations;

[0028] comparing the calculated indicator to a threshold value indicative of rain impinging on said window; and

[0029] The wiper system is activated according to the comparison result.

[0030] According to an embodiment of the present invention, the psychoacoustic indicator comprises an intelligibility index, and the threshold is selected within the range of 5% to 10%.

[0031] According to another embodiment of the present invention, wherein the psychoacoustic indicator comprises sharpness, and wherein the threshold is selected within the range of 3.8 to 4.3 acum.

[0032] According to another embodiment of the present invention, wherein the psychoacoustic indicator comprises roughness, and wherein the threshold is selected within the range of 4 to 5.2 asper.

[0033] According to the present invention, there is provided a rain detector for a vehicle window, comprising:

[0034] an accelerometer mounted on the window to generate a vibration signal;

[0035] a processor that uses the vibration signal to calculate a predetermined psychoacoustic index, the psychoacoustic index including a clarity index; and

[0036] A discriminator compares the calculated psychoacoustic indicator to a threshold value indicative of rain hitting the window, the threshold value being selected within the range of 5% to 10%.

[0037] According to another embodiment of the present invention, the processor comprises a DSP audio processor.

[0038] According to another embodiment of the present invention, the discriminator comprises a comparator.

[0039] According to the present invention, there is also provided a vehicle wiper system for a vehicle window, comprising:

[0040] a wiper assembly, the wiper assembly comprising a wiper motor driving a wiper arm;

[0041] a wiper controller, the wiper controller selectively activating the wiper motor;

[0042] an accelerometer mounted on the window to generate a vibration signal;

[0043] a processor, the processor calculating a predetermined psychoacoustic index using the vibration signal, the psychoacoustic index comprising at least one of the group consisting of a clarity index, sharpness, and roughness; and

[0044] a discriminator that compares the calculated psychoacoustic index with a threshold value indicative of rain impinging on the window and provides a command signal to the wiper controller to activate the wiper motor, wherein the threshold value comprises at least one of the group consisting of a clarity index selected within the range of 5% to 10%, a sharpness selected within the range of 3.8 to 4.3 acum, and a roughness selected within the range of 4 to 5.2 asper.

[0045] According to another embodiment of the present invention, the processor comprises a DSP audio processor.

[0046] According to another embodiment of the present invention, the discriminator comprises a comparator.

[0047] According to the present invention, there is also provided a method for operating a vehicle window wiper system, comprising:

[0048] measuring window vibrations with an accelerometer attached to the window;

[0049] Calculating psychoacoustic indices from the measured vibrations;

[0050] comparing the calculated psychoacoustic index to a threshold value indicative of rain impinging on the window; and

[0051] activating the wiper system according to the comparison result;

[0052] The calculated psychoacoustic index comprises at least one of the group consisting of clarity index, sharpness, and roughness; and

[0053] The threshold value includes at least one of a group consisting of a clarity index selected within a range of 5% to 10%, a sharpness selected within a range of 3.8 to 4.3 acum, and a roughness selected within a range of 4 to 5.2 asper.

[0054] According to the present invention, there is also provided a rain detector for a vehicle window, comprising:

[0055] an accelerometer mounted on the window to generate a vibration signal;

[0056] a processor that uses the vibration signal to calculate a predetermined psychoacoustic index, the psychoacoustic index including sharpness; and

[0057] A discriminator compares the calculated psychoacoustic index to a threshold value indicative of rain hitting the window, wherein the threshold value is selected within the range of 3.8 to 4.3 acum.

[0058] According to the present invention, there is also provided a rain detector for a vehicle window, comprising:

[0059] an accelerometer mounted on the window to generate a vibration signal;

[0060] a processor that calculates a predetermined psychoacoustic index using the vibration signal, the psychoacoustic index including roughness; and

[0061] A discriminator compares the calculated psychoacoustic indicator to a threshold value indicative of rain impacting the window, wherein the threshold value is selected within the range of 4 to 5.2 asper. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is a system diagram of an automatic wiper system on a vehicle;

[0063] Figure 2 An accelerometer mounted on a vehicle window and connected to electronics to detect rain is shown;

[0064] Figure 3 is a block diagram showing the electronic components of the present invention in more detail;

[0065] Figure 4 is a graph showing the clarity index calculated for signals collected in the presence of rain and other vibration disturbances;

[0066] Figure 5 is a discriminator for generating a wiper command signal based on the calculated clarity index;

[0067] Figure 6is a graph showing the calculated sharpness of signals collected in the presence of rain and other vibration disturbances;

[0068] Figure 7 is a graph showing the roughness calculated from signals collected in the presence of rain and other vibration disturbances;

[0069] Figure 8 is a block diagram showing another embodiment of an identifier. DETAILED DESCRIPTION

[0070] Figure 1 A portion of a vehicle 10 is shown, the vehicle 10 including a windshield 11 held on a vehicle body 12. A wiper arm 13 holding a wiper blade 14 is rotationally connected to a wiper motor 15. A wiper controller 16 activates the motor 15 in response to a manual command from an operator-controlled switch (not shown) or automatically in response to a rain detection signal from a rain detector 17. The present invention utilizes a vibration sensor 18 to characterize the vibration of the windshield 11 (or other vehicle windows, including a rear window), which is analyzed by the rain detector 17. In a preferred embodiment, the sensor 18 includes an accelerometer mounted directly on the windshield 11 within a rearview mirror assembly 20. A wiring harness 21 for the assembly 20 includes wires for connecting the sensor 18 to the detector 17.

[0071] Figure 2 A preferred embodiment is shown in more detail. The sensor 18 includes an accelerometer 25 adhesively mounted on the windshield 11. The accelerometer 25 may, for example, include a quartz shear element in a steel housing, such as the Model 3032M9 accelerometer available from Dytran Instruments, Inc. of Chatsworth, California. The ultra-thin and miniature size of the accelerometer 25 is well suited to fit within the footprint of a typical rearview mirror assembly for unobtrusive placement. The accelerometer 25 is oriented so that its sensing axis is perpendicular to the surface of the windshield 11. A coaxial cable 26 transmits the accelerometer signal to a signal conditioning circuit 29 (e.g., an amplifier) ​​via connector plugs 27 and 28 (e.g., BNC connectors). The conditioned accelerometer signal is provided to the rain detector 17, which includes an analog-to-digital converter (A / D) 30 and an indicator processor 31.

[0072] The physical behavior of water (e.g., rain) striking the windshield "microphone" creates a specific sound profile. The present invention has identified specific indicators by which this sound profile can be distinguished from other types of sounds. More specifically, the present invention preferably employs known psychoacoustic indicators, such as clarity index, sharpness, and roughness, and identifies corresponding thresholds for each indicator that clearly separate the sound of rain on the windshield from other interior and exterior noise that may be present. To support the automatic wiper function, the threshold establishes a trigger for activating the wiper system. As shown in FIG. Figure 3 As shown, the indicator processor 31 may be configured to perform a digital signal processing (DSP) indicator calculation 32 , wherein the resulting psychoacoustic indicator is examined by a discriminator 33 , which generates an automatic wiper on / off command signal.

[0073] Figure 4 The first embodiment of the psychoacoustic index shown in includes an intelligibility index. The intelligibility index (AI) estimates the intelligibility of speech in a specific noise environment or a specific transmission channel. More specifically, it estimates the percentage of speech units perceived and understood by the listener. In order to calculate the AI, the signal-to-noise ratio (SNR) of several individual frequency bands is weighted and summed. When analyzing the AI ​​of a specific sound without a speech signal for comparison, the SNR is calculated for an idealized noise spectrum, which is usually defined between 0 dB and 30 dB. For the frequency band, any signal that is 30 dB or larger than the ideal noise is set to 100%, and any signal that is 0 dB or smaller than the ideal noise is set to 0%. The commonly used algorithm for calculating AI uses a frequency band of approximately 5 1 / 3 octaves between 200 Hz and 6300 Hz. DSP hardware and software packages can be used to calculate AI% as well as sharpness, roughness and other psychoacoustic indicators useful in the present invention, such as the ArtemiS Suite available from HEADAcoustics GmbH of Herzogenrath, Germany.

[0074] Figure 4 The results of an analysis of data collected from an accelerometer mounted on a vehicle windshield that is subjected to many different conditions that cause corresponding vibrations or sounds in the windshield. For example, the vehicle is exposed to rough road noise at low speeds, the high levels of road and wind noise present during highway driving, blast noise from defrosters and panel vents associated with HVAC operation, external noise from the vehicle horn, internal noise from the audio system (e.g., music), and conversations between passengers in the vehicle. Using sampled data corresponding to each condition obtained over a long drive cycle, Figure 4, a corresponding graph of the AI ​​values ​​calculated for each condition is shown in . The AI% value for rain hitting the windshield is shown as a solid line 35, which remains near zero (e.g., less than about 2%) throughout the data collection period. In contrast, the AI% values ​​for all other test conditions shown by the dashed lines are relatively high. The lowest AI% values ​​for the other conditions correspond to heating, ventilation and air conditioning (HVAC) noise, which does not fall below about 30%. Therefore, the threshold 36 can be established somewhere between a few percentage points to about 25%, which reliably distinguishes rain from all other sound sources. Preferably, the threshold 36 can be about 5% to about 10%. Other definitions or calculation methods can also be used for AI%, so that the AI% allows negative results (i.e., less than 0%) or results greater than 100%, but the values ​​of the corresponding thresholds will be adjusted accordingly.

[0075] Figure 5 A discriminator 33 is shown having a configuration for comparing the calculated AI indicator to a threshold value 36 using a comparator 37. The calculated value of AI% is coupled to the inverting input of the comparator 37, and the threshold value 36 is coupled to the non-inverting input. As long as there is no precipitation on the windshield, the value of AI% will be above the threshold value 36. Under these conditions, the relatively high AI% level causes the output of the comparator 37 to remain at a low logic level, thereby causing the wipers to be turned off by a rain detection signal that can be used as a wiper on / off command signal. In the presence of precipitation, the value of AI% drops below the threshold value 36 and the comparator output rises to a high logic level, which indicates that rain is detected and the wipers are activated.

[0076] Figure 6 A second embodiment of a psychoacoustic indicator shown in comprises acoustic sharpness (S). Sharpness is an indicator responsive to the frequency content of noise. It is proportional to the ratio of the high frequency noise level to the total noise level. Sharpness has acum units and is preferably calculated according to standard DIN-45692. For example, calculating S typically involves the sum of specific loudness or weighted semi-variance divided by the total loudness. Figure 6 A trace 40 of the sharpness S for windshield vibrations caused by rain is shown, having an average value of about 4.8 acum and always remaining above 4.2 acum. The calculated sharpness S for all other sound sources is always below about 4.0 acum. Therefore, a sharpness threshold 41 in the range of about 3.8 to about 4.3 acum may be used, with a most preferred threshold of about 4.1 acum. To avoid false triggering at peaks or valleys of the calculated signal, a time average before comparison with the threshold may be used.

[0077] Figure 7The third embodiment of the psychoacoustic index shown in includes acoustic roughness (R). Roughness is an index used to simulate the response of the human ear to the pulsation or beating that occurs due to the time-varying frequency components of the sound. It is calculated in units of asper. When a 1kHz sinusoidal tone with 60dB is modulated at a frequency of 70Hz, a roughness of 1asper is generated. Figure 7 A trace 45 of the roughness R for windshield vibrations caused by rain is shown, which has an average value of about 6 asper and always remains above 5 asper. The calculated roughness R for all other sound sources is always below about 4 asper. Therefore, a roughness threshold 46 in the range of about 4 to about 5.2 asper can be used, with a most preferred threshold of about 5 asper.

[0078] Using any of the foregoing indices, the present invention includes a method of operating a wiper system for a vehicle window. During a vehicle drive cycle, a controller (such as a controller in a body control module) measures window vibrations using an accelerometer attached to the window. The controller calculates a psychoacoustic index based on the measured vibrations, where the index may include a clarity index, sharpness, or roughness. The calculated index is compared to a threshold value indicating rain hitting the window. The wiper system is activated based on the comparison result.

[0079] Rain detection can be based on using only one psychoacoustic metric. Alternatively, the metrics can be combined, such as Figure 8 As shown. Thus, the output of comparator 37 is coupled to an input of logic block 50 based on its comparison between the calculated AI% and the AI ​​threshold. The calculated sharpness S is compared with the sharpness threshold by comparator 51, which provides the comparison result to logic block 50. The calculated roughness R is compared with the roughness threshold by comparator 52, which provides the comparison result to logic block 50. The logic block may implement a voting scheme for generating taps for the wiper on / off command signal based on a predetermined number of psychoacoustic indicators indicating rainfall detection. The predetermined number may be set to one, two, or all three indicators indicating rainfall.

[0080] The foregoing description has shown rain detection which uses a reliable and inexpensive sensor to trigger automatic windshield wiper operation. Detection covers the entire window glass, so there is no need to specifically strike a small optical sensor as with prior systems. The present invention can be easily implemented on the rear glass at the rear and on the front glass. The preferred high capacity accelerometer is much less expensive than known optical sensors. In addition, the placement of the accelerometer on the glass can be used for other functions such as emergency vehicle sirens detection, railroad crossing signals, vehicle horns, or other sounds based on a unique profile of sound signal detection striking the windshield.

Claims

1. A rain detector for a vehicle window, comprising: an accelerometer mounted on the window to generate a vibration signal; a processor that calculates a predetermined psychoacoustic index using the vibration signal; and a discriminator that compares the calculated psychoacoustic indicator to a threshold value indicative of rain hitting the window, The psychoacoustic index includes at least one of a clarity index, sharpness, and roughness, and the threshold includes at least one of the following: a clarity index selected within the range of 5% to 10%, a sharpness selected within the range of 3.8 to 4.3 acum, and a roughness selected within the range of 4 to 5.2 asper.

2. The rain detector of claim 1, wherein the processor comprises a DSP audio processor. The rain detector of claim 1 , wherein the discriminator comprises a comparator.

4. A motor vehicle wiper system for a vehicle window, comprising: a wiper assembly, the wiper assembly comprising a wiper motor driving a wiper arm; a wiper controller, the wiper controller selectively activating the wiper motor; an accelerometer mounted on the window to generate a vibration signal; a processor that calculates a predetermined psychoacoustic index using the vibration signal; and a discriminator that compares the calculated psychoacoustic index to a threshold value indicative of rain impinging on the window and provides a command signal to the wiper controller to activate the wiper motor, The psychoacoustic index includes at least one of a clarity index, sharpness, and roughness, and the threshold includes at least one of the following: a clarity index selected within the range of 5% to 10%, a sharpness selected within the range of 3.8 to 4.3 acum, and a roughness selected within the range of 4 to 5.2 asper.

5. The wiper system according to claim 4, wherein the processor comprises a DSP audio processor. The wiper system according to claim 4 , wherein the discriminator comprises a comparator.

7. A method of operating a vehicle window wiper system, comprising: measuring window vibrations with an accelerometer attached to the window; Calculating psychoacoustic indices from the measured vibrations; comparing the calculated psychoacoustic index to a threshold value indicative of rain impacting said window; and According to the comparison result, the wiper system is activated. The psychoacoustic index includes at least one of a clarity index, sharpness, and roughness, and the threshold includes at least one of the following: a clarity index selected within the range of 5% to 10%, a sharpness selected within the range of 3.8 to 4.3 acum, and a roughness selected within the range of 4 to 5.2 asper.

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