Optical Fruit Firmness Measurement for High-Speed Sorting
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Solution Overview
Problem
Conventional firmness measurement devices for fruits and vegetables face challenges in achieving high-speed, accurate, and non-destructive measurements, particularly due to issues with ambient light distortion, product shape and size variations, and the inability to detect fresh damage.
Innovation Solution
A measuring device using light sources to transmit measuring signals, a camera to capture irradiated and scattered surface areas, and a detection module to determine firmness based on the ratio of these areas, synchronized with product movement, enabling high-speed and reliable firmness measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a penetrometer is used to measure penetration resistance, then firmness measurement can be performed, but the measurement cannot be performed at high speed and products are damaged
Solution Approach 1:
The patent replaces the mechanical penetrometer system with an optical measurement system using light sources and cameras. The light sources transmit measuring signals through the product, and cameras capture the transmitted light patterns. This substitution eliminates mechanical contact and damage while enabling high-speed non-contact measurement at production line speeds.
Solution Approach 2:
The patent changes the measurement parameter from mechanical penetration resistance to optical transmission characteristics. By measuring how light transmits through the product and analyzing the light patterns, the system determines firmness without physical contact, thereby achieving both high speed and non-destructive measurement.
2Reliability
If non-destructive measurements using acoustic signals or near-infrared spectrometry are used, then product damage is avoided, but measurements cannot be performed reliably at high speed for moving products
Solution Approach 1:
The patent employs periodic action by using pulsed light sources that transmit measuring signals at regular intervals synchronized with product movement. Multiple light sources are activated sequentially as products move through the measurement zone, enabling continuous high-speed measurement of moving products while maintaining reliable non-destructive detection.
3Reliability
If conventional spectrometry is used for measurement, then non-destructive measurement is achieved, but fresh damage is insufficiently visible because internal decomposition is still getting started
Solution Approach 1:
The patent applies preliminary action by detecting optical changes in products immediately after damage occurs, before internal decomposition processes fully develop. The light transmission method detects subtle changes in light scattering and absorption patterns that occur at the moment of damage, enabling early detection of fresh damage that conventional spectrometry misses until decomposition is well advanced.
4Productivity
If light sources are used to transmit measuring signals, then high-speed measurement is enabled, but ambient light and product shape variations cause measurement uncertainty
Solution Approach 1:
The patent uses another dimension by capturing two-dimensional light transmission patterns with cameras instead of one-dimensional point measurements. The camera records the entire light pattern transmitted through the product, providing spatial information about light scattering and absorption across the product surface, which compensates for variations in product shape and size.
Solution Approach 2:
The system incorporates feedback by using the captured light patterns to dynamically adjust measurements. The camera records actual light transmission patterns, and the system analyzes these patterns to compensate for ambient light interference and product variability, thereby maintaining high measurement accuracy despite environmental challenges.
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 reliable and fast firmness measurement, capable of detecting fresh damage, and supports sorting systems by providing accurate classification of fruits and vegetables.
Implementation Method 1
The measuring signal will partially penetrate under the outer product surface and there disperse, i.e. scatter. This is visible to the camera as a scatter surface area
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
The invention relates to a measuring device for measuring the firmness of products, such as fruit and vegetables, a sorting device provided therewith and a method therefor. The measuring device according to the invention comprises: a signal device provided with one or more light sources configured to transmit a number of measuring signals to the product while the product is being advanced in a transport direction with a transport device; a camera device placed at an angle to and/or in line with the signal device and configured to record a product surface irradiated with the measuring signal and a scatter surface area of the measuring signal around the irradiated product surface while the product is being advanced; and a detection module connected operatively to the signal device and camera device and configured to determine the firmness of the product on the basis of obtained camera images.