Greater safety in plant traffic thanks to smart forklift trucks

At automotive supplier REHAU Automotive’s plant in Brake on the Lower Weser, production and dispatch are mainly taken care of by forklift trucks. As the processes in production became increasingly complex and dynamic, the large number of items involved meant that finally it was also necessary to reorganise the entire safety concept for internal transport. Working jointly with the Hamburg-based intralogistics expert STILL, a pioneering safety system was implemented for plant traffic. Based on smart driver assistance systems, AI-assisted cameras and visual warning signs that actively warn pedestrians of danger by means of projection, the optimised safety system should in future become the benchmark for other production sites as well.

REHAU Automotive: a successful polymer specialist for over 70 years

On 6 September 1964, the REHAU plant in Brake was established in a space of 2,750 m2, with 15 employees. First producing piping, REHAU Automotive specialised in injection moulding, painting and assembling polymer systems for the bodywork attachments of cars from famous automotive manufacturers. Matthias Blum, Supervisor Production Logistics, explains: “Every day, we have around 180 trucks either arriving in the incoming goods area or taking our bumper systems and external attachments out for delivery. This means that we are issuing up to 6,000 driving instructions per day for internal transport, which are processed by the 91 industrial trucks of the STILL electric forklift fleet.”

Thanks to constant expansion, the REHAU plant now employs more than 1,000 people in 80,000 m2 of hall space on a premises covering 234,000 m2 in total. REHAU Automotive is a German company based in Rehau in Upper Franconia and is one of five companies in the Rehau Group. In 2023, the overall group generated revenue of more than EUR 4.5 billion with a workforce of approx. 20,000 spread over 190 locations worldwide.

Optimum safety standards for transportation

Over the years, the large product range has also made the workflows in production logistics increasingly complex. Consequently, faulty processes in the production supply put safety in plant traffic at risk. “To achieve optimum safety standards, we finally got together with the intralogistics expert STILL, taking advantage of the company’s vast experience and problem-solving expertise to re-organise our transportation,” says Matthias Blum. Michael Dänekas, STILL Regional Service Manager Safety & Energy Solutions, adds: “Our Safety Assist functions support the forklift drivers via sophisticated warning systems and automated intervention, in order to reduce accident and injury risks to a minimum. Our driver assistance systems are smart assistants for day-to-day warehouse routines and internal transport. The automated processes, ergonomic working and fatigue-free operation increase safety significantly.”

Today, the optimised transportation safety system has virtually eliminated the risk of accidents in plant traffic. Thanks to the wireless zone detection, there is almost no collision damage at hall doors. Truck speeds are also limited, which reduces the risk of accidents considerably. In addition to this, pedestrians are actively warned and protected at dangerous crossings by STOP signs that are instantly projected as the forklift trucks approach. Moreover, state-of-the-art AI camera systems for persondetection actively provide the driver with multi-level visible and audible warnings in the event of danger, slowing the truck down and even bringing it to a standstill.

Smart driver assistance system: wireless zone detection protects hall doors

In the Brake plant, the hall doors are controlled by motion detectors. Matthias Blum: “The increased volume of traffic meant that trucks occasionally came to a halt in the middle of the door area. This also resulted in accidents and collision damage at the hall doors. So the most important requirement for the new safety system with wireless zone detection was speed reduction, to reduce to a minimum the risk of accidents involving the building infrastructure and to protect pedestrian traffic.” Door zone areas, driving speeds and forklift truck lift mast heights were analysed jointly with STILL, with the collected data being parametrised in Safety Assist. Furthermore, the 36 trucks of the forklift fleet were fitted with radio antennas and connected to the truck control system at the driver interface. Relevant receiving sensor for the wireless data transmission were mounted in a fixed position at 26 hall doors.

Now if a truck drives into the danger zone of a hall door, it immediately sends a wireless transmission to both door modules that are mounted at set distance parallel to the roadway. This contains all the information for activating predefined safety functions such as reducing driving speed and switching on warning lights for pedestrians. Zoning Assist manages the performance of the forklift truck in real time. Continuous wireless triangulation measurement, that is, measuring the angles in the triangle between the forklift truck, door module 1 and door module 2, allows the hall door to open at the right time and also remain open until the truck leaves the danger zone behind the door. As an additional safeguard, the maximum top speed can only be activated by pressing the accelerator pedal again.

“With the wireless zone detection from STILL, we now have a reliable gate solution and also an automated and safe process for drivers who approach the doors at too high a speed. As it stands, there is hardly any collision damage at the hall doors,” confirms Matthias Blum.

Precise and stable wireless technology with lower costs

Via transmitters and receivers, the system communicates using short range digital wireless technology, the ultra-wideband range (UWB), which is less fault-prone in an industrial environment. With wireless UWB, the spatial and directional data generated at high frequencies allows objects to be located with an accuracy of up to ten centimetres. “The UWB radio signal is precise and stable, so only one active antenna is needed on each forklift truck roof. Moreover, both the hall doors and the projector lighting technology are controlled by the same radio signal. The advantages of this are obvious. The acquisition costs for wireless UWB are lower compared to other technologies, plus you only have to invest in the plant infrastructure once,” explains Michael Dänekas. So if structural conditions change, the wireless zone detection from STILL can be adapted quickly and flexibly to the new circumstances. If, for example, a plant traffic hazard point changes, the projector for the lighting technology with the integrated radio module can be easily repositioned. The advantages of zoning technology were also crucial criteria in the decision to award the contract, according to the STILL project manager.

Driving speed restrictions reduce the risk of accidents considerably

The maximum driving speeds in halls and outdoor areas can also be limited using the speed parameters in the zone detection. As Matthias Blum explains: “This reduces the risk of accidents considerably. Due to the high level of pedestrian traffic in the halls, the challenge was to limit the maximum forklift truck speed to 10 km/h without reducing productivity, or requiring additional personnel. In outdoor areas, on the other hand, we set the speed limit at 16 km/h because the transport routes are long and there is less pedestrian traffic.” All the safety and performance functions are monitored with the STILL Easy Control display and control unit. The limited speed is visually highlighted by an additionalLED installed in the cockpit, which is clearly visible and lights up red when activated. It means that the driver has all the relevant information in view at all times and can activate the truck’s performance functions including driving speed limitations, acceleration and lifting behaviour, depending on the application.

Modern camera systems minimise the risk of accidents

The new AI-assisted camera system from STILL detects people and objects resembling people in real time. Thanks to the integrated AI processor, no additional hardware is required for person detection. The camera does not have to be attached only at the rear of the truck; it can also be attached at the front or at the sides of the forklift, where potential hazards may emerge during the work process. The camera works effectively, even under extreme conditions between −40 °C and +85 °C, and a system comprising several cameras can be established. For rear monitoring, a camera is positioned at the rear of the truck, on the rear counterweight or overhead guard, for example. This camera is activated automatically when the truck reverses, so that the driver can identify people and objects behind the truck.

The driver is warned in two stages, firstly by the camera image and secondly by an acoustic signal over a loudspeaker inside the forklift truck. In the detection zone, a moderate frequency acoustic signal is triggered and the person is framed in yellow on the monitor. The option is also available to slow the truck down. Finally, in the warning area, there is a continuous audible alarm and the person is framed in red, where the optional STOP function reduces the risk of accidents to a minimum. Both the detection zones and the warning mechanisms can be configured as desired. The HD resolution screen ensures accuracy of detail and the robust design ensures optimum functionality. Thomas Köhle, Plant Director of the Brake site, is impressed with the new safety system for transportation: “By having trucks with the highest safety standards, we are taking decisive action to counteract the ever-increasing dangers of warehouse operation and internal transport. On average, we add at least double the value for every euro that we spend on preventive measures. We also improve the image of our Brake plant, both among our own employees and our contractors.”

Active visual warning signals increase vigilance

The use of fixed and mobile safety lighting installations makes it possible to reduce personal injury and collisions in busy work areas. The plant therefore has several LED projectors for STILL Safety Lighting systems on driving routes and walkways, which instantly project clearly visible floor markings for pedestrians when forklift trucks are approaching. The immediate projection of a stop sign makes pedestrians more aware and vigilant, while the projection neither fades nor gets worn over time. LED projectors are also replacing painted guidelines on the ground in high-traffic areas. If the plant traffic conditions change, the projectors and the receiving modules for data transmissions can be quickly and flexibly positioned at the new danger points, meaning you only have to invest in the plant infrastructure once. The perfect addition to the Safety Lighting System is the STILL Warning Zone Light Plus that is also installed on the forklift. When the truck is switched on, two strips of light are projected to the left and right of the forklift, and a semi-circle is project at the rear. This therefore acts as a visual warning for pedestrians and other drivers in the immediate vicinity of the truck.

Summary

The optimised STILL safety system for plant traffic not only minimises the risk of accidents, it also minimises energy costs – as until now, faulty hall doors were left open for long periods of time. The automated assistance functions make life far easier for drivers, who receive 6,000 driving instructions every day. Staff productivity and satisfaction also increase. “The smart Safety Assist functions are milestones for safety in plant traffic. Our internal transport system is the benchmark for other production sites and also a flagship project for our entire company,” underlines Matthias Blum.