JP2018036144A - System and method for measuring distance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable acquisition of more accurate distance images by avoiding the influence of crosstalk.SOLUTION: A distance measurement system of the present invention comprises a first and second distance measurement devices. The distance measurement system satisfies a condition expressed as: n×f=n×f, where n,n: a natural number and n≠n, f, Trespectively represent a first modulation frequency and a period of modulation light of the first distance measurement device, and f, Trespectively represent a second modulation frequency and a period of modulation light of the second distance measurement device. At each of a plurality of timings that divide an emission period by three or four, each of the first and second distance measurement devices receives light and detects phase states that are different from relative phase states of a modulation frequency of the other device during a predetermined time interval.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical flight type distance measurement technique for measuring a distance to an object.

  The distance detection device includes a stereo method using a plurality of cameras and a pattern projection method. A light-of-flight distance measurement (TOF: Time of Flight) method is a relatively small method with high accuracy and high processing speed. There is a thing using. The TOF method is a method of measuring the time until the reflected light reaches the light receiver by irradiating the space whose distance is to be measured with intensity-modulated light. An indirect method for detecting time as a phase shift of a modulation frequency is known.

  When a plurality of devices are used in a TOF-type distance measuring device that utilizes modulated light, particularly in a device system that acquires a two-dimensional distance image in a predetermined range, reflected light of intensity-modulated light emitted from another distance measuring device Is detected by the light receiver simultaneously with the intensity-modulated light irradiated by itself. Therefore, there is a problem that crosstalk occurs in the received light modulation light and an error occurs in the detected value of the distance measurement value.

  As a countermeasure, Patent Document 1 discloses a technique for reducing optical crosstalk with other devices by performing time-division emission for each irradiation region in the device.

Japanese Patent Laying-Open No. 2015-227781

  However, in the technique of time-division emission as disclosed in Patent Document 1, when synchronization is ensured in order to obtain a sufficient effect, the time required to obtain continuous distance images increases, and the distance image update speed is increased. It will be in a state that must be reduced. Therefore, an object of the present invention is to avoid the influence of crosstalk due to the use of a plurality of devices and to acquire a more accurate range image.

In order to solve the above-described problems, the present invention provides an irradiation unit that emits modulated light, a light receiving unit that receives reflected light of the modulated light emitted by the irradiation unit, and a detection that detects reception of reflected light by the light receiving unit. A distance measurement device comprising: a first distance measurement device and a second distance measurement device comprising: means; and a calculation means for measuring a flight time of light based on a detection result of the detection means and calculating a distance to the object. In the system, the first modulation frequency of the modulated light of the first distance measuring device is f ₁ , the period is T ₁ , and the second modulation frequency of the modulated light of the second distance measuring device is f ₂ , when the period is T ₂ , n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _{2: a} natural number and n ₁ ≠ n ₂ is satisfied, and the first distance measuring device emits light in each of the timing of the period T ₁ 3 or 4 divided The relative phase states different n ₂ pieces of phase states each of the second modulation frequency f ₂ is received and detected at a predetermined time width, the number of n ₂ receiving detecting k ₁ times (where k ₁ is a natural number) performing a 1 detection means and first calculation means for calculating the distance to the object of the first distance measurement device based on the calculated value of the 90 ° phase difference signal, and the second distance measurement device emits light At each of a plurality of timings at which the period T ₂ is divided into three or four, n ₁ phase states having different relative phase states with respect to the _first modulation frequency f ₁ are received and detected with a predetermined time width, and the n ₁ a second detection processing means for receiving and detecting the k ₂ times (where k ₂ is a natural number), the second to calculate the distance to the object of the second distance measuring device based on the calculated value of 90 ° phase difference signal And calculating means.

  According to the above configuration, in the present invention, it is possible to avoid the influence of crosstalk due to the use of a plurality of devices, and to acquire a more accurate range image.

1 is a schematic diagram of an optical flight type distance measurement system according to an embodiment. The figure explaining the optical flight phase lag detection processing method of the optical flight type distance measuring device which concerns on embodiment. FIG. 4 is a timing diagram of four-phase sampling detection in the first distance measuring apparatus according to the first embodiment. FIG. 4 is a timing diagram of four-phase sampling detection in the second distance measuring apparatus according to the first embodiment. FIG. 10 is a timing diagram of four-phase sampling detection in the first distance measuring apparatus according to the second embodiment. FIG. 10 is a timing diagram of four-phase sampling detection in the second distance measuring apparatus according to the second embodiment. FIG. 10 is a timing diagram of three-phase sampling detection in the first distance measuring apparatus according to the third embodiment. FIG. 10 is a timing diagram of three-phase sampling detection in the second distance measuring apparatus according to the third embodiment. FIG. 10 is a timing diagram of three-phase sampling detection in the first distance measuring apparatus according to the fourth embodiment. FIG. 10 is a timing diagram of three-phase sampling detection in the second distance measuring apparatus according to the fourth embodiment. FIG. 10 is a timing diagram of one sampling phase detection in the first, second, and third distance measuring devices according to the fifth embodiment.

  FIG. 1 is a schematic diagram showing a configuration of an optical flight type distance measuring system according to the present embodiment. As shown in FIG. 1, the optical flight-type distance measurement system includes a first optical flight-type distance measurement device and a second optical flight-type distance measurement device. It has a configuration.

  The light irradiation unit 10 includes a light source 11 such as an LED or a laser, an optical member 12 that establishes a light irradiation region such as a lens or a diffusing plate, and the light source modulation unit 13 is controlled by the controller 14, whereby an object (object). The configuration is such that 15 regions are irradiated with modulated light. The scattered reflected light reflected by the object includes a light receiving unit 16 that condenses the reflected light from a predetermined region on the light receiving element array 18 via a condensing lens 17 that collects the light. The light receiving unit has a detection wavelength filter corresponding to the emission wavelength of the irradiated light. Then, a light reception detection processing section (detection means) 19 that performs light signal and photoelectric conversion electrical signal processing, and a distance calculation processing section (calculation means) 20 that calculates the distance to the object from the detection signal of the light reception detection processing section 19. Prepare.

  Next, the basic concept of the indirect method detection principle for detecting the delay time due to optical flight as the phase delay of the modulation frequency in each optical flight type distance measuring device will be described with reference to FIG. Here, sinusoidal modulated light, which is the most ideal modulation waveform for phase delay detection, will be described as an example. FIG. 2A is a timing chart showing temporal changes of a) modulation control signal, b) irradiation modulated light, and c) received light modulated light + environment light. Although it is desirable to change the applied value of the modulation frequency according to the target measurement distance range, target reflectance, and the like, it is usually around 30 MHz when the measurement target is around 5 m. c) In the received light modulated light + environment light, DC light or DC light external environment light whose change is slow with respect to the modulation frequency is also detected. b) Irradiation modulated light and c) Light reception modulated light + environment light are ideally expressed as the following formulas 1 and 2.

b (t) = α [1 + sin (2πft)] (Formula 1)
Here, f is the modulation frequency and α is the central light intensity.

c (t) = BG (t) + αβ [1 + sin (2πft−θ)] (Formula 2)
Here, BG (t) is the ambient light, β is the reflected light efficiency, and θ is the flight time phase delay.

In FIG. 2A, A ₀ , A ₉₀ , A ₁₈₀ , and A ₂₇₀ indicate detection phase timings that are divided into four equal parts with respect to a predetermined reference of irradiation modulated light in one light receiving element. Four-phase reflected light is detected at the timing. The detection time width of the reflected light is not particularly defined at the detection timing of each reflected light, and a predetermined time width may be set. However, in consideration of the amplitude value of the detected light quantity, it is general that the modulation period is ½. Assuming that the received light detection time is ½ of the modulation period and 1 / f = T, A ₀ can be expressed as in the following Equation 3. Note that the integration period as the light reception detection time indicates a relative phase state with the irradiation modulated light.

A ₉₀ , A ₁₈₀ , and A ₂₇₀ can be expressed in the same manner as the following formulas 3, 4, and 5.

In actual measurement processing, A ₀ , A ₉₀ , A ₁₈₀ , and A ₂₇₀ are detected over a plurality of sections, and the SN characteristics such as addition and average are taken into consideration in consideration of dynamic changes such as movement of the object. To improve the process. Furthermore, the detected signals A ₀ and A ₁₈₀ , A ₉₀ and A ₂₇₀ are treated as DC component light because the signal component is out of phase and the external environment light etc. changes slowly with respect to the modulation frequency. Is possible. Therefore, by taking the differential of A ₀ and A ₁₈₀ (A ₀ -A ₁₈₀ ) and the differential of A ₉₀ and A ₂₇₀ (A ₉₀ -A ₂₇₀ ), the received light modulated light component from which the DC component such as ambient light is removed Extraction is possible, and it contributes to SN improvement by differential detection. The differential signals (A ₀ -A ₁₈₀ ) and (A ₉₀ -A ₂₇₀ ) correspond to the light flight time (phase delay), and are two-phase signals having a phase difference of 90 ° as shown in FIG. It becomes.

Further, the Lissajous waveforms of the differential signals (A ₀ -A ₁₈₀ ) and (A ₉₀ -A ₂₇₀ ) corresponding to the light flight time (phase delay) are as shown in FIG. Therefore, a phase state corresponding to the light flight time (phase delay) of the received modulated light with respect to the irradiation modulated light by performing an arctangent calculation of the differential signals (A ₀ -A ₁₈₀ ) and (A ₉₀ -A ₂₇₀ ). θ can be calculated. Therefore, the phase delay θ can be expressed as in the following Equation 7.
θ = ATAN2 [(A ₉₀ −A ₂₇₀ ), (A ₀ −A ₁₈₀ )] (Formula 7)

  Here, ATAN2 [y, x] is an arctangent calculation function that discriminates the quadrant and converts it to ± π phase. Thereby, a phase lag corresponding to the light flight time between the irradiation modulated light and the received light modulated light is detected, and the distance to the reflection object is calculated from the phase lag θ and the speed of light c by the following formula 8. The relationship shown in FIG.

  In the embodiments described below, the detection process described above will be described as the basis of the processing algorithm. However, as described above, the type of light intensity modulated light is not limited to the sine wave described above. For example, pulsed light, triangular wave light, etc. can be considered, and if the detection processing principle is also based on the irradiation light, if the light intensity ratio at each detection phase timing and the phase lag are calculated from quadrant discrimination, the reflected light will be reflected as described above. The distance of the object can be calculated. Further, the integration period corresponding to the light reception detection time is not limited to 1 / 2T, and the above description is valid for an arbitrary integration period except for some conditions.

In the following examples, the first modulation frequency f ₁ (light emission period: T ₁ ) of the first optical flight type distance measurement device and the second optical flight type distance measurement device, which are features of the present embodiment, are used. The relationship with the second modulation frequency f ₂ (light emission period: T ₂ ) is
n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _2: natural number and n ₁ ≠ n ₂
In the following description, some n ₂ / n ₁ conditions and sampling phase conditions will be described as examples.

In “Example 1”, an example in which n ₂ / n ₁ is other than an odd value and a plurality of timing phases to be detected are set to four equally divided phases will be described.

In “Example 2”, an example in which n ₂ / n ₁ is an odd value and a plurality of timing phases to be detected are divided into four phases will be described. (Detection of 4 divisions other than “Example 1”)
In “Example 3”, an example in which n ₂ / n ₁ is not a natural number or a multiple of 3 and a plurality of timing phases to be detected are divided into three equal phases will be described.

In “Embodiment 4,” an example in which n ₂ / n ₁ is a natural number and other than a multiple of 3 and a plurality of timing phases to be detected are divided into three equal phases will be described. (Detection in three divisions other than “Example 3”)

In “Example 5”, when three optical flight-type distance measuring devices are used in the same space, an example in which two n ₂ / n ₁ are all natural numbers will be described.

Example 1
In the first embodiment, the first modulation frequency: f ₁ (period: T ₁ ) of the first optical flight type distance measuring device and the second modulation frequency: f ₂ (second optical flight type distance measurement device). Period: T ₂ )
n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _2: natural number and n ₁ ≠ n ₂
N ₂ / n ₁ is n ₁ = 2 and n ₂ = 3 other than odd numbers, and a plurality of timing phases to be detected are divided into four equally divided phases (0 °, 90 °, 180 °, 270 An example) is described with reference to FIGS. FIG. 3 is a timing chart in the first distance measuring device in this embodiment, and FIG. 4 is a timing chart in the second distance measuring device.

3 and 4, A ₀ , A ₉₀ , A ₁₈₀ , and A ₂₇₀ show timing diagrams of the time change of reflected light in each optical flight type distance measuring device. In the figure, a dotted line indicates a light reception modulation waveform when only the first optical flight type distance measurement device exists, and a broken line indicates a light reception modulation waveform when only the second optical flight type distance measurement device exists. A solid line indicates a received light modulation waveform in which the first and second modulation frequencies are superimposed in the case where the first and second optical flight distance measuring devices coexist. Accordingly, each device receives and detects intensity-modulated light on which the first and second modulation frequencies as indicated by the solid line are superimposed.

In this state, a detection processing method in the first apparatus will be described with reference to FIG. In the figure, the detection sampling timings of 0 °, 90 °, 180 °, and 270 ° in the first apparatus are indicated as f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ , respectively. Yes. Further, in the drawing, a gray portion indicates a detection time region in each sampling phase. That is, the detection timing phase is shifted by 90 ° at f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ .

In this embodiment, since n ₁ = 2 and n ₂ = 3, in the first device, n ₂ : 3 sampling detection ranges (n ₁ ) having different modulation frequencies and relative phase relationships of the second device. .1) is set as the minimum detection unit. Furthermore, for the improvement of the SN ratio, a natural number _{k 1} set _{(n 2 .1, n 2 .2~n} 2 .k 1) f 1 _A 0 sampling _{detection, f 1 _A 90, f 1} _A 18, f _{1 for} _A ₂₇₀ . In this detection processing method, a description will be given regarding the principle of extracting only the frequency f ₁ component of the detected signal. The first received modulated light + environment light can be expressed as Equation 9 by the method described above.
c ₁ (t) = BG ₁ (t) + α ₁ β ₁ [1 + sin (2πf ₁ t−θ ₁ )] +
α ₂ β ₁₂ [1 + sin (2πf ₂ t−θ ₁₂ )] (Formula 9)

Here, f ₁ is the modulation frequency of the first device, α ₁ is the modulation center light intensity of the first device, BG ₁ (t) is the ambient light of the first device, β ₁ is the reflected light efficiency of the first device, θ ₁ delayed flight time phase of the first device, f ₂ is the modulation frequency of the second device. Α ₂ is the modulation center light intensity of the second device, β ₁₂ is the reflected light efficiency of the second device irradiation light in the first device, and θ ₁₂ is the second device irradiation light / reflected light in the first device. The flight time phase delay.

Under these notations, in the light reception detection time of f ₁ _A _{0 in} this example, n ₂ (three) detection phases different in relative phase from f _{2 of} the second device are consecutive relative phases of f ₁ _. It can be expressed as Equation 10 as 0, T ₁ , 2T ₁ .

Here, the third item, which is the reflected detection light of the irradiation light from the second device in each integral term of Equation 10, has a relationship between the first and second frequencies of n ₁ × f ₁ = n ₂ × f. ₂ , n ₁ = 2 and n ₂ = 3, and T ₁ = n ₁ / n ₂ T ₂ = 2 / 3T ₂ . Therefore, it can be converted as shown in Equation 11.

  Further, in Expression 11, when attention is paid to the integral term of the second term, the following Expression 12 is obtained, and the integral term of the second term of Expression 11 is “0”. It can also be seen that it does not depend on the integration period.

Therefore, the integral term of light reception from the second device shown in Equation 11 is the modulation center light intensity α ₂ of the second device and the reflected light efficiency β ₁₂ of the second device irradiation light in the first device. This is the integrated value of the DC light that is the average received light quantity α ₂ β ₁₂ that is the product. Therefore, without depending on the phase delay state theta ₁₂ of the irradiation / light reflected color from the second device, the form of the DC value to depend only integration period. Similarly for f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ , the form of the integrated DC value that does not depend on θ ₁₂ corresponding to the optical flight time from the second device but depends only on the integration period. Become.

As a result, with respect to (f ₁ _A ₀ −f ₁ _A ₁₈₀ ) and (f ₁ _A ₉₀ −f ₁ _A ₂₇₀ ) applied to the arc tangent calculation, the integrated DC value from the second device is also differentially canceled, and FIG. As shown in 3 (B), the detected value is a two-phase sine wave depending on the flight time. Accordingly, the arc tangent calculation result reflects only the reflected light from the first device and becomes a phase difference detection result that avoids crosstalk from the second device, and the time of flight from the object in the first device. And the distance between the objects can be measured from the relationship with the speed of light c.

Furthermore, the integration periods of f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ are the same. Therefore, in the detection region in which the change in the ambient light during the integration period is sufficiently small, the DC component of (f ₁ _A ₉₀ -f ₁ _A ₂₇₀ ) does not depend on the integration period (f ₁ _A ₀ -f ₁ _A ₁₈₀ ). Will be cancelled. _Further, the same value is basically independent of the _{ATAN2 [(f 1 _A 90 -f} 1 _A 270) / (f 1 _A 0 -f 1 _A 180)] also the integration period.

In addition, the SN ratio of the detection signal can be improved by repeating these detections k ₁ times. repeating sequence of k ₁ is not particularly _{defined, f 1 _A 0, f 1} _A 90, f 1 _A 180, f 1 _A 270 a may be performed sequentially _{k 1} times detected. Alternatively, the detection may be performed in a sequence combined with other system constraints, such as repeating a series of detections of (f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , f ₁ _A ₂₇₀ ) k ₁ times.

Next, a detection processing method in the second apparatus will be described with reference to FIG. In FIG. 4, the detection sampling timings of 0 °, 90 °, 180 °, and 270 ° in the second apparatus are respectively indicated as f ₂ _A ₀ , f ₂ _A ₉₀ , f ₂ _A ₁₈₀ , and f ₂ _A _270. ing. In the figure, the gray portion indicates the light reception detection time region in each sampling phase. That is, the detection timing is shifted by 90 ° at f ₂ _A ₀ , f ₂ _A ₉₀ , f ₂ _A ₁₈₀ , and f ₂ _A ₂₇₀ . In this example, since n ₁ = 2 and n ₂ = 3, as a feature of the present embodiment, the second device has n ₁ (2) different modulation frequencies and relative phase relationships of the first device. to set the detection range of the sampling of (n 2 _.1) to minimize detection unit. Furthermore, for the improvement of the SN ratio, a natural number _{k 2} set _{(n 1 .1, n 1 .2~n} 1 .k 2) f 2 _A 0 sampling _{detection, f 2 _A 90, f 2} _A 180, f performed on ₂ _A _270.

In this detection processing method, adding a description with respect to the principle of extracting only the frequency f ₂ component of the detected signal. Similar to the above-described contents regarding the light reception detection in the first device, the second light reception modulated light + environment light can be expressed as Equation 13 similarly to Equation 9.
c ₂ (t) = BG ₂ (t) + α ₁ β ₂₁ [1 + sin (2πf ₁ t−θ ₂₁ )] +
α ₂ β ₂ [1 + sin (2πf ₂ t−θ ₂ )] (Formula 13)

Here, f ₁ is the modulation frequency of the first device, α ₁ is the modulation center light intensity of the first device, β ₂₁ is the reflected light efficiency of the first device irradiation light in the second device, and θ ₂₁ is the second the first device irradiating light / reflected light phase at the device delay, f ₂ is the modulation frequency of the second device. Also, α ₂ is the modulation center light intensity of the second device, BG ₂ (t) is the ambient light of the second device, β ₂ is the reflected light efficiency of the second device, and θ ₂ is the time-of-flight phase delay of the second device. is there.

Under these notations, in the light reception detection time of f ₂ _A ₀ in the present embodiment, n ₁ : the two detected phases are different in relative phase from f _{1 of} the first device: the relative phase 0 in which f ₂ _ is continuous. , T ₂ can be expressed as in Equation 14.

Here, as in the description of the first device, the second item, which is the reflected detection light of the irradiation light from the first device in each integral term of Equation 14, is the relationship between the first and second frequencies. N ₁ × f ₁ = n ₂ × f ₂ , n ₁ = 2 and n ₂ = 3, and T ₂ = n ₂ / n ₁ T ₁ = 3 / 2T ₁ . Therefore, it can be converted as shown in Equation 15.

  Further, when attention is paid to the integral term of the second term in Equation 15, the following Equation 16 is obtained, and the integral term of the second term of Equation 15 becomes “0” by addition of a half cycle delay, and also depends on the integration period. I understand that I don't.

Therefore, the integral term of light reception from the first device shown in Formula 15 is the modulation center light intensity α ₁ of the first device and the reflected light efficiency β ₂₁ of the first device irradiation light in the first device. It becomes the DC light integral value of the received light average light quantity α ₁ β ₂₁ which is the product. This does not depend on the phase state θ ₂₁ of the irradiation / reflection light from the first device, but takes the form of a DC value depending only on the integration period.

As a result, with respect to (f ₂ _A ₀ −f ₂ _A ₁₈₀ ) and (f ₂ _A ₉₀ −f ₂ _A ₂₇₀ ) applied to the arc tangent calculation, the integrated DC value from the first device is also differentially canceled. As shown in 4 (B), the detected value is a two-phase sine wave depending on the flight time. Therefore, the arc tangent calculation result reflects only the reflected light from the second device, becomes a phase difference detection result that avoids crosstalk from the first device, and the optical flight time from the object in the second device. And the distance between the objects can be measured from the relationship with the speed of light c.

Furthermore, the integration periods of f ₂ —A ₀ , f ₂ —A ₉₀ , f ₂ —A ₁₈₀ , and f ₂ —A ₂₇₀ are the same. Therefore, in the detection region where the change in ambient light during the integration period is sufficiently small, the DC component of (f ₂ _A ₀ -f ₂ _A ₁₈₀ ) and (f ₂ _A ₉₀ -f ₂ _A ₂₇₀ ) is independent of the integration period. Will be cancelled. Atan2 [(f ₂ —A ₉₀ −f ₂ —A ₂₇₀ ) / (f ₂ —A ₀ −f ₂ —A ₁₈₀ )] is basically the same value without depending on the integration period.

In addition, as described in the first apparatus, the detection signal SN ratio can be improved by repeating these detections k ₂ times.

  According to the present embodiment, even when two optical flight distance measuring devices that employ relatively close modulation frequencies that cannot be separated by the LPF or HPF of the transmission system are used for the same space and the same object, High-precision distance measurement that avoids optical crosstalk becomes possible.

In this example, n ₁ = n ₂ and n ₂ = 3 where n ₁ / n ₂ is other than an odd number have been described as examples. However, the present invention is not limited to n ₁ = 2 and n ₂ = 3. When n ₁ ≠ n ₂ and n ₁ / n ₂ is other than an odd value, the above-described principle enables the measurement of the time of flight of only the reflected modulation light of the target detection frequency, and the two It is possible to provide a utilization form in which the optical flight type distance measuring device is used for the same space and the same object.

(Example 2)
In the second embodiment, the first modulation frequency f ₁ (cycle: T ₁ ) of the first optical flight type distance measurement device and the second modulation frequency f ₂ (cycle: _second cycle) of the second optical flight type distance measurement device. T ₂ )
n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _2: natural number and n ₁ ≠ n ₂
FIG. 5 and FIG. 6 are used with respect to an example in which n ₂ / n ₁ is an odd value n ₁ : 1, n ₂ : 3, and a plurality of timing phases to be detected are divided into four phases. I will explain. FIG. 5 is a timing chart in the first apparatus, and FIG. 6 is a timing chart in the second apparatus.

In FIGS. 5 and 6, A ₀ , A ₉₀ , A _{180 ′} , and A _{270 ′} are timing diagrams of the time variation of the reflected light in each optical flight type distance measuring device. In the figure, a dotted line indicates a light reception modulation waveform when only the first optical flight type distance measurement device exists, and a broken line indicates a light reception modulation waveform when only the second optical flight type distance measurement device exists. A solid line indicates a received light modulation waveform in which the first and second modulation frequencies are superimposed in the case where the first and second optical flight distance measuring devices coexist. Accordingly, each apparatus receives intensity-modulated light on which the first and second modulation frequencies indicated by the solid lines are superimposed.

In this state, a detection processing method in the first device will be described with reference to FIG. In the figure, the detection sampling timings of 0 °, 90 °, 180 °, and 270 ° in the first apparatus are indicated as f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ , respectively. Yes. In the figure, the gray portion indicates the light reception detection time region in each sampling phase. That is, the detection timing is shifted by 90 ° at f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ . In this example, since n ₁ = 1 and n ₂ = 3, as a feature of the present embodiment, in the first device, n ₂ : 3 samplings each having a different modulation frequency and relative phase relationship of the second device. to set the detection range of the _(n 2 .1) to minimize detection unit. Furthermore, for the improvement of the SN ratio, a natural number _{k 2} set _{(n 1 .1, n 1 .2~n} 1 .k 2) f 1 _A 0 sampling _{detection, f 1 _A 90, f 1} _A 180, f _{1 for} _A ₂₇₀ .

In this detection processing method, a description will be given regarding the principle of extracting only the frequency f ₁ component of the detected signal. As described in the first exemplary embodiment, the first light reception modulated light + environment light can be expressed as Equation 9. Further, in the light reception detection time of f ₁ —A ₀ in this example, n ₂ : different in relative phase from f _{2 of} the second device: three detection phases are the relative phases 0, T ₁ , and f ₁ as 2T ₁ can be expressed as equation 10.

Here, the third item, which is the reflected detection light of the irradiation light from the second device in each integral term of Formula 10, is such that the relationship between the first and second frequencies is n ₁ × f ₁ = n ₂ ×. Since f ₂ , n ₁ = 1, n ₂ = 3 and T ₁ = n ₁ / n ₂ T ₂ = 1 / 3T ₂ , conversion can be performed as in Equation 17. In this example, the first apparatus having a relatively high modulation frequency is subjected to the same detection as in the first embodiment, and the results of Expressions 17 and 18 are obtained.

  Further, when attention is paid to the integral term of the second term in Equation 17, the following Equation 18 is obtained, and it can be seen that the integral term of the second term of Equation-17 becomes zero and does not depend on the integration period.

Therefore, the integral term of light reception from the second device shown in Equation 17 is the modulation center light intensity α ₂ of the second device and the reflected light efficiency β ₁₂ of the second device irradiation light in the first device. It becomes a DC light integral value of the received light average light quantity α ₂ β ₁₂ which is the product. This does not depend on the phase state theta ₁₂ of the irradiation / light reflected color from the second device, the form in which DC value depends only on the integration period. Similarly for f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ , the form of the integrated DC value that does not depend on θ ₁₂ corresponding to the optical flight time from the second device but depends only on the integration period. Become.

As a result, with respect to (f ₁ _A ₀ −f ₁ _A ₁₈₀ ) and (f ₁ _A ₉₀ −f ₁ _A ₂₇₀ ) applied to the arc tangent calculation, the integrated DC value from the second device is also differentially canceled, and FIG. The detected value becomes a two-phase sine wave depending on the flight time as shown in FIG. Therefore, the arc tangent calculation result reflects only the reflected light from the first device, and is a phase difference detection result that avoids crosstalk from the second device. Therefore, the light flight time from the object in the first device can be calculated, and the distance between the objects can be measured from the relationship with the speed of light c.

Furthermore, the integration periods of f ₁ _A ₀ , f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ are the same. Therefore, in the detection region in which the change in the ambient light during the integration period is sufficiently small, the DC component of (f ₁ _A ₉₀ -f ₁ _A ₂₇₀ ) does not depend on the integration period (f ₁ _A ₀ -f ₁ _A ₁₈₀ ). Will be cancelled. _Further, the same value is basically independent of the _{ATAN2 [(f 1 _A 90 -f} 1 _A 270) / (f 1 _A 0 -f 1 _A 180)] also the integration period.

In addition, as described above, the S / N ratio of the detection signal can be improved by repeating these detections k ₁ times.

Next, a detection processing method in the second apparatus will be described with reference to FIG. In the figure, the timings of the four-phase detection sampling in the second device are indicated as f ₂ _A ₀ , f ₂ _A ₉₀ , f ₂ _A _{180 ′} and f ₂ _A _{270 ′} , respectively. In the drawing, the gray portion indicates the accumulated charge detection region in each sampling phase. If n ₁ / n _{2 in} this example is an odd value, if the same processing as in Example 1 is performed, the first frequency component cannot be canceled in the second device detection, and the crosstalk component remains.

When n ₂ / n _{1 in} this example is an odd value, the processing of the second device in which the modulation frequency is lower than that of the first device is different from that of the first embodiment. The one detection phase (f ₂ _A _{180 ′} , f ₂ _A _{270 ′ in the} figure) that forms a pair with a phase difference of 180 ° shown in the first embodiment is modulated by the first device having a high modulation frequency. Detection is performed by shifting the frequency by a half period. In other words, detection is performed by shifting the detection phase in the second device by n ₁ / (2n ₂ ) cycles. In this example, as shown in the drawing, the detection phase is shifted forward in the same direction for f ₂ _A _{180 ′} and f ₂ _A _{270 ′} . However, the polarity of the detection phase shift is not limited, and f ₂ _A _{180 ′} and f ₂ _A _{270 ′} may be shifted backward on the premise of shifting in the same direction so as not to break the final 90 ° phase state. . Further, the same effect can be obtained even if the target of detection phase shift is f ₂ _A _{0 ′} and f ₂ _A _{90 ′} .

This detection processing method will be further described. Similarly to the first embodiment, the second received light modulated light + ambient light can also be expressed as in Expression 13. Under these notations, n ₁ : 1 detection phase f ₂ _A ₀ , f ₂ _A _{180 ′} having a relative phase different from f ₁ of the first device of the second device is the second device as described above. Can be expressed as Equation 19 and Equation 20 by shifting the detection phase at n ₁ / (2n ₂ ) periods.

Here, as described in the first apparatus, the second item, which is the reflected detection light of the irradiation light from the first apparatus of Expressions 19 and 20, has the relationship between the first and second frequencies. , N ₁ × f ₁ = n ₂ × f ₂ , n ₁ : 1 and n ₂ : 3, and T ₂ = n ₂ / n ₁ T ₁ = 3T ₁ . Therefore, conversion can be performed as in Expression 21 and Expression 22.

Here, although the components of the irradiation / reflected light from the first device remain in the equations 21 and 22, respectively, the components are in-phase components. FIG. 6 (B) and FIG. 6 (C) show the flight time dependence of the detected value at that time, respectively. As shown in the drawing, f ₂ _A ₀ -f ₂ _A _{180 ′} finally expressed as a 0 ° phase is expressed by Equation 23 below.

According to Equation 23, the component of the irradiation / reflection light from the first device is canceled out to “0”. Furthermore, if the assumption the time variation of the ambient light component BG ₂ in the detection period is sufficiently small, even the first term becomes "0". Further, compared to the first embodiment, the light reception detection value of the second device is reduced to sin (π / 3), that is, sin (πn ₁ / n ₂ ) here. For this reason, f ₂ _A ₉₀ and f ₂ _A _{270 ′} can be expressed in the same way, as shown in Equation 24.

Accordingly, the components of the irradiation / reflection light from the first device are canceled out even at f ₂ _A ₉₀ and f ₂ _A _{270 ′} and become “0”.

As described above, f ₂ _A ₀ , f ₂ _A _{180 ′} , f ₂ _A ₉₀ , and f ₂ _A _{270 ′} have the results shown in FIG. By shifting the detection phase, the detection value amplitude decrease sin (πn ₁ / n ₂ ) occurs, but the 90 ° phase difference of only the reflected light detection of the second device that avoids crosstalk from the first device. A two-phase sine wave can be obtained. Therefore, it is possible to calculate the time of flight of light from the object in the second device, avoiding crosstalk from the first device, and to measure the distance between objects from the relationship with the speed of light c. Become.

Furthermore, the integration periods of f ₂ —A ₀ , f ₂ —A ₉₀ , f ₂ —A _{180 ′} , and f ₂ —A _{270 ′} are the same. Therefore, in the detection region in which the change in ambient light during the integration period is sufficiently small, (f ₂ _A ₀ -f ₂ _A _{180 ′} ) and (f ₂ _A ₉₀ −f ₂ _A _{270 ′} ) without depending on the integration period. The DC component is cancelled. _Further, the same value is basically independent of the _{ATAN2 [(f 2 _A 90 -f} 2 _A 270 ') / (f 2 _A 0 -f 2 _A 180')] also integrated detection period. _{Incidentally, f 2 _A 90 -f 2 _A} 270 ', f 2 _A 0 -f 2 _A 180' with respect to the irradiation light by the phase shift operation, the phase becomes πn ₁ / _n 2/2 shifted result, It is necessary to calculate the distance considering the phase delay corresponding to the optical flight time.

In addition, as described in Embodiment 1, the SN ratio of the detection signal can be improved by repeating these detections k ₂ times.

  As described above, according to the present embodiment, even when two optical flight-type distance measuring devices are used for the same space and the same object, distance measurement with accuracy that avoids optical crosstalk is possible. It becomes possible. In particular, even when using two optical flight-type distance measuring devices that employ relatively close modulation frequencies that cannot be separated by LPF or HPF in the transmission system, the sampling phase and the number of additions or averaging can be devised. Frequency separation detection is possible.

In this example, n ₁ = 1 and n ₂ = 3, where n ₂ / n ₁ is an odd value, have been described as an example, but are not limited to n ₁ = 1 and n ₂ = 3. When n ₁ ≠ n ₂ and n ₂ / n ₁ is an odd value, it is possible to measure the time of flight of only the reflected modulated light of the target detection frequency according to the above-described principle, and the two light It is possible to provide a utilization form in which the flight-type distance measuring device is used for the same space and the same object.

(Example 3)
In the third embodiment, the first modulation frequency: f ₁ (period: T ₁ ) of the first optical flight type distance measurement device and the second modulation frequency: f ₂ (of the second optical flight type distance measurement device). Period: T ₂ )
n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _2: natural number and n ₁ ≠ n ₂
With reference to FIGS. 7 and 8, an example in which n ₂ / n ₁ is not a natural number (or a multiple of 3) and a plurality of timing phases to be detected are set to three equally divided detection phases under the condition To do. FIG. 7 is a timing chart in the first device, and FIG. 8 is a timing chart in the second device.

7 and 8, A ₀ , A ₁₂₀ , and A ₂₄₀ show timing diagrams of the temporal change of reflected light in each optical flight type distance measuring device. In the figure, a dotted line indicates a light reception modulation waveform when only the first optical flight type distance measurement device exists, and a broken line indicates a light reception modulation waveform when only the second optical flight type distance measurement device exists. A solid line indicates a received light modulation waveform in which the first and second modulation frequencies are superimposed when the first and second optical flight distance measuring devices coexist. Accordingly, each apparatus receives intensity-modulated light on which the first and second modulation frequencies indicated by the solid lines are superimposed. The modulation waveform in this example is the same as that in the first embodiment, but in this example, a case where the detection phase is three phases will be described.

In this state, a detection processing method in the first apparatus will be described with reference to FIG. In the figure, the detection sampling timings of 0 °, 120 °, and 240 ° in the first apparatus are indicated as f ₁ _A ₀ , f ₁ _A ₁₂₀ , and f ₁ _A ₂₄₀ , respectively. In the drawing, the gray portion indicates the accumulated charge detection region in each sampling phase. That is, the detection timing is shifted by 120 ° at f ₁ _A ₀ , f ₁ _A ₁₂₀ , and f ₁ _A ₂₄₀ .

In this example, since n ₁ = 2 and n ₂ = 3, as a feature of the present embodiment, n ₂ : 3 samplings in which the modulation frequency and relative phase relationship of the second device are different from each other in the first device. to set the detection range of the _(n 2 .1) to minimize detection unit. Furthermore, for the improvement of the SN ratio with respect to _{f 1 _A 0, f 1 _A} 120, f 1 _A 240 sampling detection of natural numbers _{k 1} set _{(n 2 .1, n 2 .2~n} 2 .k 1) To implement.

In this detection processing method, a description will be given regarding the principle of extracting only the frequency f ₁ component of the detected signal. As in the first embodiment, the first received light-modulated light + ambient light can be expressed as Equation 9 by the method described above.

In the light receiving detection time of _f 1 _A ₀ in this example, the 2 _{f 2} of the apparatus and the relative phase difference _n 2: a three detection phases _{f 1} _ successive relative phase, _{0, T} 1, 2T ₁ is represented by Formula 10 as in the first embodiment. The light receiving detection period was _T 1/2, but not limited thereto.

As a result, as shown in Embodiment 1, without depending on the phase state theta ₁₂ of the irradiation / light reflected color from the second device, the integral DC value becomes a form that depends only on the integration period. Similarly for f ₁ _A ₁₂₀ and f ₁ _A ₂₄₀ , the integrated DC value depends only on the integration period without depending on θ ₂ corresponding to the light flight time from the second device, and the first device The detected value depends on θ ₁ corresponding to the time of flight of light.

Here, the 120 ° phase difference signals of f ₁ _A ₀ , f ₁ _A ₁₂₀ , and f ₁ _A ₂₄₀ can be converted into a 90 ° phase difference by the following trigonometric function processing.
2cos (α) sin (β) = sin (α−β) −sin (α + β), 2sin (α) sin (β) = cos (α−β) −cos (α + β), 2cos (α) cos (β) = Cos (α-β) + cos (α + β)

Here, since the DC component of the ambient light detection is included in each of f ₁ _A ₀ , f ₁ _A ₁₂₀ , and f ₁ _A ₂₄₀ , this is taken into consideration in the conversion to the 90 ° phase difference signal, and the differential processing is performed once. The conversion to be performed.

Specifically, f ₁ _A ₀ and f ₁ _A ₁₂₀ , f ₁ _A ₁₂₀ and f ₁ _A ₂₄₀ are each set to be ± 60 ° different from each other, and a Cos function is generated. Further, differential processing and addition processing of these Cos functions are performed, and processing for obtaining Sin and Cos functions, respectively, is performed. Formulas 25 and 26 show calculation formulas for calculating the calculated value of the 90 ° phase difference signal of these processes. However, constant coefficients were omitted.
Sin _{based: (f 1 _A 0 -f 1} _A 120) - (f 1 _A 120 -f 1 _A 240)
(Formula 25)
Cos _{system: (f 1 _A 0 -f 1} _A 120) + (f 1 _A 120 -f 1 _A 240)
(Formula 26)

Therefore, it is possible to convert 120 ° phase difference three-phase detection into 90 ° phase difference and obtain the phase lag by arctangent calculation by the following Expression 27.
θ ₁ = ATAN2 [(f ₁ _A ₀ −f ₁ _A ₁₂₀ ) + (f ₁ _A ₁₂₀ −f ₁ _A ₂₄₀ ),
_{f 1 _A 0 -f 1 _A 120} ) - (f 1 _A 120 -f 1 _A 240)] ( formula 27)

Further, a detection processing method in the second apparatus will be described with reference to FIG. In the figure, the detection sampling timings of 0 °, 120 °, and 240 ° in the second apparatus are indicated as f ₂ _A ₀ , f ₂ _A ₁₂₀ , and f ₂ _A ₂₄₀ , respectively. In the drawing, the gray portion indicates the accumulated charge detection region in each sampling phase. That is, the detection timing is shifted by 120 ° at f ₂ _A ₀ , f ₂ _A ₁₂₀ , and f ₂ _A ₂₄₀ . In this example, since n ₁ = 2 and n ₂ = 3, as a feature of the present embodiment, the first device has n ₁ : 2 samplings in which the modulation frequency and the relative phase relationship of the second device are different from each other. The detection range (n ₁ .1) is set as the minimum detection unit. Furthermore, for the improvement of the SN ratio with respect to a natural number _{k 2} set _{(n 1 .1, n 1 .2~n} 1 .k 2) sampling the detection of _{f 2 _A 0, f 2 _A} 120, f 2 _A 240 To implement.

In this detection processing method, adding a description with respect to the principle of extracting only the frequency f ₂ component of the detected signal. Similar to the first embodiment, the first received light-modulated light + ambient light can be expressed as Equation 13 by the method described above.

In the light reception detection time of f ₂ _A ₀ in this example, n ₁ = 2 detection phases, which are different in relative phase from f _{1 of} the first device, are 0 and T ₂ as continuous relative phases of f ₂ _. Similar to the first embodiment, it can be expressed as Expression 14. Although the detection charge integration period is T _1/2 , this is not restrictive.

As a result, as shown in the first embodiment, the second term of Expression 14 is “0” from Expression 15 and Expression 16. That is, the DC value depends only on the integration period without depending on the phase state θ ₂₁ of the modulated irradiation / reflected light from the first device.

Similarly for f ₂ _A ₁₂₀ and f ₂ _A ₂₄₀ , the DC value does not depend on the phase delay θ ₂₁ corresponding to the optical flight time from the first device, but depends only on the integration period, and from the second device. The detected value depends on the phase delay θ ₂ corresponding to the light flight time.

Therefore, the 120 ° phase difference signals of f ₂ _A ₀ , f ₂ _A ₁₂₀ , and f ₂ _A ₂₄₀ can be converted into 90 ° phase difference signals of Equation 28 and Equation 29 as in the first apparatus of this example (however, The constant coefficients are omitted).
Sin _{based: (f 2 _A 0 -f 2} _A 120) - (f 2 _A 120 -f 2 _A 240)
(Formula 28)
Cos system: (f ₂ _A ₀ −f ₂ _A ₁₂₀ ) + (f ₂ _A ₁₂₀ −f ₂ _A ₂₄₀ )
(Formula 29)

Therefore, it is possible to convert 120 ° phase difference three-phase detection into 90 ° phase difference and obtain the phase delay by arctangent calculation by the following Equation 30.

θ ₂ = ATAN2 [(f ₂ —A ₀ −f ₂ —A ₁₂₀ ) + (f ₂ —A ₁₂₀ −f ₂ —A ₂₄₀ ),
_{f 2 _A 0 -f 2 _A 120} ) - (f 2 _A 120 -f 2 _A 240)] ( formula 30)

As described above, the S / N ratio of the detection signal can be improved by repeating the detection method described above k ₁ times and k ₂ times in the first and second devices, respectively.

Example 4
In this embodiment, the first modulation frequency: f ₁ (period: T ₁ ) of the first optical flight type distance measuring device and the second modulation frequency: f ₂ (second optical flight type distance measurement device). Period: T ₂ )
n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _2: natural number and n ₁ ≠ n ₂
A case where the detected multiple timing phase in the optical flight type distance measuring device of the second frequency is a three-divided phase when n ₁ / n ₂ is not a natural number and a multiple of 3 will be described. In this example, the case of n ₁ / n ₂ = 2 is taken as an example and will be described with reference to FIGS. FIG. 9 is a timing chart in the first device, and FIG. 10 is a timing chart in the second device.

9 and 10, A ₀ , A ₁₂₀ , and A ₂₄₀ show timing diagrams of the temporal change of reflected light in each optical flight type distance measuring device. In the figure, a dotted line indicates a light reception modulation waveform when only the first optical flight type distance measurement device exists, and a broken line indicates a light reception modulation waveform when only the second optical flight type distance measurement device exists. A solid line indicates a received light modulation waveform in which the first and second modulation frequencies are superimposed when the first and second optical flight distance measuring devices coexist.

In FIG. 9, the detection sampling timings of 0 °, 120 °, and 240 ° in the first device are indicated as f ₁ _A ₀ , f ₁ _A ₁₂₀ , and f ₁ _A ₂₄₀ , respectively. In the drawing, the gray portion indicates the accumulated charge detection region in each sampling phase. Since the processing method regarding the sampling condition is the same as the contents related to the mathematical expressions 25 to 27 described in the third embodiment although the modulation frequency of the second apparatus is different, the description in this example is omitted. According to Equation 27, 120 ° phase difference three-phase detection can be converted into 90 ° phase difference, and the phase difference can be obtained by arctangent calculation, and distance measurement can be performed.

FIG. 10 shows detection sampling timings of 0 °, 120 °, and 240 ° in the second device as f ₂ _A ₀ , f ₂ _A ₁₂₀ , and f ₂ _A ₂₄₀ , respectively. In the drawing, the gray portion indicates the accumulated charge detection region in each sampling phase. Here, in the three-phase detection in which n ₁ / n ₂ is a natural number and other than a multiple of 3, there is a restriction on the third embodiment with respect to the integral charge detection in the second device. The limitation is the light reception integral width of f ₂ , and the light reception integral width W_f ₂ is expressed by the following Expression 31.

Here, INT (x) is a function that returns the largest integral value not fractional part of x, m is a natural number, provided that in the continuous measurement _{k 2} ≧ _2: a _{W_} f2 <T2. For example, if m is “1” in n ₂ / n ₁ = ₂ , 4, 5, 7, 8..., W _{f2 of the} light reception time width is 1 / 2T ₂ , 1 / 2T ₂ , 2 / 5T ₂ , 3 / 7T ₂ and 3 / 8T ₂ . Furthermore, when expressed them in _{T 1, T 1, 2T 1} , 2T 1, 3T 1, 3T 1 becomes basically respectively, the detection width of an integer multiple period of _{T 1.} That is, the integrated charge detection width in the second device is an integral multiple of the light source irradiation / reflection modulation frequency in the first device, and the charge detection value is a DC component.

Therefore, using the formulas 28 and 29, the charge detection value processing similar to that of the first device is performed in the second device. As described above, in the values of (f ₂ —A ₀ −f ₂ —A ₁₂₀ ) and (f ₂ —A ₁₂₀ −f ₂ —A ₂₄₀ ) in Equations 28 and 29, detection of irradiation / reflected light from the first device is performed. The value is a DC component. Therefore, it is canceled by the differential calculation in the same manner as the detection of ambient light. Therefore, the detection components of Equation 28 and Equation 29 are the detection values of only the irradiation / reflection light in the second device, and the influence of the first device can be eliminated. Therefore, using the above detection period, 120 ° phase difference three-phase detection is converted into 90 ° phase difference as shown in Equation 30 and Equation 29, and the phase difference is reversed. The distance can be measured by the second device by obtaining the value by the tangent calculation. In addition, the SN ratio of the detection signal can be improved by repeating the detection method described above k ₁ times and k ₂ times in the first and second devices, respectively, as in the above-described embodiment.

(Example 5)
In the fifth embodiment, an example in which three optical flight type distance measuring devices are used in the same space and two n ₁ / n ₂ are all natural numbers will be described. First modulation frequency: f ₁ (period: T ₁ ), second modulation frequency: f ₂ (period: T ₂ ), and third modulation frequency of the third optical flight type distance measuring device: f ₃ In (period: T ₃ ), the relationship between the two frequencies is
_{n 12 × f 1 = n 21} × f 2, n 13 × f 1 = n 31 × f 3, n 23 × f 2 = n 32 × f 3,
n ₁₂ , n ₁₃ , n ₂₁ , n ₂₃ , n ₃₁ , n _32: natural numbers, and n ₁₂ = kn ₂₁ , n ₂₃ = kn ₃₂ , n ₁₃ = k ² n ₃₁
A description will be given of an embodiment in which a plurality of timing phases to be detected are four equally divided phases (0 °, 90 °, 180 °, 270 °) under the above conditions. First, the received light modulation light + environment light of each device can be expressed as Equation 32 by the method described above.
c ₁ (t) = BG ₁ (t) + α ₁ β ₁ [1 + sin (2πf ₁ t−θ ₁ )] +
α ₂ β ₁₂ [1 + sin (2πf ₂ t−θ ₁₂ )] +
α ₃ β ₁₃ [1 + sin (2πf ₃ t−θ ₁₃ )]
c ₂ (t) = BG ₂ (t) + α ₂ β ₂ [1 + sin (2πf ₂ t−θ ₂ )] +
α ₁ β ₂₁ [1 + sin (2πf ₁ t−θ ₂₁ )] +
α ₃ β ₂₃ [1 + sin (2πf ₃ t−θ ₂₃ )]
c ₃ (t) = BG ₃ (t) + α ₃ β ₃ [1 + sin (2πf ₃ t−θ ₃ )] +
α ₁ β ₃₁ [1 + sin (2πf ₁ t−θ ₃₁ )] +
α ₂ β ₃₂ [1 + sin (2πf ₂ t−θ ₃₂ )]
(Formula 32)

In this example, the case of an even multiple of k = 2 is taken as an example. FIG. 11 shows an integral detection timing diagram of quadrant, 0 ° phase detection in the first, second, and third devices. In this example, k ^ ² = 4, so in the first device, 2 samples × 2 sets having different relative phase states from the second device, 4 samples × 1 set having different relative phase states from the third device, That is, a total of 4 samples is the minimum number of detected phase timings. Similarly, in the second apparatus, one sample × 2 sets having a relative phase state different from that of the first apparatus, and 2 samples × 1 set having a different relative phase state from the third apparatus, that is, a total of two samples has a minimum detection phase timing. Number. Similarly, in the third apparatus, one sample having a relative phase state different from that of the first apparatus and one sample having a relative phase state different from that of the second apparatus become the minimum detection timing. Therefore, the detected value in the first device is expressed as the following Expression 33.

  Here, similarly to the above-described embodiment, the terms of the detection light by irradiation from other than the first apparatus are respectively expressed as follows. The detection of the irradiation / reflection light of the second device by the first device is expressed by Equation 34, and the detection of the irradiation / reflection light of the third device by the first device is expressed by Equation 35.

Further the second and converting the detected period of irradiation / reflection light of the third device to cycle representation of each frequency _{(T 1 = T 2/2} , T 1 = T 3/4), of the second device The detection of the irradiated / reflected light with the first device can be expressed as Equation 36. Further, the detection of the irradiation / reflected light of the third device by the first device can be expressed as Expression 37.

Therefore, the irradiated / reflected light from the second and third devices is converted into a DC component without affecting the time of flight. The same result is obtained in the other 90 °, 180 °, and 270 ° phases of the four equal divisions, and the irradiation light from the second and third devices in f ₁ _A ₉₀ , f ₁ _A ₁₈₀ , and f ₁ _A ₂₇₀ / The reflected light is converted into a DC component without affecting the light flight time. Furthermore, the DC component is also canceled by taking a difference from (f ₁ _A ₉₀ -f ₁ _A ₂₇₀ ) and (f ₁ _A ₀ -f ₁ _A ₁₈₀ ). Therefore, the phase delay due to the optical flight time of the first device excluding the influence of other devices is calculated from ATRAN2 [(f ₁ —A ₉₀ −f ₂ —A ₂₇₀ ) / (f ₁ —A ₀ −f ₂ —A ₁₈₀ )]. , The distance to the reflection object can be calculated by Equation 8.

  Similarly, the detection value of the second device can be expressed as in Equation 38.

  Here, the terms of the detection light by irradiation from other than the second device in Expression 38 are expressed as follows. In other words, the detection of the irradiation / reflection light of the first device with the second device is expressed as Equation 39, and the detection of the irradiation / reflection light of the third device with the second device is expressed as Equation 40.

The above first and converting the detected period of the illuminating light of the third device to cycle representation of each frequency _{(T 2 = 2T 1, T} 2 = T 3/2), the irradiation / reflection light of the first device The detection by the second device can be expressed as Equation 41. Further, the detection of the irradiation / reflected light of the third device by the second device can be expressed as Equation 42.

  Therefore, the irradiation light / reflected light from the third device shown in Formula 42 is converted into a DC component without affecting the light flight time.

  Further, a description will be added regarding the detection of the irradiation / reflected light of the first device by the second device. In the detection of the irradiation / reflected light of the first device by the second device, it is not converted into a DC component, and the modulation component of the irradiation / reflected light of the first device remains. Here, the detection of the 180 ° phase difference of the irradiation / reflection light of the first device in the second device is represented by the following Expression 43.

The 0 ° phase detection formula 41 and the 180 ° phase detection formula 43 have the same waveform component with respect to the modulation component of the first device. Therefore, the irradiation light / reflected light from the first device is also canceled by taking the differential of (f ₁ _A ₀ -f ₁ _A ₁₈₀ ). The same result is obtained in the phase detection of 90 ° and 270 °, and the DC component and the in-phase modulation are obtained by taking a difference from (f ₂ _A ₀ -f ₂ _A ₁₈₀ ) and (f ₂ _A ₉₀ -f ₂ _A ₂₇₀ ). Ingredients are also cancelled. Therefore, the phase delay due to the optical flight time of the second device excluding the influence of other devices is calculated from ATRAN2 [(f ₂ —A ₉₀ −f ₂ —A ₂₇₀ ) / (f ₂ —A ₀ −f ₂ —A ₁₈₀ )]. , The distance to the reflection object can be calculated by Equation 8.

  Similarly, the detected value of the third device can be expressed as in Equation 44.

  Here, the terms of the detection light by irradiation from other than the third device are respectively expressed as follows. The detection of the irradiation / reflection light of the first device by the third device is expressed by Equation 45, and the detection of the irradiation / reflection light of the second device by the third device is expressed by Equation 46.

When the detection period of the irradiation light of the first and third apparatuses is converted into a period expression of each frequency (T ₃ = 4T ₁ , T ₃ = 2T ₂ ), the irradiation / reflection light of the first apparatus The detection by the device 3 can be expressed as Equation 47. Further, the detection of the irradiation / reflected light of the second device by the third device can be expressed as Formula 48.

Therefore, when setting the detection integration period T _3/2, since the integration period becomes the first, an integral multiple of the second modulation period, the detection value is the DC component of. However, since the DC componentization of the above formulas 47 and 48 depends on the integration period, further explanation will be given regarding expandability. Here, similarly to the description of the second device described above, when the detection state at the detection timing of the 180 ° phase difference is seen, the detection of the irradiation / reflected light of the first device by the third device is expressed by Equation 49. The detection of the irradiation / reflected light of the second device with the third device is expressed by Equation 50.

The 0 ° phase detection equations 47 and 48 and the 180 ° phase detection equations 49 and 50 have the same waveform component with respect to the modulation components of the first and second devices. Therefore, the irradiation light / reflected light from the first and second devices is also canceled by taking a difference of (f ₃ _A ₀ -f ₃ _A ₁₈₀ ). The same result is obtained in 90 ° and 270 ° phase detection, and a DC component and an in-phase modulation component are obtained by taking a difference from (f ₃ _A ₀ -f ₃ _A ₁₈₀ ) and (f ₃ _A ₉₀ -f ₃ _A ₂₇₀ ). Will also be canceled. _{Therefore, ATAN2 [(f 3 _A 90} -f 3 _A 270) / (f 3 _A 0 -f 3 _A 180)] regardless detection integration period from light flight third device discharges the influence of other devices The phase lag due to time is calculated. Then, the distance to the reflection object can be calculated by Expression 8.

FIG. 11B shows the phase delay dependency of (f ₁ _A ₀ -f ₁ _A ₁₈₀ ) and (f ₁ _A ₉₀ -f ₁ _A ₂₇₀ ) obtained by the processing described above. _{Further, f 2 _A 0 -f 2 _A} 180) and _{(f 2 _A 90 -f 2 _A} 270), f 3 _A 0 -f 3 _A 180) and each of _{(f 3 _A 90 -f 3 _A} 270) Also shows phase lag dependency.

In the above description, k = 2, that is, the case where the light source modulation frequency ratio of the first, second, and third devices is two times and four times the even number times has been described as an example.
_{n 12 × f 1 = n 21} × f 2, n 13 × f 1 = n 31 × f 3, n 23 × f 2 = n 32 × f 3,
n ₁₂ , n ₁₃ , n ₂₁ , n ₂₃ , n ₃₁ , n _32: natural numbers, and n ₁₂ = kn ₂₁ , n ₂₃ = kn ₃₂ , n ₁₃ = k ² n ₃₁
As a condition, it is possible to cope with the case where k is 3 and the frequency ratio is an odd number by the same processing. In the above embodiment, the number of devices is three. However, the number of devices is not limited to three, and the number of frequency ratios up to a power of (i-1) is increased for i devices at both odd and even numbers. If a countermeasure is taken, the above-described processing can be applied.

(Other examples)
As described above, in Examples 1 to 5, the detection means method for avoiding optical crosstalk when using a plurality of optical flight type distance measuring devices has been described. In the above-described embodiment, the sine wave is used as an example of the light source modulation waveform. However, not only the sine wave but also a pulse rectangular wave and a triangular wave are equivalent to a sine wave in terms of periodicity and 50% duty. For example, the present invention can be applied to these modulated waveforms based on the same principle.

  In the above-described embodiment, the processing with a single pixel has been described. In a case where one light receiving element is employed in an actual apparatus system, the modulated irradiation light from the light source is converted into a small beam spot, the spot is two-dimensionally scanned, and the present invention is applied to the detection of the condensed reflected light, thereby scanning region Distance information on the xy plane, so-called distance image can be obtained. Further, the present invention can be applied to a light receiving element that takes the form of a one-dimensional or two-dimensional array. Then, the light source light is irradiated radially by a plurality of LED light sources, laser light transmitted through the diffuse transmission plate, and the like, and the reflected light is condensed on the array light receiving element by using a condensing lens. It is also possible to obtain a distance image.

  In addition to the processing of the present invention in the case of using a plurality of optical flight type distance measuring devices, the light source wavelength / detection wavelength can be changed between the devices. Alternatively, by using so-called wavelength separation in combination with switching means, it is possible to use a device having the number of light source wavelengths × the number of modulation frequencies while avoiding optical crosstalk in the same space. Correspondence is also possible.

  In the above-described embodiment, the detection method / means when using a plurality of optical flight type distance measuring devices has been described. Examples of objects using a plurality of optical flight-type distance measuring devices include fields such as augmented reality (AR), virtual reality (VR), and mixed reality (MR). In these fields, distance measuring devices are actively used to recognize spatial information as a three-dimensional space and enhance reality. Furthermore, in the three-dimensional space recognition using the field of view and the light irradiation, a so-called occlusion phenomenon occurs in which the distance of the object behind the object cannot be recognized due to the shadow of the object in front. Under these circumstances, there is a limit to the viewing angle of a three-dimensional image in one measuring device, and it is conceivable that a plurality of distance measuring devices are arranged in a space in a direction that avoids an increase in viewing angle or occlusion. In this case, accuracy deterioration due to optical crosstalk between devices occurs as a problem, but crosstalk can be avoided by applying the distance measuring device of this embodiment. As a result, three-dimensional space recognition over a wide range becomes possible, and the amount of spatial information in systems such as AR, VR, and MR increases, leading to improved reality accuracy.

  The above embodiment is an example in which a distance measuring device is fixedly arranged in a space. Further, the distance measuring device is mounted on a head mounted display (HMD), which is characteristic in AR, VR, MR, etc. It can also be applied to spatial feature recognition and object recognition. In a case where a measuring device is mounted on an HMD, when multiple HMD wearers experience AR, VR, MR, etc. in the same space, the HMD wearer causes various positions and state changes such as movement and proximity. Thus, spatial separation for avoiding crosstalk becomes extremely difficult. And detection accuracy deteriorates due to optical crosstalk, and accurate spatial information cannot be obtained. If the above-described distance measuring apparatus / method for avoiding crosstalk between apparatuses is applied to a plurality of HMDs, optical crosstalk between a plurality of apparatuses can be avoided and more accurate distance information can be obtained in each HMD. It becomes possible and leads to improvement of experience reality accuracy.

  The present invention supplies software (programs) for realizing the functions of the above-described embodiments to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. To be executed. Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. The present invention is not limited to the above embodiments, and various modifications (including organic combinations of the embodiments) are possible based on the spirit of the present invention, and these are excluded from the scope of the present invention. is not. That is, the present invention includes all the combinations of the above-described embodiments and modifications thereof.

DESCRIPTION OF SYMBOLS 10 Light irradiation part 11 Light source 13 Light source modulation part 14 Controller 15 Object 16 Condensing light-receiving part 19 Light reception detection part,
20 Distance calculation processing unit

Claims (10)

Based on the detection result of the irradiation means for emitting the modulated light, the light receiving means for receiving the reflected light of the modulated light emitted by the irradiation means, the detection means for detecting the reception of the reflected light by the light receiving means, and the detection result of the detection means A distance measuring system comprising a first distance measuring device and a second distance measuring device having a calculation means for measuring a flight time of light and calculating a distance to an object,
The first modulation frequency of the modulated light of the first distance measuring device is f ₁ , the period is T ₁ , the second modulation frequency of the modulated light of the second distance measuring device is f ₂ , and the period is T ₂ , n ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _{2: a} natural number and n ₁ ≠ n ₂
The first distance measuring device includes:
At each of a plurality of timings at which T ₁ of the light emission period is divided into three or four, n ₂ phase states having different relative phase states with respect to the _second modulation frequency f ₂ are received and detected with a predetermined time width, and the n ₂ a first detection means for carrying out number of receiving and detecting the k ₁ times (where k ₁ is a natural number),
First calculating means for calculating the distance to the object of the first distance measuring device based on the calculated value of the 90 ° phase difference signal,
The second distance measuring device is
At each of a plurality of timings at which T ₂ of the light emission period is divided into three or four, n ₁ phase states having different relative phase states with respect to the _first modulation frequency f ₁ are received and detected with a predetermined time width, and the n _A second detection processing means for performing one light detection detection k ₂ times (where k ₂ is a natural number);
And a second calculating means for calculating a distance to an object of the second distance measuring device based on a calculated value of the 90 ° phase difference signal. The plurality of timing phases detected by the first detection means and the second detection means when the n ₂ / n ₁ is other than an odd value is a quadrant phase. Distance measuring system. When n ₂ / n ₁ is an odd value and f ₂ <f ₁ , the timing of the detection phase of the distance measuring device of the _second modulation frequency f ₂ is divided into four, and 90 in the timing of the four divided detection. ° The detection timing of the detection signal paired with each phase difference signal

The distance measurement system according to claim 1, wherein: The plurality of timing phases detected by the first detection means and the second detection means when the n ₂ / n ₁ is not a natural number or a multiple of 3, is a phase of three equal divisions. Item 2. The distance measuring system according to Item 1. When n ₂ / n ₁ is a natural number other than a multiple of 3, the detection timing phase of the second detection means is a three-divided phase;
INT (x) is a function that returns an integer value obtained by truncating the fractional part of x, and when m is a natural number, W _{f2 of the} light reception time width is calculated.

The distance measurement system according to claim 1, wherein: The distance measurement system includes three or more distance measurement devices, and when two of the three or more distance measurement devices are the first distance measurement device and the second distance measurement, any of the n ₂ The distance measuring system according to claim _{1, wherein} / n ₁ is a natural number.   The light receiving means includes a two-dimensional array of a plurality of light receiving elements, and includes a detection processing means and a calculation processing means for each of the light receiving elements, and a generating means for generating a two-dimensional distance image. The distance measuring system according to any one of 1 to 6.   2. The first distance measuring device and the second distance measuring device according to claim 1, wherein the irradiation unit irradiates a plurality of wavelengths, and a detection wavelength filter of the light receiving unit is made to correspond to the emission wavelength. 8. The distance measuring system according to any one of 7 above.   The distance measuring system according to claim 1, wherein the first distance measuring device and the second distance measuring device are head mounted display devices. Based on the detection result of the irradiation means for emitting the modulated light, the light receiving means for receiving the reflected light of the modulated light emitted by the irradiation means, the detection means for detecting the reception of the reflected light by the light receiving means, and the detection result of the detection means A distance measurement method in a distance measurement system comprising a first distance measurement device and a second distance measurement device having a calculation means for measuring a flight time of light and calculating a distance to an object,
The first modulation frequency of the modulated light of the first distance measuring device is f ₁ , the period is T ₁ , the second modulation frequency of the modulated light of the second distance measuring device is f ₂ , and the period is T _2. N ₁ × f ₁ = n ₂ × f ₂ n ₁ , n _{2: a} natural number and n ₁ ≠ n ₂
The first distance measuring device includes:
At each of a plurality of timings at which T ₁ of the light emission period is divided into three or four, n ₂ phase states having different relative phase states with respect to the _second modulation frequency f ₂ are received and detected with a predetermined time width, and the n ₂ Detection of received light is performed k ₁ times (where k ₁ is a natural number)
Calculating the distance to the object of the first distance measuring device based on the calculated value of the 90 ° phase difference signal;
The second distance measuring device is
At each of a plurality of timings at which T ₂ of the light emission period is divided into three or four, n ₁ phase states having different relative phase states with respect to the _first modulation frequency f ₁ are received and detected with a predetermined time width, and the n _One light detection is performed k ₂ times (where k ₂ is a natural number)
A distance measuring method, comprising: calculating a distance to an object of the second distance measuring device based on a calculated value of the 90 ° phase difference signal.

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