Dambach is thus implementing a distributed control concept with superimposed head control and decentralized, autonomously operating transport vehicle control, all in fail-safe design from the Siemens Simatic S7-1500 portfolio. The cost-optimized decentralized controllers in particular met the exact requirements in terms of features and size. The vehicles communicate via so-called leaky waveguides (RCoax antennas) along the route(s). The proven IWLAN cable with a precisely defined radio field is predestined for logistics applications with many moving components in difficult environments characterized by reflections.

The driving orders are coordinated centrally, safety areas, routes and order assignments are monitored and visualized in the new SCADA system based on Simatic WinCC. Each vehicle adjusts its own driving dynamics and positions itself precisely. So precisely, in fact, that distances of at least 35 millimetres on the routes and in the region of 25 millimetres at the pick-up and delivery points are safely possible. This means that two trolleys can transfer their loads simultaneously next to each other in the tightest of spaces.

Safety in use

In the event of a fault, for example when an emergency stop is triggered or a safety gate is opened, the vehicles in the relevant safety area are brought to a controlled standstill and their drives are brought into a safe state. Data transmission via Profinet and Profisafe takes place via industry-proven Scalance W734-1 IWLAN clients on board the Dambach rail carts and several stationary Scalance W778 IWLAN access points distributed throughout the system. This ensures very short, deterministic response times - and therefore maximum security. The IWLAN technology, which has become the new Dambach standard, is certified for worldwide use and can be used without subsequent testing, which further simplifies international projects.

The logistics specialist also relies on Siemens for the drive technology of its rail carts, with the inductive DC power supply and the requirement for a visibly more compact design defining the scope. Suitable Simogear geared motors and Sinamics frequency inverters were jointly specified and tested and qualified for operation at 500 volts and 720 volts DC respectively. The travel drive is controlled by a powerful Sinamics G120 in the control box with higher-level position control in the Simatic technology object.

A Simogear geared motor with Sinamics G115D motor-mounted frequency inverter is used in the base of the trolleys for the boom movement. The system supports temperature ranges down to -30 °C and therefore also addresses demanding deep-freeze applications. The multi-certification enables international use without specific country variants.

"You can tell that both inverters are descended from high-end devices, especially the unusually high control quality and versatility in this price/device class," says Dirk Lorenz, Product Manager at Dambach. "This enabled us to implement dynamic encoderless vector control on the line and precise position control via PLC at the transfer stations." The software of both inverters supports the STO (Safe Torque Off) safety function via Profisafe as a basic feature, so that the required safety could be implemented without additional hardware and complex wiring.

The drive specialists from Siemens have also contributed to a solution that allows the inverters to be operated at the power limit of the inductive supply in any operating situation, which is 3 kilowatts at 500 volts direct current. This enables an acceleration of up to 0.7 m/s² and travel speeds of up to 150 m/min and prevents impermissible overloading of the inductive power supply (falling below the DC link voltage) and thus malfunctions while at the same time ensuring maximum acceleration yield. In addition to the central visualization in the SCADA system, there is a connection box for a portable HMI (human-machine interface) device on each vehicle and at important junctions, currently the Simatic HMI KTP900F Mobile with a 9-inch TFT display. This allows localized image content to be called up and, for example, rail carriages to be moved in manual mode. All this with a transport vehicle length that is only slightly longer than a Euro pallet.

Engineering under one roof

A decisive added value of an integrated automation solution from Siemens is the joint engineering for control, peripherals, HMI, drives and communication in the Totally Integrated Automation Portal, or TIA Portal for short. This standardizes the project planning and programming of standard and safety tasks, saves multiple entries in previously different programs and shortens the engineering process with prefabricated standard, safety, motion control and HMI modules (templates). A standardized Siemens module library for intralogistics applications was easily integrated, so that all vehicle coordination and material flow control tasks could also be implemented very quickly.

"By using selected Siemens components, we were able to meet the increasingly important customer requirement for optimum space utilization," adds Dirk Lorenz. The compact inverters and controllers have made a significant contribution to achieving the target of an approximately 20 percent smaller rail cart and also to keeping within the ever-tight budget. The Monoflex system has now proven itself in several international projects in the food, beverage and automotive sectors and has demonstrated its significantly higher performance.

Dambach is already in the implementation phase with the 720-volt version of the Monoflex system, which removes the previous power limitation. This in turn enables around 25 percent greater acceleration, higher transport speeds and therefore even more handling capacity. "With this solution, we have achieved a very modern, future-proof state of the art in terms of both warehouse logistics and automation," says Dirk Lorenz.

From materialfluss 6/2023