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Aiming at the Truss deployable mechanism, this paper conducts research on assembly technology based on a Six-degree-of-freedom parallel mechanism. For the assembly of the Complex rod system and Hinged mechanism, research on Precise control technology of parallel mechanisms is conducted to improve the Assembly positioning accuracy to ±0.05 mm. Under external constraints, the Adjustment amount of the Six-degree-of-freedom parallel mechanism is insufficient for the Seven-rod rotating shaft. Through theoretical analysis, the Adjustment amount that needs to be remedied for the parallel mechanism is calculated, enabling the Seven-rod rotating shaft to be adjusted into position expressly. The research outcome is applied in the model quest and lays a foundation for the subsequent assembly of truss deployable mechanisms.

Information encryption technique has broad applications in individual privacy, military confidentiality, and national security, but traditional electronic encryption approaches are increasingly unable to satisfy the demands of strong safety and large bandwidth of high-speed data transmission over network. Optical encryption technology could be more flexible and effective in parallel programming and multiple degree-of-freedom data transmitting application. Here, we show a dual-layer optical encryption fluorescent polymer waveguide chip based on optical pulse-code modulation technique. Fluorescent oligomers were doped into epoxy cross-linking SU-8 polymer as a gain medium. Through modifying both the external pumping wavelength and operating frequency of the pulse-code modulation, the sender could ensure the transmission of vital information is secure. If the plaintext transmission is eavesdropped, the external pumping light will be switched, and the receiver will get warning commands of ciphertext information in the standby network. This technique is suitable for high-integration and high-scalability optical information encryption communications. Data security of internet is increasingly more demanding in the current era, yet the traditional electronic approach is limited in speed and efficiency. Here, the authors proposed a dual-layer optical encryption fluorescent polymer waveguide chip based on optical pulse-code modulation to mitigate the limitations.

By analyzing the mechanic’s characteristics of the hydraulic cylinder of the moving arm of the lifting mechanism under several extreme working conditions, the mathematical model of optimizing the hinged position of the lifting mechanism is established with the minimum and maximum load of the hydraulic cylinder of the moving arm as the optimization objective. The problem of multi-objective optimization is dealt with by the method of extremely large and extremely small and solved by the optimization algorithm. Through optimization, the maximum force of the hydraulic cylinders can be markedly reduced, the force characteristics of the lifting mechanism can be improved, and the ultimate load at the hinge point of each hydraulic cylinder can be reduced. The optimization method provides an important basis for the parameter design and improvement of the lifting mechanism and similar products.

In this paper, the direct and inverse kinematics problems for a particular type of 3-DOF, 3-PSP parallel manipulator are considered. The proposed direct kinematics solution is based on an existing one in the literature, but with an alternative, simplified second stage in the solution’s formulation. An explicit analytical solution of the inverse kinematics problem is also proposed for one of the manipulator’s operational modes, requiring one pass through the direct kinematics solution. The proposed solutions can be seamlessly extended to the inverted parallel structure.

Data proliferation in the digital age necessitates robust encryption techniques to protect information privacy. Optical encryption leverages the multiple degrees of freedom inherent in light waves to encode information with parallel processing and enhanced security features. However, implementations of large-scale, high-security optical encryption have largely remained theoretical or limited to digital simulations due to hardware constraints, signal-to-noise ratio challenges, and precision fabrication of encoding elements. Here, we present an optical encryption platform utilizing scattering multiplexing ptychography, simultaneously enhancing security and throughput. Unlike optical encoders which rely on computer-generated randomness, our approach leverages the inherent complexity of light scattering as a natural unclonable function. This enables multi-dimensional encoding with superior randomness. Furthermore, the ptychographic configuration expands encryption throughput beyond hardware limitations through spatial multiplexing of different scatterer regions. We propose a hybrid decryption algorithm integrating model- and data-driven strategies, ensuring robust decryption against various sources of measurement noise and communication interference. We achieved optical encryption at a scale of ten-megapixel pixels with 1.23 µm resolution. Communication experiments validate the resilience of our decryption algorithm, yielding high-fidelity results even under extreme transmission conditions characterized by a 20% bit error rate. Our encryption platform offers a holistic solution for large-scale, high-security, and cost-effective cryptography. The authors propose an optical encryption platform that enhances security and throughput through scattering multiplexing ptychography, realizing encryption at a scale of 10-megapixel pixels with 1.23 µm resolution.

This paper presents a parallel manipulator with two universal-prismatic-universal (UPU)-type active limbs and one revolute-spherical (RS)-type passive limb which is used as a stabilizing platform based on the shipboard helicopter’s landing process and its kinematics are studied systematically. First, a 3D model of this stabilized platform is constructed, and its degrees of freedom are analyzed. Second, analytic formulas for solving the inverse kinematics and calculating the required lengths of each limb are derived and modeled using Simulink ® . Third, a Simscape™ model is constructed for the proposed design, and finally, the comparison of the results between the two models is done.

For the problem of quickly obtaining the range of load forces in a specific direction at the end-effector of an eight-cable, six-degree-of-freedom redundantly driven cable-parallel robot, a method based on geometric approaches in six-dimensional space for judging the extremum of the end-effector platform force is proposed, which involves shifting the convex hull formed by six-dimensional hyperplanes and intersecting it with a line or a two-dimensional section to determine the extremum of the feasible force of the end-effector, enabling rapid judgment of the force range that the platform can generate in any given orientation. Using an eight-cable, six-degree-of-freedom mechanism as an example, the proposed method establishes an end-effector position-acceleration image and utilizes position-acceleration curves to plan motion trajectories. The computed trajectory of cable forces satisfies the imposed constraints.

A deployable manipulator has the characteristics of a small installation space and a large workspace, which has great application prospects in small unmanned platforms. Most existing deployable manipulators are designed based on rigid links, whose complexity and mass inevitably increase sharply with increasing numbers of rigid links and joints. Inspired by the remarkable properties of tape springs, this paper proposes novel deployable parallel tape-spring manipulators with low mass, simple mechanics, and a high deployed-to-folded ratio. First, a double C-shaped tape spring is presented to improve the stability of the structure. The combined fixed drive component (CFDC) and combined mobile drive component (CMDC) are designed. Then, novel 2-DOF and 3-DOF deployable translational parallel manipulators are proposed based on the CFDC and CMDC, and their degrees-of-freedom (DOFs), kinematics, and stability are analyzed. The coiled tape spring is regarded as an Archimedean spiral, which can significantly improve the accuracy of kinematic analysis. The correction coefficient of the Euler formula is obtained by comparison with simulation results and experimental results. Furthermore, the stability spaces of the 2-DOF and 3-DOF deployable parallel manipulators are given. Finally, a prototype is fabricated, and experiments are conducted to validate the proposed design and analysis.

With the rapid development of the manufacturing industry, industrial automation equipment represented by computer numerical control (CNC) machine tools has put forward higher and higher requirements for the machining accuracy of parts. Compared with the multi-axis serial platform solution, the parallel platform solution is theoretically more suitable for high-precision machining equipment. There are many parallel platform solutions, but not one can provide a common physical platform to test the effectiveness of a variety of control algorithms. To achieve the goals, this paper is based on the Stewart six degrees of freedom parallel platform, and it mainly studies the platform construction. This study completed the mechanical structure design of the parallel platform. Based on the microprogrammed control unit (MCU) + pre-driver chip + three-phase full bridge solution, we have completed the circuit design of the motor driver. We wrote the program of MCU to drive six parallel robotic arms as well as the program of the parallel platform control center on the PC, and we completed the system joint debugging. The closed-loop control effect of the parallel platform workspace pose is realized.

Due to the effects of swing motion, the performances and internal flow characteristics of marine centrifugal pump undergo some unsteady variations in the marine environment. The hydraulic test system with six degree of freedom parallel motion platform is established to study the pump performance characteristics at the different heel angles of steady roll position and pitch position. The pump head gradually decreases as heel angle increases. The pump head has decreased by 7% to reach the minimum at the 15° heel angle of roll position. At the same heel angle, the head at the roll position is lower than that at the pitch position under the rated flow condition. The fluid in the impeller passage is subjected to the additional inertial force of roll motion or pitch motion under unsteady swing motion, inducing some flow bias phenomena in the velocity field. The unsteady development of flow velocity induces the intense vortex motion, and the shedding and dissipation of interblade vortices are affected. The periodic flow-induced pulsation characteristics obviously appear in the impeller passage. The pulsation periodicity and pressure amplitude are influenced due to the swing motion. The pitch motion induces the greater hydraulic excitation and fluid-induced vibration amplitude. In addition to the pressure pulsation at the low frequencies, the pulsation amplitude at 20 times the shaft frequency is evident under pitch motion.