In this paper,we establish common fixed point theorems for expansive map?pings on b-metric-like space and coincidence point for f-weakly isotone increasing mappings in partially ordered b-metric-like space.The main re...In this paper,we establish common fixed point theorems for expansive map?pings on b-metric-like space and coincidence point for f-weakly isotone increasing mappings in partially ordered b-metric-like space.The main results generalize and extend several well-known comparable results from the existing literature.Moreover,some examples are provided to illustrate the main results.展开更多
In this paper,a high-fidelity computational fluid dynamics(CFD)and rigid body dynamics(RBD)coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin proj...In this paper,a high-fidelity computational fluid dynamics(CFD)and rigid body dynamics(RBD)coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin projectile.The platform's reliability is validated by reproducing the characteristic resonance instability of such projectiles.By coupling the solution of the Unsteady Reynolds-Averaged Navier-Stokes equations and the seven-degree-of-freedom RBD equations,the virtual flight simulations of fixed canard dual-spin projectiles at various curvature trajectories are achieved,and the dynamic mechanism of the trajectory following process is analyzed.The instability mechanism of the dynamic instability during trajectory following process of the fixed canard dual-spin projectile is elucidated by simulating the rolling/coning coupled forced motion,and subsequently validated through virtual flight simulations.The findings suggest that an appropriate yaw moment can drive the projectile axis to precession in the tangential direction of the trajectory,thereby enhancing the trajectory following stability.However,the damping of the projectile attains its minimum value when the forward body equilibrium rotational speed(-128 rad/s)is equal to the negative of the fast mode frequency of the projectile.Insufficient damping leads to the fixed canard dual-spin projectile exiting the dynamic stability domain during the trajectory following,resulting in weakly damped instability.Keeping the forward body not rotating or increasing the spin rates to-192 rad/s can enhance the projectile's damping,thereby improving its dynamic stability.展开更多
自由漂浮空间机器人(Free-floating space robots,FFSRs)凭借其运动自由度高、工作寿命长等优势,已成为长期在轨服务的关键无人设备。然而空间环境变化导致的外部扰动,以及因燃料消耗、系统参数辨识不准确等因素导致的模型不确定性会增...自由漂浮空间机器人(Free-floating space robots,FFSRs)凭借其运动自由度高、工作寿命长等优势,已成为长期在轨服务的关键无人设备。然而空间环境变化导致的外部扰动,以及因燃料消耗、系统参数辨识不准确等因素导致的模型不确定性会增加空间机器人高精度控制的难度。本文针对自由漂浮空间机器人存在外部扰动和模型不确定性的场景,设计了一种基于扰动补偿的模型预测控制方法。基于固定时间稳定性理论设计扰动观测器,使扰动估计误差在不依赖于初始误差的常数上界内实现收敛。同时,将扰动估计值补偿入模型预测控制器,提高集总扰动条件下预测模型的准确性,进一步地利用模型预测控制滚动优化的特点,实现了空间机器人约束条件下高精度控制。本文证明了扰动观测器与基于扰动补偿模型预测控制器的稳定性,并通过数值仿真验证了方法的有效性。展开更多
基金Supported by the National Natural Science Foundation of China(12001249)the Natural Science Foundation of Jiangxi Province(20232BAB211004)the Educational Commission Science Programm of Jiangxi Province(GJJ2200523)。
文摘In this paper,we establish common fixed point theorems for expansive map?pings on b-metric-like space and coincidence point for f-weakly isotone increasing mappings in partially ordered b-metric-like space.The main results generalize and extend several well-known comparable results from the existing literature.Moreover,some examples are provided to illustrate the main results.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2141254 and U23B6009)。
文摘In this paper,a high-fidelity computational fluid dynamics(CFD)and rigid body dynamics(RBD)coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin projectile.The platform's reliability is validated by reproducing the characteristic resonance instability of such projectiles.By coupling the solution of the Unsteady Reynolds-Averaged Navier-Stokes equations and the seven-degree-of-freedom RBD equations,the virtual flight simulations of fixed canard dual-spin projectiles at various curvature trajectories are achieved,and the dynamic mechanism of the trajectory following process is analyzed.The instability mechanism of the dynamic instability during trajectory following process of the fixed canard dual-spin projectile is elucidated by simulating the rolling/coning coupled forced motion,and subsequently validated through virtual flight simulations.The findings suggest that an appropriate yaw moment can drive the projectile axis to precession in the tangential direction of the trajectory,thereby enhancing the trajectory following stability.However,the damping of the projectile attains its minimum value when the forward body equilibrium rotational speed(-128 rad/s)is equal to the negative of the fast mode frequency of the projectile.Insufficient damping leads to the fixed canard dual-spin projectile exiting the dynamic stability domain during the trajectory following,resulting in weakly damped instability.Keeping the forward body not rotating or increasing the spin rates to-192 rad/s can enhance the projectile's damping,thereby improving its dynamic stability.
文摘自由漂浮空间机器人(Free-floating space robots,FFSRs)凭借其运动自由度高、工作寿命长等优势,已成为长期在轨服务的关键无人设备。然而空间环境变化导致的外部扰动,以及因燃料消耗、系统参数辨识不准确等因素导致的模型不确定性会增加空间机器人高精度控制的难度。本文针对自由漂浮空间机器人存在外部扰动和模型不确定性的场景,设计了一种基于扰动补偿的模型预测控制方法。基于固定时间稳定性理论设计扰动观测器,使扰动估计误差在不依赖于初始误差的常数上界内实现收敛。同时,将扰动估计值补偿入模型预测控制器,提高集总扰动条件下预测模型的准确性,进一步地利用模型预测控制滚动优化的特点,实现了空间机器人约束条件下高精度控制。本文证明了扰动观测器与基于扰动补偿模型预测控制器的稳定性,并通过数值仿真验证了方法的有效性。
