Search results

The paper aims to present the design, validation and integration of a universal fabric gripper. Flexible material handling is one of the most challenging problems occurring in the field of manipulator robots. Because textile products shape and properties can widely vary, each textile and each technological operation should have its own specialized gripper. The objective of the work described here is therefore to design a universal gripper able to grip and transfer every kind of textile.

The design objectives are the ability to handle panels of varying shapes and sizes without material deformation and/or folding, and the easy integration with commercially available manipulator robots. To answer initial requirements and increase the textile gripping reliability, we opted to combine three different gripping technologies: vacuum, intrusion and pinch.

Each system was first validated independently through static tests. The vacuum technology offers a high reliability to handle impermeable materials. The intrusion technology is reliable for the manipulation of high porosity materials, while the pinch technology shows good results for all soft fabrics when combined with the vacuum technology. Then, the limits of the new gripper in terms of gripping capacity, compressed air consumption and characteristics and limitations of the flexible material handled were put in evidence using a robot arm. An automated selection program of the gripper based on the material characteristics has also been developed and implemented.

This paper fulfills an identified need to design a universal gripper able to grip and transfer every different kind of cut textile.

For size reasons, adapted sensors, able to measure intrinsic mechanical properties of fabrics, have not been developed yet. The study aims at developing a sensor that can be inserted within a specific textile, a “complex” fabric used as seat‐cover fabrics, and consisting of an assembly of three layers.

Piezoelectric polymer sensors containing polyvinylidene fluoride (PVDF) were chosen. A total of 20 “complex” were studied. A characterisation in compression was achieved, using the Kawabata Evaluation System. The best‐adapted measurement method using a PVDF sensor has been required. The method consists in analyzing the response under compressive stress of a PVDF disc using the resonant frequency of the material. A constraint series is applied to the fabric in the sensor area; the maximal phase at the sensor's resonant frequency is taken up for each one.

Phase variation is linear and differs according to the studied “complex”. A correlation study between Kawabata compression parameters and slopes did not show any relationship between slope values and compression properties when the surface fabrics of “complex” are compared, but a classification in “families” is possible when different foams are considered.

Further studies should demonstrate whether these “smart” textiles could find applications in the automotive field, to measure accurately the mass of a passenger. The influence of the external parameters (vibrations, temperature variations) has to be checked, knowing that the sensor is not depending on moisture. To complete the study, the sensor has to be tested in a real situation, i.e. inserted in a car‐seat, in contact with a human body.

This study promises development of a sensor that can be inserted into a specific textile, a “complex” fabric used as a seat‐cover, consisting of an assembly of three layers.