LASER DISTANCE MEASURING APPARATUS

• US 20200132797A1
• Filed: 09/11/2019
• Published: 04/30/2020
• Est. Priority Date: 10/25/2018
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: KAMEYAMA, Shumpei, YANAGISAWA, Takayuki, IMAKI, Masaharu, ITO, Yusuke, TSUZAKI, Yosuke, KAWAI, Masahiro
• Granted Patent: US 11,592,513 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 1/30 the synchronised signals being continuous waves or intermittent trains of continuous waves, the intermittency not being for the purpose of determining direction or position line and the transit times being compared by measuring the phase difference
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487

Abstract

To provide a laser distance measuring apparatus which can increase the measurement frequency per unit time by suppressing the increase in the data amount expressing the measurement time, while ensuring the distance measurement precision and the measurable distance. A laser distance measuring apparatus measures, with a time resolution, a light receiving time which is a time from a time point when the laser beam generating unit emits the laser beam to a time point when the light receiving unit outputs the light receiving signal; calculates an object distance which is a distance to the object, based on the measurement result of the light receiving time by the time measuring device; and changes the time resolution of the time measuring device used for calculation of the object distance, based on detection information.

Claims

1. A laser distance measuring apparatus comprising:

a laser beam generator that emits a laser beam;

a light receiver that receives a reflected light of the laser beam reflected by an object, and outputs a light receiving signal;

a time measuring device that measures, with a time resolution, a light receiving time which is a time from a time point when the laser beam generator emits the laser beam to a time point when the light receiver outputs the light receiving signal; and

a distance calculator that calculates an object distance which is a distance to the object, based on the measurement result of the light receiving time by the time measuring device,

wherein the distance calculator changes the time resolution of the time measuring device used for calculation of the object distance, based on detection information.

2. The laser distance measuring apparatus according to claim 1,

wherein the detection information is at least one of the light receiving time, a time change of the light receiving time, a speed of a vehicle on which the laser distance measuring apparatus is mounted, an acceleration of the vehicle, and an inclination of the vehicle.

3. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time, and

wherein the distance calculator enlarges the time resolution as the measured light receiving time becomes long.

4. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time, and

wherein the distance calculator enlarges the time resolution, when the time measuring device cannot measure the light receiving time.

5. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time, and

wherein by referring to a resolution setting data in which setting value of the time resolution is preliminarily set in each of a plurality of divided regions in which a possible range of the light receiving time is divided, the distance calculator sets the time resolution of the divided region corresponding to the measured light receiving time.

6. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time, and

wherein the distance calculator changes the time resolution so that a value obtained by adding a margin time to the measured light receiving time becomes a maximum measurable light receiving time.

7. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time, and

wherein the distance calculator changes the time resolution at this time measurement, based on the light receiving time measured immediately before.

8. The laser distance measuring apparatus according to claim 1, further comprising:

a scanning mechanism that change an irradiation angle of the laser beam, and

a scanning controller that controls the scanning mechanism to scan the irradiation angle of the laser beam periodically,

wherein the detection information is the light receiving time, and

wherein the distance calculator changes the time resolution at this time measurement, based on the light receiving time measured at the irradiation angle of the last time scanning period corresponding to the irradiation angle of this time measurement.

9. The laser distance measuring apparatus according to claim 1,

wherein the time measuring device is a counter type, and is a time digital converter which converts signal in time domain into a digital value.

10. The laser distance measuring apparatus according to claim 1,

wherein the time measuring device is a capacitor charge type, and changes the time resolution, by performing A/D conversion of an output voltage of a capacitor, using a plurality of A/D converters in which widths of voltage measurement range are different with each other.

11. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time,

wherein a plurality of the time measuring devices in which the time resolutions are different with each other are provided,

wherein the distance calculator selects the one time measuring device used for this time measurement, from the plurality of time measuring devices, based on the measured light receiving time, and

wherein the distance calculator calculates the object distance based on the measurement result of the light receiving time of the one selected time measuring device.

12. The laser distance measuring apparatus according to claim 1,

wherein the detection information is the light receiving time,

a plurality of the time measuring devices in which the time resolutions are different with each other are provided,

wherein the distance calculator selects the one measurement result of the light receiving time used for calculation of the object distance, from the plurality of the measurement results of the light receiving time which are measured by the plurality of time measuring devices,

wherein the distance calculator calculates the object distance based on the one selected measurement result of the light receiving time.