Method and system for fast calibration of three-dimensional (3D) sensors
First Claim
1. A method of calibrating a time-of-flight (TOF) system of the type that emits optical energy of a known phase, detects a portion of said optical energy reflected from a target object a distance Z away, and determines Z by examining phase shift in detected reflected optical energy relative to said known phase of emitted optical energy, the method comprising the following steps:
- (a) disposing a target object a distance Zx from said TOF system, said distance Zx being within operating distance range of said TOF system;
(b) altering said known phase of said emitted optical energy by at least two known phase values;
(c) for each known phase value of said emitted optical energy, determining from detected reflected optical energy a corresponding phase shift relative to said known phase;
(d) using corresponding relative phase shift determined at step (c) to form an electrical model of detection characteristics of said TOF system;
(e) storing data representing said electrical model;
wherein data stored at step (e) is useable during run-time operation of said TOF system to provide calibrated values of Z responsive to phase shift in detected reflected optical energy.
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Accused Products
Abstract
Rapid calibration of a TOF system uses a stationary target object and electrically introduces phase shift into the TOF system to emulate target object relocation. Relatively few parameters suffice to model a parameterized mathematical representation of the transfer function between measured phase and Z distance. The phase-vs-distance model is directly evaluated during actual run-time operation of the TOF system. Preferably modeling includes two components: electrical modeling of phase-vs-distance characteristics that depend upon electrical rather than geometric characteristics of the sensing system, and elliptical modeling that phase-vs-distance characteristics that depending upon geometric rather than electrical characteristics of the sensing system.
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Citations
20 Claims
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1. A method of calibrating a time-of-flight (TOF) system of the type that emits optical energy of a known phase, detects a portion of said optical energy reflected from a target object a distance Z away, and determines Z by examining phase shift in detected reflected optical energy relative to said known phase of emitted optical energy, the method comprising the following steps:
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(a) disposing a target object a distance Zx from said TOF system, said distance Zx being within operating distance range of said TOF system; (b) altering said known phase of said emitted optical energy by at least two known phase values; (c) for each known phase value of said emitted optical energy, determining from detected reflected optical energy a corresponding phase shift relative to said known phase; (d) using corresponding relative phase shift determined at step (c) to form an electrical model of detection characteristics of said TOF system; (e) storing data representing said electrical model; wherein data stored at step (e) is useable during run-time operation of said TOF system to provide calibrated values of Z responsive to phase shift in detected reflected optical energy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of improving elliptical error calibration in a time-of-flight (TOF) system of the type that emits optical energy of a known phase, detects a portion of said optical energy reflected from a target object a distance Z away, and determines Z by examining phase shift in detected reflected optical energy relative to said known phase of emitted optical energy, the method comprising the following steps:
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(i) disposing a target object at at least one distance Zy<
Zf from said TOF system, where Zf is a shortest distance whereat elliptical error arising from geometry of phase detection of said TOF system is negligible;(ii) for each said distance Zy determining from detected, reflected optical energy a corresponding phase shift relative to said known phase; (iii) for each said distance Zy, obtaining a phase value from an electrical model of phase-vs-distance formed for said TOF system; (iv) obtaining a difference in phase value between phase determined at step (ii) and phase obtained from step (iii), and using said difference in phase to form an elliptical error model; wherein said elliptical error model is useable during run-time operation of said TOF system to provide improved calibrated values of Z<
Zf responsive to phase shift in detected reflected optical energy. - View Dependent Claims (15, 16)
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17. A time-of-flight (TOF) system of the type that emits optical energy of a known phase, detects a portion of said optical energy reflected from a target object a distance Z away, and determines Z by examining phase shift in detected reflected optical energy relative to said known phase of emitted optical energy, the TOF including means for altering known phase emitted by said TOE system, and further including memory storing a distance-vs-phase calibration model used to calibrate said TOF system, said calibration model obtained according to a method comprising the following steps:
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(a) disposing a target object a distance Zx from said TOF system, said distance Zx being within operating distance range of said TOF system; (b) causing said means for altering known phase to vary said known phase of said emitted optical energy by at least two known phase values; (c) for each known phase value of said emitted optical energy, determining from detected reflected optical energy a corresponding phase shift relative to said known phase; (d) using corresponding relative phase shift determined at step (c) to form an electrical model of detection characteristics of said TOE system; (e) storing data representing said electrical model in said memory; wherein data stored in memory at step (e) is useable during run-time operation of said TOF system to provide calibrated values of Z responsive to phase shift in detected reflected optical energy. - View Dependent Claims (18, 19, 20)
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Specification