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This study presents a predefined-time control strategy for rigid spacecraft, employing dynamic predictive techniques to achieve robust and precise attitude tracking within predefined time constraints. Advanced predictive algorithms are used to effectively mitigate system uncertainties and environmental disturbances. The main contributions of this work are introducing adaptive global optimization for period updates, which relaxes the original restrictive conditions; ensuring easier parameter adjustments in predefined-time control, providing a nonconservative upper bound on system stability; and developing a continuous, robust control law through terminal sliding mode control and predictive methods. Extensive simulations confirm the control scheme reduces attitude tracking errors to less than 0.01 degrees at steady state, demonstrating the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

To enhance the precision of on-orbit assembly for large space optical telescopes, the control of attitude motion in the Autonomous Space-based Simulator (ASS) is imperative. This paper presents a robust finite-time trajectory tracking control method aimed at improving the position and attitude tracking performance of ASS. Considering the dynamic characteristics inherent in ASS, we introduce an improved non-singular fast terminal sliding mode controller (INFTSMC) incorporating an adaptive fuzzy mechanism to attain finite-time error convergence and robust control. The adaptive fuzzy logic control (AFLC) method yields an equivalent gain, eliminating discontinuous switching in terminal sliding mode control (TSMC). This reduction minimizes chattering in control inputs and compensates for uncertainties and time-varying disturbances within the dynamic model. The proposed method's effectiveness is validated through comprehensive simulation and experimental studies. • The Adaptive Fuzzy Improved Non-singular Fast Terminal Sliding Mode Control strategy is designed. • Precise tracking of Autonomous Space-based Simulators with uncertainties and external disturbances is achieved. • The proposed control scheme ensures finite-time convergence of trajectory tracking errors. [ABSTRACT FROM AUTHOR]

High-speed scanning is a huge challenge to the motion control of step-scanning gene sequencing stage. The stage should achieve high-precision position stability with minimal settling time for each step. The existing step-scanning scheme usually bases on fixed-step motion control, which has limited means to reduce the time cost of approaching the desired position and keeping high-precision position stability. In this work, we focus on shortening the settling time of stepping motion and propose a novel variable step control method to increase the scanning speed of gene sequencing stage. Specifically, the variable step control stabilizes the stage at any position in a steady-state interval rather than the desired position on each step, so that reduces the settling time. The resulting step-length error is compensated in the next acceleration and deceleration process of stepping to avoid the accumulation of errors. We explicitly described the working process of the step-scanning gene sequencer and designed the PID control structure used in the variable step control for the gene sequencing stage. The simulation was performed to check the performance and stability of the variable step control. Under the conditions of the variable step control where the IMA6000 gene sequencer prototype was evaluated extensively. The experimental results show that the real gene sequencer can step 1.54 mm in 50 ms period, and maintain a high-precision stable state less than 30 nm standard deviation in the following 10 ms period. The proposed method performs well on the gene sequencing stage. [ABSTRACT FROM AUTHOR]

This paper presents key design ideas and performance of the transducer for multi-direction wind energy harvesting. Lead zirconate titanate (PZT) and cantilever beam are introduced to set up the piezoelectric vibrator unit for vibration-to-electric energy conversion. The conversion circuit and the storage unit are designed to output and store electric energy. In addition, wireless data transmission system based on microprocessor is proposed to realize information acquisition for data acquisition nodes. The experimental results show that the transducer achieves good practical property, and it can fill a 25 mAh lithium polymer battery with the continuous 40 min work in the 11 m s−1 wind speed environment. The transducer can work without the wind direction restrictions. It can be widely used in data monitoring, wireless data transmission and other fields with simple structure, high energy utilization rate, low cost and environmental-friendly. [ABSTRACT FROM AUTHOR]