A STRESS-COMPONENT-SELECTIVE TACTILE SENSOR ARRAY

A stress-component-selective tactile array, based on piezoelectric polymers, and its associated data acquisition system are described. The seven-taxel sensor array is made up of elements sensitive to one or more components of the stress field acting upon them. The six independent components or the stress tensor can bc calculated from a linear combination of the responses of the six miniaturized elements composing each taxel. The array is developed with the aim of obtaining a skin-like tactile sensor able to perform fine-form discrimination of objects in contact with it. It is also thought to be instrumental in revealing phenomena related to incipient slippage during object manipulation and grasping. The multi-component sensor, based on 42 miniaturized piezoelectric polymer discs, is supported by a polyimide sheet with microlithographically defined electrodes. The sensor elements are embedded into a rubber layer with appropriate thickness in order to sample properly the stress field and to obtain good signal-to-noise ratio at the input of the electronic signal processing unit. Preliminary experiments to test the ability of individual sensor elements to resolve normal and shear stress components have shown good agreement with the responses predicted by analytical solutions of elastic contact problems.