Infrared small target detection is a challenging task with important applications in the field of remote sensing. The idea of density peaks searching for infrared small target detection has been proved to be effective. However, if high-brightness clutter is close to the target, the distance from the target pixel to the surrounding density peak will be very small, which easily leads to missing detection. In this paper, a new detection method, named modified density peaks searching and local gray difference (MDPS-LGD), is proposed. First, a local heterogeneity indicator is used as the density to suppress high-brightness clutter, and an iterative search is adopted to improve the efficiency in the process of searching for density peaks. Following this, a local feature descriptor named the local gray difference indicator (LGD) is proposed according to the local features of the target. In order to highlight the target, we extract the core area of the density peak by a random walker (RW) algorithm, and take the maximum response of the minimum gray difference element in the core region as the LGD of the density peak. Finally, targets are extracted using an adaptive threshold. Extensive experimental evaluation results in various real datasets demonstrate that our method outperforms state-of-the-art algorithms in both background suppression and target detection.

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Magnetorquer is the device to create the magnetic dipole moment as a result of the interaction between spacecraft moment and the magnetic field. Because the magnetic dipole moment is inversely proportional the third power of the orbit height, magnetorquer is generally used as attitude control system actuator for low earth orbit satellite. In this paper, the design is suitable for the tens of kilograms of microsatellites. In view of low earth orbit satellite locates the region of strong magnetic field intensity, and taking into account the advantages of simple and reliable, magnetorquer must have large output torque, low residual moment, small size, and light weight, this paper is designed to meet these requirements.