  As more robots are implemented for contact-rich tasks, tactile sensors are in
increasing demand. For many circumstances, the contact is required to be
compliant, and soft sensors are in need. This paper introduces a novelly
designed soft sensor that can simultaneously estimate the contact force and
contact location. Inspired by humans' skin, which contains multi-layers of
receptors, the designed tactile sensor has a dual-layer structure. The first
layer is made of a conductive fabric that is responsible for sensing the
contact force. The second layer is composed of four small conductive rubbers
that can detect the contact location. Signals from the two layers are firstly
processed by Wheatstone bridges and amplifier circuits so that the measurement
noises are eliminated, and the sensitivity is improved. An Arduino chip is used
for processing the signal and analyzing the data. The contact force can be
obtained by a pre-trained model that maps from the voltage to force, and the
contact location is estimated by the voltage signal from the conductive rubbers
in the second layer. In addition, filtering methods are applied to eliminate
the estimation noise. Finally, experiments are provided to show the accuracy
and robustness of the sensor.
