Development of a capacitive slip sensor using internal air gap

Accurate recognition of an object plays an important role in ensuring safe grasping of robotic hand operation. For this reason, usage of proper tactile sensors are essential for robots to recognize objects. In this paper, we present a wide-range functional tactile sensor that can be used for slippage information collector as well as for a protective cover. This sensor has a thin air gap between the polymer layers, which is to be deformed upon a slip motion. When slip occurs on the surface, relative displacement occurs between the object and the sensor surface. This displacement causes deformation of the sensor, which can detect the slippage by measuring the changing capacitance. Since the slip detection algorithm only exploits the change in capacitance, no complicated signal processing such as frequency analysis is required. Therefore, no large data processing is required to detect the slip, and the time delay can also be minimized. These advantages can greatly help the robot hand to react instantly when preventing the object from slip.