In this paper, a novel method is mentioned using a spherical magnetohydrodynamic attitude adjusting mechanism for threeaxis attitude adjustment of satellite. The time variation of the flow velocity, angular momentum and output torque is studied in the proposed mechanism. The numerical results could be used for optimizing attitude mechanism design, and provide guidance for following experimental research.
Accurate 3D perception is vital for the localization of mobile robots and autonomous vehicles. Sparse 3D LIDAR scanners and 3D vision sensors (stereo and RGB-D cameras) are commonly used environment perception sensors. The former could provide accurate but sparse-range data, while the latter is dense but full of uncertainty. Since the acquired depth map by each sensor alone could not accurately perceive complex surrounding environment, an innovative probabilistic fusion model based on Bayesian Kriging (BK) is proposed for dense high-precision depth map estimation, to fully utilize the complementary characteristics of the two distinct sensors. Combing the geometric piece-wise planar hypotheses of the scene, the noisy disparity map from the 3D vision sensor is segmented into multiple small planes. In each segmented plane, the BK-based fusion estimator is founded to predict depth for each pixel with sparse scattered LIDAR points. In particular, we focus on analyzing the spatial variation prior and correlation between these two types of data, based on regionalized variable theory. Experiments on various scenes of KITTI stereo datasets are carried out to demonstrate the effectiveness of our algorithm, and validate the superiority compared with existing fusion methods.
The fluid momentum ring based on magnetohydrodynamics (MHD) as an actuator for satellite attitude control has advantages in terms of reliability that are not found in conventional flywheel mechanisms. In the design study of the fluid momentum ring based on MHD, the paper presents an optimized design of the magnetic circuit of the fluid ring and a coupled FEM analysis of the multi-physics field of the electric-magnetic-fluid. The proposed design is able to reduce the influence of the induced magnetic field generated by the current on the intrinsic magnetic field and reduce the coupling effect between the electric and magnetic fields. Unlike the general motor structure, the magnetic field in the fluid cavity acts at a greater distance. Here the magnetic circuit is designed purposefully and optimized using particle swarm algorithm. Finally, the designed fluid momentum ring is simulated with FEM to analyze the coupled electric-magnetic-fluid multiphysical field.
In this paper, a novel mechanism is proposed for three-axis attitude adjustment of a satellite. The purpose of the simulation is to analyze flow field of the spherical MHD attitude controller on the flow field distribution, angular momentum, and output torque. According to the numerical results, a combination of pole and slot numbers is proposed for the physical design of MHD-SAC. This study can provide a reference for the optimal design of the attitude adjusting mechanism.
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