TOF Sensor Distance Correction via Intensity Variation Analysis
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Solution Overview
Problem
Time-of-flight (TOF) sensors face measurement accuracy issues due to temperature variations and high dynamic ranges of reflectivity in the viewing space, leading to distance measurement offset errors.
Innovation Solution
The TOF sensor employs multiple distance measurement principles, such as phase measurement and pulsed TOF, and uses focal length adjustments to calibrate and correct distance values, along with intensity variation analysis to ensure accurate absolute distance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TOF sensors use standard distance measurement methods, then device complexity is low, but measurement precision deteriorates due to temperature and reflectivity variations
Solution Approach 1:
The patent combines multiple distance measurement principles (phase measurement TOF and pulsed TOF) into a single sensor system. The processor integrates signals from both measurement methods and applies correction factors to compensate for temperature and reflectivity variations, achieving high measurement precision without requiring separate calibration systems.
Solution Approach 2:
The system continuously monitors temperature and reflectivity conditions, using this feedback information to dynamically adjust correction factors applied to distance measurements. The processor modifies measurement results in real-time based on environmental conditions, maintaining measurement precision across varying operating conditions.
2Measurement precision
If the sensor measures both phase difference and time duration for calibration, then measurement precision improves, but loss of time increases due to additional measurement cycles
Solution Approach 1:
The system performs preliminary calibration measurements during manufacturing or initial setup to establish baseline correction factors. These pre-computed correction factors are stored and applied to subsequent distance measurements without requiring repeated calibration cycles, thereby maintaining high precision while minimizing measurement time during normal operation.
Solution Approach 2:
The sensor performs calibration measurements periodically rather than continuously. The system alternates between rapid distance measurements using both phase and pulsed TOF methods and periodic calibration cycles, achieving accurate distance data while limiting time loss to only the necessary calibration intervals.
3Measurement precision
If correction factors are applied for temperature and reflectivity compensation, then measurement precision improves, but device complexity increases due to additional processing
Solution Approach 1:
The system changes operational parameters (correction factors) based on environmental conditions rather than changing the fundamental measurement hardware. The processor adjusts measurement results by applying temperature and reflectivity-dependent correction factors, achieving high precision without adding complex physical components or measurement systems.
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 enhances the accuracy and reliability of distance measurements by compensating for temperature and reflectivity-related errors, providing precise absolute distance information in varying environmental conditions.
Implementation Method 1
generate distance information for a pixel corresponding to an object in the viewing space based on time-of-flight analysis of the reflected light
Implementation Method 2
a receiving lens element configured to receive reflected light and to direct the reflected light to a photo-receiver array
Data Source
AI summary
A time-of-flight (TOF) sensor device includes: an illumination component that emitting a light beam toward a viewing space; a receiving lens element receiving reflected light and directing the reflected light to a photo-receiver array; and a processor. The processor is configured to generate distance information for a pixel corresponding to an object in the viewing space based on time-of-flight analysis of the reflected light; record a variation of an intensity of the reflected light from the object over time to yield intensity variation information; record a variation of the distance information for the pixel corresponding to the object over time to yield distance variation information; and apply a correction factor to the distance information in response to a determination that the intensity variation information and the distance variation information do not conform to an inverse-square relationship.