JP2010014502A - Optical range finder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical range finder capable of heightening measuring accuracy by suppressing an influence of dispersion of measured values. <P>SOLUTION: An obstacle sensor 31 is equipped with an output control part 41 for controlling a light projection element 36 so that each modulated light having each of two different frequencies is emitted alternately, a distance operation part 42 for operating a measured distance to a body T to which light is projected based on the modulated light received by a light receiving element 37, the first determination part 43 for determining whether a difference between each measured distance operated twice by the modulated light having the first frequency is within the first prescribed range or not, the second determination part 44 for determining whether a difference between each measured distance operated twice by the modulated light having the second frequency is within the second prescribed range or not, and an overall determination part 46 for determining correctness/wrongness of the measured distance operated by the distance operation part 42 based on each determination result by the first determination part 43 and the second determination part 44. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical distance measuring device that scans light on a projection object and detects a distance to the projection object based on reflected light from the scanning region.

  The automatic transfer device is equipped with an optical distance measuring device to detect obstacles and the like in the travel area and the work area. In the optical distance measuring device, the light emitted from the light projecting unit is reflected by a rotating mirror, the optical axis is swung around, the reflected light reflected by the obstacle is received, and the light projecting unit What detects a distance from the phase difference between the emitted light and the reflected light received by the light receiving unit (AM modulation method (phase difference method)) is used.

  Such an AM modulation type optical distance measuring device may erroneously determine that the distance of one wavelength of the modulation frequency is 0 m. For example, when modulation is applied at a frequency of 50 MHz, one wavelength of light is about 3 m. However, in the case of this range sensor, if there is a high reflectance such as a stainless steel plate in the vicinity of 3 m, the level of the reflected light is high, so the high-level reflected light is received and the distance is calculated with the vicinity of 0 m. It may be determined that the reflector is near.

In order to prevent such a malfunction, light is modulated with a plurality of frequencies, and it is determined that the distance calculation value is appropriate only when the distances calculated with the light of each frequency match. For example, in Patent Document 1, when the light projecting / receiving device is directed in the same direction and rotated by a predetermined step angle while changing the modulation frequency, the modulated light emitted from the light projecting element is reflected by the projection object and returned to the light receiving element. An obstacle detection sensor is disclosed in which a distance is measured from the phase change of the two and the difference between the measurement values of two consecutive steps is within a certain allowable range, and is handled as a correct distance measurement value. According to this, the measurement value by the reflected light from the projection object located farther than the measurable distance limited by the modulation frequency can be excluded as an error value.
JP 2002-90454 A

  However, the conventional obstacle detection sensor has the following problems.

  That is, it is possible to remove measurement values that are outside the allowable range, but the influence of variations in measurement values cannot be eliminated, and the accuracy of measurement values cannot be increased.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an optical distance measuring device capable of suppressing the influence due to variations in measurement values and increasing the measurement accuracy.

  The optical distance measuring device of the present invention measures the distance to the projection object from the difference between the phase of the light emitted from the light projecting unit and the phase of the light when the light is reflected by the projection target and received by the light receiving unit. The optical distance measuring device includes an output control unit, a distance calculation unit, a first determination unit, a second determination unit, and a comprehensive determination unit. The output control unit controls the light projecting unit so as to alternately emit modulated light having two different frequencies of the first frequency and the second frequency. The distance calculation unit calculates a measurement distance to the projection target based on the modulated light received by the light receiving unit. The first determination unit determines whether or not the difference between the measurement distances calculated based on the modulated light having the first frequency two or more times is within the first predetermined range. The second determination unit determines whether or not the difference between the measurement distances calculated based on the modulated light having the second frequency two or more times is within the second predetermined range. The comprehensive determination unit determines whether the measurement distance calculated based on the distance calculation unit is correct (whether a distance value is output) based on the determination results of the first determination unit and the second determination unit.

  Here, the measurement distance determined to be correct may be a measurement distance calculated from a certain modulated light, or an average value of measurement distances calculated from modulated light of the first frequency. It may be an average value of measurement distances calculated from modulated light of two frequencies.

  By using four or more measurement distances, it is possible to suppress the influence of variations in the measurement distance calculated from the modulation value of the first frequency or the second frequency, and it is possible to increase the measurement accuracy. .

  The optical distance measuring device includes an average value of measurement distances calculated based on the modulated light of the first frequency two times or more and an average value of measurement distances calculated based on the modulated light of the second frequency two times or more. And a third determination unit that determines whether the difference between the average values is within the third predetermined range, and the comprehensive determination unit makes a determination based on the determination result of the third determination unit. Preferably it is done.

  Thereby, it becomes possible to further suppress the influence of the variation in the measurement distance calculated from the modulation value of the first frequency or the second frequency, and the measurement accuracy can be increased.

  In the optical distance measuring device, it is preferable that the first determination unit and the second determination unit respectively determine using a measurement distance calculated based on two consecutive modulated lights.

  Here, based on a total of four measurement distances, that is, a measurement distance calculated by two times of the modulated light of the first frequency and a measurement distance calculated by two times of the modulated light of the second frequency, the measurement distance Correct / incorrect judgment is made.

  According to the optical distance measuring device of the present invention, it is possible to suppress the influence due to variations in measurement values and increase the measurement accuracy.

  The overhead traveling vehicle 2 including the obstacle sensors (optical distance measuring devices) 30 and 31 according to the embodiment of the present invention will be described below with reference to FIGS.

[Configuration of overhead traveling vehicle 2]
The overhead traveling vehicle 2 is a transport device that transports the article 10 in a clean room or the like, and transports the article along a traveling rail 4 arranged in a ceiling space or the like as shown in FIG. Then, the article 10 is delivered to and from the load port 8 arranged on the ground side.

  As shown in FIG. 1, the overhead traveling vehicle 2 includes a carriage 12, a power receiving device 14, a frame 16, a lateral feed unit 18, a θ drive 20, a lifting drive unit 22, a lifting platform 24, an obstacle. Sensors 30 and 31 are provided.

  The carriage 12 travels in the travel rail 4. The power receiving device 14 receives power from a litz wire or the like provided on the traveling rail 4 by non-contact power feeding and performs communication using the litz wire or the like. The frame 16 is supported by a shaft extending from the carriage 12. The lateral feed unit 18 moves a later-described θ drive 20, a lift drive unit 22, and a lift platform 24 with respect to the traveling rail 4 in the lateral direction. The θ drive 20 rotates the elevating drive unit 22 in a horizontal plane. The elevating drive unit 22 elevates the elevating platform 24 with a suspension material such as a belt, a rope, and a wire, and delivers the article 10 to and from the load port 8. The elevator 24 holds the article 10 to be conveyed.

  The overhead traveling vehicle 2 further includes fall prevention covers 25 and 26 and a fall prevention unit 28. The fall prevention covers 25 and 26 are provided at the front and rear in the traveling direction of the overhead traveling vehicle 2. The fall prevention part 28 is arranged so as to be able to protrude and retract from the fall prevention covers 25 and 26.

  The obstacle sensor 30 is disposed in the lower part of the fall prevention cover 25 in front of the traveling direction, and the obstacle sensor 31 is disposed in front of the fall prevention cover 25 in front of the traveling direction. The obstacle sensor 30 detects an obstacle such as a person who tries to access the load port 8 or an article placed in the vicinity of the load port 8 when the elevator 24 is lowered toward the load port 8. To do. The obstacle sensor 31 detects an obstacle within a predetermined angle range ahead of the traveling direction and within a predetermined distance.

[Configuration of Obstacle Sensor 31]
FIG. 3 is a control function block diagram showing the overall configuration of the obstacle sensor 31 according to one embodiment of the present invention. Since the obstacle sensor 30 has the same configuration, the description thereof is omitted here.

  The obstacle sensor 31 measures the distance to the projection target from the difference between the phase of the light emitted from the light projecting unit and the phase of the light when the light is reflected by the projection target and received by the light receiving unit. However, the accuracy of the measurement distance is increased by a method described later. The obstacle sensor 31 mainly includes a light projecting circuit 38, a light projecting / receiving device 32, a light receiving circuit 39, and a control unit 40. The light projector / receiver 32 includes a light projecting element (light projecting unit) 36, a light receiving element (light receiving unit) 37, a light projecting mirror 34, a light receiving mirror 35, and a pulse motor 33.

  The light projecting circuit 38 is controlled by an output control unit 41 (to be described later) to generate a light emission signal, and inputs the light emission signal to the light projecting element 36. The light projecting element 36 emits high-frequency pulsed light based on a signal from the light projecting circuit 38. The light projecting mirror 34 reflects the emitted light emitted from the light projecting element 36 toward the projection target T. The light receiving mirror 35 reflects incident light from the projection target T toward the light receiving element 37. The pulse motor 33 rotates the light projecting mirror 34 and the light receiving mirror 35 simultaneously in the same direction. The light receiving element 37 receives the reflected light reflected by the projection target T, converts the reflected light into a light receiving signal that is an electrical signal, and inputs the converted light receiving signal to the light receiving circuit 39. The light receiving circuit 39 amplifies the received light reception signal and detects a phase change between the light emission signal and the light reception signal. The light receiving circuit 39 converts the phase change into a detection signal that is an electrical signal, and inputs the detection signal to the control unit 40.

  The control unit 40 is a microcomputer having functional blocks that perform various controls of the light projecting circuit 38, the light projecting / receiving device 32, and the light receiving circuit 39, calculation of measurement distance, determination of measurement distance, and the like. The control unit 40 includes an output control unit 41 as a functional block, a distance calculation unit 42, a first determination unit 43, a second determination unit 44, a third determination unit 45, and a comprehensive determination unit 46. I have.

  The output control unit 41 controls the light projecting circuit 38 so that the light projecting elements 36 alternately emit modulated light of two different frequencies of 30 MHz (first frequency) and 34 MHz (second frequency).

  The distance calculation unit 42 calculates the measurement distance to the projection target T based on the detection signal input from the light receiving circuit 39.

  The first determination unit 43 determines whether the difference between the measurement distances calculated by the distance calculation unit 42 is within the first predetermined range based on at least two consecutive 30 MHz modulated lights. In the present embodiment, it is determined whether or not the difference in measurement distance calculated by two times of 30 MHz modulated light is within a range of 20 cm.

  The second determination unit 44 determines whether the difference between the measurement distances calculated by the distance calculation unit 42 is within the second predetermined range based on at least two consecutive 34 MHz modulated lights. In the present embodiment, it is determined whether or not the difference in measurement distance calculated by two times of 34 MHz modulated light is within a range of 20 cm.

  The third determination unit 45 calculates the difference between the average value of the measurement distance calculated based on at least two times of 30 MHz modulated light and the average value of the measurement distance calculated based on at least two times of 34 MHz modulated light. Is calculated, and it is determined whether or not the difference between the average values is within a range of 14 cm. In the present embodiment, a difference between an average value of measurement distances calculated by two times of modulated light of 30 MHz and an average value of measurement distances calculated by two times of modulated light of 34 MHz is calculated, and the average value thereof is calculated. It is determined whether the difference is in the range of 14 cm.

  Based on the determination results of the first determination unit 43, the second determination unit 44, and the third determination unit 45, the comprehensive determination unit 46 outputs the correctness of the measurement distance calculated by the distance calculation unit 42, that is, the distance value. Then, it is determined whether or not an obstacle exists using this distance. In the present embodiment, the first determination unit 43 determines that the difference between the two measurement distances calculated based on the 30 MHz modulated light is within a range of 20 cm, and the second determination unit performs the 34 MHz modulation. It is determined that the difference between the two measurement distances calculated based on the light is within a range of 20 cm, and based on the average value of the two measurement distances calculated based on the 30 MHz modulated light and the 34 MHz modulated light. When it is determined that the difference from the average value of the two measurement distances calculated in the above is within a range of 14 cm, the distance value is calculated and output using the measurement distances D1 to D4 calculated in the distance calculation unit 42. .

[Description of Operation of Obstacle Sensor 31]
Here, the operation of the obstacle sensor 31 will be described based on the flowchart of FIG.

  In step S1, the obstacle sensor 31 is initialized. Specifically, the internal data is initialized.

  In step S2, the obstacle sensor 31 performs distance measurement in a measurement range of 160 degrees, for example, while performing distance measurement for each rotation step of Δθ (for example, 0.18 degrees). And the control part 40 determines whether it is the distance measurement in the range of 160 degree | times. If it is determined that the measurement is within the range of 160 degrees, the process proceeds to step S3. If it is determined that the measurement is not performed outside the range of 160 degrees, step S2 is repeated once again.

  In step S <b> 3, the light projecting circuit 38 switches the frequency of the modulated light output from the light projecting element 36 according to control by the output control unit 41. Specifically, switching is performed so that modulated light of frequencies of 30 MHz (first frequency) and 34 MHz (second frequency) are alternately output every one step rotation.

  In step S <b> 4, the distance calculation unit 42 calculates the distance to the projection target T based on the detection signal input from the light receiving circuit 39. Specifically, the distance calculating unit 42 modulates the phase of the modulated light emitted from the light projecting element 36 detected by the light projecting circuit 38 and the modulation when the modulated light is reflected by the projection target T and received by the light receiving element 37. The distance to the projection target T is calculated based on the difference from the light phase, that is, the phase change. Then, the calculated distance to the projection target T is stored in the storage unit 47.

  In the present embodiment, in the following steps S5 to S12, there is a function of determining whether there is an error in the measurement distance calculated in step S4. Here, the measurement distance in the modulated light of 30 MHz received in step S4 is the measurement distance D1, and the measurement distance calculated by the modulated light of 34 MHz is the measurement distance D2 and the measurement distance D1 is calculated once before the measurement distance D1 is calculated. Four measurements with the measurement distance D3 as the measurement distance D3 calculated two times before the calculation and the measurement distance D4 as the measurement distance calculated with the 34 MHz modulation light three times before the calculation of the measurement distance D1 A method of performing correct / incorrect determination using the distance will be specifically described.

  Note that the measurement distance is not exactly the same because the measurement target position moves in the measurement performed every one step rotation while changing the frequency of the modulated light. However, since the measurement target position moves along the outer shape of the projection T, there is little change in the distance even when a plurality of adjacent points are compared. The distance measurement of this phase difference method is possible under the condition that the distance 2L that the light wave reciprocates is smaller than one wavelength λ of the light wave, and the principle that the upper limit distance Lm that cannot be measured is determined by the modulation frequency f Is used. That is, when the speed of light is C (m / s), Lm = C / 2f. For example, when measurement is performed at 30 MHz and 34 MHz, the upper limit distance Lm is 5.0 m and 4.4 m, respectively. . When both are compared here, as shown in FIG. 5, at 30 MHz, the measurement distance is 0 m when it reaches 5.0 m, and at 34 MHz, the measurement distance is 0 m when it reaches 4.4 m. For this reason, when the measurement distance L is 4.4 m ≦ distance L <5.0 m, the difference is 4.4 m, and when the measurement distance is 5.0 m or more, a difference of 0.6 m occurs. This phase difference distance measurement uses this relationship to extract only measured values in the measurable range as correct data.

  In step S5, the first determination unit 43 determines whether or not the difference in measurement distance calculated based on two consecutive 30 MHz modulated lights is within 20 cm (within the first predetermined range). . Specifically, it is determined whether or not the difference between the measurement distance D1 and the measurement distance D3 calculated in step S4 is within 20 cm. And when the 1st determination part 43 determines with the difference of the measurement distance computed based on 2 times of continuous 30-MHz modulated light being within 20 cm, it transfers to step S6, and if it is not within 20 cm When it determines, it transfers to step S12.

  In step S6, the first determination unit 43 calculates the average value Da1 of the measurement distances D1 and D3 in step S5.

  In step S7, the second determination unit 44 determines whether or not the difference in measurement distance calculated based on two consecutive 34 MHz modulated lights is within 20 cm (within the second predetermined range). . Specifically, it is determined whether or not the difference between the measurement distance D2 and the measurement distance D4 calculated in step S4 is within 20 cm. And when the 2nd determination part 44 determines with the difference of the measurement distance computed based on the 2 times of continuous 34-MHz modulated light being within 20 cm, it transfers to step S8, and if it is not within 20 cm When it determines, it transfers to step S12.

  In step S8, the second determination unit 44 calculates the average value Da2 of the measurement distances D2 and D4 in step S7.

  In step S9, the third determination unit 45 performs the measurement calculated based on the average value of the measurement distances calculated based on the two consecutive 30 MHz modulated lights and the two consecutive 34 MHz modulated lights. A difference from the average value of the distance is calculated, and it is determined whether or not the difference between these average values is within 14 cm (third predetermined range). Specifically, whether or not the difference between the average value Da1 of the measurement distances D1 and D3 calculated in step S6 and the average value Da2 of the measurement distances D2 and D4 calculated in step S8 is within 14 cm. judge. When the third determination unit 45 determines that the difference between the average value Da1 and the average value Da2 is within 14 cm, the process proceeds to step S10. When the third determination unit 45 determines that the difference is not within 14 cm, the process proceeds to step S12.

  In step S10, the third determination unit 45 calculates an average value Da between the average value Da1 of the measurement distances D1 and D3 and the average value Da2 of the measurement distances D2 and D4 in step S7.

  In step S11, the comprehensive determination unit 46 determines whether the average value Da calculated in step S10 is correct. Specifically, the overall determination unit 46 outputs the average value Da calculated in step S10 based on the determination results of the first determination unit 43, the second determination unit 44, and the third determination unit 45 as a distance value. Determine if. Here, the average value Da is output as a distance value, and the presence or absence of an obstacle is determined.

  In step S12, the comprehensive determination unit 46 determines whether the measurement distances D1 to D4 are correct. Specifically, the comprehensive determination unit 46 determines whether to output the measurement distances D1 to D4 as distance values based on the determination results of the first determination unit 43, the second determination unit 44, and the third determination unit 45. . Here, the comprehensive determination unit 46 determines not to output the measurement distances D1 to D4 as distance values, and at this time, determines that there is no obstacle.

And the determination of the said step S3-step S12 is performed repeatedly.
As described above, the obstacle sensor 31 of the present embodiment is received by the light receiving element 37 and the output control unit 41 that controls the light projecting element 36 so as to alternately emit modulated light of two different frequencies of 30 MHz and 34 MHz. The difference between the distance calculation unit 42 that calculates the measurement distance to the projection target T based on the modulated light and the measurement distances D1 and D3 calculated based on the two modulated lights of 30 MHz is within 20 cm (first predetermined The first determination unit 43 that determines whether the difference is within the range) and the difference between the measurement distances D2 and D4 calculated based on the two modulated lights of 30 MHz are within 20 cm (second predetermined range). And a general determination unit 46 that determines whether the measurement distances D1 to D4 calculated by the distance calculation unit 42 are correct based on the determination results of the first determination unit 43 and the second determination unit 44. Have As a result, the influence of variation in the measurement distance calculated from the modulation value of each frequency can be suppressed, so that an obstacle within a predetermined angle range in front of the traveling direction and within the predetermined distance is accurately detected. It becomes possible. As a result, when driving the overhead traveling vehicle 2, it is possible to accurately determine whether the overhead traveling vehicle 2 is traveling or stopped.

  Furthermore, in the obstacle sensor 31 of the present embodiment, based on the average value Da1 of the measurement distances D1 and D3 calculated based on the two consecutive 30 MHz modulated lights and the two consecutive 34 MHz modulated lights. A third determination unit 45 is provided that calculates a difference between the calculated measurement distances D2 and D4 and the average value Da2, and determines whether the difference between the average values is within 14 cm (third predetermined range). . As a result, it is possible to further suppress the influence of the variation in the measurement distance, so that the measurement accuracy can be further increased.

[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

(A)
In the obstacle sensor 31 of the above embodiment, in step S5, the difference between the measurement distances calculated by the first determination unit 43 using two consecutive 30 MHz modulated lights (measurement distance D1 and measurement distance D3) is 20 cm. In step S7, the difference between the measurement distances (measurement distance D2 and measurement distance D4) calculated by the second determination unit 44 using two consecutive 34 MHz modulated lights is 20 cm. An example of determining whether it is within the range has been described. However, the present invention is not limited to this.

  For example, in steps S5 and S7, the first determination unit and the second determination unit may determine whether each difference between three or more consecutive measurement distances is within a predetermined range. Moreover, it does not need to be continuous. In this case, the greater the number of measurements, the better the accuracy of measurement and accuracy of measurement distance measurement, but the processing time in the control unit increases in proportion to this, so the processing specifications of the control unit and the traveling of the overhead traveling vehicle It is desirable to set the optimal number of measurements in consideration of speed and the like.

(B)
In the obstacle sensor 31 of the above-described embodiment, the example in which the number of measurements of the first determination unit 43 and the second determination unit 44 for determining whether the measurement distance is correct or not is set to the same two times has been described. However, the present invention is not limited to this.

  For example, the number of measurements in the determination by the first determination unit and the determination by the second determination unit may be different from each other, such as twice in the first determination unit and three times in the second determination unit.

(C)
In the obstacle sensor 31 of the above-described embodiment, the output control unit 41 has been described with an example in which the light projecting element 36 is controlled so as to alternately emit modulated light having two different frequencies of 30 MHz and 34 MHz. However, the present invention is not limited to this.

  For example, the output control unit may control the light projecting element so as to alternately emit modulated light of two different frequencies of 50 MHz and 43 MHz. Also in this case, the same effect as the obstacle sensor 31 according to the above embodiment can be obtained.

(D)
In the obstacle sensor 31 of the above embodiment, the example in which the determinations performed by the first determination unit 43, the second determination unit 44, and the third determination unit 45 are performed in the order of step S5 to step S9 has been described. However, the present invention is not limited to this.

(E)
In the obstacle sensor 31 of the above embodiment, each determination value (difference between the measurement distance D1 and the measurement distance D3, the measurement distance D2 and the measurement) in all of the first determination unit 43, the second determination unit 44, and the third determination unit 45. When it is determined that the difference between the distance D4, the average value Da1 of the measurement distances D1 and D3, and the average value Da2 of the measurement distances D2 and D4) is within each predetermined range, it is determined that the measurement distance D1 is correct An example was given and explained. However, the present invention is not limited to this.

  For example, the comprehensive determination unit may determine that the measurement distance is correct when it is determined that each value in the first determination unit and the second determination unit is within each predetermined range. In addition, the comprehensive determination unit determines that the determination value is within the predetermined range in the third determination unit even if the first determination unit and the second determination unit determine that each determination value is not within the predetermined range. When it is done, it may be determined that the measurement distance is correct.

(F)
In the obstacle sensor 31 of the above embodiment, the comprehensive determination unit 46 performs correct / incorrect determination based on the determination result of the first determination unit 43, and executes correct / incorrect determination based on the determination result of the second determination unit 44, An example of a sequential execution type in which correctness / incorrectness determination is executed based on the determination result of the third determination unit 45 has been described. However, the present invention is not limited to this.

  For example, a method may be used in which the comprehensive determination unit comprehensively determines correctness after each of the first determination unit, the second determination unit, and the third determination unit performs determination.

(G)
In the obstacle sensor 31 of the above-described embodiment, as the functional blocks in the control unit 40, the output control unit 41, the distance calculation unit 42, the first determination unit 43, the second determination unit 44, the third determination unit 45, and the comprehensive determination unit 46. The example of configuring the storage unit 47 has been described. However, the present invention is not limited to this.

  For example, the present invention can be realized not as a functional block included in a microcomputer but as a correctness determination program for causing a computer to execute the measurement distance correctness determination method including the above steps.

  According to the present invention, since it becomes possible to provide an optical distance measuring device with improved measurement accuracy, it can be widely applied as an optical distance measuring device mounted on, for example, an unmanned traveling vehicle or a mobile robot. .

1 is a side view of an overhead traveling vehicle including an obstacle sensor according to an embodiment of the present invention. 1 is a front side view of an overhead traveling vehicle including an obstacle sensor according to an embodiment of the present invention. FIG. 2 is a block diagram of control functions of an obstacle sensor included in FIG. 1. The flowchart of the correctness determination in the obstacle sensor contained in FIG. The block diagram explaining the principle of distance measurement by phase detection.

Explanation of symbols

2 Overhead traveling vehicle 4 Traveling rail 8 Load port 10 Article 12 Cart 14 Power receiving device 16 Frame 18 Cross feed unit 20 θ drive 22 Elevating drive unit 24 Elevating platform 25 Fall prevention cover 28 Fall prevention unit 30, 31 Obstacle sensor (optical measurement) Distance device)
32 Light Emitter / Receiver 33 Pulse Motor 34 Light Emitting Mirror 35 Light Receiving Mirror 36 Light Emitting Element (Light Emitter)
37 Light receiving element (light receiving part)
38 Light Emitting Circuit 39 Light Receiving Circuit 40 Control Unit 41 Output Control Unit 42 Distance Calculation Unit 43 First Determination Unit 44 Second Determination Unit 45 Third Determination Unit 46 Total Determination Unit 47 Storage Unit T Projected Object a Detection Area

Claims (3)

An optical distance measuring device that measures the distance to the projection object from the difference between the phase of the light emitted from the light projecting unit and the phase of the light when the light is reflected by the projection object and received by the light receiving unit. There,
An output control unit that controls the light projecting unit so as to alternately emit modulated light of two different frequencies of the first frequency and the second frequency;
A distance calculation unit that calculates a measurement distance to the projection object based on the modulated light received by the light receiving unit;
A first determination unit that determines whether a difference between the measurement distances calculated based on the modulated light of the first frequency at least twice is within a first predetermined range;
A second determination unit that determines whether a difference between the measurement distances calculated based on the modulated light of the second frequency at least twice is within a second predetermined range;
Based on the determination results of the first determination unit and the second determination unit, a comprehensive determination unit that determines the correctness of the measurement distance calculated by the distance calculation unit;
An optical distance measuring device. The average value of the measurement distance calculated based on the modulated light of the first frequency two or more times and the average value of the measurement distance calculated based on the modulated light of the second frequency two or more times And a third determination unit that determines whether the difference between the average values is within a third predetermined range,
The comprehensive determination unit performs right / wrong determination of the measurement distance based on a determination result of the third determination unit.
The optical distance measuring device according to claim 1. The first determination unit and the second determination unit are respectively determined using the measurement distances calculated based on the two consecutive modulated lights.
The optical distance measuring device according to claim 1.

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