Removing a workpiece from the feeder and placing it in the appropriate holder for further processing is a monotonous work step. It is perfectly suited to automation - and yet is still often done by hand. Conventional pick & place systems, on the other hand, usually slow themselves down with long changeover times when different workpieces need to be processed.

Erfurt-based system integrator Seitec, in collaboration with drive specialist SEW-Eurodrive, has rethought this task area from the ground up. The result is a flexible handling solution that combines all the components of a pick & place system in a single, convenient user interface. The machine can process hundreds of very different workpieces with minimal changeover times. The IEC software module 'Movikit ProductionLineControl' from SEW-Eurodrive was used to manage and track the workpieces in the machine. It enables workpieces to be transferred from one moving belt to another moving belt.

In a classic control system setup, various complete, closed systems have to communicate and function with each other. Each is usually equipped with its own control system, its own operation and special components.

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The processes are stored in the unit's control system. Using touch functions on the control panel, a machine operator can quickly adjust the system to a new workpiece. If a gripper needs to be changed, the machine prompts this in the same interface and parks the central robot in the appropriate position. The process takes about one minute in total, which saves time compared to systems that require intervention in various operating units on the machine for adjustments - especially when handling small batch sizes.

The customer also wanted to be able to operate the camera via the visualization of the entire system. This means that neither a laptop nor software is required to run in the system with new parts or to teach in new contours.

Reduced complexity thanks to standardized interface

With the integrated control system, the camera is also operated via the visualization of the entire system. With the modular design, the individual components are connected to each other via standard interfaces, which ultimately contributes to a longer system service life.

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The first example of this innovative complete solution 'Seibot' was ordered by a large medium-sized production company for the processing and manufacturing sector. The order was triggered by a not-so-rare problem: a partial system of the production line, which has only been in use for ten years, has already been discontinued by the manufacturer. The old machine can no longer be adapted to new requirements with reasonable effort and is therefore no longer future-proof.

As a solution, Seitec and SEW-Eurodrive jointly developed a standardized interface between the robot controller with the 'Movikit Robotics' software module and the higher-level system controller. This combination is suitable for all robot geometries from Scara to 6-axis articulated arm robots. Compared to conventional systems of this type, the complexity has been significantly reduced. The advantage of this concept is that the position and dynamic values of the robot for the pick & place process can be set via the visualization of the higher-level control system. This allows machine setters and maintenance staff to optimize the production process at any time, eliminating the need for a separate control panel or special software. The simple and modular design using standard industrial components and the consistent use of standard interfaces also increases the service life of the system.

Separate different geometries

CMP servo motors with precision servo gearboxes from the PxG series - here a test setup - drive the tripod robot.

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The heart of the system is currently a tripod robot with an additional rotary axis, which is equipped with two different grippers as required. It is driven by four servomotors from the 'CMP' series with PxG gearboxes from SEW-Eurodrive in the P5 version (for high dynamics). The workpieces are separated in advance using two different methods. A camera for industrial image processing, which is integrated into the overall system via Ethernet/IP, records the shape and position of currently around 130 different workpieces on the feed belt. In line with the current state of the art, this no longer has to be transparent, which simplifies handling and servicing. In addition, the pick belt and the place belt can be arranged at any angle to each other. The system thus provides the standardized basis for the kinematics of the pick & place robot with four degrees of freedom.

The customer's aim was to place several workpieces on a goods carrier every second in preparation for the next work step. These targets were achieved with the system.

Simple operation

If a new workpiece is to be taught in, the system is configured in just a few minutes via the control panel using the intelligent 'UHX65' Movi-C controller from SEW-Eurodrive. The process is then saved as a new "recipe". If the robot needs more degrees of freedom or a different camera at some point, each component could be easily changed thanks to the non-proprietary interfaces. They could then be integrated into the system with little effort using the kinematics data already available in the Movi-C controller. Anything between two and six degrees of freedom is possible.

The author: Hans-Joachim Müller is market manager for drive electronics at SEW-Eurodrive in Bruchsal.

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The feed belts with ten additional servomotors from SEW-Eurodrive are also controlled by the same controller, which in this way already has an internal image of the entire kinematics of the system. Because the robot and the belts form a system with the parts, the encoder information from the belts is received directly by the 'UHX' controller. This means that the robot knows the encoder values and the positions of the belts. Up to ten robots, 2000 products and 200 storage boxes can be managed.