Range Sensor Offset Compensation Using Reference Positions
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Solution Overview
Problem
Range sensors, such as time-of-flight cameras, face measurement errors due to internal delay variations caused by temperature drift, ageing, and manufacturing tolerances, which are difficult to compensate without increasing hardware complexity and cost.
Innovation Solution
A method that determines and compensates for range offset by using post-processing software to calculate differences between measured and predetermined distances to stationary reference positions, allowing for on-the-fly correction without additional hardware, such as optical or electrical feedback paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated hardware elements are used to compensate internal delay variations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces dedicated hardware elements (electrical/optical feedback paths, additional sensors) with a software-based post-processing method. The evaluation unit calculates range offset by comparing measured distances to reference positions using algorithmic processing rather than hardware compensation mechanisms, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The range sensor system performs self-calibration by using its own measurement capabilities to determine range offset. The evaluation unit utilizes the sensor's existing distance measurement function to measure reference positions and calculate corrections, eliminating the need for external calibration hardware or feedback paths.
2Reliability
If calibration is performed during production only, then manufacturing precision is maintained, but reliability deteriorates due to temperature drift and ageing
Solution Approach 1:
The patent implements dynamic range offset compensation that adapts to changing environmental conditions. The system periodically recalibrates by measuring reference positions and updating offset values in real-time, allowing the measurement system to adjust to temperature drift and ageing effects rather than relying on static production calibration.
Solution Approach 2:
The patent performs preliminary measurement of reference positions to determine range offset before actual distance measurements are taken. This pre-calibration step using known reference positions allows the system to compensate for environmental variations proactively, improving reliability without requiring complex continuous monitoring hardware.
3Measurement precision
If optical feedback path is used for synchronization, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces optical feedback paths with a software-based synchronization method. The evaluation unit achieves synchronization by calculating time offsets through algorithmic processing of reference position measurements, eliminating the need for physical optical feedback infrastructure while maintaining synchronization accuracy.
4Device complexity
If post-processing software is used for offset compensation, then device complexity is reduced, but processing time increases
Solution Approach 1:
The patent performs range offset calculation as a preliminary step before actual distance measurements are processed. By determining the offset value once using reference positions and applying it to subsequent measurements, the system minimizes processing time for the main measurement function while maintaining hardware simplicity.
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 provides robust and simple distance information correction, maintaining high frame rates and accuracy without requiring specific light paths or temperature measurements, even if one reference position is blocked, and can handle a large number of reference points without significant processing complexity increase.
Implementation Method 1
time-of-flight (ToF) image sensors... determines the distance based on the time needed for a light signal to travel from the camera to an object in the scene, and back
Data Source
AI summary
A method for compensating range offset of a range sensor located in a predetermined position in a spatial environment and comprising a pixel array adapted for measuring a distance, the spatial environment comprising at least two stationary reference positions located at predetermined reference distances, the method comprising the steps of: a) determining distance values to the reference positions; b) calculating differences between the distance values and the corresponding reference distances; c) determining a range offset value as the maximum of the differences; d) measuring distance values to positions within the spatial environment using the pixel array; e) correcting the measured distance values by subtracting the determined in-situ range offset value from each of the measured distance values.