Unstable goods can finally stack up against the rest with 3D camera-enabled automated storage and retrieval system
Automatically stacking goods in a bulk storage area continues to pose technical challenges. It becomes even more difficult when it involves goods that are not rigid. Anyone who has ever stacked several six packs of bottled water knows how challenging this can be, and it doesn’t get any easier on a larger scale. That’s why ek robotics collaborated with SICK to employ 3D cameras in conjunction with an innovative image analysis software. Not only did they tackle the oft wobbly task of navigating an automated storage and retrieval system, but successfully tested it during a customer pilot project.
Automated guided vehicles (AGVs) are still very limited in their ability to automatically store and retrieve pallets, especially when the load on the pallets is unstable and can slip during transport. This makes an accurate process absolutely essential—even more so when pallets need to be stacked. This process can now be implemented using high-performance, industrial-grade 3D cameras. The cameras’ task is to record three-dimensional data on the size, position, and state of the load, as well as important information about the properties of its surroundings.
The key to success: 3D snapshot technology
The Visionary-T 3D vision sensor works on the principle of optical time-of-flight measurement. The 3D camera sends light signals out into the surrounding area and receives the reflected signals again. When mounted underneath the fork arms of the autonomous transport robot (ATR), the Visionary-T captures a three-dimensional representation of the entire area in front of the fork arms.
Image left: 3D depth map: Besides distance values (here color-coded, red = near, blue = far), 3D time-of-flight cameras also provide a black and white image of the scene; Image center/right: Principle of operation of the 3D time-of-flight technology
How the autonomous forklift truck learns to see
For each pixel location, the 3D time-of-flight technology reflects light to the Visionary-T. With the help of the phase shift, the Visionary-T then calculates the distance between the camera and the objects in the scene. Different phase shifts of the light correspond to different distances. In this way, several tens of thousands of pixels are recorded simultaneously with no moving physical parts inside the camera. This allows 3D point clouds to be recorded in real time, even for static scenes. Because the distance information is recorded “in a single shot,” this is also referred to as 3D snapshot technology—the forklift can “see.”
The requisite durability for industrial applications is evident not only in the housing used, but also in the fact that the camera can be operated 24/7 and delivers precise and reliable 3D data—even in difficult light conditions and fluctuating temperatures. This is ensured for the SICK camera by, amongst other things, a powerful illumination unit, a sophisticated thermal management system and intelligent pre-processing of the captured 3D raw data.
Safe pickup and stacking of unstable goods
Ever the pioneering solution, SICK’s journey to develop an intelligent automated guided system for automated loading and unloading wasn’t a solo one. They worked in close collaboration with the AGV system manufacturer ek robotics in Rosengarten near Hamburg, Germany, using their software for the camera to evaluate the recorded data in real time.
“We have taught the forklift to see. The vehicle is therefore able to detect the exact type and position of the goods being transported as well as the pallets. This has been refined to the point where the AGV can distinguish, for example, whether the identified upper edge of the load is the packing film or the load itself,” said Karsten Bohlmann, Head of Research & Development at ek robotics. “This enables the transport robot to safely pick up and safely transport even unstable loads of unequal height.”
The proof is in the pudding…or bottles
While trialing the transport of empty bottled water to test the reliability of the process, the solution resulted in a significantly lower error rate compared to manual control. Both stacking and unstacking were not only performed with a higher level of precision and less transport damage, but also achieved maximum operational safety. The success of this development has inspired ek robotics to tackle more challenging applications with the help of SICK and 3D camera technology.
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