Rangefinder and method for collecting calibration data
First Claim
1. A method for calibrating a rangefinder having a transmitter for emitting a beam towards a target and a receiver for detecting a reflected beam, wherein an uncalibrated flight time of the beam and the reflected beam is measured by a counter, the method comprising:
- determining a first relationship between flight times and target ranges, wherein the first relationship has a corresponding first slope;
generating a first simulated range measurement by measuring a first discharge time of a capacitor;
generating a second simulated range measurement by measuring a second discharge time of the capacitor;
calculating a second relationship between flight times and target ranges based on the first and second simulated range measurements, wherein the second relationship has a corresponding second slope;
using the second relationship to correlate an uncalibrated range measurement to the first relationship; and
determining a distance to a target.
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Accused Products
Abstract
An apparatus and method for calibrating range measurements are provided wherein calibration data is collected with each range measurement or group of range measurements. The calibration data comprise a plurality of simulated range measurements. In one embodiment, the simulated range measurements are used to analyze errors that vary with time and environmental conditions. Range measurements are calibrated by correlating a measured flight time of a transmitted and reflected laser beam with the simulated range measurements and a relationship between laser beam flight times and target ranges based on the speed of the laser beam.
74 Citations
26 Claims
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1. A method for calibrating a rangefinder having a transmitter for emitting a beam towards a target and a receiver for detecting a reflected beam, wherein an uncalibrated flight time of the beam and the reflected beam is measured by a counter, the method comprising:
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determining a first relationship between flight times and target ranges, wherein the first relationship has a corresponding first slope;
generating a first simulated range measurement by measuring a first discharge time of a capacitor;
generating a second simulated range measurement by measuring a second discharge time of the capacitor;
calculating a second relationship between flight times and target ranges based on the first and second simulated range measurements, wherein the second relationship has a corresponding second slope;
using the second relationship to correlate an uncalibrated range measurement to the first relationship; and
determining a distance to a target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A rangefinder configured to determine a calibrated range to a target, the rangefinder comprising:
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a transmitter configured to emit a beam towards the target;
a receiver configured to detect a reflected beam from the target;
timing circuitry configured to measure a flight time between the emission of the beam from the transmitter and a detection of the reflected beam by the receiver;
a calibration section configured to determine calibration data related to dynamic factors; and
a processor configured to adjust the flight time based on the calibration data. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A system for measuring a range to a target, the system comprising:
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a means for storing a first parameter proportional to a flight time of a beam and for storing second and third parameters proportional to respective first and second calibration times;
a means for measuring the stored first, second and third parameters to respectively produce an uncalibrated range measurement and first and second simulated range measurements; and
a means for correlating the uncalibrated range measurement to the first and second simulated range measurements. - View Dependent Claims (24)
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25. A method for measuring a range to a target, the method comprising:
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measuring at least a first time corresponding to a beam traveling between the range finder and the target;
collecting calibration data by simulating a second time and a third time corresponding to the beam traveling between the range finder and the target;
correlating the at least a first time to the second time and the third time; and
outputting a range. - View Dependent Claims (26)
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Specification