Capacitive Proximity Sensor Skin for Contactless Material Detection

In this paper, we present a method for contactless material detection with capacitive proximity sensing skins. Our new approach extends the current state-of-the-art proximity and distance sensing methods and measures the characteristic impedance spectrum of an object to obtain material properties. By this, we gain further material information besides of the near field information in a contactless and non-destructive way. The measurement method requires sensors that provide absolute distance and frequency based capacitance measurement capabilities and can be applied to similar systems. The sensor system described in this paper measures proximity with a capacitance based sensor and absolute distance based on time-of-flight (ToF)sensors. Attached on a robot, we gain information about the robot's near field environment. The information is important not only for human- machine- interaction, but also for grasping and manipulation. We focus on signal processing and evaluate our method with measurements of numerous different materials and present a solution to differentiate between them.