3D Position Measurement Using Twisted Light Stripes
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Solution Overview
Problem
Current distance measurement technologies using light are complex, costly, and prone to noise and errors, especially when measuring fast-moving objects or those with irregular shapes or reflectivity, due to reliance on amplitude-based calculations and imaging arrays.
Innovation Solution
A system utilizing multiple stripes of light, twisted and tilted relative to each other, measures the timing of light pulses as objects pass through to determine their 3D position without the need for imaging arrays or amplitude-based calculations, employing LEDs and photodetectors for efficient and low-cost distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time of flight measurement using lasers is used, then distance measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces expensive, complex laser systems with inexpensive LEDs that emit light pulses. The LEDs are low-cost, easily manufactured components that can be mass-produced, eliminating the need for costly laser equipment while maintaining the time of flight measurement capability through optical signal transmission.
Solution Approach 2:
The patent substitutes the mechanical/optical complexity of laser systems with an electrical control system that modulates LED emission. By using electronic timing circuits to control LED pulse generation and photodetector signal processing, the system replaces complex optical alignment and maintenance requirements with simpler electronic control mechanisms.
2Ease of manufacture
If LEDs and photodetectors are used for time of flight measurement, then cost is reduced, but noise levels increase requiring complex electronics
Solution Approach 1:
The patent employs periodic modulation of the LED at specific frequencies and uses synchronous detection at the photodetector output. By modulating the LED at a known frequency and using phase-sensitive detection, the system distinguishes the modulated signal from ambient noise and interference, allowing simple electronics to achieve high signal-to-noise ratios without complex filtering or processing circuits.
Solution Approach 2:
The patent uses optical bandpass filtering centered on the LED emission wavelength to reject out-of-band noise. By selecting filters that pass only the specific wavelength range of the LED emission, the system eliminates much of the ambient light noise and interference before the signal reaches the photodetector, reducing the burden on subsequent electronic processing.
3Measurement precision
If imaging arrays are used for position measurement, then measurement capability is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent divides the measurement task into separate functional components: distance measurement using time of flight with LEDs and photodetectors, and position measurement using stripe pattern recognition with a simple linear photodetector array. This segmentation allows each subsystem to use the simplest possible components for its specific function, avoiding the need for complex imaging arrays to perform both tasks simultaneously.
Solution Approach 2:
The patent extracts the position measurement function from the imaging task by using projected stripe patterns that encode spatial information. Instead of capturing full images and processing them computationally, the system extracts position information directly from the timing and intensity patterns of light received by simple photodetectors, separating the measurement functions into dedicated simple subsystems.
4Ease of operation
If amplitude-based calculations are used for position measurement, then measurement is simplified, but reliability decreases for objects with irregular shapes or reflectivity
Solution Approach 1:
The patent uses periodic modulation of the LED and synchronous detection to measure the time of flight based on phase differences rather than signal amplitudes. By measuring when the modulated signal arrives at the photodetector relative to the modulation phase, the system determines distance and position independently of the object's reflectivity or shape, as the phase measurement is insensitive to variations in reflected signal strength.
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
Enables quick, efficient, and accurate 3D position measurement of objects using low-cost optical devices, reducing noise and complexity by focusing on timing rather than amplitude, suitable for applications like security and consumer product monitoring.
Implementation Method 1
measuring the timing of received light pulses from each of the stripes as the target passes through them
Implementation Method 2
employing LEDs and photodetectors for efficient and low-cost distance measurement
Data Source
AI summary
A system shines a series of light stripes across an area. A target object passes through the area and light is reflected to the system from the light stripes as it passes through. Based on the timing of the received light from each of the light stripes, the system calculates the position and velocity of the target object.