Modeling elastomer displacements for tactile sensing applications
Abstract
Many capacitancebased tactile sensors measure the displacements of an elastic substrate at multiple sites. A large number of sensing applications, however, require knowledge of the surface forces. This report considers the problem of reconstructing these surface forces from the measured displacements. Two models for reconstruction are considered. Contacts in which the area is much smaller than the dimensions of the compliant surface are modelled using a linear elastic halfspace. Analyses of the deformations using this model confirm a strong coupling between normal and tangential displacements for normal, tangential or arbitrary loads. Using a spatial frequency formulation, the minimum spatial sampling densities for reconstructing displacements (as a prerequisite to reconstructing forces) are shown to be significantly smaller than those required for reconstructing strains. The second model, the bonded spring, is introduced for surface contacts which extend over the entire sensor surface. A nonlinear stressstrain relationship is included since tactile sensors undergo relatively large deformations. An empirical relationship between elastic pad geometry and the effective modulus of elasticity is also presented.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 February 1990
 Bibcode:
 1990STIN...9021370N
 Keywords:

 Deformation;
 Detection;
 Displacement;
 Elastomers;
 Manipulators;
 Mathematical Models;
 Robots;
 StressStrain Relationships;
 Surface Properties;
 Tactile Sensors (Robotics);
 Touch;
 Accuracy;
 Coatings;
 Computerized Simulation;
 Data Processing;
 Friction;
 Interfaces;
 Measuring Instruments;
 Transducers;
 Variations;
 Instrumentation and Photography