Fraunhofer Institute for Material Flow and Logistics IML
Chassis
The STUART chassis is an innovative, patented chassis concept. It solves the static over-determination of conventional four-wheeled chassis without costly and maintenance-intensive springs, dampers, or actuators. Thanks to its simple design, the chassis can be scaled in size and load capacity and is suitable for almost any application.
The STUART chassis has one front and one rear support wheel, as well as two drive wheels placed centrally, forming a central differential drive axis. All wheels are connected to each other with simple levers and joints, forming two coupled support triangles. This allows all four wheels to maintain contact with the ground at all times.
This chassis design ensures the stability of four-wheeled chassis and prevents the typical "tilting" of unsprung four-wheel vehicles on uneven ground. The lever ratios are designed in such a way that the majority of the transported load acts on the drive axis, ensuring sufficient contact pressure for the drive at all times. The central differential drive and low overall height ensure good maneuverability even in tight spaces. This characteristic eliminates the need to restructure the operating environment due to lack of space. The fact that all four wheels have ground contact at all times allows the use of AGV with the STUART chassis even in halls with highly uneven ground, which is actually unsuitable for AGV, as it does not require extensive renovation. Due to the lack of unnecessary suspension on the chassis, the loading surface remains a non-yielding plane that does not change its position during the loading process. Furthermore, it is not necessary to compromise between good suspension for the empty or loaded vehicle.
Load transfer station
The load transfer station, which was developed in conjunction with the STUART demonstrator, follows the same guiding principle as STUART: mechanically simple and cost-effective design without actuators and additional sensors/electronics.
The station consists of two supports fitted with roller conveyors, which serve as a support surface for the transport unit (in this case an EU pallet). In the front area (entrance to the station), approx. 50 cm of the roller tracks are inclined slightly downwards so that the pallet can be pushed onto the roller track by the vehicle as it drives into the station. This means that no active lifting device is required on either the vehicle or the station. The transport unit is lifted from the vehicle and transferred to the station solely by the AGV travelling forwards. Depending on the design of the station, the AGV can drive through the station without stopping after the load has been transferred or stop in the station and drive out in reverse. To pick up a transport unit waiting at the station, the AGV drives into the station in reverse orientation and can then push the load off the roller conveyor with a simple gripper mechanism and transfer it to the tines of the vehicle.