Machine vision is a revolutionary technology, leading to drastic transformations in various industries. But we face unique challenges in different industries for the development of an optimal machine vision system. For example, the Food and Beverage industry, which must satisfy stringent standards for hygiene and quality, can be a harsh environment for industrial vision systems.
Although most industrial vision machines are created in sterile lab environments, they need to work in challenging conditions in industrial workspaces that can be hazardous or harmful.
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What is a Hazardous Environment?
- An improperly filled packet may add particulate matter like flour to the environment. This can incapacitate the system or affect its accuracy. The viewing apparatus may get clouded affecting the quality and accuracy of the image.
- Certain industries require wash downs by high-pressure hosing systems. This can cause water to get into the machine or the pressure to disturb the alignment and therefore affect the quality of images taken.
- Certain cleaning agents may prove corrosive for the outer enclosure in which the machine system is housed.
- Enclosures in mining operations don’t just have to keep out dust, moisture, and excessive heat, they also must keep out sunlight that can affect image quality adversely.
- Early-warning weather systems operate in extreme weather leading to industrial vision systems being affected by precipitation and huge variations in temperatures.
- Outdoor applications where machine vision systems are installed on cars face various weather conditions and vibrations.
- Underwater systems must perform in the presence of water pressure.
Major Factors Affecting Image Quality
Motion blur refers to the streaking of rapidly moving objects in an image. When objects move during exposure (integration), they may be captured by adjacent pixels. The image appears smeared in the direction of motion of the object.
Temperature variance affects machine vision systems. This occurs where external conditions or the heat generated by surrounding components of the machine exceeds the maximum operating temperature of the sensor.
Increased temperatures can lead to more noise in the image. This thermal noise affects the resolution negatively. In addition, temperature affects the performance of LED illumination. LEDs themselves generate heat as well as light and this can cause malfunctions.
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Ingress Protection Marking or International Protection Marking
The Ingress Protection Code or International Protection Code, IEC standard 60529 classifies and rates the degree of protection provided by mechanical casings and electrical enclosures against intrusion, dust, accidental contact, and water.
The IP rating format consists of the letters “IP” followed by two numbers and, occasionally, an optional letter. When no protection rating relates to a certain criterion, an “X” acts as the placeholder. Here is how to read it –
- The first number, ranging from zero to six, denotes the level of protection the assembly offers against the ingress of solid particles.
- The second number, ranging from zero to eight, denotes the level of protection the assembly offers against the ingress of liquid. The liquid-ingress range recently has been extended to nine to include a rating for high-pressure, high-temperature wash-down applications.
- Additional letters may be added after the two digits, such as “f” which means that the product is resistant to oil.
How to optimize machine vision equipment?
- To ensure that you have the right industrial machine vision system installed, conduct a stress test. It will help you optimize for the environment and the system being inspected.
- Motion blur can be removed by increasing the shutter speed of the camera or using lasers for illumination.
- There are various ways to overcome temperature variance and prevent image quality from deteriorating,
- Solid-state Peltier coolers can be used to reduce the sensor’s temperature.
- For indoor applications, a heat sink and fans with adequate airflow to cool the sensors will work.
- The heat coming from an LED can be compensated by using a lighting controller that can adjust light output and keep temperatures within the acceptable range. Water cooling or other coolants can help in certain harsh environments.
- Fan cooling or even liquid cooling can be used to dissipate heat and lower the thermal resistance of an industrial camera.
How to protect industrial vision systems?
To get optimal performance from a machine vision system in an environment having particulate matter, enclosures are built for protection. These can be custom-built as per specifications and regulatory requirements.
NEMA ratings can be used for enclosures for wider acceptability. NEMA 12, 12K – NEMA 12 and NEMA 12K enclosures are intended for general purpose and indoor use. The NEMA 12 and 12K enclosures protect against dripping and splashing water, are rust-resistant, and do not include knockouts (partially punched openings that can be removed to accommodate cables, connectors, and/or conduits).
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Machine vision can be equipped to work in harsh and hazardous environments. Machine vision has revolutionized quality in food-packaging, crop harvesting machinery, industrial construction machinery, consumer automotive guidance systems, weather systems, unmanned robotic machinery, marine biology equipment, etc.
It is ready to take on the challenges thrown up by harsh and hazardous environments.