9 October 1995 Phase-lead reconstruction of a photoelastic tactile sensor
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In this paper, a novel tactile photoelastic transducer for normal forces is presented. When a normal input force profile is applied to the tranduction medium, stress is generated in the photoelastic layer making it birefringent. Consequently, circularly-polarized input light becomes elliptically polarized at the output due to the introduction of a phase-lead distribution. If a circular-reflection polaridoscope is used, the output light-intensity is a circular function of the total phase-lead distribution. The first part of the paper describes the forward analysis of the transducer using finite-element analysis to determine the stress distribution in the transducer. Then, the phase-lead distribution is determined using the theory of photoelasticity. The second part of the paper describes a technique for the recovery of the phase-lead distribution from the ideal noise-free light-intensity distribution. Also, a verification method is proposed to determine whether a recovered phase-lead distribution is the correct one or not. In the third part of the paper, we consider the nonideal situation, where the light-intensity distribution is no longer noise-free. Quantization errors added to the detected light-intensity distribution are also considered. Recovering the phase-lead distribution under noisy conditions constitutes an ill-posed problem. An algorithm that accurately and effectively determines the phase-lead distribution from a noisy light-intensity distribution is presented. The inverse-tactile problem is solved using an optimization function.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ricardo E. Saad, A. Bonen, K. C. Smith, B. Benhabib, "Phase-lead reconstruction of a photoelastic tactile sensor", Proc. SPIE 2570, Experimental and Numerical Methods for Solving Ill-Posed Inverse Problems: Medical and Nonmedical Applications, (9 October 1995); doi: 10.1117/12.224182; https://doi.org/10.1117/12.224182

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