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Specific satellites with ultralong wings play a crucial role in many fields. However, external disturbance and self-rotation could result in undesired vibrations of the flexible wings, which affect the normal operation of the satellites. In severe cases, the satellites would be damaged. Therefore, it is imperative to conduct vibration suppression for these flexible structures. Utilizing fuzzy-proportional integral derivative control and deep reinforcement learning (DRL), two active control methods are proposed in this article to rapidly suppress the vibration of flexible structures with quite small controllable force based on a cable-driven parallel robot. Inspired by the output law of DRL, a new control method named Tang and Sun control is innovatively presented based on the Lyapunov theory. To verify the effectiveness of these three control methods, three groups of simulations with different initial disturbances are implemented for each method. Besides, to enhance the contrast, a passive pretightening scheme is also tested. First, the dynamic model of the cable-driven parallel robot which comprises four cables and a flexible structure is established using the finite element method. Then, the dynamic behavior of the model under the controllable cable force is analyzed by the Newmark-ß method. Finally, these control methods are implemented by numerical simulations to evaluate their performance, and the results are satisfactory, which validates the controllers' ability to suppress vibrations. [ABSTRACT FROM AUTHOR]

Aimed at addressing issues concerning the need for performing heavy calculations and difficulties encountered while determining cable tension in cable-driven parallel robots (CDPRs) equipped with 2 redundant cables, a non-iterative method for calculating cable tension feasible region (CTFR) is introduced herein. Additionally, several geometric methods have been proposed for cable-tension optimization of CDPRs based on CTFR from the perspectives of the lowest power consumption, safety optimization, and highest stiffness. The proposed methods employ geometric methods of calculation without the need for a large number of iterations. First, a calculation algorithm for cable-tension polygons based on Graham's scanning has been introduced followed by analysis of its time complexity to effectively obtain CTFR of CDPRs or demonstrate the singularity of CDPRs. Further, a new method has been introduced to evaluate the safety of optimization results. The said safety of results obtained via use of the proposed optimization methods based on CTFR has been evaluated and analyzed. Finally, a dual-thread PID force/position hybrid control method has been used to exercise real-time control over cable tension in CDPRs. Results obtained from experimental and theoretical analyses performed in this study verify the appropriateness and efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

• The concept of stiffness controllability degree is proposed to measure stiffness controllability. • A method for calculating the cable tension constraint workspace based on the cable tension feasible region is given. • The stiffness and stiffness controllability of the four configurations of cable-driven parallel robots are analyzed. To examine the influence of the configuration of a cable-driven parallel robot (CDPR) on its stiffness and stiffness controllability, a concept for a cable tension constraint workspace (CTCW) of CDPRs is introduced. Using a static force analysis, a static CDPR model was established and its stiffness model and a method for optimizing the cable tension were reviewed. To analyze and appraise the CDPR global and local stiffness controllability, a new concept of stiffness controllability degree is proposed and defined. In addition, a calculation method is proposed that uses the cable tension feasible region to effectively obtain the CTCW of the CDPRs according to the cable tension constraint condition. The driving cable layouts of the various CDPR configurations were optimized to maximize the CTCW volume as a performance index. In addition, the stiffness and stiffness controllability of each configuration CDPR were analyzed. The results of the theoretical and experimental analyses validated the efficacy of the presented method and serve as reference for the use of robots in practical applications or for design optimization. [ABSTRACT FROM AUTHOR]

Specific satellites with ultra-long wings easily suffer from violent vibrations caused by the external disturbance and self-rotation, which do harm to flexible wings and affect the normal operation of satellites. In severe cases, the satellites would be damaged. Therefore, achieving rapid vibration suppression is particularly critical. Besides, to protect flexible wings from damage and reduce energy consumption, the control force should be small. Considering the above two issues comprehensively, a scheme using cable-driven parallel robots (CDPRs) to suppress vibrations is proposed. Furthermore, the influence of different configurations of CDPRs on the control effect is studied in the paper. First, the dynamic model of the CDPR which is comprised of four cables and a flexible structure is established using the finite element method. Then, the dynamic behavior of the model under the controllable cable force is analyzed by the Newmark-β method. An optimization index including the settling time, the maximum cable force and energy consumption is presented. Based on the index, six kinds of CDPRs with different configurations are tested under the control of the proposed Fuzzy-PID method and an active control method, respectively. As a comparison, a passive control scheme is also tested. Finally, numerical simulations are implemented to evaluate the effect of the vibration suppression, and the results are satisfactory. [ABSTRACT FROM AUTHOR]