基于Unity3D的工作面液压支架群组空间支护姿态数字孪生重构方法

煤炭是我国的关键能源,保障煤炭资源安全高效开采对我国具有重要战略意义。我国煤炭资源以井工开采为主,生产环境较恶劣且工人劳动强度大,智能化开采因其减人提效理念内涵成为我国煤炭行业高质量发展的必由之路。液压支架是井工开采关键支护装备,其支护性能同时受本体支护姿态及群组关联姿态影响。受井下复杂开采条件影响,液压支架支护姿态信息获取困难,因此如何智能精准地感知液压支架群组空间支护姿态是制约智能化建设的重大难题之一。为精准描述工作面液压支架群组空间支护姿态,首先分析了液压支架群组空间连接关系,建立了基于多杆双驱的液压支架自姿态感知模型和基于空间多线协同定姿的架群姿态感知模型,分析了不同求解策略对自姿态模型解算性能影响。随后借助三维互动平台Unity3D搭建了工作面液压支架群组数字孪生环境,开发了基于工作面真实场景数据驱动的可视化系统。最后,依托山东某矿对所述方法开展了工程验证,结果表明提出的液压支架群组空间支护姿态孪生重构方法能精确映射实际液压支架群组真实空间支护位态,解决了液压支架支护本体支护姿态信息易受现场振动干扰和支架群组关联姿态信息缺失难题。论文所提方法为工作面多智能体运行行为全场景虚拟再现及工作面智能化建设提供思路借鉴。

Maneuver and vibration reduction of flexible spacecraft using sliding mode/command shaping technique

A generalized scheme based on the sliding mode and component synthesis vibration suppression (CSVS) method has been proposed for the rotational maneuver and vibration suppression of an orbiting spacecraft with flexible appendages. The proposed control design process is twofold: design of the attitude controller followed by the design of a flexible vibration attenuator. The attitude controller using only the attitude and the rate information for the flexible spacecraft (FS) is designed to serve two purposes: it forces the attitude motion onto a pre-selected sliding surface and then guides it to the state space origin. The shaped command input controller based on the CSVS method is designed for the reduction of the flexible mode vibration, which only requires information about the natural frequency and damping of the closed system. This information is used to discretize the input so that minimum energy is injected via the controller to the flexible modes of the spacecraft. Additionally, to extend the CSVS method to the system with the on-off actuators, the pulse-width pulse-frequency (PWPF) modulation is introduced to control the thruster firing and integrated with the CSVS method. PWPF modulation is a control method that provides pseudo-linear operation for an on-off thruster. The proposed control strategy has been implemented on a FS, which is a hub with symmetric cantilever flexible beam appendages and can undergo a single axis rotation. The results have been proven the potential of this technique to control FS.

A comparing design of satellite attitude control system based on reaction wheel

The disturbance caused by the reaction wheel with a current controller greatly influences the accuracy and stability of the satellite attitude control system. To solve this problem, the idea of speed feedback compensation control reaction wheel is put forward. This paper introduces the comparison on design and performance of two satellite attitude control systems, which are separately based on the current control reaction wheel and the speed feedback compensation control reaction wheel. Analysis shows that the speed feedback compensation control flywheel system may effectively suppress the torque fluctuation. Simulation results indicate that the satellite attitude control system with the speed feedback compensation control flywheel has improved performance.

Lightweight and polarized self-attention mechanism for abnormal morphology classification algorithm during traditional Chinese medicine inspection

Objective To propose a Light-Atten-Pose-based algorithm for classifying abnormal morphol-ogy in traditional Chinese medicine(TCM)inspection to solve the problem of relying on manual labor or expensive equipment with personal subjectivity or high cost.Methods First,this paper establishes a dataset of abnormal morphology for Chinese medi-cine diagnosis,with images from public resources and labeled with category labels by several Chinese medicine experts,including three categories:normal,shoulder abnormality,and leg abnormality.Second,the key points of human body are extracted by Light-Atten-Pose algo-rithm.Light-Atten-Pose algorithm uses lightweight EfficientNet network and polarized self-attention(PSA)mechanism on the basis of AlphaPose,which reduces the computation amount by using EfficientNet network,and the data is finely processed by using PSA mecha-nism in spatial and channel dimensions.Finally,according to the theory of TCM inspection,the abnormal morphology standard based on the joint angle difference is defined,and the classification of abnormal morphology of Chinese medical diagnosis is realized by calculat-ing the angle between key points.Accuracy,frames per second(FPS),model size,parameter set(Params),and giga floating-point operations per second(GFLOPs)are chosen as the eval-uation indexes for lightweighting.Results Validation of the Light-Atten-Pose algorithm on the dataset showed a classification accuracy of 96.23%,which is close to the original AlphaPose model.However,the FPS of the improved model reaches 41.6 fps from 16.5 fps,the model size is reduced from 155.11 MB to 33.67 MB,the Params decreases from 40.5 M to 8.6 M,and the GFLOPs reduces from 11.93 to 2.10.Conclusion The Light-Atten-Pose algorithm achieves lightweight while maintaining high ro-bustness,resulting in lower complexity and resource consumption and higher classification accuracy,and the experiments prove that the Light-Atten-Pose algorithm has a better overall performance and has practical application in the pose estimation task.

ADAPTIVE SET STABILIZATION OF THE ATTITUDE OF A RIGID SPACECRAFT WITHOUT ANGULAR VELOCITY MEASUREMENTS

The global adaptive set stabilization problem of the attitude of a rigid spacecraft is addressed in this paper. Two different cases are considered. First, by using adaptive backstepping method, the authors design a global adaptive control law for the attitude control system with unknown inertia matrix such that the attitude and the angular velocities can be globally asymptotically stabilized to a set consisting of two equilibria. And then, based on the obtained backstepping adaptive law, the authors consider the case that the angular velocities are not measurable. By introducing an auxiliary state, a semi-global adaptive set stabilization law without angular velocity measurements is also designed. It is rigorously proved that, for the two cases, both of the closed loop systems satisfy the set stability. The effectiveness of the proposed methods is verified by simulation results.

ROBUST ATTITUDE CONTROL OF A 3DOF HELICOPTER WITH MULTI-OPERATION POINTS

A 3DOF (three degrees of freedom) helicopter attitude control system with multi-operationpoints is described as a MIMO time-varying uncertain nonlinear system with unknown constant param-eters,bounded disturbance and nonlinear uncertainty,and a robust output feedback control methodbased on signal compensation is proposed.A controller designed by this method consists of a nominalcontroller and a robust compensator.The controller is linear time-invariant and can be realized easily.Robust attitude tracking property of closed-loop system is proven and experimental results show thatthe designed control system can guarantee high precision robust attitude control under multi-operationpoints.