The 12 Second Goal - Laser 3D Vision Guides Robot Process Worker

 

The science fiction of factories staffed by robotic workers has rapidly become reality in many industries, more recently lamb and beef processing, where the focus and main impact is on improving yield rather than replacing workers. Since early 2000, Scott Technology Ltd has been meeting the challenges of the highly paced meat processing industry with robotics and machine vision. The robotic systems work together to form the front end of a fully automated boning room located at Finegand Freezing works in South Otago, New Zealand and are tested and refined whilst functioning alongside a human workforce, processing around 1.8 million lambs per year.   This development has now been replicated multiple times in other processing facilities in both Australia and New Zealand.


Since robots were first dreamt of the overriding aim has been to perform jobs that are mundane, repetitive and dangerous. The boning room’s lamb forequarter cutting system is an ideal example. The boning automation begins with the ‘Primal System’ scanning the carcass via x-ray and cutting the hindquarter, middle (saddle) and forequarter. The forequarter system is comprised of a Kuka KR-60, 6 axis industrial robot, equipped with a purpose built end-effector to grip and manipulate the cut forequarter and a vertical bandsaw to dissect the meat. There is no chance of the meat slipping in the hands as often happens to process workers who cannot wear protective mesh gloves that can catch on the bandsaw blade. The bandsaw itself is modified and mounted with servo controlled rotational axis; its movements precisely controlled by the robot. The forequarter is split and the brisket, neck and shanks are cut. While knuckle tipping can be a separate operation, it is usually also performed by the robot/bandsaw system and can be accurately located and cut at high speed.

A meat workers working life is physically difficult and the repetitive nature of the work takes its toll. Furthermore despite strict Health and Safety policy the job is hazardous and accidents with the bandsaw are common. Lacerations, amputations and musculoskeletal injuries are common, estimated by New Zealand’s ACC (Accident Compensation Corporation) at 51 injuries per 1000 meat processing workers.

Scott’s machine vision Team Leader, Donald Liddell is quick to point out “We are not trying to replace people, but trying to reduce hazardous tasks. The robot could be resented but actually it’s welcomed and the workers grumble when it’s off-line.” 

The lamb carcasses can vary greatly due to age, time of year and general variations in anatomy. 3D vision systems are ideal in situations like these, where variability is an intrinsic feature of the product itself. Scott’s system deals with this complex topography by using laser triangulation, combining the information from three laser line scanner units that project a laser stripe onto the forequarter to gain detailed 3-dimensional information. Projecting a narrow band of light onto a three-dimensionally shaped surface produces a line of illumination that appears distorted from other perspectives. The recorded displacement of the stripe can be directly converted into 3D coordinates and processed with Scott’s specialised in-house software to create an exact geometric reconstruction.  

The robot arm draws the forequarter through the scanning area, eliminating the need for extra handling. The resulting image guides both the robot and the bandsaw movements in harmony, quickly and accurately making the required cuts. With a complete image of the external profile of the meat than a human can achieve, the robot can disassemble the forequarter to not only increase the yield but repeatedly improve the quality of each cut of meat, greatly increasing its market value.

Although the forequarter systems has been working effectively in a production environment for several years it still requires some refining before its commercial release. With the aim to process 10 forequarters per minute there are improvements to be gained in cycle time. However the most valuable aspect of the system is its ability to protect workers from a difficult and dangerous task. This will help attract and retain the labor force, ensure a safe operational environment and still allow maximum conversion of raw product to high value cuts; attractive attributes to any company wishing to stay competitive.

 
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