Capacitive proximity skin for non-contact liquid state measurement of robot grippers with different structures

Handling liquid-filled containers is a frequently encountered yet challenging task for robotics. In this paper, a novel capacitive proximity skin was developed to measure liquid levels before grasping, improving the performance of robotics in application areas like domestic service, manufacturing, healthcare, and food processing. This capacitive proximity skin features a flexible structure that is readily adaptable to a variety of grippers, and it seamlessly integrates with Robot Operating System (ROS)-based control systems. Experiments were performed to compare this proximity skin against non-flexible capacitive proximity sensors, focusing on detection frequency and working distance. The results showed that the capacitive proximity skin achieved data-lossless detection in 0.08 s (12.5 Hz) and contactless measurement of liquid level within 0.7 cm, making it highly suitable for grasping operations. This capacitive proximity skin offers as a versatile solution for robotic applications that involve unsealed liquid-filled containers, and it has the potential for application across a wide range of industries.