The efficient dynamic modeling and vibration transfer analysis of a fluid-delivering branch pipeline (FDBP) are essential for analyzing vibration coupling effects and implementing vibration reduction optimization. Therefore, this study proposes a reduced-order dynamic modeling method suitable for FDBPs and then analyzes the vibration transfer characteristics. For the modeling method, the finite element method and absorbing transfer matrix method (ATMM) are integrated, considering the fluid–structure coupling effect and fluid disturbances. The dual-domain dynamic substructure method is developed to perform the reduced-order modeling of FDBP, and ATMM is adopted to reduce the matrix order when solving fluid disturbances. Furthermore, the modeling method is validated by experiments on an H-shaped branch pipeline. Finally, transient and steady-state vibration transfer analyses of FDBP are performed, and the effects of branch locations on natural characteristics and vibration transfer behavior are analyzed. Results show that transient vibration transfer represents the transfer and conversion of the kinematic, strain, and damping energies, while steady-state vibration transfer characteristics are related to the vibration mode. In addition, multiple-order mode exchanges are triggered when branch locations vary in frequency-shift regions, and the mode-exchange regions are also the transformation ones for vibration transfer patterns.
Small tracking error correction for electro-optical systems is essential to improve the tracking precision of future mechanical and defense technology. Aerial threats, such as “low, slow, and small (LSS)” moving targets, pose increasing challenges to society. The core goal of this work is to address the issues, such as small tracking error correction and aiming control, of electro-optical detection systems by using mechatronics drive modeling, composite velocity–image stability control, and improved interpolation filter design. A tracking controller delay prediction method for moving targets is proposed based on the Euler transformation model of a two-axis, two-gimbal cantilever beam coaxial configuration. Small tracking error formation is analyzed in detail to reveal the scientific mechanism of composite control between the tracking controller’s feedback and the motor’s velocity–stability loop. An improved segmental interpolation filtering algorithm is established by combining line of sight (LOS) position correction and multivariable typical tracking fault diagnosis. Then, a platform with 2 degrees of freedom is used to test the system. An LSS moving target shooting object with a tracking distance of S = 100 m, target board area of A = 1 m2, and target linear velocity of v = 5 m/s is simulated. Results show that the optimal method’s distribution probability of the tracking error in a circle with a radius of 1 mrad is 66.7%, and that of the traditional method is 41.6%. Compared with the LOS shooting accuracy of the traditional method, the LOS shooting accuracy of the optimized method is improved by 37.6%.
The planned missions to explore the surfaces of the Moon and Mars require high exploration efficiency, thus imposing new demands on the mobility system of planetary rovers. In this paper, a design method for a high-speed planetary rover (HPR) is proposed, and the representative configurations are modeled and simulated. First, the influence of the planetary surface environment on the design of HPRs is analyzed, and the design factors for HPRs are determined by studying a single-wheel suspension. Second, a design methodology for HPRs is proposed. The adaptive suspension mechanisms of a four-wheeled rover are synthesized using the all-wheel-attachment condition and position and orientation characteristics theory, which are expressed in the form of a graph theory for the increase in elastic components and active joints. Finally, a dynamic model is built, and a simulation is carried out for the proposed rover. The validity of the proposed method and rover is verified, thus highlighting their potential application in future planetary exploration.
Achieving dynamic compliance for energy-efficient legged robot motion is a longstanding challenge. Although recent predictive control methods based on single-rigid-body models can generate dynamic motion, they all assume infinite energy, making them unsuitable for prolonged robot operation. Addressing this issue necessitates a mechanical structure with energy storage and a dynamic control strategy that incorporates feedback to ensure stability. This work draws inspiration from the efficiency of bio-inspired muscle–tendon networks and proposes a controllable torsion spring leg structure. The design integrates a spring-loaded inverted pendulum model and adopts feedback delays and yield springs to enhance the delay effects. A leg control model that incorporates motor loads is developed to validate the response and dynamic performance of a leg with elastic joints. This model provides torque to the knee joint, effectively reducing the robot’s energy consumption through active or passive control strategies. The benefits of the proposed approach in agile maneuvering of quadruped robot legs in a realistic scenario are demonstrated to validate the dynamic motion performance of the leg with elastic joints with the advantage of energy-efficient legs.
The concept of remote center of motion (RCM) is pivotal in a myriad of robotic applications, encompassing areas such as medical robotics, orientation devices, and exoskeletal systems. The efficacy of RCM technology is a determining factor in the success of these robotic domains. This paper offers an exhaustive review of RCM technologies, elaborating on their various methodologies and practical implementations. It delves into the unique characteristics of RCM across different degrees of freedom (DOFs), aiming to distill their fundamental principles. In addition, this paper categorizes RCM approaches into two primary classifications: design based and control based. These are further organized according to their respective DOFs, providing a concise summary of their core methodologies. Building upon the understanding of RCM’s versatile capabilities, this paper then transitions to an in-depth exploration of its applications across diverse robotic fields. Concluding this review, we critically analyze the existing research challenges and issues that are inherently present in both RCM methodologies and their applications. This discussion is intended to serve as a guiding framework for future research endeavors and practical deployments in related areas.
Printed circuit boards (PCBs) are representative composite materials, and their high-quality drilling machining remains a persistent challenge in the industry. The finishing of the cutting edge of a microdrill is crucial to drill performance in machining fine-quality holes with a prolonged tool life. The miniature size involving submicron scale geometric dimensions, a complex flute shape, and low fracture toughness makes the cutting edge of microdrills susceptible to breakage and has been the primary limiting factor in edge preparation for microdrills. In this study, a newly developed cutting edge preparation method for microdrills was tested experimentally on electronic printed circuit boards. The proposed method, namely, shear thickening polishing, limited the cutting edge burrs and chipping on the cutting edge, and this in turn transformed the cutting edge’s radius from being sharp to smooth. Moreover, the edge–edge radius could be regulated by adjusting the processing time. PCB drilling experiments were conducted to investigate the influence of different cutting edge radii on wear, hole position accuracy, nail head value, and hole wall roughness. The proposed approach showed 20% enhancement in hole position accuracy, 33% reduction in the nail head value, and 19% reduction in hole wall roughness compared with the original microdrill. However, a threshold is needed; without it, excessive shear thickening polishing will result in a blunt edge, which may accelerate the wear of the microdrill. Wear was identified as the primary factor that reduced hole quality. The study indicates that in printed circuit board machining, microdrills should effectively eliminate grinding defects and maintain the sharpness of the cutting edge as much as possible to obtain excellent drilling quality. Overall, shear thickening polishing is a promising method for cutting edge preparation of microdrills. Further research and optimization can lead to additional improvements in microdrill performance and contribute to the continued advancement of printed circuit board manufacturing.
Manufacturing flexible magnetic-driven actuators with complex structures and magnetic arrangements to achieve diverse functionalities is becoming a popular trend. Among various manufacturing technologies, magnetic-assisted digital light processing (DLP) stands out because it enables precise manufacturing of macro-scale structures and micro-scale distributions with the assistance of an external magnetic field. Current research on manufacturing magnetic flexible actuators mostly employs single materials, which limits the magnetic driving performance to some extent. Based on these characterizations, we propose a multi-material magnetic field-assisted DLP technology to produce flexible actuators with an accuracy of 200 μm. The flexible actuators are printed using two materials with different mechanical and magnetic properties. Considering the interface connectivity of multi-material printing, the effect of interfaces on mechanical properties is also explored. Experimental results indicate good chemical affinity between the two materials we selected. The overlap or connection length of the interface moderately improves the tensile strength of multi-material structures. In addition, we investigate the influence of the volume fraction of the magnetic part on deformation. Simulation and experimental results indicate that increasing the volume ratio (20% to 50%) of the magnetic structure can enhance the responsiveness of the actuator (more than 50%). Finally, we successfully manufacture two multi-material flexible actuators with specific magnetic arrangements: a multi-legged crawling robot and a flexible gripper capable of crawling and grasping actions. These results confirm that this method will pave the way for further research on the precise fabrication of magnetic flexible actuators with diverse functionalities.
