The dynamic response of a tactile sensor

Tests were performed on a thumb-shaped tactile sensor containing an 8 by 20 array of tactile elements. Each element measures the strain of the rubber finger material at a point below the surface of the finger. To characterize the finger behavior, a precision force application device was designed. Static tests determined the steady-state linearity of the elements with respect to force magnitude. The frequency response was determined in the range of 0.10 to 20 Hz. Permanent deformation due to stress was seen to be predictable. The Maxwell-Kelvin model for viscoelasticity was fit to the stress-strain data obtained by probing the finger and recording the applied force and the strain response of a single element. Results showed it to be better than a spring model. A second-order model was also fit to the stress-strain data. The model was inverted to predict the magnitude of the force of a point contact given the strain of one tactile element. The inverse model predicted the fore better than the spring model.<>