In this paper, the flexible solar wing support structure is taken as the research object, and the vibration is actively controlled by the piezoelectric material. In this paper, the Euler-Bernoulli beam theory is used to simplify the overall model structure. The principle of Language and the hypothetical modal method are used to derive the dynamic model of the piezoelectric flexible system. The obtained system dynamics model was simulated by PID control, and good results were obtained.
© Published under licence by IOP Publishing Ltd.

In this paper, the key technology in NC system, acceleration and deceleration control, is applied to path planning of manipulator. A two-phase adaptive path acceleration and deceleration control method is proposed, which reduces the requirement of S-shaped curve acceleration and deceleration control method on the shortest path length, and improves the smoothness of trapezoidal acceleration and deceleration control. On the whole, it improves the rapidity of accurately reaching the target position and the smoothness of manipulator's movement.
© Published under licence by IOP Publishing Ltd.

This paper deals with the dynamic precision analysis of a linear-type rail redundant sliding manipulator. Based on the analysis of the mechanism structure, kinematics, stiffness performance and dynamic characteristics of the redundant sliding manipulator, the dynamic error caused by elastic deformation of links is analyzed. A mathematical model of the dynamic precision of the redundant sliding manipulator system is established in this paper by the geometric method. The influence of parameters such as equivalent stiffness and moment of inertia on the dynamic error of the manipulator is analyzed and parameter optimization schemes are proposed to reduce the dynamic error. Simulation analysis and experiment verify the dynamic precision of the redundant sliding manipulator. This paper provides a theoretical guidance for the high-precision operations of the redundant sliding manipulator.
© 2020, Springer Nature Singapore Pte Ltd.

In this paper, the flexible solar wing support structure is taken as the research object, and the vibration is actively controlled by the piezoelectric material. In this paper, the Euler-Bernoulli beam theory is used to simplify the overall model structure. The principle of Language and the hypothetical modal method are used to derive the dynamic model of the piezoelectric flexible system. The obtained system dynamics model was simulated by PID control, and good results were obtained. © Published under licence by IOP Publishing Ltd.

At present, vision-based hand gesture recognition is very important in human-robot interaction (HRI). This non-contact method enables natural and friendly interaction between people and robots. Aiming at this technology, a two-stream CNN framework (2S-CNN) is proposed to recognize the American sign language (ASL) hand gestures based on multimodal (RGB and depth) data fusion. Firstly, the hand gesture data is enhanced to remove the influence of background and noise. Secondly, hand gesture RGB and depth features are extracted for hand gesture recognition using CNNs on two streams, respectively. Finally, a fusion layer is designed for fusing the recognition results of the two streams. This method utilizes multimodal data to increase the recognition accuracy of the ASL hand gestures. The experiments prove that the recognition accuracy of 2S-CNN can reach 92.08 $$\%$$ on ASL fingerspelling database and is higher than that of baseline methods. © 2020, Springer Nature Switzerland AG.

At present, vision-based hand gesture recognition is very important in human-robot interaction (HRI). This non-contact method enables natural and friendly interaction between people and robots. Aiming at this technology, a two-stream CNN framework (2S-CNN) is proposed to recognize the American sign language (ASL) hand gestures based on multimodal (RGB and depth) data fusion. Firstly, the hand gesture data is enhanced to remove the influence of background and noise. Secondly, hand gesture RGB and depth features are extracted for hand gesture recognition using CNNs on two streams, respectively. Finally, a fusion layer is designed for fusing the recognition results of the two streams. This method utilizes multimodal data to increase the recognition accuracy of the ASL hand gestures. The experiments prove that the recognition accuracy of 2S-CNN can reach 92.08 $$\%$$ on ASL fingerspelling database and is higher than that of baseline methods.
© 2020, Springer Nature Switzerland AG.

目的人体关节软骨具有承受负荷和吸收震荡的重要功能。但关节软骨中无血管、淋巴和神经分布,因而缺乏自身修复能力。关节软骨损伤的治疗是国内外骨科工作者研究的重点和难点,使用人造材料对关节软骨进行替代是常用治疗方法。聚乙烯醇（PVA）水凝胶因其良好的生物相容性被广泛用作软骨替代材料。然而,PVA水凝胶通常不具有多孔结构,生物活性差。致力于研发一种兼具高强度和多孔结构的PVA水凝胶,提高PVA水凝胶的生物活性。方法 通过调控新型成孔剂（琼脂糖）用量和优化循环冷冻-解冻工艺,制备PVA水凝胶。通过低温X射线衍射、傅里叶

This paper focuses on the recursive identification of the time-varying state-space model of the on-orbit rigid-flexible coupling spacecraft caused by structural configuration change, and a recursive predictor-based subspace identification (RPBSID) method is applied to implement the online identification of the system model recursively. Comparing with the classical subspace algorithms such as the time-varying eigensystem realization algorithm (TV-ERA), the RPBSID method does not need to construct the corresponding Hankel matrix for each time instant when solving the state variables, and thereby reducing the amounts of data in the identification process. Furthermore, an adaptive filter is applied in this recursive algorithm and thus the ability of noise resistance is also increased. In numerical simulations, the time-varying state-space model of the spacecraft is estimated by using the RPBSID and TV-ERA approaches, and the system responses with respect to the test inputs for the two methods are also compared. The computed results of the test responses illustrate that the RPBSID algorithm can be used to effectively identify the time-varying state-space model parameters of the rigid-flexible coupling spacecraft, and the corresponding computational efficiency of the algorithm is also better than that of the classical identification method.
© 2018 KASHYAP.