Gel-Based Force Sensor for Robotic Applications

Abstract

This article presents the development, characterisation and validation of a highly sensitive distributed tactile sensor based on conductive acrylamide and dimethyl sulphoxide (AM-DMSO) organogels for applications in soft robotics. To overcome limitations such as ionic polarisation of the gel and parasitic electrical impedances at the interface between the gel and the electrodes, the authors propose a signal conditioning circuit that implements the four-electrode method in alternating current. Through various experimental tests, it is demonstrated that the sensor exhibits excellent linear behaviour during the charging phase and variations in sensitivity depending on the distribution and distance between the electrodes, although it exhibits hysteresis due to the viscoelastic nature of the material. Finally, the practical viability of the device is validated by integrating it into a robotic gripper with flexible fingers for handling fragile objects, using an adaptive control strategy based on gain planning that adjusts the force controller parameters in real time according to the contact area identified by the organogel.