Detecting the Rotation Direction in Contactless Angular Velocity Sensors Implemented With Rotors Loaded With Multiple Chains of Resonators

In this paper, a strategy to detect the rotation direction in angular displacement and velocity sensors based on rotors loaded with circular chains of split ring resonators (SRRs) is presented. The rotor (made of a dielectric material) is loaded with two concentric SRR chains for measuring the angular velocity (angular velocity chains) and with one additional (also concentric) non-periodic resonator chain for detecting the direction of motion (rotation direction chain). The stator is a CPW transmission line placed below the rotor chains, in close proximity to them, with the line axis oriented in the radial direction of the rotor. A novel relevant contribution of this paper concerns the detailed study of the rotation direction sensor, from which we have concluded that the design must be completely different than the one of the angular velocity sensor (single SRR on the rotor). By this means, the transmission coefficient of the CPW is modulated by rotor motion (through electromagnetic coupling), as the SRRs of the different chains cross the CPW axis. By injecting a double-tuned signal to the line (with carrier frequencies tuned to the SRR resonance frequencies of both chains), two superposed amplitude modulated (AM) signals at the output port of the CPW arise. From the envelope of both AM signals, discriminated by means of a designed diplexer, the angular velocity and the rotation direction can be determined.