TOF Sensor Calibration via Electrical Phase Offset
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Solution Overview
Problem
Existing three-dimensional (3D) camera systems based on time-of-flight (TOF) principles face inefficiencies in calibration, requiring large physical spaces, long times, and significant storage for calibration data, especially when dealing with high-volume production and large operating ranges, due to the need for mechanical repositioning of target objects and extensive data interpolation.
Innovation Solution
The method introduces an electrical phase offset into the TOF system to emulate target object relocation, allowing for calibration using a stationary object and reducing data storage needs by constructing a parameterized model that accounts for both electrical and physical characteristics, enabling faster and more compact calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical repositioning of target objects is used for calibration, then calibration coverage across large operating ranges is improved, but calibration time and device complexity increase
Solution Approach 1:
The patent replaces mechanical repositioning of target objects with electrical phase offset modulation. Instead of physically moving targets to different positions, the system introduces electrical phase offsets to simulate the effect of target relocation, thereby achieving comprehensive calibration coverage without mechanical movement. This substitution dramatically reduces calibration time while maintaining adaptability across large operating ranges.
Solution Approach 2:
The patent changes the calibration approach by modifying electrical parameters (phase offsets) rather than physical parameters (target position). By sweeping through different electrical phase offset values, the system achieves the same calibration effect as mechanical repositioning would provide, but much more quickly and without mechanical complexity.
2Measurement precision
If extensive calibration data is collected for high precision, then model accuracy is improved, but storage requirements increase
Solution Approach 1:
The patent extracts only the essential calibration information needed for accurate modeling, rather than storing extensive raw calibration data. By using electrical phase offset modulation, the system derives precise calibration parameters with minimal data requirements, extracting only the necessary information for high-accuracy distance-to-phase mapping while discarding redundant data.
Solution Approach 2:
The patent transforms calibration from a data-intensive process to a parameter-efficient process by changing from storing extensive spatial calibration data to storing compact electrical phase offset characteristics. This parameter change enables high model accuracy with significantly reduced storage requirements.
3Productivity
If electrical phase offset modulation is used, then calibration speed is improved, but system complexity may increase
Solution Approach 1:
The patent replaces complex mechanical repositioning systems with simpler electrical phase offset modulation circuitry. The electrical implementation requires only standard electronic components for phase modulation, avoiding the need for mechanical stages, motors, and control systems, thereby increasing calibration speed while actually reducing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces calibration time and storage requirements, enhances model accuracy, and eliminates the need for mechanical repositioning, making it suitable for high-volume production while maintaining precision.
Implementation Method 1
TOF is determined by examining relative phase shift between transmitted light signals and light signals reflected from a target object
Implementation Method 2
Three-dimensional (3D) cameras (or sensors) based on time-of-flight (TOF) principle acquire distance information from object(s) in a scene being imaged
Implementation Method 3
Each pixel detector is a quantum efficiency modulated differential pixel detector
Data Source
AI summary
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.