We describe a dual-axis atomic spin gyroscope based on an alkali metal-noble gas comagnetometer. Alkali metal vapor is optically pumped, and then the noble gas is hyperpolarized along the z axis. When sensing a transverse rotation, the polarized noble gas will be induced to precess and produce an effective magnetic field in the x – y plane for alkali metals to precess under. Operating in the spin-exchange relaxation-free regime, alkali atoms are modulated by the z axis magnetic field and serve as an integrated in-situ dual-axis magnetometer to detect the gyroscopic precession in the x and y axes simultaneously, using a single probe beam. By using the parametric modulation technique, the low frequency drift is effectively suppressed and a bias instability of less than 0.05 deg/h has been achieved in our dual-axis atomic spin gyroscope.

To improve the performance of the surface permanent magnet synchronous motor (SPMSM) drives, a sensorless control scheme based on the sliding-mode observer (SMO) with an orthogonal phase-locked loop (PLL) incorporating two synchronous frequency-extract filters (SFFs) is proposed. The rotor position estimation errors are analyzed. The analysis results show that the harmonic errors of the estimated signal are hardly to eliminate completely. Therefore, an improved adaptive notch filter (ANF) -the SFF is proposed to extract the fundamental wave of the rotor position estimation before applying to the PLL. This method of the PLL combined SFFs can compensate the estimated back electromotive force (EMF) harmonic error efficiently and adaptively. An experimental driveline system used for testing the electrical performance of the developed magnetically suspended motor is built. The effectiveness and the feasibility of the proposed method are validated with the experimental results. Key words-sensorless, rotor position estimated error, adaptive compensation, high-speed surface permanent magnet synchronous motor (SPMSM), Sliding-Mode observer (SMO)

We report the latest results of searching for possible new macro-scale spin-spin-velocity-dependent forces (SSVDFs) based on specially designed iron-shielded SmCo5 (ISSC) spin sources and a spin exchange relaxation free (SERF) co-magnetometer. The ISSCs have high net electron spin densities of about 1.7 × 10 21 cm −3 , which mean high detecting sensitivity; and low magnetic field leakage of about ∼mG level due to iron shielding, which means low detecting noise. With help from the ISSCs, the high sensitivity SERF co-magnetometer, and the similarity analysis method, new constraints on SSVDFs with forms of V6+7, V8, V15, and V16 have been obtained, which represent the tightest limits in force range of 5 cm -1 km to the best of our knowledge.

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