An Angular Sensor Based on Differential Electrical Signals at the Rotating Interface for Humanoid Robot Control and Interactions

Robots are becoming increasingly intelligent, and sensing technology plays a crucial role in their development. The joint position information provided by angular sensors is the basis for the robot to achieve high-precision motion control. Traditional angular sensors based on photoelectric and electromagnetic principles typically suffer from bulky size and high-power consumption, making it difficult to meet the compact integration requirements of intelligent robots. Here, we developed an angular sensor based on differential electrical signals at the rotating interface. The angular sensor consists of alternately arranged electrodes as the stator and a dielectric film as the rotor. Two sets of alternating electrodes can extract differential electrical signals during rotation to sense angular displacement and velocity. The sensitivity can be improved by the optimization of the electrode structure parameters and the selection of the dielectric film material, achieving an angular displacement sensitivity of 24.5 nC/rad and an angular velocity sensitivity of 23.3 nA s/rad. Furthermore, the wear during rotation is reduced by increasing the dielectric film hardness and decreasing the electrode surface roughness, thereby enhancing long-term operational stability. The lightweight and compact features of the sensors allow them to be integrated directly into the robot's joints for real-time monitoring of kinematic parameters and trajectory planning in teaching mode. In addition, the angular sensor can also monitor the flexion of human joints for robotic teleoperation. This method breaks through the size, power consumption and accuracy limitations of traditional angular sensors, and has a promising prospect in the fields of robotics and human-robot interactions.