查看更多>>摘要：The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology for manufacturing of the FWMAV's body,greatly reducing assembly errors.Traditionally,studies on flapping wing aircraft are limited to open-loop wing kinematics control.In this work,an instantaneous closed-loop wing trajectory tracking control system is introduced to minimize wings'trajectory tracking errors.The control system is based on Field-Oriented Control(FOC)with a loop shaping compensation technique near the flapping frequency.Through frequency analysis,the loop shaping compensator ensures the satisfactory bandwidth and performance for the closed-loop flapping system.To implement the proposed controller,a compact autopilot board integrated with FOC hardware is designed,weighing only 2.5 g.By utilizing precise wing trajectory tracking control,the hummingbird-inspired FWMAV demonstrates superior ability to resist external disturbances and exhibits reduced attitude tracking errors during hovering flight compared to the open-loop wing motion.
查看更多>>摘要：Passively stabilized double-wing Flapping Micro Air Vehicles(FMAVs)do not require active control and exhibit good electromagnetic interference resistance,with significant research value.In this paper,the dynamic model of FMAV was established as the foundation for identifying flapping damping coefficients.Through a pendulum experiment,we ascertain the flapping damping of the damper using the energy conservation method.Besides,fitting relationships between the damper area,damper mass,and the moment of inertia are developed.The factors influencing the bottom damper damping are deter-mined using correlation coefficients and hypothesis testing methods.Additionally,stable dampers are installed on both the top and bottom of the FMAV to achieve passive stability in simulations.The minimum damper areas for the FMAV were optimized using genetic algorithms,resulting in a minimum top damper area of 128 cm2 and a minimum bottom damper area of 80 cm2.A prototype with a mass of 25.5 g and a wingspan of 22 cm has been constructed.Prototype testing demonstrated that FMAV can take off stably with a 3 g payload and a tilt angle of 5°.During testing,the area-to-mass ratio of the FMAV reached 7.29 cm2/g,achieving passive stability with the world's smallest area-to-mass ratio.
查看更多>>摘要：Effectively controlling active power-assist lower-limb exoskeletons in a human-in-the-loop manner poses a substantial chal-lenge,demanding an approach that ensures wearer autonomy while seamlessly adapting to diverse wearer needs.This paper introduces a novel hierarchical control scheme comprising five integral components:intention recognition layer,dynamics feedforward layer,force distribution layer,feedback compensation layer,as well as sensors and actuators.The intention rec-ognition layer predicts the wearer's movement and enables wearer-dominant movement through integrated force and position sensors.The force distribution layer effectively resolves the statically indeterminate problem in the context of double-foot support,showcasing flexible control modes.The dynamics feedforward layer mitigates the effect of the exoskeleton itself on movement.Meanwhile,the feedback compensation layer provides reliable closed-loop control.This approach mitigates abrupt changes in joint torques during frequent transitions between swing and stance phases by decomposed dynamics.Validating this innovative hierarchical control scheme on a hydraulic exoskeleton platform through a series of experiments,the results demonstrate its capability to deliver assistance in various modes such as stepping,squatting,and jumping while adapting seamlessly to different terrains.
查看更多>>摘要：This paper presents a novel method for optimizing the contact force of a hexapod robot to enhance its dynamic motion stability when one of its legs fails.The proposed approach aims to improve the Force Angle Stability Margin(FASM)and adapt the foot trajectory through contact force optimization to achieve safe and stable motion on various terrains.The foot force optimization approach is designed to optimize the FASM,a factor rarely considered in existing contact force optimization methods.By formulating the problem of enhancing the motion stability of the hexapod robot as a Quadratic Programming(QP)optimization problem,this approach can effectively address this issue.Simulations of a hexapod robot using a fault-tolerant gait,along with real field experiments,were conducted to validate the effectiveness and feasibility of the contact force optimization approach.The results demonstrate that this approach can be used to design a motion controller for a hexapod robot with a significantly improved motion stability.In summary,the proposed contact force optimization method offers a promising solution for enhancing the motion stability of hexapod robots with single leg failures and has the potential to significantly advance the development of fault-tolerant hexapod robots for various applications.
查看更多>>摘要：Quadruped robots which have flexibility and load-bearing capacity,are regarded as the best mobile platform for remote operation in unstructured and restricted environments.In the process of remote operation of quadruped robots,their status is inevitably influenced by complex environments.To monitor the robot's real-time operation status and make necessary adjustments,this paper focuses on the single-leg of a quadruped robot,proposes a single-leg virtual-real interaction system based on Digital Twin,and studies its virtual-real interaction characteristics.The virtual-reality interaction system contains single-leg physical entity,single-leg virtual model,control system,data service system and communication system,enabling interactive applications for single-leg visual state monitoring and real-time control optimization.This paper creates a high-fidelity model based on the physical entity;provides a system performance analysis method based on the system framework;analyzes virtual-real interaction delay based on communication scheme;conducts stand and jump test based on the single-leg mathematical model and analyzes the interaction characteristics under position/force control.This system provides new insights for real-time monitoring and control optimization of quadruped robots.
查看更多>>摘要：This paper investigates the motion control of the heavy-duty Bionic Caterpillar-like Robot(BCR)for the maintenance of the China Fusion Engineering Test Reactor(CFETR).Initially,a comprehensive nonlinear mathematical model for the BCR system is formulated using a physics-based approach.The nonlinear components of the model are compensated through nonlinear feedback linearization.Subsequently,a fuzzy-based regulator is employed to enhance the receding horizon opti-mization process for achieving optimal results.A Deep Neural Network(DNN)is trained to address disturbances.Conse-quently,a novel hybrid controller incorporating Nonlinear Model Predictive Control(NMPC),the Fuzzy Regulator(FR),and Deep Neural Network Feedforward(DNNF),named NMPC-FRDNNF is developed.Finally,the efficacy of the control system is validated through simulations and experiments.The results indicate that the Root Mean Square Error(RMSE)of the controller with FR and DNNF decreases by 33.2 and 48.9％,respectively,compared to the controller without these enhancements.This research provides a theoretical foundation and practical insights for ensuring the future highly stable,safe,and efficient maintenance of blankets.
查看更多>>摘要：This paper designs a soft robot with a multi-chamber,multi-airbag mimicking soft biological structure,where the airbags of the same chamber are interconnected with each other.The upper and lower chambers are separated by an intermediate layer(thin plate),which is extended and widened to achieve robot movement and balance.By applying pressure to the different chambers of the soft robot,it is possible to produce a variety of bionic movements of the inchworm and caterpillar.Due to the strong nonlinearity and infinite number of degrees of freedom properties of the material,it is impossible to obtain the analytical solution of the bending morphology and pressure of the soft robot directly.Therefore,a method to establish a mathematical model of soft robot deformation based on the classical stacked plate theory is proposed,and a chain composite model of soft robot bending motion is established based on the large-deflection modeling method.This paper proposes a method to generate a multi-mode soft robot motion control based on the Central Pattern Generator(CPG)using a single controller,which achieves the switching of sine wave-like patterns,half-wave-like patterns,and dragging patterns by adjust-ing frequency,amplitude and period of parameters.Finally,a pneumatic control platform is built for the validation of the theoretical model and different experimental models of the motion of the robot.And comparation of the different motion modes of the soft robot under similar non-load and load conditions.
查看更多>>摘要：Researching the cooperative operation and functional expansion of multiple minirobot assemblies has the potential to bring about significant advancements in the practical applications of minirobots.In this study,we present a novel assembly sys-tem comprised of arc-shaped NdFeB magnetic minirobots.These minirobots can be individually utilized as assembly units,allowing for function expansion and comprehensive capability enhancement.We fabricate four Semicircular Arc Magnetic Minirobots(SAMM)arranged in different configurations and analyze their force and motion characteristics.Furthermore,by using this unit as a base,various expansion structures such as latches,petals,and rings can be assembled through reason-able combinations.We define the comprehensive reinforcement interval by comparatively analyzing changes in the unit's motion characteristics and operational capabilities.Precise motion manipulation is employed to verify the rationality of the basic unit structure and the feasibility of the assembly scheme.Our proposed self-assembly scheme for magnetic minirobots exhibits great potential and may be used as a paradigm for future research on expanding the functionality of minirobots.
查看更多>>摘要：It has been demonstrated that the flexibility of the structure can enhance the kinematic performance of the underwater bionic robotic fish.Furthermore,the thrust of the underwater robotic fish can be further enhanced by changing the stiffness of the tail when the motion frequency of the propulsion system increases.This paper proposes a novel actuator,the pneumatic variable stiffness imitation dolphin tail actuator(PVSA),which combines soft robotics with the structural characteristics and movement mode of a biological dolphin.The PVSA comprises a pneumatic bi-directional bending soft actuator and a pull-wire-driven variable stiffness mechanism.The soft actuator is capable of mimicking the dorsoventral movement of dolphins by changing the pressure difference between the cavities,thereby achieving bending deformation.The variable stiff-ness mechanism is based on the stiffness mechanism of particle interference and the structural characteristics of vertebrate endoskeleton,with the objective of achieving variable stiffness.The parameters of the PVSA are optimised using numerical simulations and experimental studies,and then designed underwater experiments are conducted to investigate the effects of amplitude,stiffness and frequency on the propulsive performance of the PVSA.The results demonstrate that the PVSA is capable of enhancing thrust by adjusting its own stiffness and movement frequency.The development of the PVSA provides a reference for the research of related underwater bionic propulsion technology.
查看更多>>摘要：As an effective therapy for treating unilateral neglect,Mirror Therapy(MT)is employed in the upper limb motor function rehabilitation of hemiplegic patients.However,traditional MT has a serious limitation—the Impaired Limb(IL)doesn't actually move.In this study,a novel performance-based assistance strategy suitable for Robotic Mirror Therapy(RMT)based on MT is proposed.A guiding assistance based on the progress difference HL and IL is constructed in trajectory guidance,and a multi-stiffness region correction force field based on trajectory tracking error is designed to constrain IL's deviation from the intended path in trajectory correction assistance.To validate the presented strategy,a series of experiments on a RMT system based on the end-effector upper limb rehabilitation robot are conducted.The results verify the performance and feasibility of this strategy.
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