Christmas time is calendar time. When the turn of the year approaches, the production of personalised calendars reaches its peak. Individually designed calendars are appreciated as a year-round reminder of happy moments. By means of their pick & place solution in a printing shop, the start-up Unchained Robotics help to deliver the personalised calendars to the customers as quickly as possible. The central elements: a collaborative robot and the 3D sensor from ifm.
An industrial area on the outskirts of Paderborn in East Westphalia: this is where large quantities of calendars are produced. Whether 100 copies for business customers or individual copies for private individuals who create their own personal calendar on online portals: a great variety of calendars in different formats from DIN A5 to DIN A3 are packed for shipment and fed to the pick & place station from Unchained Robotics. Here, a laser scanner automatically detects the bar code to allow tracking via track & trace, before the calendar is picked from the conveyor belt by a collaborative robot and placed on a transport pallet or in a post box – neatly sorted by size.
The heart of the robot installation is the 3D sensor from ifm, the O3D. The operating principle of the O3D is based on the time-of-flight principle. By means of 23,000 pixels arranged in a matrix, the 3D sensor detects the time needed by the light emitted to reach the sensor again as a reflection per capture. Based on this data, the O3D precisely calculates the spatial dimensions of objects and scenes. "This aspect played an important role in our decision for the O3D," says Mladen Milicevic, one of the founders of Unchained Robotics. "No other equipment or process stops are necessary, because the sensor exactly detects the height, basic form, angle and displacement of each package. This means that the packages can be placed on the conveyor belt without observing a particular arrangement or orientation. This reduces the strain on the employees and accelerates the manual process," explains Milicevic.
"We particularly opted for the O3D and for ifm because of the easy integration into our in-house developed software," Milicevic continues. "And if we had questions, ifm's support helped us quickly and competently." Based on the data, the software from Unchained Robotics can exactly calculate where the robot has to place its suction cups on the package to be handled. This ensures that the calendar is always picked up at equilibrium and at optimum orientation.
The high precision obtained by the 3D sensor is indispensable for the pick & place task carried out by the robot. "Particularly if the calendars are placed in post boxes, space is at a premium. The robot has to move with great precision and within small tolerance values to prevent its arm or the calendar from colliding with the metal walls.
Depending on the format, the robot places up to 12 calendars in a 3x4 pattern at the placement location. Thanks to the precise positioning, a stack height of up to 70 centimetres is possible even on open pallets. "The reliable and precise detection of the height also plays an important role when it comes to selecting the placement location within the pattern," explains Milicevic. "The robot places the packages according to a special height algorithm taking into account the individual package heights. The packages are sorted so that the highest point is always furthest from the robot. Besides, the packed calendars form a virtually homogeneous, flat surface when the maximum stack height is reached."
With a frequency rate of eight seconds, the pick & place solution of the start-up also masters the high requirements placed on it in the time before Christmas, when up to 6,000 calendars per day leave the printing shop. The packages can have a weight of up to eight kilograms. "This is within the limits of the technical data of a collaborative robot arm," explains Milicevic. "If heavier weights were to be moved or faster frequency rates were required, we would use a more powerful industrial robot. This would be no great problem, as the robot only plays a minor role in our solution. The core of our universal solution is the combination of camera and software, which makes the solution not only suitable for calendars: It is also suitable for any pick & and place process in which products are placed on or picked up from pallets." Another advantage of this powerful combination of sensor and software: As no other system components are required besides the robot arm, the costs for implementation are kept to a minimum.
The O3D is a central element of the pick & place solution from Unchained Robotics. Thanks to the exact detection in three dimensions of the packages, the 3D sensor provides reliable information to the software which helps to precisely control the robot arm. Even during the printing shop's busiest times, the calendars are reliably put in the correct placement location – and reach the customers in time.