Robotic food processing now with x-ray vision

X-ray imaging has been added to the arsenal of sensing technologies being used to guide robotic food processing and packaging systems. Zen Automation has been working closely with Melbourne-based Applied Sorting Technologies in using x-ray sensing to expand the capabilities of robotics systems, particularly for processing fresh fruit and vegetables.

Robots are playing an increasingly important role in helping Australian and New Zealand producers maintain high quality standards for their products while at the same time helping to lower costs and reduce waste. Compared with the manufacturing of mechanical and electronic goods, in which parts are generally consistent in terms of their size and shape, the food industry has always presented greater challenges in adapting robots.

So far, most of the robots used in food manufacturing have been associated with simple tasks like carton palletising.

To employ robots 'upstream' of packaging, in the actual processing of food it has been necessary to develop robots that can deal with variations inherent in the products being processed. This can include variations in size and colour as well as internal structure and defects like overripeness, bruising damage, etc. This is particularly the case in processing fruits and vegetables like broccoli heads, lettuces, etc.

Also, robots used in food processing often have to cope with products delivered with random orientation and placement on a belt and with environmental issues like extremes in humidity or temperature.

On the other hand, x-ray systems have been used by the food industry for several years, generally as an inspection tool to detect contaminants like metal, bone fragments or glass. Their main purpose has been to separate out defective products by means of mechanical deflection devices.

The integration of x-ray machines and robots through the combined efforts of Zen Automation Technology and Applied Sorting Technologies has revolutionised the way food processors can handle their products. In new machines to be built on a joint basis, the x-ray unit is applied as an imaging sensor, to identify not only contamination but also the physical attributes of the product such as internal defects or damage as well as the product's geometry, including its orientation, size, shape and position.

The x-ray system makes an assessment of each item passing along a conveyor based on pre-programmed criteria and passes information to one or more robots dedicated to the system. This information enables the robot/s to pick items from the conveyor regardless of their position or orientation and present them either for packaging or further processing, depending on the x-ray assessment.

Typical applications where x-ray imaging can be used to guide robots include looking internally for damage caused by insects or disease and either grading the product accordingly or directing automatic trimming robots to remove the defect.

In one application, x-rayed items are picked from a conveyor belt and presented to a cutting or trimming device to further process the products in order to present a consistency of quality in the finished products.

Another application being investigated by Zen Automation and Applied Sorting is lettuce inspection and core removal. Fresh lettuces can be scanned to detect stones and insect damage. At the same time, two directional measurements taken from the images are used to provide core position and orientation so the lettuce can be aligned with a blade mounted next to the robot. This provides for automatic core removal.

In smallgoods manufacturing, random sausages on a belt can be x-rayed for metal or bone fragments, picked up by the robot, regardless of their orientation, correctly aligned and placed into trays for shrink-wrapping.

According to Zeng Li, managing director of Zen Automation, "Every situation is different and we bring together the best combination of technologies to provide a turnkey solution. X-ray imaging is new in food processing robotics but it has a lot of potential. Applied Sorting is an Australian-based company specialising in x-ray imaging and we expect that by working with them we can give our clients a wider range of solutions for their needs."