JP5617751B2 - Vehicle approach warning device - Google Patents

Description

  The present invention relates to a vehicle approach warning device that warns the surroundings that a vehicle is approaching by generating sound from the vehicle.

  In recent years, electric vehicles (EV cars), hybrid cars (HV cars), etc. have structurally low noise, and it is difficult for pedestrians to notice the approach of these vehicles. Vehicle approach warning devices that generate simulated running sounds are being installed in order to raise awareness of being in a car. The vehicle approach warning device improves recognition to pedestrians by adding processing such as changing the voice frequency and sound pressure according to the driver's accelerator operation state and vehicle driving state when driving at low speed with low road noise. (For example, refer to Patent Document 1).

  Specifically, the vehicle approach warning device controls the sound pressure generated according to the accelerator opening operated by the driver. FIG. 3 is a graph showing the relationship of the sound pressure increase rate with respect to the accelerator opening. The sound pressure increase rate indicates how many times the sound pressure is generated with respect to the reference sound pressure using the sound at the time of accelerator off and brake off as the reference sound pressure.

  As shown in this figure, the sound pressure increase rate is designed to increase in a directly proportional relationship as the accelerator opening increases. That is, the sound pressure increase rate is linearly changed with respect to the accelerator opening. Thereby, the sound pressure generated according to the accelerator opening operated by the driver is controlled.

JP 2009-35195 A

  However, the area where the accelerator opening is low has play of the accelerator, and the area where the accelerator opening is high is rarely used in urban areas where sound generation by the vehicle approach notification device is required. If the sound pressure increase rate is set linearly with respect to the change in%, the change in sound pressure does not match the accelerator operation state. For this reason, there is a problem that it is difficult for the pedestrian to recognize the driver's accelerator operation state.

  In view of the above points, an object of the present invention is to enable a pedestrian to accurately recognize an accelerator operation state by enabling sound generation that is more suitable for an actual accelerator operation state.

  In order to achieve the above object, according to the first aspect of the present invention, in the vehicle approach warning device for warning the approach of the vehicle by controlling the sound pressure of the sound from the sounding body (3) mounted on the vehicle, Corresponding to the accelerator operation state, it has a memory for storing a functional expression or map indicating the relationship between the accelerator operation state and the sound pressure, inputs an operation state detection signal indicating the accelerator operation state, and inputs the operation state detection signal Calculates the sound pressure corresponding to the accelerator operation state indicated by the microcomputer (21a) having the output unit (21a) for generating the sound output corresponding to the sound pressure, and the sound generated from the output unit (21a) An amplifier (24) for supplying a current corresponding to the output to the sounding body (3), and the relationship between the accelerator operation state and the sound pressure is such that the sound pressure gradually increases when the accelerator operation state is smaller than the first predetermined value. In addition, the pressure gradually increases, and in the range of the first predetermined value or more and the second predetermined value or less, the sound pressure increases with a rising gradient larger than the first predetermined value, and the range of the second predetermined value or more and the third predetermined value or less. Then, the rising slope of the sound pressure is smaller than that in the range of the first predetermined value or more and the second predetermined value or less, and in the range exceeding the third predetermined value, the sound pressure is saturated at the maximum value. It is a feature.

  Thus, when the accelerator operation state is less than or equal to the first predetermined value, the sound pressure is gradually and gently increased, and in the range greater than or equal to the first predetermined value and less than or equal to the second predetermined value, the sound pressure is less than the first predetermined value. The sound pressure increase gradient is increased, the sound pressure increase gradient is decreased in the range from the second predetermined value to the third predetermined value, and the sound pressure is saturated at the maximum value in the range greater than the third predetermined value. A curve is used. For this reason, there is almost no change in the sound pressure in a region where the frequency of occurrence of the accelerator operation is low, particularly in the range of the play of the accelerator, and the change in the sound pressure may be increased in a range where the frequency of occurrence of the accelerator operation is high and pronunciation is particularly necessary. It becomes possible. Therefore, it becomes possible to produce a sound that matches the actual accelerator operation state, making it easier for the pedestrian to recognize the accelerator operation state by the driver.

  For example, as described in claim 2, the microcomputer (21) can store the relationship between the accelerator operation state and the sound pressure increase rate as the relationship between the accelerator operation state and the sound pressure. In this case, as described in claim 3, the microcomputer (21) uses the sound pressure at the start of sound generation as the reference sound pressure, and uses the sound pressure obtained by multiplying the reference sound pressure by the rate of increase in sound pressure as the sound output. It can be generated from the output unit (21a).

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a block diagram of a vehicle approach warning system including a vehicle approach warning device according to a first embodiment of the present invention. (A) is the graph which showed the integration curve of the occurrence frequency of accelerator opening based on an experimental result, and accelerator opening-occurrence frequency, (b) showed the relationship of the sound pressure increase rate with respect to accelerator opening. It is a graph. It is the graph which showed the relationship of the sound pressure increase rate with respect to the conventional accelerator opening.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
FIG. 1 is a block diagram of a vehicle approach warning system including a vehicle approach warning device according to the present embodiment. With reference to this figure, the vehicle approach warning system including the vehicle approach warning device concerning this embodiment is demonstrated.

  As shown in FIG. 1, the vehicle approach alarm system includes various sensors 1 a and 1 b, a vehicle approach alarm device 2, and a speaker 3. In the vehicle approach warning system, the vehicle approach warning device 2 generates a sound from the speaker 3 which is a sounding body based on the running state detection signals transmitted from the various sensors 1a and 1b, thereby detecting the approach of the vehicle to the surrounding pedestrians. Alarm. Here, the vehicle approach warning device 2 is separated from the speaker 3, but the speaker 3 may be integrated with the vehicle approach warning device 2.

  The various sensors 1a and 1b constitute vehicle state acquisition means. As the various sensors 1a and 1b, a vehicle speed sensor 1a and an accelerator opening sensor 1b are provided. The vehicle speed sensor 1a outputs a detection signal indicating the vehicle speed as a vehicle running state detection signal, and the accelerator opening sensor 1b outputs a detection signal indicating the accelerator opening as an accelerator operation state detection signal. For this reason, the vehicle approach warning device 2 inputs each detection signal indicating the vehicle speed and the accelerator opening as a vehicle state detection signal, and generates a sound according to the accelerator operation state such as the accelerator opening and the vehicle speed and the vehicle running state. Take control.

  The vehicle approach warning device 2 includes a microcomputer 21, a low-pass filter (hereinafter referred to as LPF) 22, and a power amplifier (hereinafter referred to as AMP) 23.

  The microcomputer 21 has a memory (not shown) and a digital analog converter (hereinafter referred to as DAC) 21a. In the memory, data such as a sound generation control program and PCM (pulse code modulation), specifically a reference sound pressure and a sound generation pitch (reproduction speed) (hereinafter referred to as a reference sound pressure and a reference pitch) are stored. A function formula or map of sound pressure associated with the accelerator operation state indicated by the vehicle state detection signal and the traveling state of the vehicle is stored. For example, sound generation starts when the accelerator is off and the brake is off. The sound pressure and sound pitch at the start of sound generation are used as the reference sound pressure (sound amplitude) and reference pitch, and these reference sound pressure and reference pitch are By controlling according to the vehicle state, the sound is generated according to the vehicle state.

  Specifically, the microcomputer 21 calculates a sound pressure and a sound generation pitch corresponding to the accelerator operation state and the vehicle traveling state indicated by the vehicle state detection signal, and generates a sound output from the DAC 21a so that sound can be generated accordingly. Let For example, the DAC 21a reads the data stored in the memory of the microcomputer 21 multiplied by the rate of increase in sound pressure at a predetermined sampling period, and generates an output obtained by converting the data into an analog value. A sound output having an amplitude with a corresponding sound pressure is generated. The microcomputer 21 changes the sampling period in accordance with the pitch of the sound corresponding to the running state of the vehicle so that the DAC 21a can generate a sound output corresponding to the running state of the vehicle.

  The sound pressure is basically set so as to increase as the accelerator opening increases. As a result, sound pressure can be generated according to the magnitude of the accelerator operation state by the driver, and the accelerator operation state can be easily recognized by the pedestrian. Further, the pitch of pronunciation is set to be faster (shorter) as the vehicle speed becomes faster. The pronunciation pitch is adjusted by changing the sampling period, and the shorter the sampling period, the faster the pronunciation pitch. Therefore, the faster the vehicle approaches the pedestrian, the faster the pronunciation pitch, the easier it is for the pedestrian to recognize the running state of the vehicle. Of these, the relationship between the accelerator opening and the sound pressure is a feature of the present invention, and details of this relationship will be described later.

  The LPF 22 corresponds to filter means, removes high frequency noise components, and generates an output corresponding to the output of the DAC 21a. For example, the LPF 22 stores a voltage corresponding to the output of the DAC 21 a in a built-in capacitor and outputs it to the AMP 23.

  The AMP 23 causes a current corresponding to the output of the LPF 22 to flow through the speaker 3 based on voltage application from a constant voltage source (not shown). The sound pressure generated by the speaker 3 is determined according to the magnitude (amplitude) of the current supplied from the AMP 23, and the magnitude of the current supplied from the AMP 23 is determined by the output waveform of the LPF 22 corresponding to the output of the DAC 21a. For this reason, if the output according to a vehicle state detection signal is generated from the microcomputer 21, the electric current which AMP23 flows will be changed according to this.

  Next, the relationship between the accelerator opening and the sound pressure described above will be described with reference to FIG.

  First, in order to perform sound pressure control with respect to the accelerator opening, a traveling pattern such as an urban area is set, and a vehicle speed range (for example, 0 to 20 km / h) in which sound is generated by the vehicle approach warning device 2 is periodically (for example, 100 ms). ) Accelerator opening frequency was measured. Based on the experimental results, an accelerator opening-occurrence frequency integration curve (accelerator opening occurrence frequency integration curve) was created. As a result, an occurrence frequency and integration curve as shown in FIG. 2A were obtained.

  As shown in this figure, with regard to the frequency of occurrence of the accelerator opening, the accelerator opening is concentrated in the range of 5 to 55%, and the median value of the range is set to the highest frequency, the median value below the median value. In the above, a normal distribution in which the frequency gradually decreases is taken. Sound generation by the vehicle approach warning device 2 is performed in a low-speed vehicle speed region where the road noise of the vehicle does not occur so much, and the accelerator opening is rarely high in that region. For this reason, the accelerator opening is concentrated in a low range of 5 to 55%. Therefore, when an accelerator opening occurrence frequency integration curve corresponding to the occurrence frequency of the accelerator opening is drawn, a curve with a larger inclination is obtained as the occurrence frequency of the accelerator opening is higher.

  If the relationship of the sound pressure increase rate to the accelerator opening is set based on this accelerator opening occurrence frequency integration curve, the accelerator opening occurrence frequency integration curve shown in FIG. 2B can be drawn. In other words, when the sound pressure increase rate is increased as the accelerator opening increases, if the sound pressure increase rate can be adjusted within the range of 1.0 to 2.0 times, the adjustment By combining the accelerator opening occurrence frequency integrated value curve in the possible range, the accelerator opening occurrence frequency integrated curve of FIG. 2B is drawn. Specifically, an S-shaped curve obtained by smoothing a curve indicating the relationship between the accelerator opening degree and the sound pressure increase rate on the accelerator opening occurrence frequency integration curve by a moving average, for example, in a range where the accelerator opening degree is 0 to 5%. The rate of increase in the sound pressure is gradually and gradually increased, and the gradient of increase in the sound pressure is increased in the range of 5 to 50% than in the range of 0 to 5%, and in the range of 50 to 55%. The gradient of the increase rate of the sound pressure is reduced, and control is performed with a curve that saturates the increase rate of the sound pressure at the maximum value when the accelerator opening is 55% or more.

  Thus, the accelerator opening occurrence frequency integration curve is set such that the rate of change of the sound pressure increase rate is high in a region where the accelerator opening occurrence frequency is high. That is, there is almost no change in the sound pressure in a region where the accelerator opening is low, particularly in the range of the play of the accelerator, the frequency of occurrence of the accelerator opening is high, and the change in the sound pressure is particularly required in the range where the sound generation by the vehicle approach warning device 2 is particularly necessary. It becomes possible to enlarge. This makes it easier for the pedestrian to recognize the accelerator operation state by the driver.

  Although the method of changing the sound pressure has been described here, the sounding pitch (reproduction speed) can be shortened as the vehicle speed increases as in the conventional case.

  As described above, the vehicle approach warning device 2 according to the present embodiment is configured. In such a vehicle approach warning device 2, based on the detection signal indicating the accelerator opening inputted from the accelerator opening sensor 1b, the sound pressure increase rate corresponding to the accelerator opening is shown in FIG. It is calculated from the opening occurrence frequency integration curve. Then, data obtained by multiplying the reference sound pressure data by the sound pressure increase rate is read at every predetermined sampling period, converted into an analog value, and generated as a sound output from the DAC 21a. The sampling period is set based on a detection signal indicating the vehicle speed input from the vehicle speed sensor 1a. Then, the sound output is subjected to noise removal through the LPF 22 and then amplified through the AMP 23, and a current corresponding to the output of the AMP 23 is passed through the speaker 3, so that sound corresponding to the accelerator operation state and the vehicle running state is generated. Done.

  In performing such sound generation, as described above, as the accelerator opening occurrence frequency integrated value curve indicating the sound pressure increase rate with respect to the accelerator opening, for example, the accelerator opening is a first predetermined value (for example, 5%), the first 2 is used in which the sound pressure increase rate is changed separately when a predetermined value (for example, 50%) and a third predetermined value (for example, 55%). Specifically, when the accelerator opening is equal to or smaller than the first predetermined value, the sound pressure increase rate is gradually and gradually increased, and within the range equal to or larger than the first predetermined value and equal to or smaller than the second predetermined value, the first predetermined value or smaller. The increase gradient of the sound pressure increase rate is made larger than that of the time, and the increase gradient of the sound pressure increase rate is reduced when the accelerator opening is in the range from the second predetermined value to the third predetermined value, and is greater than the third predetermined value. Uses a curve that saturates the sound pressure rise rate at the maximum value. For this reason, there is almost no change in the sound pressure in a region where the accelerator opening is low, particularly in the range of the play of the accelerator, the frequency of occurrence of the accelerator opening is high, and the change in the sound pressure is particularly required in the range where sound generation by the vehicle approach warning device 2 is particularly necessary. Can be increased. Therefore, it becomes possible to produce a sound that matches the actual accelerator operation state, making it easier for the pedestrian to recognize the accelerator operation state by the driver.

(Other embodiments)
In the above embodiment, the sound pressure is changed according to the accelerator opening, and the pitch of the sound (reproduction speed) is changed according to the vehicle speed. However, these are merely examples. For example, both the sound pressure and the sounding pitch may be changed according to the accelerator opening. In this case, as the accelerator opening increases, it is preferable to increase the sound pressure and shorten the pronunciation pitch. Even in this case, the relationship between the accelerator opening and the sound pressure increase rate is shown in FIG. It only has to be like the occurrence frequency integrated value curve.

  In the microcomputer 21, the sound output is generated from the DAC 21a. However, the sound output may be generated using a PWM controller. When using the PWM controller to change the sound pressure or the pitch of the sound according to the vehicle speed or the accelerator opening, for example, changing the duty ratio of on / off of the PWM output according to the accelerator opening, and depending on the vehicle speed The sampling period of the PWM output may be changed. In such a case, the rate of increase in sound pressure is expressed as a duty ratio, and the relationship between the accelerator opening and the duty ratio is increased while increasing the duty ratio of the PWM output as the accelerator opening increases. It is sufficient that the accelerator opening generation frequency integrated value curve shown in FIG.

  Moreover, in the said embodiment, the accelerator opening degree generation frequency integration curve is calculated | required by moving average so that the change of the sound pressure increase rate with respect to the change of an accelerator opening may become smooth. Thereby, the change of the sound pressure when the sound is generated is made smoother. However, these changes need not necessarily be smooth. That is, when the accelerator opening is less than or equal to the first predetermined value, the rate of increase in the sound pressure is gradually and gently increased, and in the range greater than or equal to the first predetermined value and less than or equal to the second predetermined value than when it is less than or equal to the first predetermined value. Increase the slope of the sound pressure increase rate, decrease the slope of the sound pressure increase rate when the accelerator opening is in the range from the second predetermined value to the third predetermined value, and further increase the sound pressure in the range greater than the third predetermined value. Any relationship that saturates the rate of increase at the maximum value may be used.

  In addition, as the relationship between the accelerator operation state and the sound pressure, the relationship between the accelerator opening and the sound pressure increase rate is used, but the accelerator pedal depression amount (detection signal of the pedal sensor) may be used instead of the accelerator opening. The sound pressure itself may be used instead of the sound pressure increase rate.

DESCRIPTION OF SYMBOLS 1a Vehicle speed sensor 1b Accelerator opening sensor 2 Vehicle approach warning device 3 Speaker 21 Microcomputer 21a DAC
22 LPF
23 AMP

Claims (3)

In the vehicle approach warning device that warns the approach of the vehicle by controlling the sound pressure of the sound from the sounding body (3) mounted on the vehicle,
Corresponding to the accelerator operation state by the driver, it has a memory for storing a functional expression or map indicating the relationship between the accelerator operation state and the sound pressure, and inputs an operation state detection signal indicating the accelerator operation state, A microcomputer (21) having an output unit (21a) for calculating a sound pressure corresponding to the accelerator operation state indicated by the operation state detection signal and generating a sound output corresponding to the sound pressure;
An amplifier (24) for flowing a current corresponding to the sound output generated from the output unit (21a) to the sound generator (3);
The relationship between the accelerator operation state and the sound pressure is such that when the accelerator operation state is smaller than a first predetermined value, the sound pressure gradually and gradually increases, is greater than the first predetermined value and is a second predetermined value. In the following range, the sound pressure becomes higher with a rising gradient larger than the first predetermined value, and in the range not less than the second predetermined value and not more than the third predetermined value, not less than the first predetermined value and not more than the second predetermined value. The vehicle approach warning device is characterized in that the rising slope of the sound pressure is smaller than that in a range, and the sound pressure is a curve that saturates at a maximum value in a range exceeding the third predetermined value. The microcomputer (21) stores the relationship between the accelerator operation state and the sound pressure increase rate as the relationship between the accelerator operation state and the sound pressure,
When the accelerator operation state is smaller than the first predetermined value, the sound pressure increase rate gradually and gradually increases, and in the range of the first predetermined value and the second predetermined value or less, the sound pressure increase rate is increased. The sound pressure becomes higher at a rising gradient larger than the first predetermined value, and the sound pressure is higher in the range of the second predetermined value and lower than the third predetermined value than in the range of the first predetermined value and lower than the second predetermined value. 2. The vehicle approach warning device according to claim 1, wherein an increasing gradient of the increasing rate is reduced and the sound pressure increasing rate is a curve that saturates at a maximum value in a range exceeding the third predetermined value.   The microcomputer (21) uses the sound pressure at the start of sound generation as a reference sound pressure, and generates a sound pressure obtained by multiplying the reference sound pressure by the sound pressure increase rate from the output unit (21a) as the sound output. The vehicle approach warning device according to claim 2.

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