Design of a Test Bench to Measure In-Plane Friction Forces Produced by a New Under-Actuated Modular Device

Flexible and adaptive systems for handling and transporting materials within companies and warehouses are increasingly being studied in order to respond to the variability of production and the market. Following this trend, the authors, seeking a simplified design and control, proposed a novel under-actuated modular surface that exploits the friction forces generated by idler rotors inside the modules, for object manipulation. On this subject, the paper concerns the design of two novel measurement set-ups for the determination of parameters fundamental to the single module functioning and the validation of its analytical model. In particular, the test benches are designed to collect the friction forces exchanged between the device rotor and the object moving on top of it, simulating a normal working condition of the surface. The first set-up is specifically dedicated to identify the friction coefficients in the two main directions of the rotor, i.e. along the axis of rotation and in the perpendicular direction. While the second set-up is focused on the validation of the analytical model, thanks to the simultaneous measurement of the two in-plane friction forces caused by the object moving in different directions with respect to the rotor axis. The article describes the operating principles of the test benches and the analytical models for interpreting the data. In addition, some results concerning friction coefficients are introduced. These verify the basic operating assumptions and therefore evidence the module functioning and the quality of the novel test benches, opening their use also for similar transport devices.