Calibration support device and calibration support method

Abstract

A calibration support device (200) supports calibration for determining a correction amount corresponding to an actual distance to an object when correcting the distance to the object measured by a distance measurement device (100). The distance measurement device (100) comprises: a light-emitting unit (10) that emits light to the object; a light-receiving unit (20) that receives reflected light from the object that has reflected the light emitted by the light-emitting unit (10) ; and a distance calculation unit (40) that calculates a distance to the object based on the amount of the reflected light received by the light-receiving unit (20). The calibration support device (200) comprises: an acquisition unit (110) that acquires drive conditions for the distance measurement device (100); and a determination unit (120) that, based on the acquired drive conditions, determines the number of one or more dense arrangement ranges in which some correction points, among a plurality of correction points indicating positions to acquire data for determining a correction amount, are arranged more densely than in other ranges within the distance measurement range.

Description

Calibration support apparatus and calibration support method

[0001] The present disclosure relates to a calibration support apparatus and a calibration support method that support calibration of a distance measuring device.

[0002] Conventionally, distance measuring devices employing an indirect ToF (Time of Flight) method are known. A distance measuring device employing the indirect ToF method includes, for example, a light emitting unit and a light receiving unit. In such a distance measuring device, the light receiving unit receives light reflected by an object from the light emitted by the light emitting unit, and the distance to the object is calculated based on a signal based on the reflected light output from the light receiving unit.

[0003] Furthermore, in a distance measuring device, an error may occur in the measured distance to an object due to various factors. Therefore, techniques for correcting such distance errors are known (see, for example, Patent Document 1).

[0004] Patent Document 1 discloses that a correction formula is generated based on measurement values obtained by measuring the distance to a measurement sample while changing the distance from the distance measuring device to the measurement sample, and distance correction is performed using the correction formula.

[0005] Japanese Unexamined Patent Publication No. 2021-117036

[0006] As in the technique described in Patent Document 1, when correcting a distance measured by a distance measuring device using a correction formula, or when performing correction according to the actual distance to a measurement object, it is necessary to acquire data for determining the correction amount of the correction through calibration. In this case, correction accuracy can be improved as the number of data acquisition points increases. On the other hand, an increase in the number of data acquisition points increases the load in calibration, such as an increase in the time and energy required for calibration.

[0007] The present disclosure provides a calibration support apparatus and the like that support calibration for determining a correction amount of a distance measured by a distance measuring device, so that the load in calibration can be reduced while suppressing a decrease in correction accuracy.

[0008] A calibration support device according to one aspect of the present disclosure is a calibration support device that assists in calibration to determine a correction amount corresponding to the actual distance to an object when correcting the distance to an object measured by a distance measuring device, wherein the distance measuring device comprises a light-emitting unit that emits light to the object, a light-receiving unit that receives reflected light reflected by the object from the light emitted by the light-emitting unit, and a distance calculation unit that calculates the distance to the object based on the amount of reflected light received by the light-receiving unit, and the calibration support device comprises an acquisition unit that acquires the driving conditions of the distance measuring device, and a determination unit that determines the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points arranged in the distance measuring range of the distance measuring device, which indicate positions for acquiring data to determine the correction amount, are arranged more densely than other ranges within the distance measuring range.

[0009] A calibration support method according to one aspect of the present disclosure is a calibration support method for supporting calibration to determine a correction amount corresponding to the actual distance to an object when correcting the distance to an object measured by a distance measuring device, wherein the distance measuring device comprises a light-emitting unit that emits light to the object, a light-receiving unit that receives reflected light reflected by the object from the light emitted by the light-emitting unit, and a distance calculation unit that calculates the distance to the object based on the amount of reflected light received by the light-receiving unit, and the calibration support method includes an acquisition step of acquiring the driving conditions of the distance measuring device, and a determination step of determining the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points arranged in the distance measuring range of the distance measuring device, which indicate positions for acquiring data for determining the correction amount, are arranged more densely than other ranges within the distance measuring range.

[0010] According to this disclosure, it is possible to support calibration for determining the amount of correction for the distance measured by a distance measuring device, while suppressing a decrease in correction accuracy and reducing the load on calibration.

[0011] Figure 1 is a functional block diagram showing an example of the configuration of a calibration support device according to an embodiment. Figure 2 is a schematic diagram of the pixel array of the solid-state image sensor in the light-receiving section of the distance measuring device. Figure 3 is a diagram showing an example of the timing of light emission and exposure in the distance measuring device. Figure 4 is a diagram showing another example of the timing of light emission and exposure in the distance measuring device. Figure 5 is a diagram showing the signal amount due to exposure when it is assumed that the reflected light has an ideal waveform. Figure 6 is a diagram showing the signal amount due to exposure when it is assumed that the actual waveform of the reflected light is a triangular wave. Figure 7 is a diagram showing an example of the relationship between the actual distance to the object and the correction amount. Figure 8 is a diagram showing the correction amount determined by calibration when the correction points are arranged at equal intervals and close together. Figure 9 is a diagram showing the correction amount determined by calibration when the correction points are arranged at equal intervals and sparsely. Figure 10 is a diagram showing the correction amount determined by calibration when a dense arrangement range for densely arranging correction points is set. Figure 11 is a diagram for explaining another driving condition in the distance measuring device. Figure 12 is a diagram showing another example of the relationship between the actual distance to the object and the correction amount. Figure 13 is a flowchart showing an example of the operation of the calibration support device according to an embodiment. Figure 14 shows an example of the location of the densely packed range determined by the determination unit. Figure 15 is a flowchart showing an example of a method for determining the locations of multiple correction points. Figure 16 is a flowchart showing an example of a calibration method for determining the correction amount according to the actual distance to the object. Figure 17 is a functional block diagram showing an example of the configuration of a distance measuring device equipped with a calibration support device.

[0012] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0013] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit the scope of this disclosure. Furthermore, components in the following embodiments that are not described in an independent claim are described as optional components. In addition, each figure is a schematic diagram and is not necessarily a strict illustration. Furthermore, substantially identical components in each figure are denoted by the same reference numerals, and redundant explanations may be omitted or simplified.

[0014] Furthermore, in this specification, terms indicating relationships between elements, such as perpendicular, parallel, or coincident, and terms indicating the shape of elements, such as circular or rectangular, as well as numerical ranges, are not expressions that represent only strict meanings, but also expressions that include substantially equivalent ranges, such as differences of a few percent.

[0015] Furthermore, in this specification, ordinal numbers such as "first," "second," etc., unless otherwise specified, do not mean the number or order of constituent elements, etc., but are used for the purpose of avoiding confusion and distinguishing similar constituent elements, etc.

[0016] (Embodiment) [Configuration] First, the configuration of the calibration support device according to this embodiment will be described together with the configuration of the distance measuring device. Figure 1 is a functional block diagram showing an example of the configuration of the calibration support device 200 according to this embodiment. Figure 1 also shows an example of calibration of the distance measuring device 100 together with the calibration support device 200. Figure 2 is a schematic diagram of the pixel array of the solid-state image sensor 21 of the light-receiving unit 20 in the distance measuring device 100.

[0017] The calibration support device 200 according to this embodiment assists in calibration for correcting the distance measured by the distance measuring device 100. Before describing the configuration of the calibration support device 200, the configuration of the distance measuring device 100 will be described.

[0018] As shown in Figure 1, the distance measuring device 100 comprises a light-emitting unit 10, a light-receiving unit 20, a light-emitting exposure control unit 30, a distance calculation unit 40, and a distance correction unit 50.

[0019] The distance measuring device 100 is a distance measuring device that measures the distance to an object using an indirect Time of Flight (TF) method. For example, the distance measuring device 100 measures the distance to an object and generates a distance image that shows the distance to the object.

[0020] The light-emitting unit 10 is a light source that emits light onto an object. The light-emitting unit 10 emits pulsed light according to a light emission control signal input from, for example, the light emission exposure control unit 30. The light-emitting unit 10 includes, for example, a light-emitting element such as a light-emitting diode or laser element that emits infrared light (IR), and an optical system that receives light from the light-emitting element and controls the light distribution of the light from the light-emitting element.

[0021] The light-receiving unit 20 receives reflected light that is reflected by an object from the light-emitting unit 10. The light-receiving unit 20 performs multiple exposures, each starting at a different timing relative to the emission of pulsed light by the light-emitting unit 10. Each of the multiple exposures is performed for a predetermined period. The predetermined period is, for example, the same as the pulse width of the pulsed light emitted by the light-emitting unit 10. The light-receiving unit 20 includes a solid-state image sensor 21 that generates a signal based on the received reflected light. Although not shown in Figure 1, the light-receiving unit 20 may further include an optical system that guides the reflected light to the solid-state image sensor 21 and a bandpass filter that transmits light of a predetermined wavelength.

[0022] The solid-state image sensor 21 is, for example, a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. As shown in Figure 2, the solid-state image sensor 21 has a pixel array composed of multiple pixels 22 arranged in two dimensions. In Figure 2, for illustrative purposes, a configuration of 4 pixels horizontally and 4 pixels vertically, for a total of 16 pixels, is shown, but the number of pixels 22 in the solid-state image sensor 21 is not particularly limited. Multiple pixels 22 may, for example, have the same configuration as each other.

[0023] Each of the multiple pixels 22 receives incident light and generates a signal based on the received incident light. More specifically, each of the multiple pixels 22 converts the incident light into a signal charge and generates a signal based on the converted signal charge. The multiple pixels 22 receive reflected light as incident light, which is light emitted by the light-emitting unit 10 and reflected by the object. Each of the multiple pixels 22 includes at least one photoelectric conversion element that receives reflected light and converts it into an electric charge. For example, a photodiode can be used as the photoelectric conversion element.

[0024] Each of the multiple pixels 22 outputs a signal based on the charge obtained from exposure according to the exposure control signal input from the light emission exposure control unit 30. Each of the multiple pixels 22 is exposed at multiple different timings based on the light emission from the light emission unit 10 and outputs a signal for each exposure. Note that the multiple pixels 22 may be exposed at multiple different timings based on the light emission from the light emission unit 10 by two or more adjacent pixels 22.

[0025] The solid-state image sensor 21, for example, transfers the charge obtained by exposure according to the exposure control signal for each pixel 22 to a vertical transfer path or charge storage unit, and reads out a signal based on the charge obtained by exposure. The charges obtained by exposure at multiple different timings based on the light emission by the light emission unit 10 are read out as individual signals. The solid-state image sensor 21, for example, performs AD (Analog to Digital) conversion in the signal readout and outputs the AD-converted digital signal.

[0026] The light emission exposure control unit 30 controls the emission of light by the light-emitting unit 10 and the exposure by the plurality of pixels 22. The light emission exposure control unit 30 outputs various control signals to control the driving of the light-emitting unit 10 and the light-receiving unit 20. As a control signal to control the driving of the light-emitting unit 10, the light emission exposure control unit 30 outputs, for example, a light emission pulse that instructs the light-emitting unit 10 to emit pulsed light with a predetermined pulse width. The light emission exposure control unit 30 also outputs an exposure pulse that instructs each pixel 22 to be exposed as a control signal to control the driving of the plurality of pixels 22 of the light-receiving unit 20. Each pixel 22 is exposed for a predetermined period according to the exposure pulse, for example, and accumulates signal charge. In this specification, the exposure period means the period during which signal charge used for reading out the signal is generated. Therefore, even if light is incident on a pixel 22 and signal charge is generated, if the signal charge is discharged or otherwise not used for reading out the pixel signal, it is considered unexposed.

[0027] The distance calculation unit 40 calculates the distance to the object based on the amount of reflected light received by the light receiving unit 20. When the light receiving unit 20 performs multiple exposures that start at different timings based on the emission of pulsed light by the light emitting unit 10, the distance calculation unit 40 calculates the distance to the object based on the signals generated by the light receiving unit 20 for each pair of exposures whose timings are adjacent to each other. For example, the distance calculation unit 40 generates a distance image showing the distance to the object based on the signals generated by each of the multiple pixels 22 from the multiple exposures. Details of the calculation of the distance to the object will be described later.

[0028] The distance correction unit 50 corrects the distance to the object calculated by the distance calculation unit 40. Hereinafter, the distance to the object calculated by the distance calculation unit 40 will also be referred to as the "calculated distance". The distance correction unit 50 has, for example, a conversion formula or conversion table for correcting the calculated distance, and corrects the calculated distance using the said conversion formula or conversion table. In the said conversion formula or conversion table, the calculated distance and the corrected distance are associated. The said conversion formula or conversion table is determined, for example, based on a correction amount corresponding to the actual distance to the object. In the said conversion formula or conversion table, for example, the actual distance to the object is the corrected distance, and the distance obtained by adding the correction amount (positive or negative value) to the actual distance to the object is the calculated distance before correction. The correction amount is determined by calibration. The determination of the correction amount by calibration may be performed by the distance correction unit 50. In other words, the distance correction unit 50 may include a calibration device that performs calibration for correcting the distance measured by the distance measuring device 100. Details of the relationship between the actual distance and the correction amount will be described later.

[0029] The light emission exposure control unit 30, the distance calculation unit 40, and the distance correction unit 50 are processing circuits implemented, for example, by a memory for storing a program and a processor for executing the program. Although they are separate functional blocks, all or part of the light emission exposure control unit 30, the distance calculation unit 40, and the distance correction unit 50 may be composed of the same memory and processor. Furthermore, at least one of the light emission exposure control unit 30, the distance calculation unit 40, and the distance correction unit 50 may be a dedicated logic circuit that performs a predetermined processing.

[0030] Next, the calibration of the calibration support device 200 according to this embodiment will be described.

[0031] As shown in Figure 1, the calibration support device 200 comprises an acquisition unit 110 and a determination unit 120.

[0032] The acquisition unit 110 acquires the driving conditions for the distance measuring device 100. For example, the acquisition unit 110 acquires the driving conditions for at least one of the light-emitting unit 10 and the light-receiving unit 20 from the light-emitting exposure control unit 30 as the driving conditions for the distance measuring device 100.

[0033] The determination unit 120 determines, based on the driving conditions acquired by the acquisition unit 110, the number of one or more densely packed areas in which some of the correction points among the multiple correction points arranged within the distance measuring range of the distance measuring device 100 are arranged more densely than other areas within the distance measuring range. The multiple correction points are points that indicate the positions in which data is acquired to determine the amount of correction according to the actual distance to the object when correcting the distance to the object measured by the distance measuring device 100. A densely packed area is a part of the distance measuring range of the distance measuring device 100, and if the number of densely packed areas is two or more, the densely packed areas do not overlap with each other and are not continuous.

[0034] The determination unit 120 may further determine the positions of one or more densely packed ranges and multiple correction points. The determination unit 120 outputs, for example, correction point sequence data indicating the positions of the determined multiple correction points. The correction point sequence data is input to, for example, the distance correction unit 50 and used for calibration of the distance measuring device 100. As will be described in detail later, when the determination unit 120 determines the positions of one or more densely packed ranges, the acquisition unit 110 further acquires extreme value position information indicating the positions that are extreme values ​​of the correction amount in the distance range to the object that can be calculated based on the exposure pair described above. The determination unit 120 determines the positions of one or more densely packed ranges based on the driving conditions and extreme value position information acquired by the acquisition unit 110. Then, the determination unit 120 determines the positions of multiple correction points based on the determined positions of one or more densely packed ranges.

[0035] The acquisition unit 110 and the determination unit 120 are processing circuits implemented, for example, by a memory for storing the program and a processor for executing the program. Although they are separate functional blocks, all or part of the acquisition unit 110 and the determination unit 120 may be composed of the same memory and processor. Furthermore, at least one of the acquisition unit 110 and the determination unit 120 may be a dedicated logic circuit that performs predetermined processing. Details of the processing performed by the acquisition unit 110 and the determination unit 120 will be described later.

[0036] [Correction Amount] Next, the correction amount used when correcting the distance calculated by the distance measuring device 100 will be explained along with the principle of distance measurement by the distance measuring device 100.

[0037] The distance measuring device 100 measures the distance to an object, for example, using the pulsed ToF method. The pulsed ToF method is an indirect ToF method in which the light-emitting unit 10 emits pulsed light of a predetermined pulse width to measure the distance to an object. In the pulsed ToF method, the distance to an object is measured based on the time difference between the time the light-emitting unit 10 emits pulsed light and the time the light-receiving unit 20 receives the reflected pulsed light from the object.

[0038] Figure 3 shows an example of the timing of light emission and exposure in the distance measuring device 100. In Figure 3, "Emitted Light" indicates the light emission pulse that shows the timing of light emission by the light-emitting unit 10. Also in Figure 3, "Exposure A0", "Exposure A1", "Exposure BG0", and "Exposure BG1" indicate the exposure pulse that shows the timing of exposure by the pixels 22 of the light-receiving unit 20. In addition, Figure 3 shows an example of the timing of reflected light from an object to which light emitted by the light-emitting unit 10 is reflected, along with the timing of light emission and exposure in the distance measuring device 100.

[0039] The light emission pulse and exposure pulse shown in Figure 3 are output, for example, from the light emission and exposure control unit 30. The light emission and exposure control unit 30 causes the light emission unit 10 to emit light using the light emission pulse and exposes multiple pixels 22 of the light receiving unit 20 using the exposure pulse. In the example shown in Figure 3, the light emission and exposure control unit 30 causes the light emission unit 10 to emit pulsed light during the period when the light emission pulse is at a high level. Also in the example shown in Figure 3, the light emission and exposure control unit 30 exposes the pixels 22 during the period when the exposure pulse is at a low level. The mode of the control signals for controlling the light emission unit 10 and the light receiving unit 20 is not particularly limited, as long as the period of light emission from the light emission unit 10 and the exposure period from the light receiving unit 20 can be defined.

[0040] As shown in Figure 3, the light emission exposure control unit 30 outputs a light emission pulse with pulse width T. In other words, the light emission unit 10 emits pulsed light with pulse width T. The light emission exposure control unit 30 also outputs multiple exposure pulses with pulse width T corresponding to exposure A0, exposure A1, exposure BG0, and exposure BG1. In other words, the pixels 22 of the light receiving unit 20 are exposed for a period of pulse width T corresponding to each exposure pulse. The periods of exposure A0, exposure A1, exposure BG0, and exposure BG1 do not overlap. Exposure A0 and exposure A1 start at different timings relative to the emission of pulsed light by the light emission unit 10, and are exposures for the pixels 22 to generate signals based on reflected light. In the example shown in Figure 3, exposure A0 starts simultaneously with the start of pulsed light emission. Exposure A1 starts with a pulse width T delay from the start of exposure A0. Exposure BG0 and exposure BG1 are exposures for the pixels 22 to generate signals based on background light. In other words, exposure BG0 and exposure BG1 are performed at a timing such that reflected light does not enter the pixels 22. Exposure BG0 and exposure BG1 are started, for example, at a timing sufficiently delayed from the emission of pulsed light by the light-emitting unit 10. Note that performing exposure BG0 and exposure BG1 is not mandatory, and in environments with little background light, exposure BG0 and exposure BG1 may not be performed.

[0041] Pixel 22, for example, has multiple charge storage units, and the charges generated by exposure A0, exposure A1, exposure BG0, and exposure BG1 are distributed and stored in different charge storage units. Multiple signals are then read out according to the amount of charge stored in each of the multiple charge storage units. For example, the number of exposures A0, A1, BG0, and BG1 is the same as the number of charge storage units in pixel 22. However, the number of charge storage units in pixel 22 may be less than the number of exposures A0, A1, BG0, and BG1. In this case, for example, exposures A0, A1, BG0, and BG1 may be performed using two or more pixels 22, or the frame may be divided into multiple subframes, and exposures A0, A1, BG0, and BG1 may be performed on each of the multiple subframes.

[0042] In the pulsed ToF method, the distance to a target object can be calculated from the delay time between the emission of pulsed light and the return of the reflected light after being reflected off the target object. The delay time can be calculated from the ratio of signals generated by receiving the reflected light during exposures A0 and A1. Therefore, when exposure is performed at the timing shown in FIG. 3, the distance value (Depth) indicating the distance to the target object is calculated by the following formula (1).

[0043]

[0044] Here, T is the aforementioned pulse width T, and c is the speed of light. Further, S0 is a value obtained by subtracting the signal generated by exposure BG0 from the signal generated by exposure A0. S1 is a value obtained by subtracting the signal generated by exposure BG1 from the signal generated by exposure A1. The influence of background light can be subtracted by using S0 and S1 to calculate the distance value. Note that the signal value of the signal generated by exposure A0 may be used as S0, and the signal value of the signal generated by exposure A1 may be used as S1.

[0045] When the above formula (1) is used to calculate the distance value, the width of the ranging range of the ranging device 100 depends on the pulse width T, and is specifically T·c / 2. Further, in the example shown in FIG. 3, exposure A0 starts simultaneously with the start of the light emission pulse, so the ranging range is from 0 to T·c / 2. For example, when the pulse width T is 8 ns, the ranging range is approximately from 0 m to 1.2 m.

[0046] Note that although the example shown in FIG. 3 shows exposure timing based on one emission of pulsed light, in actual practice, the light emission and exposure shown in FIG. 3 are repeatedly performed within a frame, and signals based on multiple times of light emission and exposure are read out from the pixels 22.

[0047] In the pulsed ToF method, the ranging range can be shifted by changing the exposure timing relative to the emission of pulsed light. FIG. 4 is a diagram showing another example of light emission and exposure timings in the ranging device 100.

[0048] Figure 4 shows an example in which exposure A0 and exposure A1 start with a time delay of P compared to the example shown in Figure 3. Therefore, in the example shown in Figure 4, exposure A0 starts with a time delay of P from the start of pulse light emission. As a result, when exposure is performed at the timing shown in Figure 4, the distance value (Depth) indicating the distance to the object is calculated by the following equation (2).

[0049]

[0050] Equation (2) is obtained by adding P・c / 2 to the right-hand side of equation (1) above, where P is the time P mentioned above.

[0051] In the example shown in Figure 4, as in the example shown in Figure 3, the width of the distance measurement range by the distance measuring device 100 is T・c / 2, but the distance measurement range is shifted to the far side by P・c / 2 from the example shown in Figure 3, and is P・c / 2 to P・c / 2 + T・c / 2. For example, if the pulse width T is 8 ns and P・c / 2 is 0.1 m, the distance measurement range will be approximately 0.1 m to 1.3 m.

[0052] Here, in equations (1) and (2) above, the distance to the object can be calculated accurately when the waveform of the reflected light is an ideal rectangular wave. However, when the waveform of the reflected light is different from a rectangular wave, an error occurs between the calculated distance and the actual distance to the object. Therefore, in order to improve the accuracy of distance measurement by the distance measuring device 100, it becomes necessary to correct for this error.

[0053] For example, the pulsed light actually emitted from the light-emitting unit 10 has a low intensity at the start of emission and may have a triangular wave shape, so the actual waveform of the reflected light may also be triangular. Figure 5 shows the signal amount due to exposure when the reflected light is assumed to have an ideal waveform. Figure 6 shows the signal amount due to exposure when the actual waveform of the reflected light is assumed to be triangular. In Figures 5 and 6, "a" is the start time of exposure A0 relative to the start of pulsed light emission, "b" is the start time of exposure A1 and the end time of exposure A0 relative to the start of pulsed light emission, "k" is the height of the ideal waveform (square wave) of the reflected light, and "Φ" is the time from the start of exposure A0 to the start of reception of the reflected light (i.e., delay time). Also, in Figure 6, the height of the triangular wave of the reflected light is the same "k" as the ideal waveform. Note that in Figure 6, the actual waveform of the reflected light is assumed to be triangular for explanatory purposes, but the actual waveform of the reflected light is not limited to a triangular wave.

[0054] Assuming the ideal and actual waveforms of the reflected wave as shown in Figures 5 and 6, the ideal correction amount corresponding to the actual distance to the object when correcting the distance to the object measured by the distance measuring device 100 can be calculated as follows. Here, the distance value (Depth) indicating the distance to the object is calculated by the following equation (3).

[0055]

[0056] Here, D is a constant used to convert the ratio of the signals generated by exposure A0 and exposure A1 into a distance value, and E corresponds to P・c / 2 in equation (2) above. As shown in the example in Figure 3, if P is zero, then E is also zero. Furthermore, in equation (3), for simplification, the subtraction of the signals generated by exposure BG0 and exposure BG1, which is performed in equations (1) and (2) above, is omitted, and the distance value (Depth) is calculated using the ratio of the signals A0 and A1, which are generated by exposure A0 and exposure A1.

[0057] First, let's explain the case where the reflected light is a rectangular wave as shown in Figure 5. In this case, A0 + A1 = k(b - a). Also, A1 = kΦ. Therefore, the distance value (Depth) is the value calculated by the following equation (4).

[0058]

[0059] Next, we will explain the case where the reflected light is a triangular wave as shown in Figure 6. In this case, A0 + A1 = k(b - a). Also, if we denote the triangular wave as nx + m, then A1 can be expressed by the following equation (5).

[0060]

[0061] Therefore, the distance value (Depth) is the value calculated by the following formula (6).

[0062]

[0063] Furthermore, since n = k / (b-a) and m = -k(a+Φ) / (b-a), equation (6) above can be transformed into equation (7) below.

[0064]

[0065] From the above, the difference in distance between the case where the reflected light is an ideal rectangular wave and the case where the reflected light is a triangular wave is calculated by the following equation (8), which is obtained by subtracting the distance value calculated by equation (7) from the distance value calculated by equation (4) above.

[0066]

[0067] The correction amount required to correct the reflected light from a triangular wave to an ideal rectangular wave is calculated by the following equation (9), as the sign of the difference amount is reversed.

[0068]

[0069] Figure 7 shows an example of the relationship between the actual distance to the object and the correction amount. In Figure 7, the ideal correction amount determined based on the above equation (9) according to the actual distance to the object is shown. In Figure 7 and in Figures 8 to 10 described later, "a" and "b" are distances corresponding to time "a" and time "b", respectively, based on the start of pulse light emission shown in Figures 5 and 6. Therefore, in Figure 7, etc., the range of actual distances from a to b is the distance range that can be calculated based on the signal generated by the light receiving unit 20 for each pair of exposure A0 and exposure A1, and is the distance measuring range of the distance measuring device 100. In Figure 7, etc., the correction amount calculated by the above equation (9) is zero when Φ is zero, but in reality, in the distance measuring device 100, there may be error factors other than the error caused by the waveform of the reflected light described above, so in Figure 7, a negative offset due to this factor is added to the correction amount calculated by the above equation (9). The same applies to Figures 8 to 10 and 12 described later.

[0070] As shown in Figure 7, in equation (9) above, the correction amount changes nonlinearly with respect to the actual distance. Specifically, since the correction amount is a quadratic function of Φ, there is only one extremum at the position indicated by (A) between a and b. Also, in equation (9), the extremum corresponds to the position of (a + b) / 2.

[0071] In the distance measuring device 100, deviations from the expected error and individual differences exist, so it is necessary to determine the correction amount by calibration. Increasing the number of correction points from which data for determining the correction amount is acquired improves the accuracy of the correction, but increasing the number of correction points increases the workload in calibration.

[0072] Furthermore, regarding the arrangement of correction points, in conventional techniques such as those shown in Patent Document 1, the correction points are arranged at equal intervals within the distance measurement range. When correction points are arranged at equal intervals as in conventional techniques, if there is an extreme value of the correction amount as shown in Figure 7, reducing the number of correction points significantly reduces the accuracy of the correction. Figure 8 shows the correction amount determined by calibration when correction points are arranged at equal intervals and close together. Figure 9 shows the correction amount determined by calibration when correction points are arranged at equal intervals and sparsely. In the examples shown in Figures 8 and 9, the correction amount determined by calibration is determined by interpolating the correction amounts between multiple correction points. As shown in Figure 8, when correction points are arranged close together, the correction amount determined by calibration is almost the same as the ideal correction amount. On the other hand, as shown in Figure 9, when correction points are sparsely arranged, no correction points are placed near the extreme value of the correction amount shown in (A), and the difference between the ideal correction amount and the correction amount determined by calibration becomes large near the extreme value of the correction amount, reducing the accuracy of the correction. This is because, at the extreme values ​​of the correction amount, the increase and decrease of the correction amount reverse as the actual distance increases. Therefore, if the correction point is not placed near the extreme value, the correction amount cannot be accurately interpolated by interpolation.

[0073] In contrast, by varying the density of the correction points, the decrease in correction accuracy can be suppressed even when the number of correction points is reduced. Figure 10 shows the correction amount determined by calibration when a dense arrangement range for densely arranging correction points is set. In Figure 10, the correction points are densely arranged near the extreme value of the correction amount shown in (A). As a result, there is almost no difference between the ideal correction amount and the correction amount determined by calibration even near the extreme value of the correction amount, and the decrease in correction accuracy can be suppressed even while reducing the number of correction points compared to the case shown in Figure 8. Here, when the distance measuring device 100 performs distance measurement using only the pair of exposure A0 and exposure A1 for exposure of reflected light, there is only one extreme value in the correction amount, so the number of dense arrangement ranges in which correction points are densely arranged is also only one.

[0074] Next, we will explain the correction amount when the driving conditions of the distance measuring device 100 are different from the example above. Figure 11 is a diagram illustrating different driving conditions for the distance measuring device 100. In Figure 11, "Exposure A0", "Exposure A1", "Exposure A2", and "Exposure A3" show exposure pulses indicating the exposure timing by the pixels 22 of the light receiving unit 20. Also in Figure 11, along with the exposure timing in the distance measuring device 100, "Reflected Light" shows the case where the reflected light from the object to which the light emitted by the light emitting unit 10 is emitted is a triangular wave.

[0075] In the example shown in Figure 11, exposures A2 and A3 are added to exposures A0 and A1 described above as multiple exposures for the pixels 22 of the light-receiving unit 20 to generate a signal based on reflected light. Exposures A0, A1, A2, and A3 start at different timings relative to the emission of pulsed light (not shown in Figure 11) from the light-emitting unit 10. Exposure A2 starts after the start of exposure A1 with a delay of the pulse width T of the pulsed light. Exposure A3 starts after the start of exposure A2 with a delay of the pulse width T of the pulsed light. Although not shown in Figure 11, further exposures may be performed to generate a signal based on background light. In the example shown in Figure 11, the distance to the object is calculated based on the signal generated by the light-receiving unit 20 at the timing when the reflected light from each of the three pairs of exposures—pair 1 of exposure A0 and exposure A1, pair 2 of exposure A1 and exposure A2, and pair 3 of exposure A2 and exposure A3—is incident on the light-receiving unit 20. By using pair 2, it is possible to measure a distance range that is shifted to a longer distance than when using pair 1, by a distance equivalent to the pulse width T of the pulsed light. Furthermore, by using pair 3, it is possible to measure a distance range that is shifted to a longer distance than when using pair 2, by a distance equivalent to the pulse width T of the pulsed light. As a result, the distance measuring range of the distance measuring device 100 can be expanded compared to when only exposures A0 and A1 as described above are performed as multiple exposures for receiving reflected light.

[0076] Furthermore, when calculating the distance to the object using the signal generated by pair 2 or pair 3, the ideal correction amount corresponding to the actual distance to the object can be calculated in the same way as for the exposure A0 and exposure A1 pair (i.e., pair 1) described above, except that it is shifted to the far-distance side by a distance equivalent to the pulse width T of the pulsed light. Figure 12 shows another example of the relationship between the actual distance to the object and the correction amount. Figure 12 shows the ideal correction amounts when exposure A0, exposure A1, exposure A2, and exposure A3 are performed.

[0077] As shown in Figure 12, when exposures A0, A1, A2, and A3 are performed, there are three pairs of exposures for calculating the distance, so there are extreme values ​​of the correction amount at the three locations indicated by (A). Also, depending on the timing of receiving the reflected light, the pair of exposures used for distance measurement changes, so the downward-convex curve of the correction amount is repeated, and this curve switches at the two locations indicated by (B). As described above, near the extreme values ​​of the correction amount at the locations indicated by (A), it is necessary to place correction points close together in order to suppress the decrease in correction accuracy. At the switching of the correction amount curve at the locations indicated by (B), similar to the extreme values ​​of the correction amount, the increase and decrease of the correction amount reverse as the actual distance increases, so it is necessary to place correction points close together in order to suppress the decrease in correction accuracy. In other words, in order to suppress the decrease in correction accuracy, it is necessary to place correction points close together at the reversal points where the increase and decrease of the correction amount reverse as the actual distance increases. Therefore, when exposures A0, A1, A2, and A3 are performed, five densely packed areas where correction points are closely arranged are required. In this way, the number of densely packed areas necessary to suppress the decrease in correction accuracy is determined according to the number of exposures for which the light-receiving unit 20 generates a signal based on reflected light. If N is the number of exposures for which the light-receiving unit 20 generates a signal based on reflected light, the number of extreme values ​​of the correction amount is N-1, and the number of switching points in the correction amount curve is N-2. Therefore, the number of densely packed areas necessary to suppress the decrease in correction accuracy can be determined by 2N-3.

[0078] In the above explanation, it was assumed that the actual waveform of the pulsed light emitted by the light-emitting unit 10 is a triangular wave, but this actual waveform may have a shape other than a triangular wave. Therefore, there may be two or more extreme values ​​of the correction amount within the distance range to the object that can be calculated based on the exposure pairs by the light-receiving unit 20, and the formula for determining the number of densely packed ranges may be other than 2N-3.

[0079] [Operation] Next, the operation of the calibration support device 200 according to this embodiment will be described. Specifically, the calibration support method by the calibration support device 200 will be described as the operation of the calibration support device 200.

[0080] Figure 13 is a flowchart showing an example of the operation of the calibration support device 200 according to the embodiment.

[0081] As shown in Figure 13, first, the acquisition unit 110 acquires the driving conditions of the distance measuring device 100 (step S11). Step S11 is an example of an acquisition step. In step S11, the acquisition unit 110 acquires, for example, the driving conditions of at least one of the light-emitting unit 10 and the light-receiving unit 20 from the light-emitting exposure control unit 30 of the distance measuring device 100 as the driving conditions of the distance measuring device 100. The driving conditions acquired in step S11 include, for example, the number of exposures for the light-receiving unit 20 to generate a signal based on reflected light. The driving conditions acquired in step S11 may also include the pulse width T of the pulsed light emitted by the light-emitting unit 10 and the time P shown in Figure 4. The driving conditions acquired in step S11 may also include the distance measuring range of the distance measuring device 100.

[0082] Next, the determination unit 120 determines the number of one or more densely packed areas in which some of the correction points among the multiple correction points are densely packed, based on the driving conditions acquired in step S11 (step S12). Step S12 is an example of a determination step. In step S12, the determination unit 120 determines the number of one or more densely packed areas based, for example, on the number of multiple exposures. In this case, the determination unit 120 determines 2N-3 as the number of one or more densely packed areas, for example, when the number of multiple exposures is N.

[0083] Next, the acquisition unit 110 acquires extreme value position information indicating the position of the extreme value of the correction amount within the distance range to the object that can be calculated based on the exposure pairs by the light receiving unit 20 (step S13). The acquisition unit 110 acquires the extreme value position information from the user or an external device, for example, via an input interface (not shown). The extreme value position information is acquired in advance by measuring the distance to the object while changing the distance using, for example, a prototype of the distance measuring device 100 or a part of a mass-produced product of the distance measuring device 100. Alternatively, the extreme value position information may be the position of the extreme value determined from the calculation formula for the correction amount based on the actual waveform of the reflected light (for example, formula (9) above). Note that step S13 may be performed before step S14 below, for example, before step S12.

[0084] Next, the determination unit 120 determines the position of one or more densely packed ranges based on the extreme value position information obtained in step S13 (step S14). In step S14, the determination unit 120 determines the position of the densely packed range to be a position that includes the extreme value of the correction amount indicated by the extreme value position information.

[0085] As shown in the examples in Figures 11 and 12 above, when there are multiple exposure pairs for calculating distance, the extreme value position information may be information indicating the extreme value positions corresponding to all exposure pairs, or it may be information indicating the extreme value positions corresponding to one exposure pair. If the extreme value position information is information indicating the extreme value positions corresponding to one exposure pair, the determination unit 120 may determine the extreme value positions corresponding to other exposure pairs based on the extreme value positions corresponding to one exposure pair and the time difference between the start of that exposure pair and the other exposure pairs. In other words, the determination unit 120 may use other information, such as the driving conditions of the distance measuring device 100, as long as it uses at least the extreme value position information in determining the positions of one or more densely arranged ranges. Examples of the driving conditions of the distance measuring device 100 used in determining the positions of one or more densely arranged ranges include the pulse width T of the pulsed light emitted by the light-emitting unit 10, the time P shown in Figure 4, and the distance measuring range of the distance measuring device 100.

[0086] Furthermore, when there are multiple exposure pairs for calculating distance, as explained above, there is a dense arrangement range that includes not only the extreme value of the correction amount but also the switching position of the correction amount curve. Therefore, the determination unit 120 determines the dense arrangement range that includes the switching position of the correction amount curve based on the driving conditions of the light receiving unit 20 of the distance measuring device 100. The switching position of the correction amount curve can be determined, for example, by the start timing of multiple exposures based on the emission of pulsed light by the light emitting unit 10. If the multiple exposures are exposure A0, exposure A1, exposure A2, and exposure A3 as shown in Figure 11, the distances corresponding to the start of exposure A1, which is the start of exposure 2, and the start of exposure A2, which is the start of exposure 3, become the switching position of the correction amount curve.

[0087] Figure 14 shows an example of the location of the densely packed area determined by the determination unit 120. Figure 14 shows the location of the densely packed area when the multiple exposures are exposure A0, exposure A1, exposure A2, and exposure A3 as shown in Figure 11. In Figure 14, the area indicated by 2r is the densely packed area. When the number of multiple exposures is four, exposure A0, exposure A1, exposure A2, and exposure A3, N=4, so as shown in Figure 14, the number of densely packed areas is 2 × 4 - 3 = 5.

[0088] In the example shown in Figure 14, the ideal correction amount corresponding to the actual distance includes a total of five inversion points within the distance measuring range of the distance measuring device 100: three inversion points shown in (A) and two inversion points shown in (B). In Figure 14, the inversion points shown in (A) are the extreme values ​​of the correction amount shown in (A) in Figure 12, and the inversion points shown in (B) in Figure 14 are the switching points of the correction amount curve shown in (B) in Figure 12. In this case, the determination unit 120 first determines the positions of the five inversion points based on the driving conditions and extreme value position information of the distance measuring device 100, and determines the range of distance r before and after the five inversion points to be a densely arranged range. The distance r is set to a size corresponding to manufacturing variations of the distance measuring device 100, such as individual differences in the drive circuit of the light-emitting unit 10 of the distance measuring device 100. For example, if there is an individual difference of about 200 psec in the timing of pulse light emission due to the drive circuit of the light-emitting unit 10, r is set to about 10 cm.

[0089] Referring again to Figure 13, the determination unit 120 then determines the positions of multiple correction points based on the positions of one or more densely packed ranges determined in step S14 (step S15). In step S15, the determination unit 120 arranges multiple correction points within one or more densely packed ranges such that the correction points are more densely packed within the range of the distance measuring device 100 than in the ranges other than one or more densely packed ranges.

[0090] Here, an example of a method for determining the positions of multiple correction points by the determination unit 120 (step S15) will be described. Figure 15 is a flowchart showing an example of a method for determining the positions of multiple correction points.

[0091] As shown in Figure 15, first, the determination unit 120 sets the near-end distance of the distance measuring range of the distance measuring device 100 as distance X(n), which is the distance set for the placement of the correction points (step S21). The near-end distance is the distance corresponding to the start time of the exposure (for example, exposure A0 above) that starts first among the multiple exposures by the light receiving unit 20, based on the emission of pulsed light by the light emitting unit 10.

[0092] Next, the determination unit 120 determines whether or not correction points have been placed up to the far end distance (step S22). The far end distance is the distance corresponding to the start time of the exposure of the light-receiving unit 20 that starts last among the multiple exposures by the light-receiving unit 20, based on the emission of pulsed light from the light-emitting unit 10 (for example, exposure A3 above). The far end distance is also the distance obtained by adding to the near end distance the distance obtained by multiplying the number obtained by subtracting 1 from the number of multiple exposures (N-1) by c・T / 2 (see formula (1) above, etc.).

[0093] If no correction points are placed up to the far end distance (No in step S22), the determination unit 120 places a correction point at distance X(n) (step S23). Then, the determination unit 120 determines whether or not distance X(n) is within one or more densely packed areas determined in step S14 (step S24).

[0094] If the distance X(n) is not within the dense arrangement range of 1 or more (No in step S24), the determination unit 120 sets the distance X(n+1) to be set for the arrangement of the next correction point to the value obtained by adding the first distance to the distance X(n) (step S25). On the other hand, if the distance X(n) is within the dense arrangement range of 1 or more (Yes in step S24), the determination unit 120 determines the distance X(n+1) to be set for the arrangement of the next correction point to the value obtained by adding a second distance shorter than the first distance to the distance X(n) (step S26). The first distance is, for example, four times or more the second distance. For example, if c・T / 2 is 1.2m, the first distance is 20cm and the second distance is 2.5cm.

[0095] After step S25 and after step S26, the determination unit 120 sets n+1 as the new n, that is, sets distance X(n+1) as the new distance X(n), and performs step S22 again. As a result, correction points are sequentially placed between the near end distance and the far end distance. Steps S24, S25, and S26 shorten the distance between a placed correction point and the next correction point to be placed if it is within the dense placement range, and lengthen it if it is outside of one or more dense placement ranges, so that correction points can be densely placed within one or more dense placement ranges.

[0096] Then, if the determination unit 120 has placed correction points up to the far end distance (Yes in step S22), it finishes placing the correction points. As a result, all of the correction points are placed within the distance measuring range of the distance measuring device 100.

[0097] In the example shown in Figure 15, the near-end distance was initially set as distance X(n), but the far-end distance may also be set as distance X(n) initially. In this case, the correction points are sequentially placed down to the near-end distance by subtracting the first or second distance from distance X(n). In other words, in determining the positions of multiple correction points, the determination unit 120 determines the placement of multiple correction points by sequentially placing them from one of the near-end distance and far-end distance of the distance measurement range toward the other, with the near-end distance or far-end distance of the distance measurement range as the initial position. When sequentially placing multiple correction points, if the placed correction point is not within one or more densely placed areas, the determination unit 120 places the next correction point at a position shifted by one distance from the placed correction point. If the placed correction point is within one or more densely placed areas, the determination unit 120 places the next correction point at a position shifted by two distances from the placed correction point.

[0098] Furthermore, although the positions of one or more densely packed ranges and multiple correction points determined by the calibration support device 200 were described in terms of absolute distance, they may also be expressed using an index other than absolute distance. The positions of one or more densely packed ranges and multiple correction points determined by the calibration support device 200 may be expressed, for example, in terms of normalized distance, or in terms of an index that indicates a distance that can be converted to a distance, such as delay time.

[0099] The positions of the multiple correction points determined by the determination unit 120 are output as, for example, correction point series data. For example, the distance correction unit 50 acquires the correction point series data output from the determination unit 120 and performs calibration using the acquired correction point series data. Figure 16 is a flowchart showing an example of a calibration method for determining the correction amount according to the actual distance to the object. For example, the operation according to the calibration method described below is performed for each mass-produced unit of the distance measuring device 100.

[0100] As shown in Figure 16, first, the distance correction unit 50 acquires the calculated distance at each of the multiple correction points (step S31). The calculated distance acquired by the distance correction unit 50 is obtained, for example, by having the distance measuring device 100 perform a distance measuring operation while moving the position of the distance measuring device 100 or the object to a position corresponding to the distance between the multiple correction points.

[0101] Next, the distance correction unit 50 calculates the correction amount at each of the correction points (step S32). The correction amount at each of the correction points can be calculated by determining the difference between the actual distance to the object and the calculated distance at each of the correction points.

[0102] Next, the distance correction unit 50 determines the total correction amount for the distance measuring range of the distance measuring device 100 by interpolating the correction amounts between multiple correction points (step S33). The distance correction unit 50 generates a conversion formula or conversion table for correcting the calculated distance based on the determined total correction amount for the distance measuring range of the distance measuring device 100. As described above, since the correction points are densely arranged in a dense arrangement range near the point where the correction amount is reversed within the distance measuring range, even if the number of correction points is reduced, the difference between the ideal correction amount and the determined correction amount can be reduced, as shown in Figure 10. Therefore, when determining the correction amount according to the actual distance to the object, the load on calibration can be reduced while suppressing a decrease in correction accuracy.

[0103] Furthermore, the calibration for determining the correction amount corresponding to the actual distance to the object, as shown in Figure 16, is not limited to being performed by the distance correction unit 50. The calibration may be performed by the calibration support device 200, for example, by the calibration support device 200 functioning as a calibration device, or by a calibration device consisting of a computer or the like, separate from the distance measuring device 100 and the calibration support device 200. In this case, the distance correction unit 50 may, for example, obtain the total correction amount for the distance measuring range of the distance measuring device 100 that has been determined, or a conversion formula or conversion table based on the correction amount for correcting the calculated distance, and use it to correct the calculated distance.

[0104] Furthermore, the correction point series data is not limited to being used directly for calibration; for example, it may be used to search for the position of the extreme value of the correction amount. For example, the calibration support device 200 performs the operation shown in Figure 13 above using information indicating the position provisionally determined as extreme value position information, and determines the positions of multiple correction points. In this case, the position of the extreme value of the correction amount is searched for by measuring the distance to the object using the distance measuring device 100 in correspondence with the multiple correction points that have been determined.

[0105] (Other) The above description of a calibration support device according to one or more embodiments of the present disclosure has been based on embodiments, but the present disclosure is not limited to embodiments. Without departing from the spirit of the present disclosure, various modifications that a person skilled in the art can conceive of may be applied to each embodiment, and forms constructed by combining components from different embodiments may also be included within the scope of one or more embodiments of the present disclosure.

[0106] Furthermore, in the above embodiment, the calibration support device 200 may be incorporated into the distance measuring device. Figure 17 is a functional block diagram showing an example of the configuration of a distance measuring device 100A equipped with the calibration support device 200. As shown in Figure 17, the distance measuring device 100A has a configuration in which the calibration support device 200 is added to the distance measuring device 100 described above.

[0107] Furthermore, in the above embodiment, the calibration support device 200 outputs the positions of multiple correction points as correction point sequence data, but is not limited to this. The calibration support device 200 may be, for example, a device that outputs the number of one or more densely arranged ranges, or the positions of one or more densely arranged ranges.

[0108] Furthermore, in the above embodiment, each component may be realized by executing a software program suitable for each component. Each component may also be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0109] Furthermore, each component may be implemented by hardware. Each component may also be a circuit (or integrated circuit). These circuits may form a single circuit as a whole, or they may be separate circuits. Also, each of these circuits may be a general-purpose circuit or a dedicated circuit.

[0110] Furthermore, in the above embodiment, a process performed by a specific processing circuit may be performed by another processing circuit. Also, the order of multiple processes may be changed, or multiple processes may be executed in parallel.

[0111] Furthermore, the general or specific embodiments of this disclosure may be implemented as a system, apparatus, method, integrated circuit, computer program, or recording medium such as a computer-readable CD-ROM. They may also be implemented as any combination of a system, apparatus, method, integrated circuit, computer program, and recording medium.

[0112] For example, this disclosure may be implemented as a calibration support device of the above embodiment, as a control device for controlling a distance measuring device, as a calibration support method including steps (processes) performed by components constituting the calibration support device, as a program for causing a computer to execute such a calibration support method or as a program product including such a program, or as a computer-readable non-temporary recording medium on which such a program is recorded.

[0113] Examples of the calibration support device and calibration support method according to this disclosure, as described based on the embodiments described above, are shown below. The calibration support device and calibration support method according to this disclosure are not limited to the following examples.

[0114] For example, a calibration support device according to a first aspect of the present disclosure is a calibration support device that assists in calibration to determine a correction amount corresponding to the actual distance to an object when correcting the distance to an object measured by a distance measuring device, wherein the distance measuring device comprises a light-emitting unit that emits light to the object, a light-receiving unit that receives reflected light reflected by the object from the light emitted by the light-emitting unit, and a distance calculation unit that calculates the distance to the object based on the amount of reflected light received by the light-receiving unit, and the calibration support device comprises an acquisition unit that acquires the driving conditions of the distance measuring device, and a determination unit that determines the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points arranged in the distance measuring range of the distance measuring device, which indicate positions for acquiring data to determine the correction amount, are arranged more densely than other ranges within the distance measuring range.

[0115] The correction amount in a distance measuring device, which corresponds to the actual distance to an object, can change nonlinearly with respect to that actual distance. In response to this, by densely arranging correction points in calibration within a range where errors from the ideal correction amount are likely to occur due to nonlinear changes, it is possible to reduce the load on calibration while suppressing a decrease in correction accuracy. In the calibration support device according to this embodiment, the determination unit determines the number of dense arrangement ranges in which correction points are densely arranged, and the determined number of dense arrangement ranges can be used for the arrangement of multiple correction points. Therefore, the calibration support device according to this embodiment can support calibration for determining the correction amount of the distance measured by the distance measuring device in order to suppress a decrease in correction accuracy and reduce the load on calibration.

[0116] Furthermore, for example, a calibration support device according to a second aspect of the present disclosure is a calibration support device according to a first aspect, wherein in the distance measuring device, the light-emitting unit emits pulsed light to the object, the light-receiving unit performs a plurality of exposures which are started at different timings relative to the emission of pulsed light by the light-emitting unit, and generates a signal based on the reflected light, the distance calculation unit calculates the distance to the object based on the signal generated by the light-receiving unit for each pair of exposures whose timings are adjacent to each other among the plurality of exposures, and in the calibration support device, the acquisition unit acquires the driving conditions including the number of the plurality of exposures, and the determination unit determines the number of one or more densely arranged ranges based on the acquired number of the plurality of exposures.

[0117] This allows us to determine one or more densely packed areas depending on the exposure conditions of the light-receiving section.

[0118] Furthermore, for example, a calibration support device according to a third aspect of the present disclosure is a calibration support device according to a second aspect, wherein the acquisition unit further acquires extreme value position information indicating the position of the extreme value of the correction amount within the distance range to the object that can be calculated based on the signal generated by the light receiving unit for each of the exposure pairs, and the determination unit further determines the position of the one or more densely arranged ranges based on the acquired extreme value position information.

[0119] This allows the number of densely packed areas, as well as the positions of those densely packed areas, to be used for arranging multiple correction points.

[0120] Furthermore, for example, a calibration support device according to a fourth aspect of this disclosure is a calibration support device according to a third aspect, wherein the determination unit further determines the positions of the plurality of correction points based on the positions of the determined one or more densely arranged ranges.

[0121] This determines the positions of multiple correction points so that they are densely arranged within one or more densely packed areas. Therefore, by using the determined multiple correction points for calibration, the load on calibration can be reduced while suppressing a decrease in correction accuracy.

[0122] Furthermore, for example, a calibration support device according to a fifth aspect of the present disclosure is a calibration support device according to a fourth aspect, wherein the determination unit determines the positions of the plurality of correction points by sequentially arranging the plurality of correction points from one of the near end distance and far end distance of the distance measurement range toward the other, with the near end distance and far end distance of the distance measurement range as the initial position, and when sequentially arranging the plurality of correction points, if the arranged correction point is not within the range of one or more densely arranged points, the next correction point is arranged at a position moved by a first distance from the arranged correction point, and if the arranged correction point is within the range of one or more densely arranged points, the next correction point is arranged at a position moved by a second distance shorter than the first distance from the arranged correction point.

[0123] This allows multiple correction points to be placed so that they are densely arranged within one or more dense arrangement ranges, simply by setting the distance measurement range, the first distance, and the second distance.

[0124] Furthermore, for example, a calibration support method according to a sixth aspect of the present disclosure is a calibration support method that supports calibration for determining a correction amount according to the actual distance to an object when correcting the distance to an object measured by a distance measuring device, wherein the distance measuring device comprises a light-emitting unit that emits light to the object, a light-receiving unit that receives reflected light reflected by the object from the light emitted by the light-emitting unit, and a distance calculation unit that calculates the distance to the object based on the amount of reflected light received by the light-receiving unit, and the calibration support method includes an acquisition step of acquiring the driving conditions of the distance measuring device, and a determination step of determining the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points arranged in the distance measuring range of the distance measuring device, which indicate positions for acquiring data for determining the correction amount, are arranged more densely than other ranges within the distance measuring range.

[0125] This makes it possible to support calibration for determining the correction amount of the distance measured by the distance measuring device, in a manner similar to the calibration support device according to the first embodiment, while suppressing a decrease in correction accuracy and reducing the load on calibration.

[0126] The calibration support device, etc. related to this disclosure can assist in the calibration of a distance measuring device that measures the distance to an object.

[0127] 10 Light-emitting unit 20 Light-receiving unit 21 Solid-state image sensor 22 Pixel 30 Light emission exposure control unit 40 Distance calculation unit 50 Distance correction unit 100, 100A Distance measuring device 110 Acquisition unit 120 Determination unit 200 Calibration support device

Claims

1. A calibration support device that assists in calibration for determining a correction amount according to the actual distance to an object when correcting the distance to an object measured by a distance measuring device, wherein the distance measuring device comprises: a light-emitting unit that emits light to the object; a light-receiving unit that receives reflected light that has been reflected by the object from the light-emitting unit; and a distance calculation unit that calculates the distance to the object based on the amount of reflected light received by the light-receiving unit, and the calibration support device comprises: an acquisition unit that acquires the driving conditions of the distance measuring device; and a determination unit that determines the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points arranged in the distance measuring range of the distance measuring device, which indicate positions for acquiring data to determine the correction amount, are arranged more densely than other ranges within the distance measuring range, based on the acquired driving conditions, wherein the calibration support device comprises: an acquisition unit that acquires the driving conditions of the distance measuring device; and a determination unit that determines the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points that indicate positions for acquiring data for determining the correction amount are arranged more densely than other ranges within the distance measuring range.

2. The calibration support device according to claim 1, wherein the distance measuring device comprises: the light-emitting unit emits pulsed light onto the object; the light-receiving unit performs a plurality of exposures, each starting at different timings relative to the emission of pulsed light by the light-emitting unit, for generating a signal based on the reflected light; the distance calculation unit calculates the distance to the object based on the signals generated by the light-receiving unit for each pair of exposures whose timings are adjacent to each other; and the calibration support device comprises: the acquisition unit acquires the driving conditions, including the number of the plurality of exposures; and the determination unit determines the number of the one or more densely packed ranges based on the acquired number of the plurality of exposures.

3. The calibration support device according to claim 2, wherein the acquisition unit further acquires extreme value position information indicating the position of the extreme value of the correction amount within the distance range to the object that can be calculated based on the signal generated by the light receiving unit for each of the exposure pairs, and the determination unit further determines the position of the one or more densely arranged ranges based on the acquired extreme value position information.

4. The calibration support device according to claim 3, wherein the determination unit further determines the positions of the plurality of correction points based on the positions of the determined one or more densely arranged ranges.

5. The calibration support device according to claim 4, wherein the determination unit determines the positions of the plurality of correction points by sequentially arranging the plurality of correction points from one of the near end distance and the far end distance of the distance measurement range toward the other, with the near end distance and the far end distance of the distance measurement range as the initial position, and when sequentially arranging the plurality of correction points, if the arranged correction point is not within the range of one or more densely arranged points, the next correction point is arranged at a position moved by a first distance from the arranged correction point, and if the arranged correction point is within the range of one or more densely arranged points, the next correction point is arranged at a position moved by a second distance shorter than the first distance from the arranged correction point.

6. A calibration support method for assisting calibration to determine a correction amount corresponding to the actual distance to an object when correcting the distance to an object measured by a distance measuring device, the distance measuring device comprising: a light-emitting unit that emits light to the object; a light-receiving unit that receives reflected light reflected by the object from the light emitted by the light-emitting unit; and a distance calculation unit that calculates the distance to the object based on the amount of reflected light received by the light-receiving unit, the calibration support method comprising: an acquisition step of acquiring the driving conditions of the distance measuring device; and a determination step of determining the number of one or more densely arranged ranges in which some of the correction points among a plurality of correction points arranged in the distance measuring range of the distance measuring device, which indicate positions for acquiring data to determine the correction amount, are arranged more densely than other ranges within the distance measuring range, based on the acquired driving conditions.

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