A car-seat example of automated anthropomorphic testing of fabrics using force-controlled robot motions

For the last years, automation is widely used to relieve humans from repetitive tasks, primarily and firstly within manufacturing. However, for products with less ideal (or hard to model) properties, and when forces depends on human interaction, automated testing has not been explored until now. This work presents the analysis of the (human-dependent) motions/forces based on a fully implemented test case for car-seat testing. For emulation of the corresponding mechanical wear, an experimental test bench was developed. A sensor mat with a pressure gauge net was used in the test bench to determine the relevant loads, and the corresponding movements performed by the humans when sitting in a car seat were acquired by means of a photogrammetry system. Finally, to automate the reproduction of such movements by means of a dummy held by a robot, several controllers have been developed to regulate the force applied by the dummy on the seat. Simplicity and force-control performance for the human replication was also investigated in this work, showing the benefit of freely programmable (open) force control. The developed system has many practical applications, as allowing the analysis of the wearing caused by these movements on the seat upholstery. Thus, force controlled testing of fabrics using robots is a viable option. Note to Practitioners-In this paper, an experimental test bench is presented for the analysis of the mechanical response in car seats. It consists in a force control application in which the robot, by means of a dummy, must apply a controlled force on a car seat, simulating the movements of a human sitting on and standing up from the seat. This simulation is limited by the fact that normalized dummies used in tests are usually conceived to reproduce a sitting position and do not have the mobility of the human body. Furthermore, the simulation with a six axes robot limits to six the degrees of freedom the movements that can be performed with the dummy. Hence, an important part of this study consists in simplifying the human movements in order that they can be performed with the described components and still adequately reproduces the interaction between the body and the seat. In order to develop and validate this experimental test bench, the movements performed by passengers sitting on or standing up from the seat in an actual car have been firstly acquired. Therefore, a four-camera photogrammetry system and a pressure mat have been used. This paper also describes the procedures used to capture and reproduce the human body movements and their forces. In this work, an ABB IRB140 industrial robot has been used, as well as a six degree of freedom JR3 industrial force sensor. For the development of this test bench, two control architectures have been used. The first one is based on a commercial ABB software so, it can be used for application development with any ABB industrial robot. The second control architecture proposed is an open architecture allowing access to the robot state variables, much more complex motion and/or force controllers can be implemented.