Automated Visual Inspection for Plunger Depth Measurement
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Solution Overview
Problem
Traditional automated visual inspection (AVI) systems face challenges in accurately measuring the depth of plungers in syringes due to uneven syringe flange shapes, dust, debris, tray defects, and partial obscuration by tray features, leading to incorrect identification of the plunger depth and potential malfunction of auto-injector pens.
Innovation Solution
The AVI system employs a linear motorized stage for incremental vessel positioning, combined with advanced image processing techniques such as blob analysis, pixel dilation, hole-filling, erosion, and template-matching algorithms to accurately identify the uppermost edge of the syringe flange and plunger, even in the presence of artifacts, ensuring precise depth measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional edge detection algorithms are used to identify the flange top edge, then the measurement process is simple, but the measurement precision deteriorates due to uneven flange shapes, dust, debris, and tray defects causing incorrect identification
Solution Approach 1:
The patent segments the image processing task into multiple specialized algorithms: blob analysis for flange identification, edge detection for plunger identification, and artifact filtering. Each algorithm handles a specific aspect of the measurement problem, improving overall precision while managing complexity through functional decomposition
Solution Approach 2:
The patent changes the approach from direct edge detection to blob analysis with multiple processing steps including morphological operations and coordinate transformation. This parameter change in the measurement approach enables accurate identification of flange top edges despite manufacturing variations and contaminants
2Adaptability or versatility
If a fixed region of interest (ROI) is used for plunger edge detection, then the algorithm is computationally efficient, but the adaptability deteriorates causing the system to work only for single size and type of syringe
Solution Approach 1:
The patent implements dynamic ROI adjustment based on detected plunger position and syringe characteristics. Rather than using a fixed ROI, the system adapts the region of interest to match the actual plunger location and size, enabling universal compatibility across different syringe types while maintaining efficient processing through targeted analysis
Solution Approach 2:
The patent creates a universal measurement system that can handle multiple syringe sizes and types through adaptive ROI and template matching. The same algorithmic framework works across different vessel geometries by adjusting parameters rather than requiring separate dedicated systems for each syringe type
3Reliability
If conventional edge detection is used in the presence of tray features and obscuration, then the system is simple to operate, but the reliability deteriorates due to partial obscuration of plunger and flange by tray features
Solution Approach 1:
The patent applies preliminary artifact filtering and blob analysis before edge detection to remove tray features and obscuration effects. By pre-processing the image to eliminate contaminants and tray interference, the subsequent edge detection operates on cleaned data, ensuring reliable measurements even in non-cleanroom environments
Solution Approach 2:
The patent converts the harmful effect of tray features and obscuration into beneficial information by using blob analysis to identify and exclude artifact regions. The obscuration patterns themselves become indicators for artifact detection, allowing the system to distinguish between real plunger features and tray-related interference
Data Source
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AI summary
An automated visual inspection (AVI) system is described to measure the depth of plungers positioned within vessels. The AVI system implements various types of image processing as well as other techniques to identify, for a vessel, a reference point and the uppermost edge of the plunger. Because different inconsistencies and/or artifacts may be introduced within the vessel image, different processing techniques may be executed on the region containing the reference point versus the plunger region. In doing so, the AVI system provides a robust means to accurately measure plunger depth that is highly resilient to the aforementioned artifacts and consistently measures plunger depth for a wide variety and types of vessels.