To prevent the wooden door frame of traditional rural houses from being stuck due to diamond deformation under earthquake and improve the seismic capacity of rural houses, an innovative method of reinforcing the angular displacement of the wooden door frame with channel steel and the diagonal brace is proposed. The rationality of the finite element simulation is demonstrated by comparing the results of finite element simulation and quasistatic test based on reinforced and unreinforced wooden door frame specimens. On the basis of the finite element model of wooden door frame, the seismic performance of channel type and diagonal brace thickness of reinforced wooden door frame and the seismic performance of friction coefficient of unreinforced wooden door frame are studied, respectively. The results show that the lateral stiffness and the lateral bearing capacity of the reinforced wooden door frame increase with the increase of channel steel type and the diagonal brace thickness. The height of the channel steel section of the seismic reinforcement structure should be half of the unreinforced structure. With the increase of the friction coefficient, the lateral bearing capacity of the unreinforced wooden frame increases, while the ductility of the unreinforced wooden frame decreases.

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The satellite laser communication pointing system driven by a permanent magnet synchronous motor (PMSM) should have high-precision fixed-point pointing and tracking performance. However, the system motor parameter perturbation and friction disturbances affect the performance of the system. A composite control strategy for the space laser pointing mechanism based on an active disturbance rejection controller (ADRC) is proposed to solve these problems. In order to mitigate the adverse effects of current loop parameter perturbation and speed loop friction disturbance on control performance, the improved current controller and speed controller based on ADRC are designed. On these bases, an improved feedforward position controller is designed. The proposed control strategy can effectively suppress the parameter perturbation of the current loop and the friction disturbance of the speed loop, thus improving the position tracking accuracy of the pointing mechanism for the laser communication system. Experiments are carried out based on the laser pointing mechanism platform to demonstrate the correctness and effectiveness of the proposed strategy.INDEX TERMS Laser pointing system, active disturbance rejection controller (ADRC), parameter perturbation, friction disturbance, feedforward position controller I. INTRODUCTIONCompared with radio frequency communications, laser communication has a higher transmission rate, larger communication capacity, advantages of small size, lightweight, and high confidentiality [1], which has attracted widespread attention. As a critical part of space laser communication, the pointing mechanism for the laser communication system is responsible for the acquisition, tracking, and targeting (ATP), which determines whether a reliable communication link can be established [2]. The composition block diagram is shown in Figure 1, and the main equipment is a high-precision servo based on PMSM.The driving object of the ATP system is a narrow laser beam, and its beam divergence angle is usually about 50 μrad. Therefore, the laser pointing system requires higher fixed-point pointing and stable tracking accuracy. However, temperature changes and magnetic field interference exist in the space working conditions. As the

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