As an orientation measurement system,north-finder has been playing a significant role in both military and civilian fields of orientation and control.In this paper,to deal with drawbacks in the conventional north-find...As an orientation measurement system,north-finder has been playing a significant role in both military and civilian fields of orientation and control.In this paper,to deal with drawbacks in the conventional north-finding systems,a dynamic strategy based on continuous rotation modulation to measure the rotational angular velocity of the earth is proposed.By modeling the dynamic error,optimizing the process constraint and estimating dynamic noise,a method combining delay compensation and hardware adjustment,and a constrained adaptive Kalman filter(CAKF)algorithm are designed for the north-finding strategy.According to simulation and experiments,the proposed algorithm can achieve the high-precision north-finding with robust and anti-noise performance.展开更多
To improve the precision of inertial navigation system（INS） during long time operation,the rotation modulated technique（RMT） was employed to modulate the errorr of the inertial sensors into periodically varied sig...To improve the precision of inertial navigation system（INS） during long time operation,the rotation modulated technique（RMT） was employed to modulate the errorr of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of INS errors.The principle of the RMT was introduced and the error propagating functions were derived from the rotary navigation equation.Effects of the measurement error for the rotation angle of the platform on the system precision were analyzed.The simulation and experimental results show that the precision of INS was ① dramatically improved with the use of the RMT,and ② hardly reduced when the measurement error for the rotation angle was in arc-second level.The study results offer a theoretical basis for engineering design of rotary INS.展开更多
In this work, physical models of neoclassical tearing modes （NTMs） including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems durin...In this work, physical models of neoclassical tearing modes （NTMs） including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems during the suppression of NTMs by driven current, this work compares the efficiency of continuous and modulated driven currents, and simulates the physical processes of multiple modulated driven currents on suppressing rotating magnetic island. It is found that when island rotates along the poloidal direction, the suppression ability of continuous driven current can be massively reduced due to current deposition outside the island separatrix and reverse deposition direction at the X point, which can be avoided by current drive modulation. Multiple current drive has a better suppressing effect than single current drive. This work gives realistic numerical simulations by optimizing the model and parameters based on the experiments, which could provide references for successful suppression of NTMs in future advanced tokamak such as international thermonuclear experimental reactor.展开更多
Traditional gyrocompasses,while capable of providing autonomous directional guidance and path correction,face limitations in widespread applications due to their large size,making them unsuitable for compact devices.M...Traditional gyrocompasses,while capable of providing autonomous directional guidance and path correction,face limitations in widespread applications due to their large size,making them unsuitable for compact devices.Microelectromechanical system(MEMS)gyrocompasses offer a promising alternative for miniaturization.However,current MEMS gyrocompasses require the integration of motor rotation modulation technology to achieve high-precision north-finding,whereas conventional motors in previous research introduce large volume and residual magnetism,thus undermining their size advantage.Here,we innovatively propose a miniature MEMS gyrocompass based on a MEMS traveling-wave micromotor,featuring the first integration of a chip-scale rotational actuator and combined with a precise multi-position braking control system,enabling high accuracy and fast north-finding.The proposed gyrocompass made significant advancements,reducing its size to 50×42.5×24.5 mm^(3)and achieving an azimuth accuracy of 0.199°within 2 min,which is half the volume of the smallest existing similar devices while offering twice the performance.These improvements indicate that the proposed gyrocompass is suitable for applications in indoor industrial robotics,autonomous driving,and other related fields requiring precise directional guidance.展开更多
A setup for the generation of arbitrary vector beams is proposed. The setup mainly consists of a spatial light modulator（SLM）, an angle-adjustable polarization beam splitter modulator, and a spatial filtering imagin...A setup for the generation of arbitrary vector beams is proposed. The setup mainly consists of a spatial light modulator（SLM）, an angle-adjustable polarization beam splitter modulator, and a spatial filtering imaging system. Compared with the system using a birefringent beam splitter with a non-adjustable splitting angle,the polarization splitting angle of the improved setup can be adjusted by slightly rotating the related mirrors,which will bring more convenience when different wavelengths and different pixel sizes of SLMs are involved.The experimental results also demonstrate that the setup possesses a good polarization-selective imaging ability, which reveals that the setup may also be useful in polarization-selective spatial filtering imaging and polarization-encoded encryption.展开更多
基金National Natural Science Foundation of China(No.61733012)。
文摘As an orientation measurement system,north-finder has been playing a significant role in both military and civilian fields of orientation and control.In this paper,to deal with drawbacks in the conventional north-finding systems,a dynamic strategy based on continuous rotation modulation to measure the rotational angular velocity of the earth is proposed.By modeling the dynamic error,optimizing the process constraint and estimating dynamic noise,a method combining delay compensation and hardware adjustment,and a constrained adaptive Kalman filter(CAKF)algorithm are designed for the north-finding strategy.According to simulation and experiments,the proposed algorithm can achieve the high-precision north-finding with robust and anti-noise performance.
基金Sponsored by the National Natural Science Foundation of China(60604011)
文摘To improve the precision of inertial navigation system（INS） during long time operation,the rotation modulated technique（RMT） was employed to modulate the errorr of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of INS errors.The principle of the RMT was introduced and the error propagating functions were derived from the rotary navigation equation.Effects of the measurement error for the rotation angle of the platform on the system precision were analyzed.The simulation and experimental results show that the precision of INS was ① dramatically improved with the use of the RMT,and ② hardly reduced when the measurement error for the rotation angle was in arc-second level.The study results offer a theoretical basis for engineering design of rotary INS.
基金supported by National Natural Science Foundation of China(Grand Nos.11605021,11375039 and 11275034)Natural Science Foundation of Liaoning Province(Grand No.201601074)supported by'the Fundamental Research Funds for the Central Universities'(Grand Nos.3132016128 and 3132014328)
文摘In this work, physical models of neoclassical tearing modes （NTMs） including bootstrap current and multiple modulated electron cyclotron current drive model are applied. Based on the specific physical problems during the suppression of NTMs by driven current, this work compares the efficiency of continuous and modulated driven currents, and simulates the physical processes of multiple modulated driven currents on suppressing rotating magnetic island. It is found that when island rotates along the poloidal direction, the suppression ability of continuous driven current can be massively reduced due to current deposition outside the island separatrix and reverse deposition direction at the X point, which can be avoided by current drive modulation. Multiple current drive has a better suppressing effect than single current drive. This work gives realistic numerical simulations by optimizing the model and parameters based on the experiments, which could provide references for successful suppression of NTMs in future advanced tokamak such as international thermonuclear experimental reactor.
基金supported by the National Basic Research Foundation(Grant No.5140508A0501).
文摘Traditional gyrocompasses,while capable of providing autonomous directional guidance and path correction,face limitations in widespread applications due to their large size,making them unsuitable for compact devices.Microelectromechanical system(MEMS)gyrocompasses offer a promising alternative for miniaturization.However,current MEMS gyrocompasses require the integration of motor rotation modulation technology to achieve high-precision north-finding,whereas conventional motors in previous research introduce large volume and residual magnetism,thus undermining their size advantage.Here,we innovatively propose a miniature MEMS gyrocompass based on a MEMS traveling-wave micromotor,featuring the first integration of a chip-scale rotational actuator and combined with a precise multi-position braking control system,enabling high accuracy and fast north-finding.The proposed gyrocompass made significant advancements,reducing its size to 50×42.5×24.5 mm^(3)and achieving an azimuth accuracy of 0.199°within 2 min,which is half the volume of the smallest existing similar devices while offering twice the performance.These improvements indicate that the proposed gyrocompass is suitable for applications in indoor industrial robotics,autonomous driving,and other related fields requiring precise directional guidance.
基金supported by the National Natural Science Foundation of China under Grant No.11474186
文摘A setup for the generation of arbitrary vector beams is proposed. The setup mainly consists of a spatial light modulator（SLM）, an angle-adjustable polarization beam splitter modulator, and a spatial filtering imaging system. Compared with the system using a birefringent beam splitter with a non-adjustable splitting angle,the polarization splitting angle of the improved setup can be adjusted by slightly rotating the related mirrors,which will bring more convenience when different wavelengths and different pixel sizes of SLMs are involved.The experimental results also demonstrate that the setup possesses a good polarization-selective imaging ability, which reveals that the setup may also be useful in polarization-selective spatial filtering imaging and polarization-encoded encryption.
