JP2013108789A - Ranging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ranging device which achieves improved accuracy of a measured distance.SOLUTION: A drive part 14 calculates an overall error of a measured distance from the difference between a distance between a ranging device and the ground surface, which is measured when an irradiation direction of a laser beam is a vertically downward direction, and a distance between the ranging device and the ground surface, which is specified on the basis of information stored in a memory. The measured distance is corrected by using the overall error of the measured distance.

Description

  The present invention relates to a distance measuring device that measures the distance from an object by measuring the time from when a laser beam is irradiated until the reflected light reflected by the object is received.

  Conventionally, it is installed in the vicinity of a rotation axis of a vehicle door, and the object is irradiated with a pulsed laser beam so as to scan a plane shifted by a predetermined angle in the direction in which the vehicle door is opened with respect to the surface of the vehicle door. There is an apparatus that detects an object that may come into contact with a vehicle door by receiving reflected light reflected by the vehicle (see, for example, Patent Document 1).

JP 2010-101150 A

  In the apparatus described in Patent Document 1, measurement errors due to the respective parts occur due to manufacturing variations, temperature fluctuations, power supply voltage fluctuations, and the like of parts used in the light emitting circuit and the light receiving circuit. When the measurement error increases in this way, there is a problem that an object that may contact the door of the vehicle cannot be detected, and the object contacts the door of the vehicle.

  The present invention has been made in view of the above problems, and an object thereof is to improve the accuracy of the measurement distance.

  In order to achieve the above object, the invention described in claim 1 includes a light emitting circuit for irradiating a laser beam and an irradiation direction rotating mechanism for changing the irradiation direction of the laser beam so as to rotationally scan in a plane including a vertically downward direction. And a light receiving circuit that receives the reflected light reflected by the object and converts it into an electrical signal, and is present in the vicinity from the time from when the laser light is irradiated until the reflected light is received by the light receiving circuit. A distance measuring device for measuring a distance from an object to be stored, a storage means for storing information for specifying a distance between the distance measuring device and the ground, and a laser beam irradiation direction vertically downward by an irradiation direction rotating mechanism The total error of the measurement distance is calculated from the difference between the distance between the distance measurement device and the ground measured when the distance becomes the distance between the distance measurement device specified based on the information stored in the storage medium and the ground. Total error calculation Using a stage, the overall error of the measurement distance calculated by the total error calculating means is characterized by comprising a measuring distance correction means for correcting the measurement distance.

  According to such a configuration, based on information stored in the storage medium and the distance between the distance measuring device measured when the irradiation direction of the laser beam is vertically downward by the irradiation direction rotating mechanism and the ground. The total measurement distance error is calculated from the difference in distance between the specified distance measurement device and the ground, and the measurement distance is corrected using this total measurement distance error, so the accuracy of the measurement distance can be improved. .

  Further, in the invention described in claim 2, the total error calculating means calculates the error of the reflectance of the ground from the waveform output from the light receiving circuit when the irradiation direction of the laser beam is vertically downward by the irradiation direction rotating mechanism. A first measurement error as a factor is estimated, and a second measurement error due to components used in the light emitting circuit and the light receiving circuit is calculated from the difference between the total measurement distance error and the first measurement error. Yes.

  In this way, the first measurement error having the ground reflectivity as an error factor is estimated from the waveform output from the light receiving circuit when the irradiation direction of the laser beam is vertically downward, and the total error of the measurement distance is From the difference from the first measurement error, the second measurement error due to the components used in the light emitting circuit and the light receiving circuit can be calculated.

  According to the third aspect of the present invention, when the irradiation direction of the laser light is changed by the irradiation direction rotation mechanism, the reflectance of the object is determined from the waveform output from the light receiving circuit for each irradiation direction of the laser light. Reflectance measurement error estimation processing means for performing processing for estimating measurement error as a factor is provided, and the total error calculation means includes a second measurement error due to components used in the light emitting circuit and the light receiving circuit, and a laser light irradiation direction. The distance to the object is corrected by using the sum of the measurement errors having the estimated reflectance of the object as an error factor as the total error of the measurement distance.

  According to such a configuration, when the irradiation direction of the laser light changes, a measurement error in which the reflectance of the object is an error factor is estimated from the waveform output from the light receiving circuit for each irradiation direction of the laser light. The total measurement distance error is the sum of the second measurement error due to the components used in the light emitting circuit and the light receiving circuit and the measurement error caused by the reflectance of the object estimated for each laser beam irradiation direction. Therefore, even if the laser beam irradiation direction changes and the reflectance of the object changes, it is possible to accurately correct the distance to the object.

  According to a fourth aspect of the present invention, the total error calculating means estimates the first measurement error having the ground reflectance as an error factor from the waveform width output from the light receiving circuit.

  According to such a configuration, since the first measurement error having the ground reflectance as an error factor is estimated from the waveform width output from the light receiving circuit, the ground reflectance is determined as an error factor with a relatively simple circuit configuration. The first measurement error can be estimated.

  As in the fifth aspect of the invention, from the waveform width output from the light receiving circuit using a map that defines the relationship between the waveform width output from the light receiving circuit and the rise time of the waveform output from the light receiving circuit. A first measurement error having the ground reflectance as an error factor can be estimated.

  Further, the invention according to claim 6 is characterized in that the total error calculating means estimates the first measurement error with the reflectance of the ground as an error factor from the rise time of the waveform output from the light receiving circuit. .

  In this way, it is possible to detect the rise time of the waveform output from the light receiving circuit and estimate the first measurement error with the ground reflectance as an error factor.

It is a figure which shows a mode that the distance measuring device which concerns on one Embodiment of this invention was attached to the vehicle. It is a figure for demonstrating the attachment position of a distance measuring device. It is a figure which shows the structure of the optical system circuit of a distance measuring device. It is a figure for demonstrating the irradiation direction of a laser beam. It is a figure which shows the block configuration of a distance measuring device. It is the figure which showed the waveform of the laser beam at the time of changing the reflectance of an object, and the waveform of a received signal. It is the figure which showed the measurement waveform of the input signal of the LD driver circuit at the time of changing ambient temperature, and the measurement waveform of an output signal. It is a figure for demonstrating the factor of a measurement error. It is a figure which shows the relationship between the waveform width of a received signal, and a rise time. It is a figure which shows the structure of the light emitting circuit and light receiving circuit in a distance measuring device. It is a timing chart of each part of a light emitting circuit and a light receiving circuit. It is a figure for demonstrating the result of the factor analysis of the measurement error contained in a measurement distance. It is a flowchart of the control part of a distance measuring device. It is a flowchart of swing door ECU.

  FIG. 1 shows a state in which a distance measuring device 10 according to an embodiment of the present invention is attached to a vehicle (automobile) 2. The vehicle 2 is equipped with an automatic swing door system (not shown) that automatically opens and closes the door 20 of the vehicle in response to an operation on the touch sensor 21 by the user. The distance measuring device 1 is provided to detect an object existing on the flow line of the vehicle door 20 when the door is opened and closed by the automatic swing door system.

  The distance measuring device 10 is present around the vehicle door 20 by detecting the reflected light reflected on the object while changing the irradiation direction of the laser beam so as to rotate and scan the plane including the vertical downward direction. Measure the distance to the object.

  As shown in FIG. 2, the distance measuring device 10 has an optical window 11 that transmits laser light. The distance measuring apparatus 10 irradiates laser light through the optical window 11 and reflects the object through the optical window 11. Receives reflected light.

  FIG. 3 shows the configuration of the optical system circuit of the distance measuring device 10. The distance measuring apparatus 10 includes a laser diode (hereinafter referred to as LD) 12a that emits pulsed laser light, and a photodiode (hereinafter referred to as PD) 13a that receives reflected light reflected from an object and converts it into an electrical signal. The mirror 17 that reflects the direction of the laser light from the LD 12a, and the rotating mirror 18 that changes the irradiation direction of the laser light reflected on the mirror 17 and makes the reflected light reflected on the object incident on the PD 12a as the motor rotates. I have.

  The rotating mirror 18 is configured to rotate in the direction indicated by the arrow A shown in FIG. 3 by the rotation of the motor. In this way, by rotating the rotating mirror 18, as shown in FIG. 1, the irradiation direction of the laser light is changed so that the outer periphery of the vehicle door 20 is rotationally scanned, and objects around the vehicle are detected. It is supposed to be.

  Further, as shown in FIG. 4, the distance measuring device 10 includes the door mirror 22 so that the laser beam is emitted with a certain angle φ shifted from the outer surface of the vehicle door 20 in the direction in which the vehicle door 20 is opened. It is attached to the bottom of the. In this way, when the vehicle door opening is automatically controlled by shifting the irradiation direction of the laser light with respect to the outer surface of the vehicle door 20 by a certain angle φ in the direction in which the vehicle door 20 is opened, the vehicle door in advance. 20 surrounding objects can be detected.

  FIG. 5 shows a block configuration of the distance measuring apparatus 10. The distance measuring device 10 includes a light emitting circuit 12, a light receiving circuit 13, a driving unit 14, a scan angle detecting unit 15, and a control unit 16.

  The light emitting circuit 12 is a circuit that emits pulsed laser light. The light emitting circuit 12 includes the above-described LD 12a and an LD driver (not shown) for driving the LD 12a. The light emitting circuit 12 causes the LD 12a to irradiate pulsed laser light corresponding to the control signal input from the control unit 16.

  The light receiving circuit 13 is a circuit that receives reflected light that is reflected from an object and converts the laser light into an electrical signal. The light receiving circuit 13 includes the PD 13a, a current-voltage conversion circuit that converts the output signal of the PD 13a into a voltage, and a comparator for detecting the rise of the waveform of the output signal of the current-voltage conversion circuit. Details of the light emitting circuit 12 and the light receiving circuit 13 will be described later.

  The drive unit 14 includes a motor that rotates in response to a signal from the control unit 16 and a drive mechanism (none of which is shown) that transmits the rotational force of the rotation shaft of the motor to the rotary mirror 18 shown in FIG. I have. When the motor rotates in response to a signal from the control unit 16, the rotational force of the rotation shaft of the motor is transmitted to the rotating mirror 18 by the driving mechanism, and the rotating mirror 18 rotates.

  The control unit 16 is configured as a computer including a CPU, RAM, ROM, EEPROM, I / O, and the like. The CPU of the control unit 16 performs various processes in accordance with programs stored in the ROM. In addition, the control unit 16 includes a time measurement IC for measuring the time from when the LD 12a is irradiated with laser light to when it is received by the PD 13a.

  The scan angle detector 15 outputs a scan angle signal indicating the rotation angle of the rotary mirror 18. In the present embodiment, the scan angle signal is output with reference to the start position of the scan range (θ = 0 ° in FIG. 1).

  The distance measuring device 10 is connected in communication with a swing door ECU 30 to which a door opening / closing mechanism 23, a speaker 31, and a touch sensor 21 are connected.

  The door opening / closing mechanism 23 controls an electronic control damper, an opening / closing motor clutch, a latch release motor, and the like provided in the door to perform opening / closing control of the vehicle door 20 and holding control of the vehicle door 20.

  The speaker 31 outputs a sound corresponding to the sound signal input from the swing door ECU 30.

  As shown in FIG. 1, the touch sensor 21 is provided on the door knob of the vehicle door 20 and outputs a signal corresponding to a user's touch operation to the swing door ECU 30.

  In the configuration described above, when the user performs a touch operation on the touch sensor 21 provided on the vehicle door 20, the distance measuring device 10 starts a process of detecting an object around the vehicle door 20, and periodically sends it to the swing door ECU 30. Send the detection result. The swing door ECU 30 determines whether or not an object exists in the swing range of the vehicle door 20 based on the detection result from the distance measuring device 10. If there is no object in the swing range of the vehicle door 20, the vehicle door The door opening / closing mechanism 23 is instructed to open 20. In this way, the vehicle door 20 is automatically opened. In addition, when it is determined that an object is present in the swing range of the vehicle door 20, the door opening / closing mechanism 23 is instructed to stop the opening of the vehicle door 20, and a warning sound is output from the speaker 31. Call attention to.

  In the EEPROM of the control unit 16 in the distance measuring device 10, the distance between the distance measuring device 10 and the ground is stored. This distance measuring device 10 is a difference between the distance from the ground measured when the laser beam irradiation direction is vertically downward by the rotating mirror 18 and the distance between the distance measuring device 10 stored in the EEPROM and the ground. The total error of the measurement distance is calculated from the above, and the measurement distance is corrected using the total error of the measurement distance.

  Here, the measurement distance measured by the distance measuring device 10 includes measurement errors due to various factors such as manufacturing variations of components used in the light emitting circuit and the light receiving circuit, temperature fluctuations, power supply voltage fluctuations, and the like.

  Therefore, when the cause of the measurement error is analyzed, the measurement distance includes the measurement error caused by the difference in the reflectance of the object in addition to the measurement error caused by the components used in the light emitting circuit and the light receiving circuit. I understood that.

  FIG. 6 shows the measurement waveform of the laser beam output from the LD 12a and the measurement waveform of the reception signal output from the PD 13a when the reflectance of the object is varied. (A) shows the waveform of the laser beam and the measurement waveform of the received signal when the white Kent paper with high reflectance is irradiated with the laser beam, and (b) shows the laser beam on the light absorbing sheet with low reflectance. The waveform of the laser beam and the measurement waveform of the received signal when irradiating is shown. The distance from the object is 15 centimeters (cm), and the ambient temperature is 20 ° C.

  As shown in FIG. 6A, when laser light was irradiated onto white Kent paper with high reflectivity, the rising time of the waveform of the received signal was 2 nanoseconds (ns). In addition, as shown in FIG. 6B, when the light absorption sheet with low reflectance is irradiated with laser light, the rising time of the waveform of the received signal is 12 nanoseconds (ns).

  Thus, the rise time of the waveform of the received signal becomes steeper as the reflectance of the object is higher, and the rise time of the waveform of the received signal becomes slower as the reflectance of the object is lower. As a result of detailed examination, it was found that the rise time of the waveform of the received signal is substantially proportional to the reflectance of the object.

  FIG. 7 shows the measurement waveform of the input signal and the measurement waveform of the output signal of the LD driver circuit for driving the LD 12 when the ambient temperature is changed. (A) shows the measurement waveform of the input signal and the output signal of the LD driver circuit when the ambient temperature is −30 ° C., and (b) shows the measurement when the ambient temperature is 80 ° C. The measurement waveform of the input signal of the LD driver circuit and the measurement waveform of the output signal are shown.

  As shown in FIG. 7A, the propagation delay time of the LD driver circuit when the ambient temperature Ta is −30 ° C. is 16 nanoseconds (ns), and as shown in FIG. The propagation delay time of the LD driver circuit when Ta was set to 80 ° C. was 20 nanoseconds (ns).

  Thus, it was found that the propagation delay time of the LD driver circuit becomes shorter as the ambient temperature becomes lower, and the propagation delay time of the LD driver circuit becomes longer as the ambient temperature becomes higher.

  Here, the causes of the measurement error are summarized as follows: (1) propagation delay of LD driver circuit, (2) delay of LD12, (3) reflectance of object, and (4) delay of PD13 as shown in FIG. It was found that the delay of the light receiving circuit including (5) the delay of the comparator was dominant.

  Among these error factors, (1) propagation delay of LD driver circuit, (2) delay of LD12, (4) delay of light receiving circuit including delay of PD13, and (5) delay of comparator are light emitting circuit and light receiving circuit. This is due to each part. The measurement error (corresponding to the second measurement error) due to each of these parts fluctuates relatively slowly due to manufacturing variations of parts, temperature fluctuations, power supply voltage fluctuations, and the like.

  On the other hand, (3) a measurement error (corresponding to the first measurement error) due to the reflectance of the object is due to the external environment. This measurement error due to the reflectance of the object has a possibility of abrupt fluctuation due to the external environment.

  Therefore, the rise time of the received signal output from the current-voltage conversion circuit that converts the current flowing through the PD 13a into a voltage is measured, the measurement error due to the reflectance of the object is estimated from the rise time, and the reflectance of the object If the measurement distance is corrected using the measurement error, it is possible to improve the accuracy of the measurement distance. For example, if an analog / digital conversion circuit that samples an analog signal output from the PD 13a with a high-speed clock and converts it into a digital signal is mounted to measure the rise time of the received signal, measurement based on the reflectance of the object It is possible to estimate the error. However, it is not preferable to mount such an analog / digital conversion circuit because the configuration becomes complicated.

  Therefore, it was examined whether the reflectance of the object could be estimated without measuring the rise time of the received signal output from the current-voltage conversion circuit that converts the current flowing through the PD 13a into a voltage. It was found that the rising time of the received signal becomes shorter as the waveform width of the received signal output from the circuit becomes wider.

  FIG. 9 shows the relationship between the waveform width of the received signal output from the PD 13a and the rise time. As shown in this figure, it was found that there is an inversely proportional relationship between the waveform width of the received signal and the rise time of the received signal. It was also found that the relationship between the waveform width of the received signal and the rise time also changes depending on the temperature. However, it is considered that the relationship between the waveform width of the received signal and the rise time varies with temperature due to the temperature characteristics of the PD 12a.

  Therefore, the rise time of the received signal is specified from the waveform width of the received signal using the map that defines the relationship between the received signal waveform width and the received signal rise time shown in FIG. It is possible to estimate how much the time variation is.

  FIG. 10 shows the configuration of the light emitting circuit 12 and the light receiving circuit 13 in the distance measuring apparatus 10. The light emitting circuit 12 includes an LD 12a and an LD driver 12b. The light receiving circuit 13 includes a PD 13a, a current-voltage conversion circuit 13b that converts the output signal of the PD 13a into a voltage, a comparator 13c for detecting the rise of the waveform of the output signal of the current-voltage conversion circuit, and a current-voltage conversion. A comparator 13d is provided for detecting the fall of the waveform of the output signal of the circuit.

  As shown in FIG. 11, the time measurement IC 19 starts counting when the laser beam is irradiated from the LD 12a, and a period A from when the laser beam is irradiated until the rising of the waveform of the received signal is detected by the comparator 13c. Then, the difference (B−A) in the period B from when the laser beam is irradiated from the LD 12a to when the falling of the waveform of the received signal is detected by the comparator 13d is detected as the waveform width.

  FIG. 12 shows the result of the factor analysis of the measurement error included in the measurement distance. As shown in the figure, the time measured by the time measurement IC (measurement value of the time measurement IC) includes time fluctuations due to the components of the light emitting circuit and the light receiving circuit ((1) propagation delay of the LD driver circuit, (2) LD12 delay, (4) delay of the light receiving circuit including the delay of PD13, (5) delay of the comparator), and the reflected light reflected on the object after being irradiated with the laser light is received by the light receiving circuit to the time measuring IC. Time until input (light flight time that varies depending on the distance to the object) and (3) time variation due to reflectance is included in the object. Among these time variations, (3) the time variation due to the reflectance of the object can be calculated from the waveform width of the received signal. In addition, the time (light flight time) from when the laser beam is irradiated in the vertical downward direction to when the reflected light reflected from the object is received by the light receiving circuit is stored in the EEPROM. It can be calculated from the distance between the distance measuring device 10 and the ground. Specifically, (light flight time) can be calculated by multiplying the distance between the distance measuring device 10 and the ground by 2 and dividing by the speed of light.

  That is, it can be calculated as (time fluctuation due to each component of the light emitting circuit and the light receiving circuit) = (measured value of the time measurement IC) − (light flight time) − (time fluctuation due to the reflectance of the object).

  Next, processing of the control unit 16 of the distance measuring device 10 will be described with reference to FIG. The control unit 16 performs the process shown in FIG. 13 in response to an instruction from the swing door ECU 30.

  First, the motor 14 is instructed to start rotation of the motor (S100). In response to this instruction, the rotating mirror 18 starts rotating.

  Next, a process of specifying the amount of time variation due to the reflectance of the object is performed while changing the rotation angle of the rotary mirror 18 by a certain angle (S102). Specifically, the rise time of the received signal is specified from the waveform width of the received signal using the map that defines the relationship between the received signal waveform width and the received signal rise time shown in FIG. A variation amount of the measurement time due to the reflectance of the object is specified from the rise time, and a process of storing the relationship between the rotation angle of the rotating mirror 18 and the variation amount of the measurement time due to the reflectance of the object in the EEPROM is performed.

  Next, based on the scan angle signal input from the scan angle detector 15, it is determined whether or not the irradiation direction of the laser light is vertically downward (S104).

  Here, when the laser beam irradiation direction is vertically downward, the determination in S104 is YES, the circuit delay time by each component of the light emitting circuit and the light receiving circuit is calculated, and this circuit delay time is stored in the EEPROM ( S106). The circuit delay time due to each component of the light emitting circuit and the light receiving circuit can be calculated as (circuit delay time) = (measured value of time measurement IC) − (light flight time) − (time fluctuation due to reflectance of object). it can.

  Next, a distance measurement process is performed (S108). Specifically, the laser beam irradiation direction is specified based on the scan angle signal input from the scan angle detector 15, and the amount of time variation due to the reflectance of the object corresponding to the specified laser beam irradiation direction is determined from the EEPROM. At the same time, the circuit delay time due to each component of the light emitting circuit and the light receiving circuit is read from the EEPROM, and the measurement distance is corrected.

  Specifically, (light flight time) = (measured value of time measurement IC) − (time fluctuation due to each component of light emitting circuit and light receiving circuit) − (time fluctuation due to reflectance of object) (light flight time) ) Is calculated, and the measurement distance is corrected by multiplying (light flight time) / 2 by the speed of light. (Time fluctuation due to each component of the light emitting circuit and the light receiving circuit) is corrected as a fixed value regardless of the irradiation direction of the laser beam, and (Time fluctuation due to the reflectance of the object) is corrected according to the irradiation direction of the laser beam. Correct the difference.

  Next, it is determined whether an obstacle exists within the swing range of the vehicle door (S110).

  If there is an obstacle in the swing range of the vehicle door, the determination in S110 is YES, a signal indicating the presence of the obstacle is sent to the swing door ECU 30 (S112), and the process returns to S104.

  If there is no obstacle within the swing range of the vehicle door, the determination in S110 is NO, a signal indicating that there is no obstacle is sent to the swing door ECU 30 (S114), and the process returns to S104.

  The above processing is repeated, and information indicating whether or not an obstacle exists within the swing range of the vehicle door is periodically sent from the control unit 16 of the distance measuring device 10 to the swing door ECU 30. Yes.

  FIG. 14 shows a flowchart of automatic door opening control of the vehicle door by the swing door ECU 30. Next, automatic door opening control by the swing door ECU 30 will be described with reference to FIG. When the signal corresponding to the touch operation by the user is input from the touch sensor 21, the swing door ECU 30 performs the process illustrated in FIG. 14.

  First, it is determined whether or not the vehicle speed is 0 km (km) per hour based on a vehicle speed signal input from the vehicle (S200).

  Here, when the vehicle is traveling, the determination in S200 is NO, and this process ends. Further, when the vehicle is stopped and the vehicle speed is 0 km (km) per hour, the determination in S200 is YES, and then it is determined whether or not the opening degree of the vehicle door is the target opening degree. (S202). The target opening set by the user operation is stored in the EEPROM. Here, the opening degree of the vehicle door is set based on a signal input from a door opening degree sensor (not shown) that outputs a signal indicating the opening degree of the vehicle door and a target opening degree that is stored in advance in the EEPROM. It is determined whether or not the opening is reached.

  Here, when the opening degree of the vehicle door is not the target opening degree, the determination in S202 is NO, and the start of the process shown in FIG. 13 is instructed to the distance measuring device 10 (S204).

  Next, it is determined whether an obstacle exists within the swing range of the vehicle door based on a signal sent from the distance measuring device 10 (S206). Specifically, an obstacle exists in the swing range of the vehicle door based on information indicating whether or not an obstacle exists in the swing range of the vehicle door that is periodically sent from the distance measuring device 10. It is determined whether or not to do.

  Here, for example, when it is determined that there is a person within the swing range of the vehicle door and an obstacle exists within the swing range of the vehicle door, the determination of S206 is repeated. If it is determined that there is no person in the swing range of the vehicle door and there is no obstacle in the swing range of the vehicle door, then the door opening / closing mechanism 23 is instructed to open the vehicle door. (S208). Thereby, the automatic door opening of the vehicle door is started.

  Next, based on the signal sent from the distance measuring device 10, whether there is an obstacle in the swing range of the vehicle door, or whether the opening of the vehicle door has reached the target opening. Determine (S210).

  Here, when there is no obstacle in the swing range of the vehicle door and the opening degree of the vehicle door has not reached the target opening degree, the determination in S210 is NO and the process returns to S208. Accordingly, the automatic opening of the vehicle door is continued.

  If there is an obstacle within the swing range of the vehicle door, or if the opening of the vehicle door reaches the target opening, the determination in S210 is YES, and then the door opening / closing mechanism 23 is The stop of the door opening is instructed (S212), and this process is terminated. In this way, automatic door opening control of the vehicle door is performed.

  According to the above configuration, the distance is measured based on the information stored in the storage medium and the distance between the distance measuring device and the ground measured when the irradiation direction of the laser beam is vertically downward by the irradiation direction rotating mechanism. Since the total error of the measurement distance is calculated from the difference between the distance between the distance measurement device and the ground and the measurement distance is corrected using the total error of the measurement distance, the accuracy of the measurement distance can be improved.

  In addition, the first measurement error having the ground reflectivity as an error factor is estimated from the waveform output from the light receiving circuit when the irradiation direction of the laser beam is vertically downward, and the total error of the measurement distance; The second measurement error due to the components used in the light emitting circuit and the light receiving circuit can be calculated from the difference from the first measurement error having the ground reflectance as an error factor.

  Further, when the irradiation direction of the laser beam changes, a process for estimating a measurement error with the reflectance of the object as an error factor from the waveform output from the light receiving circuit is performed for each irradiation direction of the laser beam, and the light emitting circuit And the second measurement error due to the components used in the light receiving circuit and the sum of the measurement error due to the reflectance of the object estimated for each laser light irradiation direction as the error factor, Since the correction is performed, it is possible to accurately correct the distance to the object even if the reflectance of the object changes due to a change in the laser light irradiation direction.

  In addition, since the first measurement error with the ground reflectance as an error factor is estimated from the waveform width output from the light receiving circuit, the first measurement with the ground reflectance as an error factor with a relatively simple circuit configuration. The error can be estimated.

  In addition, the first reflectance having a ground reflectance as an error factor from the waveform width output from the light receiving circuit using a map defining the relationship between the waveform width output from the light receiving circuit and the rise time of the waveform output from the light receiving circuit. Can be estimated.

  In addition, this invention is not limited to the said embodiment, Based on the meaning of this invention, it can implement with a various form.

  For example, in the above-described embodiment, the difference between the distance between the ground and the distance measured by the rotating mirror 18 when the laser light irradiation direction is vertically downward, and the distance between the distance measuring device 10 stored in the EEPROM and the ground. The total error of the measurement distance is calculated from the error, and the measurement distance is corrected using the total error of the measurement distance. For example, the time for the light to reciprocate between the distance measurement device 10 and the ground is stored in the EEPROM. Alternatively, the total error of the measurement distance may be calculated using the time required for the light to reciprocate between the distance measurement device 10 and the ground.

  In addition, a temperature detection sensor for detecting the ambient temperature may be provided, and the measurement distance correction amount may be changed according to the temperature detected by the temperature detection sensor.

  In the above embodiment, various types of information are stored in the EEPROM. However, the present invention is not limited to the EEPROM, and may be configured to be stored in a flash memory, a battery-backed RAM, or the like.

  The correspondence relationship between the configuration of the above embodiment and the configuration of the claims will be described. The drive unit 14 corresponds to the irradiation direction rotation mechanism, the EEPROM of the control unit 16 corresponds to the storage unit, and the total error calculation unit. S104 and S106 correspond to the total error calculation means, S108 corresponds to the measurement distance correction means, and S102 corresponds to the reflectance measurement error estimation processing means.

DESCRIPTION OF SYMBOLS 10 Distance measuring device 12 Light emission circuit 13 Light reception circuit 14 Drive part 15 Scan angle detection part 16 Control part 20 Vehicle door 21 Touch sensor 23 Door opening / closing mechanism 30 Swing door ECU
31 Speaker

Claims (6)

A light emitting circuit for irradiating laser light, an irradiation direction rotating mechanism for changing the irradiation direction of the laser light so as to scan in a plane including a vertically downward direction, and reflected light reflected by the laser light on an object. A distance measuring device that measures the distance from an object by measuring the time from when the laser light is irradiated until the reflected light is received by the light receiving circuit. There,
Storage means for storing information for specifying the distance between the distance measuring device and the ground;
The distance is measured based on the information stored in the storage medium and the distance between the distance measuring device measured when the irradiation direction of the laser beam is vertically downward by the irradiation direction rotation mechanism. A total error calculating means for calculating a total error of the measurement distance from a difference in distance between the distance measuring device and the ground;
A distance measurement apparatus comprising: a measurement distance correction unit that corrects the measurement distance using a total error of the measurement distance calculated by the total error calculation unit.   The total error calculating means uses a reflectance of the ground as an error factor from a waveform output from the light receiving circuit when the irradiation direction of the laser beam is vertically downward by the irradiation direction rotating mechanism. A measurement error is estimated, and a second measurement error due to components used in the light emitting circuit and the light receiving circuit is calculated from a difference between the total error of the measurement distance and the first measurement error. Item 2. The distance measuring device according to Item 1. When the irradiation direction of the laser beam is changed by the irradiation direction rotation mechanism, a measurement error with the reflectance of the object as an error factor is estimated from a waveform output from the light receiving circuit for each irradiation direction of the laser beam. A reflectance measurement error estimation processing means for performing processing
The total error calculating means uses the sum of the second measurement error and a measurement error having an error factor as a reflection factor of the object estimated for each laser light irradiation direction as the total error of the measurement distance. The distance measuring device according to claim 2, wherein a distance between the distance measuring device and the distance is corrected.   4. The distance measurement according to claim 2, wherein the total error calculating unit estimates a first measurement error having the ground reflectance as an error factor from a waveform width output from the light receiving circuit. apparatus. A map defining the relationship between the waveform width output from the light receiving circuit and the rise time of the waveform output from the light receiving circuit,
The total error calculating means uses the map that defines the relationship between the waveform width output from the light receiving circuit and the rise time of the waveform output from the light receiving circuit to calculate the ground error from the waveform width output from the light receiving circuit. The distance measuring apparatus according to claim 4, wherein the first measurement error having the reflectance as an error factor is estimated.   The said total error calculation means estimates the 1st measurement error which makes the reflectance of the said ground an error factor from the rise time of the waveform output from the said light reception circuit, The Claim 2 or 3 characterized by the above-mentioned. Distance measuring device.

Images