This cobot must have good vision

When Würth opened the VZ West sales center at the Künzelsau-Gaisbach site in May 2013, Norbert Heckmann, Chairman of the Management Board of Adolf Würth GmbH & Co. KG, promised, among other things, that employees would benefit from the innovations of the new building. He said, "It will make your daily business even easier." To this end, Würth integrated modern technology and designed the workplaces ergonomically. However, the goal of dealing sustainably with the resource of manpower as well was not yet considered complete: Even today, the specialist for assembly and fastening technology checks whether tasks are too monotonous or physically demanding - as in the incoming goods department of the sales center.

Here, 30 people work in two shifts per day and move around 3,000 boxes. They stack the 500 to 5,000 gram cuboid cartons full of screws, nuts, washers or steel construction elements from pallets into small load carriers (SLC). "The total load of an employee thus amounts to several tons spread over the shift. The monotony of the job is just as stressful," clarifies Roland Schneider, Head of the Technical Department at Adolf Würth GmbH & Co. KG.

Until now, consistent rotation after four hours was the best way to counteract the ergonomics and monotony of manual processing. In order to relieve the employees, cover further growth and counteract the increasing shortage of skilled workers, Würth will increase the degree of automation in logistics.

J. Schmalz GmbH set itself the task of intelligently automating the existing manual handling process. "Moving boxes of different sizes and weights is the ideal task for our BinPicking gripper SBPG," explains Matthias Frey, Business Development Robotics. The SBPG is sufficiently long to dip into the boxes and light enough not to reduce the lift capacity of smaller robots too much. This allows a space-saving cobot from Universal Robots to guide the gripper while the Vision Eco-System for Schmalz VE4S does the seeing. By using standard components from its robotics and vision area, Schmalz provides Würth with an economical solution for less than 100,000 euros that can be implemented quickly thanks to plug-and-play systems - without much engineering effort.

The concept was quickly established, although two details were particularly challenging for Schmalz's technological know-how: firstly, picking from the pallet and tightly placing the packages in the boxes despite the high variance, and secondly, recognizing an intermediate layer with an unknown imprint. Further complicating matters here is that the design of the slip sheets can resemble that of the boxes. "The only approach that worked here in a process-safe manner was the use of artificial intelligence," explains Frey. Schmalz implemented the defined setting pattern with workpiece-specific programming. "We started with a limited range of parts, which utilized the first cell to 100 percent capacity. Now we are working on optimizing the picking performance of the subsequent cells and expanding the parts spectrum to be able to store additional items automatically."

In contrast, the challenges posed by the tight space conditions at the site and the additional task of retrieving the empty containers from a crate conveyor were relatively easy to meet. This is because a laser scanner eliminates the need for a safety fence and thus ensures a lean cell. As soon as a person approaches, the collaborative robot reduces its speed and continues to work safely with reduced forces.

To perform the various gripping tasks, the cobot can independently exchange the suction cups of the SBPG BinPicking gripper and - thanks to the MATCH quick-change module - the entire gripper. "One load picker is always on the robot arm while the other waits in the gripper station. If, for example, a crate needs to be moved, the cobot fetches the PXT gripper designed for this purpose. Thanks to the standardized connection and communication, this is immediately ready for use," explains Frey. Three suction cups, the SAOF oval, the SPB1 60 and the SPB1 80, are available to the SBPG so that the robot can safely handle any size of carton. The required vacuum is provided by the RECB pneumatic vacuum generator. Its integrated SEP nozzle ensures efficient and at the same time energy-saving operation.

Schmalz implemented software with a user interface that employees use to enter the current job. This communicates with the camera, the cobot and the safety laser scanner and, after input, adjusts the robot controller and the camera to the task. "Currently, we cover around 30 percent of the extremely extensive range of goods - and the trend is rising," explains Frey in April 2022. The special feature here is also that Würth controls the entire order management of the robotic cell via the software. What already works 100 percent are features such as the target container check, in which the camera checks whether the SLC provided is really empty, the detection and removal of the intermediate layers from the source box, and the collision check. Here, the software calculates the waypoints that the robot approaches and uses the digital twin to check whether there are any collisions. If this is the case, it avoids the obstacles and defines new waypoints.

The collaborative robot has been in operation at the VZ West distribution center since the end of December 2021. "What I hear from our staff in the incoming goods department is consistently positive - they are thrilled," reports Roland Schneider, who immediately afterwards provides an insight into the day-to-day work with the Cobot: The employees use the lift truck to move a Euro pallet with boxes into the designated area. The boxes are between 100 and 250 millimeters long, 90 to 100 millimeters high and 90 millimeters wide. The robot fetches the SLC target container itself from a conveyor belt. The robot cell fills as many SLC containers as necessary until the Euro pallet is emptied. When the totes are pushed onto the conveyor system, they are scanned and booked in the SAP system.

The solution at Würth shows how a collaborative robot in combination with a camera system and the right programming effectively relieves employees. "The cobot reduces monotonous work, significantly improves ergonomics and is therefore a valuable support. The task now is to gradually familiarize it with our entire product range so that it eases the personnel bottleneck somewhat," emphasizes Schneider, who would like to implement further projects with Schmalz and "the great team of experts around Mr. Frey".