A road train that is available 99.986% of the time, drives autonomously and chooses the fastest route is still a dream of the future for long-haul transportation. For the autonomous transport vehicles from Schiller Automatisierungstechnik GmbH, it is a reality. The company, headquartered in Osterhofen in the Lower Bavarian district of Deggendorf, recently successfully completed a project with 22 autonomous route trains on behalf of a major Bavarian car manufacturer. The fleet transports over 500 tons of material per working day from the warehouse to assembly, covering a distance of over 300 kilometers every day. During the 10-shift test, over 1,550 kilometers were completed autonomously with maximum availability.

Converting standard electric tractors into autonomous driving systems
Founded in 1985 by Ewald Schiller, Schiller Automatisierungstechnik GmbH has developed into a company with more than 240 employees in Osterhofen, Metten, Grafenau and Shenyang, China. Electrical, mechanical and IT systems for automation, logistics, cleanrooms and electrical planning are among the company's core competencies. Schiller laid the foundations for the development of solutions for autonomous tugger trains in 2018. "It quickly became clear to us that safety technology would be a key issue for our driverless transport systems, because with tugger trains, as with trailer operation in general, lane departure of the trailers is an important problem to solve," says Peter Stoiber, Head of Mobile Robotics at Schiller, explaining one of the challenges during the development work. The engineer and his team also had to calculate the error probability of all components and ensure maximum availability in order to comply with the strict machine guidelines. The development work led to the perfection of an indoor GPS, with the help of which the tugger train always recognizes where it is. This means that no structural changes are necessary for orientation during transportation. Each Schiller tugger train can also be easily adapted to changing situations in the production process and can also be used at other locations. The biggest advantage of the solution is that standard electric tugs can be converted into autonomous systems using Schiller technology.

Commercially available electric tugs are used as the basis, which Schiller converts into driverless tugger trains using standard components, including the vibration dampers from ACE © ACE Shock absorber GmbH

The task: Ensuring the electronics are fail-safe
Even if the tugger trains can still be operated by the driver after being fitted with the conversion kits, the autopilot shows its strengths day after day in everyday use. For example, when the tugger train arrives near the next work station, a smartwatch on the wrist of the responsible employee reports the status via a vibration alarm. The employee can then load or unload the wagons and give the signal "all actions completed, send train on". In this way, the route is continued without delay. Unnecessary travel times for staff are eliminated. As smart as the Schiller route train is, one thing it can't do yet is fly. And this was one of the last problems that Peter Stoiber, as Head of Mobile Robotics, had to face with his team during the development process. After all, the train sometimes has to travel on uneven tracks or cross building corridors on its many different routes through the automotive plant. These are potential danger points that endanger the reliability of the electronics. It was therefore important to prevent the control cabinet from vibrating. To achieve this, the tugger train was to be fitted with vibration dampers at the critical points.

"ACE first convinced us with its large selection of suitable components and because we were able to configure and calculate the vibration dampers on the ACE homepage." Peter Stoiber, Head of Mobile Robotics, Schiller Automatisierungstechnik GmbH © Schiller Automatisierungstechnik GmbH

"ACE's sales team then responded very quickly to our inquiry and convinced us with a sample. This gave us additional confidence in the quality and durability of the proposed solutions." Based on the key data of the maximum speed of 10 km/h and the control cabinet weight of 50 kg, four rubber-metal isolators of type AAM-52205 were determined. This family of maintenance-free and ready-to-install vibration dampers is designed to absorb loads between 0.5 kg and 22.7 kg. The small shock and vibration-isolating connecting elements therefore effectively help to protect lighter components. They isolate in all directions and can be mounted in any desired spatial axis and used for loads in the push, push and pull direction. Made of galvanized metal and with rubber components made of neoprene as standard, they can also be ordered from ACE with highly damping silicone for special applications against heavy impacts.

With a natural frequency of 16 Hz to 46 Hz, the AAM-52205 rubber-metal isolators provide effective vibration isolation in all directions, and not just for this application © ACE Shock absorber GmbH

Even though they are being used for the first time in their standard version on driverless transport systems in the logistics sector in the application described here, vehicle technology has long been familiar territory for these machine elements. ACE customers around the world use them to protect against shocks and vibrations in lighter electronic systems and components, including in off-road vehicles and trucks, which have always been steered by humans to date.

Visit ACE Stoßdämpfer GmbH from June 27-30, 2023 at automatica, hall/booth A5.518.