To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of...To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.展开更多
The lower limb exoskeletons are used to assist wearers in various scenarios such as medical and industrial settings.Complex modeling errors of the exoskeleton in different application scenarios pose challenges to the ...The lower limb exoskeletons are used to assist wearers in various scenarios such as medical and industrial settings.Complex modeling errors of the exoskeleton in different application scenarios pose challenges to the robustness and stability of its control algorithm.The Radial Basis Function(RBF)neural network is used widely to compensate for modeling errors.In order to solve the problem that the current RBF neural network controllers cannot guarantee the asymptotic stability,a neural network robust control algorithm based on computed torque method is proposed in this paper,focusing on trajectory tracking.It innovatively incorporates the robust adaptive term while introducing the RBF neural network term,improving the compensation ability for modeling errors.The stability of the algorithm is proved by Lyapunov method,and the effectiveness of the robust adaptive term is verified by the simulation.Experiments wearing the exoskeleton under different walking speeds and scenarios were carried out,and the results show that the absolute value of tracking errors of the hip and knee joints of the exoskeleton are consistently less than 1.5°and 2.5°,respectively.The proposed control algorithm effectively compensates for modeling errors and exhibits high robustness.展开更多
Automated fiber placement(AFP)enables the efficient and precise fabrication of complex-shaped aerospace composite structures with lightweight and high-performance properties.However,due to the excessive compression on...Automated fiber placement(AFP)enables the efficient and precise fabrication of complex-shaped aerospace composite structures with lightweight and high-performance properties.However,due to the excessive compression on the inner edge of the tow placed along the curved trajectory,the resulting defects represented by buckling and wrinkles in spatial tow steering can induce poor manufacturing accuracy and quality degradation of products.In this paper,a theoretical model of tow buckling based on the first-order shear deformation laminate theory,linear elastic adhesion interface and Hertz compaction contact theory is proposed to analyze the formation mechanism of the wrinkles and predict the formation of defects by solving the critical radius of the trajectory,and finite element analysis involving the cohesive zone modeling(CZM)is innovated to simulate the local buckling state of the steered tow in AFP.Additionally,numerical parametric studies and experimental results indicate that mechanical properties and geometric parameters of the prepreg,the curvature of the placement trajectory and critical process parameters have a significant impact on buckling formation,and optimization of process parameters can achieve effective suppression of placement defects.This research proposes a theoretical modeling method for tow buckling,and conducts in-depth research on defect formation and suppression methods based on finite element simulation and placement experiments.展开更多
This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of c...This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of chiral cell nodal circles while improving load transmission efficiency and enhancing manufacturing precision for 3D printing applications.A parametric design framework,integrating finite element analysis and optimization modules,is developed to enhance the wing’s multidirectional stiffness.The optimization process demonstrates that the distribution of chiral structural ligaments and nodal circles significantly affects wing deformation.The stiffness gradient optimization results reveal a variation of over 78%in tail stiffness performance between the best and worst parameter combinations.Experimental outcomes suggest that this strategy can develop metamaterials with enhanced deformability,offering a promising approach for designing morphing wings.展开更多
Variable stiffness mechanisms(VSMs)are a class of compliant mechanisms that can adjust their intrinsic stiffness,which promises to be beneficial in applications needed to interact with the environment,such as collabor...Variable stiffness mechanisms(VSMs)are a class of compliant mechanisms that can adjust their intrinsic stiffness,which promises to be beneficial in applications needed to interact with the environment,such as collaborative robots,wearable robots,and polishing robots.This paper presents the design and optimization of a novel linear VSM,called cLVSM,to produce linear motion,conversely to the majority of VSMs designed to perform rotary motion.By changing the effective length of specially designed circular beams,the cLVSM is capable of continuous stiffness regulation from a minimum value to almost rigid.Different from the VSMs which need rotation-to-translation converting mechanisms for stiffness regulation,the stiffness of the proposed design is adjusted by directly rotating the beams without the use of additional mechanisms,which contributes to improving the structural compactness,and reducing the energy loss and error in transmission.Moreover,the beam rotation needed to regulate the stiffness is almost perpendicular to the beam deflection force,which helps to reduce the torque needed for stiffness regulation.The stiffness model of the proposed VSM is developed using the screw theory,and the design parameters are optimized using the genetic algorithm.The effectiveness of the mathematical model and the performance of the design are verified by simulation and experiments.展开更多
Lower limb rehabilitation exoskeleton robots integrate sensing, control, and other technologies and exhibit the characteristics of bionics, robotics, information and control science, medicine, and other interdisciplin...Lower limb rehabilitation exoskeleton robots integrate sensing, control, and other technologies and exhibit the characteristics of bionics, robotics, information and control science, medicine, and other interdisciplinary areas. In this review, the typical products and prototypes of lower limb exoskeleton rehabilitation robots are introduced and stateof-the-art techniques are analyzed and summarized. Because the goal of rehabilitation training is to recover patients’ sporting ability to the normal level, studying the human gait is the foundation of lower limb exoskeleton rehabilitation robot research. Therefore, this review critically evaluates research progress in human gait analysis and systematically summarizes developments in the mechanical design and control of lower limb rehabilitation exoskeleton robots. From the performance of typical prototypes, it can be deduced that these robots can be connected to human limbs as wearable forms;further, it is possible to control robot movement at each joint to simulate normal gait and drive the patient’s limb to realize robot-assisted rehabilitation training. Therefore human–robot integration is one of the most important research directions, and in this context, rigid-flexible-soft hybrid structure design, customized personalized gait generation, and multimodal information fusion are three key technologies.展开更多
The previous research regarding the gait planning of quadruped robot focuses on the sequence for lifting o and placing the feet, but neglects the influence of body height. However, body height a ects gait performance ...The previous research regarding the gait planning of quadruped robot focuses on the sequence for lifting o and placing the feet, but neglects the influence of body height. However, body height a ects gait performance significantly, such as in terms of the stride length and stability margin. We herein study the performance of a quadruped robot using the equivalent mechanism concept based on metamorphosis. Assuming the constraints between standing feet and the ground with hinges, the ground, standing legs and robot body are considered as a parallel mechanism, and each swing leg is regarded as a typical serial manipulator. The equivalent mechanism varies while the robot moves on the ground. One gait cycle is divided into several periods, including step forward stages and switching stages. There exists a specific equivalent mechanism corresponding to each gait period. The robot's locomotion can be regarded as the motion of these series of equivalent mechanisms. The kinematics model and simplified model of the equivalent mechanism is established. A new definition of the multilegged robot stability margin, based on friction coe cient, is presented to evaluate the robot stability. The stable workspaces of the equivalent mechanism in the step forward stage of trotting gait under di erent friction coe cients are analyzed. The stride length of the robots is presented by analyzing the relationship between the stable workspaces of the equivalent mechanisms of two adjacent step forward stages in one gait cycle. The simulation results show that the stride length is larger with increasing friction coe cient. We herein propose a new method based on metamorphosis, and an equivalent mechanism to analyze the stability margin and stable workspace of the multilegged robot.展开更多
Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and bounding.These advanced motion abilities are related to the buffer effect of their complicated musculoskeletal systems.Ho...Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and bounding.These advanced motion abilities are related to the buffer effect of their complicated musculoskeletal systems.However,the buffer effect of most bio-robots is not satisfactory owing to the simple design of their buffer systems.In this paper,a physiological analysis of the ruminant musculoskeletal system is presented to explain the intrinsic buffer mechanism of motion.Based on the physical buffer parts of the ruminant limbs,the corresponding bionic mappings were determined.These mappings were used to guide the mechanism design of the robot multistage buffer system.The multistage buffer system includes two main buffer mechanisms:the first stage and the second stage.The buffer mechanism analysis of the first stage and multiple stages is discussed in theory to compare the effects between the normal single buffer system and the novel multistage buffer system.Then,the detailed mechanical structure of the limbs was designed based on the limb mechanism design.To further verify the superior efficacy of the multistage buffer system,the corresponding walking simulation experiments were conducted after the virtual prototype of a quadruped robot with a novel limb was built completely.Both theoretical analysis and simulation experiments prove that the bionic robot design with the novel multistage buffer system achieves better motion performance than the traditional robot buffer design and can be regarded as the design template of the robot limb.展开更多
Urgent requirements of medical devices Precision medicine has gradually become a development strategy in many countries and attracted worldwide attention in recent years due to the increasing concerns in public health...Urgent requirements of medical devices Precision medicine has gradually become a development strategy in many countries and attracted worldwide attention in recent years due to the increasing concerns in public health.Although the definition of precision medicine has less or more difference from the viewpoints of different fields,the demands on the properties of medical devices or medical materials involving biocompatibility and anti-thrombosis are gradually growingmuch more diverse and much more urgent than ever[1].This trend brings up many new research topics about materials,mechanical systems and sensors to develop advanced medical devices.How to design and on-demand fabricate the bio-materials,bio-interface and bio-systems to meet the urgent demands of medical devices is still a challenge for us.展开更多
Moles exhibit highly effective capabilities due to their unique body structures and digging techniques,making them ideal models for biomimetic research.However,a major challenge for mole-inspired robots lies in overco...Moles exhibit highly effective capabilities due to their unique body structures and digging techniques,making them ideal models for biomimetic research.However,a major challenge for mole-inspired robots lies in overcoming resistance in granular media when burrowing with forelimbs.In the absence of effective forepaw design strategies,most robotic designs rely on increased power to enhance performance.To address this issue,this paper employs Resistive Force Theory to optimize mole-inspired forepaws,aiming to enhance burrowing efficiency.By analyzing the relationship between geometric parameters and burrowing forces,we propose several forepaw design variations.Through granular resistance assessments,an effective forepaw configuration is identified and further refined using parameters such as longitudinal and transverse curvature.Subsequently,the Particle Swarm Optimization algorithm is applied to determine the optimal forepaw design.In force-loading tests,the optimized forepaw demonstrated a 79.44%reduction in granular lift force and a 22.55%increase in propulsive force compared with the control group.In robotic burrowing experiments,the optimized forepaw achieved the longest burrow displacement(179.528 mm)and the lowest burrowing lift force(0.9355 mm/s),verifying its effectiveness in reducing the lift force and enhancing the propulsive force.展开更多
To reveal the mechanism of high loading capacity,the characteristics of the mammalian leg skeletal structure are analyzed,and the horse is chosen as a typical example.The supporting situations of horse standing are pr...To reveal the mechanism of high loading capacity,the characteristics of the mammalian leg skeletal structure are analyzed,and the horse is chosen as a typical example.The supporting situations of horse standing are presented,including the symmetrical case and the unsymmetrical one.According to the results of animal anatomy,the skeletal structures of the forelimb and the hind limb are appropriately simplified to plane open-chain five-link mechanisms.The force analyses of the five-link mechanisms are presented to explore the variations of joint moments in two aspects:changing the direction of the ground reaction force and changing the posture of the leg.It is concluded that the dead-point supporting effect of the leg skeletal structure help improve the high loading capacity.It means that horses bear loads mainly by bones rather than muscles.Hence horses could carry high loads with little energy consumption of leg muscles.展开更多
The concept of remote center of motion(RCM)is pivotal in a myriad of robotic applications,encompa-ssing areas such as medical robotics,orientation devices,and exoskeletal systems.The efficacy of RCM technology is a de...The concept of remote center of motion(RCM)is pivotal in a myriad of robotic applications,encompa-ssing 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.展开更多
A key challenge is using bionic mechanisms to enhance aerodynamic performance of hover-capable flapping wing micro air vehicle(FWMAV).This paper presented a new lift system with high lift and aerodynamic efficiency,wh...A key challenge is using bionic mechanisms to enhance aerodynamic performance of hover-capable flapping wing micro air vehicle(FWMAV).This paper presented a new lift system with high lift and aerodynamic efficiency,which use a hummingbird as a bionic object.This new lift system is able to effectively utilize the high lift mechanism of hummingbirds,and this study innovatively utilizes elastic energy storage elements and installs them at the wing root to help improve aerodynamic performance.A flapping angle of 154°is achieved through the optimization of the flapping mechanism parameters.An optimized wing shape and parameters are obtained through experimental studies on the wings.Consequently,the max net lift generated is 17.6%of the flapping wing vehicle’s weight.Moreover,energy is stored and released periodically during the flapping cycle,by imitating the musculoskeletal system at the wing roots of hummingbirds,thereby improving the energy utilization rate of the FWMAV and reducing power consumption by 4.5%under the same lift.Moreover,strength verification and modal analyses are conducted on the flapping mechanism,and the weight of the flapping mechanism is reduced through the analysis and testing of different materials.The results show that the lift system can generate a stable lift of 31.98 g with a wingspan of 175 mm,while the lift system weighs only 10.5 g,providing aerodynamic conditions suitable for high maneuverability flight of FWMAVs.展开更多
The deployable telescopic boom,whose mass and stiffness play crucial roles,is extensively used in the design of space-deployable structures.However,the most existing optimal design that neglects the influence of the l...The deployable telescopic boom,whose mass and stiffness play crucial roles,is extensively used in the design of space-deployable structures.However,the most existing optimal design that neglects the influence of the locking mechanisms in boom joints cannot raise the whole stiffness while reducing the boom mass.To tackle this challenge,a novel optimization model,which utilizes the arrangement of the locking mechanisms to achieve synchronous improvement of the stiffness and mass,is proposed.The proposed optimization model incorporates a novel joint stiffness model developed based on an equivalent parallel mechanism that enables the consideration of multiple internal stiffness factors of the locking mechanisms and tubes,resulting in more accurate representations of the joint stiffness behavior.Comparative analysis shows that the proposed stiffness model achieves more than at least 11% improved accuracy compared with existing models.Furthermore,case verification shows that the proposed optimization model can improve stiffness while effectively reducing mass,and it is applied in boom optimization design.展开更多
In recent years,there has been a surge of interest in air-ground collaborative robotics technologies.Our research group designs a novel combination-separation air-ground robot(CSAGR),which exhibits rapid automatic com...In recent years,there has been a surge of interest in air-ground collaborative robotics technologies.Our research group designs a novel combination-separation air-ground robot(CSAGR),which exhibits rapid automatic combination and separation capabilities.During the combination process,contact effects between robots,as well as between robots and the environment,are unavoidable.Therefore,it is essential to conduct detailed and accurate modeling and analysis of the collision impact intensity and transmission pathways within the robotic system to ensure the successful execution of the combination procedure.This paper addresses the intricate surface geometries and multi-point contact challenges present in the contact regions of dual robots by making appropriate modifications to the traditional continuous contact force model and applying equivalent processing techniques.The validity of the developed model is confirmed through comparisons with results obtained from finite element analysis(FEA),which demonstrates its high fidelity.Additionally,the impact of this model on control performance is analyzed within the flight control system,thereby further ensuring the successful completion of the combination process.This research represents a pioneering application and validation of continuous contact theory in the dynamics of collisions within dual robot systems.展开更多
Small-scale rotorcraft unmanned robotic systems(SRURSs) are a kind of unmanned rotorcraft with manipulating devices. This review aims to provide an overview on aerial manipulation of SRURSs nowadays and promote relati...Small-scale rotorcraft unmanned robotic systems(SRURSs) are a kind of unmanned rotorcraft with manipulating devices. This review aims to provide an overview on aerial manipulation of SRURSs nowadays and promote relative research in the future. In the past decade, aerial manipulation of SRURSs has attracted the interest of researchers globally. This paper provides a literature review of the last 10 years(2008–2017) on SRURSs, and details achievements and challenges. Firstly, the definition, current state, development, classification, and challenges of SRURSs are introduced. Then, related papers are organized into two topical categories: mechanical structure design, and modeling and control. Following this, research groups involved in SRURS research and their major achievements are summarized and classified in the form of tables. The research groups are introduced in detail from seven parts. Finally, trends and challenges are compiled and presented to serve as a resource for researchers interested in aerial manipulation of SRURSs. The problem,trends, and challenges are described from three aspects. Conclusions of the paper are presented,and the future of SRURSs is discussed to enable further research interests.展开更多
Accuracy of the fitted surface is of great importance to the performance of deployable antennas utilized in space.This paper proposes a stiffness analysis based fitting accuracy optimization method for achieving the o...Accuracy of the fitted surface is of great importance to the performance of deployable antennas utilized in space.This paper proposes a stiffness analysis based fitting accuracy optimization method for achieving the optimal parameters of the parabolic cylindrical deployable antenna mechanism.The stiffness matrix of the proposed cylindrical antenna mechanism is established by assembling the stiffness of beams and tension cables.Structural deformations of the mechanism are calculated where the tensioned cable is substituted by a 2-node truss element and an equivalent force acting on the joint.Consideration of the tensity of tension cables,namely tensioned or slack,is transformed into a typical linear complementarity problem.Comparison between structural deformations of the mechanism fixed at different points is performed.Sensitivities of the geometric and structural parameters on fitting accuracy are investigated.Influence of force of the driven cable on structural deformations of antenna operated in different orbits is conducted.A fitting optimization method is proposed to minimize the structural deformations subject to constraints on volume and mass.Simulation result shows that the fitting accuracy of the antenna mechanism is improved significantly through the optimization.The proposed method can be utilized for the optimal design of other deployable mechanisms constructed by joining rigid links.展开更多
A 2 m class robotic drill was sent to the Moon and successfully collected and returned regolith samples in late 2020 by China.It was a typical thick wall spiral drill(TWSD)with a hollow auger containing a complex cori...A 2 m class robotic drill was sent to the Moon and successfully collected and returned regolith samples in late 2020 by China.It was a typical thick wall spiral drill(TWSD)with a hollow auger containing a complex coring system to retain subsurface regolith samples.Before the robotic drill was launched,a series of laboratory tests were carried out to investigate and predict the possible drilling loads it may encounter in the lunar environment.This work presents how the sampling performance of the TWSD is affected by the regolith compressibility.Experiments and analysis during the drilling and sampling process in a simulated lunar regolith environment were conducted.The compressibility of a typical lunar regolith simulant(LRS)was measured through unidirectional compression tests to study the relationship between its inner regolith stress and bulk density.A theoretical model was established to elucidate the cutting discharge behavior by auger flights based on the aforementioned relationship.Experiments were conducted with the LRS,and the results show that the sampling performance is greatly affected by the flux of the drilled cuttings into the spiral flight channels.This work helped in scheduling reasonable drilling parameters to promote the sampling performance of the robotic drill in the Chinese Chang’E 5 mission.展开更多
Many organisms have attachment organs with excellent functions,such as adhesion,clinging,and grasping,as a result of biological evolution to adapt to complex living environments.From nanoscale to macroscale,each type ...Many organisms have attachment organs with excellent functions,such as adhesion,clinging,and grasping,as a result of biological evolution to adapt to complex living environments.From nanoscale to macroscale,each type of adhesive organ has its own underlying mechanisms.Many biological adhesive mechanisms have been studied and can be incorporated into robot designs.This paper presents a systematic review of reversible biological adhesive methods and the bioinspired attachment devices that can be used in robotics.The study discussed how biological adhesive methods,such as dry adhesion,wet adhesion,mechanical adhesion,and sub-ambient pressure adhesion,progress in research.The morphology of typical adhesive organs,as well as the corresponding attachment models,is highlighted.The current state of bioinspired attachment device design and fabrication is discussed.Then,the design principles of attachment devices are summarized in this article.The following section provides a systematic overview of climbing robots with bioinspired attachment devices.Finally,the current challenges and opportunities in bioinspired attachment research in robotics are discussed.展开更多
Automated fibre placement(AFP) systems have successfully intensified the demand for high-quality composite component manufacturing in both the military and civilian fields. One of the main elements of these systems is...Automated fibre placement(AFP) systems have successfully intensified the demand for high-quality composite component manufacturing in both the military and civilian fields. One of the main elements of these systems is the AFP mechanism for accomplishing individual fibre delivery,clamp/cut/restart(CCR) and the consolidation process, and it consists of several functional submechanisms presenting strong coupling relationships and motion sequences. This review aims to summarize the development of AFP mechanisms and the associated research achievements and provide insight into the research challenges in promoting innovative design in such mechanisms. The systematic development of AFP systems is reviewed in detail, and subsequently, engineering tendency and the general principle of AFP mechanisms are introduced. Focusing on the mechanism design of AFP sub-mechanisms, including the creel assembly CCR and compaction mechanisms,the mechanical schemes as well as the AFP process parameter control are discussed. To improve system reliability and fully optimise AFP mechanisms, the essential theoretical foundation for AFP mechanisms are provided. It is believed that this attempt will help to change the design and optimisation of similar complete mechanisms. Based on the reviewed research, overall remarks and perspectives are presented to serve as a guide for exploring the possibility of novel easy-to-use and cost-effective integrated AFP applications.展开更多
基金Supported by National Natural Science Foundation of China (Grant Nos. 52375003, 52205006)National Key R&D Program of China (Grant No. 2019YFB1309600)。
文摘To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.
基金Supported by National Key R&D Program of China(Grant No.2022YFB4701200)National Natural Science Foundation of China(NSFC)(Grant Nos.T2121003,52205004).
文摘The lower limb exoskeletons are used to assist wearers in various scenarios such as medical and industrial settings.Complex modeling errors of the exoskeleton in different application scenarios pose challenges to the robustness and stability of its control algorithm.The Radial Basis Function(RBF)neural network is used widely to compensate for modeling errors.In order to solve the problem that the current RBF neural network controllers cannot guarantee the asymptotic stability,a neural network robust control algorithm based on computed torque method is proposed in this paper,focusing on trajectory tracking.It innovatively incorporates the robust adaptive term while introducing the RBF neural network term,improving the compensation ability for modeling errors.The stability of the algorithm is proved by Lyapunov method,and the effectiveness of the robust adaptive term is verified by the simulation.Experiments wearing the exoskeleton under different walking speeds and scenarios were carried out,and the results show that the absolute value of tracking errors of the hip and knee joints of the exoskeleton are consistently less than 1.5°and 2.5°,respectively.The proposed control algorithm effectively compensates for modeling errors and exhibits high robustness.
基金Supported by National Natural Science Foundation of China(Grant Nos.52205003 and 51575018)Zhejiang Provincial Natural Science Foundation(Grant No.LD22E050011)Ningbo Municipal Key Projects of Science and Technology Innovation 2025 Plan(Grant No.2022Z070).
文摘Automated fiber placement(AFP)enables the efficient and precise fabrication of complex-shaped aerospace composite structures with lightweight and high-performance properties.However,due to the excessive compression on the inner edge of the tow placed along the curved trajectory,the resulting defects represented by buckling and wrinkles in spatial tow steering can induce poor manufacturing accuracy and quality degradation of products.In this paper,a theoretical model of tow buckling based on the first-order shear deformation laminate theory,linear elastic adhesion interface and Hertz compaction contact theory is proposed to analyze the formation mechanism of the wrinkles and predict the formation of defects by solving the critical radius of the trajectory,and finite element analysis involving the cohesive zone modeling(CZM)is innovated to simulate the local buckling state of the steered tow in AFP.Additionally,numerical parametric studies and experimental results indicate that mechanical properties and geometric parameters of the prepreg,the curvature of the placement trajectory and critical process parameters have a significant impact on buckling formation,and optimization of process parameters can achieve effective suppression of placement defects.This research proposes a theoretical modeling method for tow buckling,and conducts in-depth research on defect formation and suppression methods based on finite element simulation and placement experiments.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075026 and 52192632)the Fundamental Research Funds for the Central Universities(Grant No.YWF-22-L-1119)。
文摘This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of chiral cell nodal circles while improving load transmission efficiency and enhancing manufacturing precision for 3D printing applications.A parametric design framework,integrating finite element analysis and optimization modules,is developed to enhance the wing’s multidirectional stiffness.The optimization process demonstrates that the distribution of chiral structural ligaments and nodal circles significantly affects wing deformation.The stiffness gradient optimization results reveal a variation of over 78%in tail stiffness performance between the best and worst parameter combinations.Experimental outcomes suggest that this strategy can develop metamaterials with enhanced deformability,offering a promising approach for designing morphing wings.
基金Supported by National Key R&D Program of China(Grant No.2022YFB4701200)Ningbo Municipal Key Projects of Science and Technology Innovation 2025 Plan(Grant No.2022Z070)National Natural Science Foundation of China(Grant No.52205004).
文摘Variable stiffness mechanisms(VSMs)are a class of compliant mechanisms that can adjust their intrinsic stiffness,which promises to be beneficial in applications needed to interact with the environment,such as collaborative robots,wearable robots,and polishing robots.This paper presents the design and optimization of a novel linear VSM,called cLVSM,to produce linear motion,conversely to the majority of VSMs designed to perform rotary motion.By changing the effective length of specially designed circular beams,the cLVSM is capable of continuous stiffness regulation from a minimum value to almost rigid.Different from the VSMs which need rotation-to-translation converting mechanisms for stiffness regulation,the stiffness of the proposed design is adjusted by directly rotating the beams without the use of additional mechanisms,which contributes to improving the structural compactness,and reducing the energy loss and error in transmission.Moreover,the beam rotation needed to regulate the stiffness is almost perpendicular to the beam deflection force,which helps to reduce the torque needed for stiffness regulation.The stiffness model of the proposed VSM is developed using the screw theory,and the design parameters are optimized using the genetic algorithm.The effectiveness of the mathematical model and the performance of the design are verified by simulation and experiments.
基金Supported by National Key R&D Program of China(Grant No.2016YFE0105000)National Natural Science Foundation of China(Grant No.91848104)
文摘Lower limb rehabilitation exoskeleton robots integrate sensing, control, and other technologies and exhibit the characteristics of bionics, robotics, information and control science, medicine, and other interdisciplinary areas. In this review, the typical products and prototypes of lower limb exoskeleton rehabilitation robots are introduced and stateof-the-art techniques are analyzed and summarized. Because the goal of rehabilitation training is to recover patients’ sporting ability to the normal level, studying the human gait is the foundation of lower limb exoskeleton rehabilitation robot research. Therefore, this review critically evaluates research progress in human gait analysis and systematically summarizes developments in the mechanical design and control of lower limb rehabilitation exoskeleton robots. From the performance of typical prototypes, it can be deduced that these robots can be connected to human limbs as wearable forms;further, it is possible to control robot movement at each joint to simulate normal gait and drive the patient’s limb to realize robot-assisted rehabilitation training. Therefore human–robot integration is one of the most important research directions, and in this context, rigid-flexible-soft hybrid structure design, customized personalized gait generation, and multimodal information fusion are three key technologies.
基金Supported by National Natural Science Foundation of China(Grant Nos.51775011,91748201)
文摘The previous research regarding the gait planning of quadruped robot focuses on the sequence for lifting o and placing the feet, but neglects the influence of body height. However, body height a ects gait performance significantly, such as in terms of the stride length and stability margin. We herein study the performance of a quadruped robot using the equivalent mechanism concept based on metamorphosis. Assuming the constraints between standing feet and the ground with hinges, the ground, standing legs and robot body are considered as a parallel mechanism, and each swing leg is regarded as a typical serial manipulator. The equivalent mechanism varies while the robot moves on the ground. One gait cycle is divided into several periods, including step forward stages and switching stages. There exists a specific equivalent mechanism corresponding to each gait period. The robot's locomotion can be regarded as the motion of these series of equivalent mechanisms. The kinematics model and simplified model of the equivalent mechanism is established. A new definition of the multilegged robot stability margin, based on friction coe cient, is presented to evaluate the robot stability. The stable workspaces of the equivalent mechanism in the step forward stage of trotting gait under di erent friction coe cients are analyzed. The stride length of the robots is presented by analyzing the relationship between the stable workspaces of the equivalent mechanisms of two adjacent step forward stages in one gait cycle. The simulation results show that the stride length is larger with increasing friction coe cient. We herein propose a new method based on metamorphosis, and an equivalent mechanism to analyze the stability margin and stable workspace of the multilegged robot.
基金Supported by the National Key Research and Development Program of China(Grant No.2019YFB1309600)the National Natural Science Foundation of China(Grant Nos.51775011&91748201).
文摘Large quadruped mammals,such as ruminants,have outstanding motion ability,including running and bounding.These advanced motion abilities are related to the buffer effect of their complicated musculoskeletal systems.However,the buffer effect of most bio-robots is not satisfactory owing to the simple design of their buffer systems.In this paper,a physiological analysis of the ruminant musculoskeletal system is presented to explain the intrinsic buffer mechanism of motion.Based on the physical buffer parts of the ruminant limbs,the corresponding bionic mappings were determined.These mappings were used to guide the mechanism design of the robot multistage buffer system.The multistage buffer system includes two main buffer mechanisms:the first stage and the second stage.The buffer mechanism analysis of the first stage and multiple stages is discussed in theory to compare the effects between the normal single buffer system and the novel multistage buffer system.Then,the detailed mechanical structure of the limbs was designed based on the limb mechanism design.To further verify the superior efficacy of the multistage buffer system,the corresponding walking simulation experiments were conducted after the virtual prototype of a quadruped robot with a novel limb was built completely.Both theoretical analysis and simulation experiments prove that the bionic robot design with the novel multistage buffer system achieves better motion performance than the traditional robot buffer design and can be regarded as the design template of the robot limb.
文摘Urgent requirements of medical devices Precision medicine has gradually become a development strategy in many countries and attracted worldwide attention in recent years due to the increasing concerns in public health.Although the definition of precision medicine has less or more difference from the viewpoints of different fields,the demands on the properties of medical devices or medical materials involving biocompatibility and anti-thrombosis are gradually growingmuch more diverse and much more urgent than ever[1].This trend brings up many new research topics about materials,mechanical systems and sensors to develop advanced medical devices.How to design and on-demand fabricate the bio-materials,bio-interface and bio-systems to meet the urgent demands of medical devices is still a challenge for us.
基金financially supported in-part by the National Natural Science Foundation of China(52275011)the Natural Science Foundation of Guangdong Province(2023B1515020080)+3 种基金the Natural Science Foundation of Guangzhou(2024A04J2552)the Fundamental Research Funds for the Central Universities,the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(CAST)(2021QNRC001)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023A1515011253)the Higher Education Institution Featured Innovation Project of Department of Education of Guangdong Province(GrantNo.2023KTSCX138).
文摘Moles exhibit highly effective capabilities due to their unique body structures and digging techniques,making them ideal models for biomimetic research.However,a major challenge for mole-inspired robots lies in overcoming resistance in granular media when burrowing with forelimbs.In the absence of effective forepaw design strategies,most robotic designs rely on increased power to enhance performance.To address this issue,this paper employs Resistive Force Theory to optimize mole-inspired forepaws,aiming to enhance burrowing efficiency.By analyzing the relationship between geometric parameters and burrowing forces,we propose several forepaw design variations.Through granular resistance assessments,an effective forepaw configuration is identified and further refined using parameters such as longitudinal and transverse curvature.Subsequently,the Particle Swarm Optimization algorithm is applied to determine the optimal forepaw design.In force-loading tests,the optimized forepaw demonstrated a 79.44%reduction in granular lift force and a 22.55%increase in propulsive force compared with the control group.In robotic burrowing experiments,the optimized forepaw achieved the longest burrow displacement(179.528 mm)and the lowest burrowing lift force(0.9355 mm/s),verifying its effectiveness in reducing the lift force and enhancing the propulsive force.
基金supported by the National Basic Research Program of Chinathe National Natural Science Fundation for Distinguished Young Scholar (51125020)
文摘To reveal the mechanism of high loading capacity,the characteristics of the mammalian leg skeletal structure are analyzed,and the horse is chosen as a typical example.The supporting situations of horse standing are presented,including the symmetrical case and the unsymmetrical one.According to the results of animal anatomy,the skeletal structures of the forelimb and the hind limb are appropriately simplified to plane open-chain five-link mechanisms.The force analyses of the five-link mechanisms are presented to explore the variations of joint moments in two aspects:changing the direction of the ground reaction force and changing the posture of the leg.It is concluded that the dead-point supporting effect of the leg skeletal structure help improve the high loading capacity.It means that horses bear loads mainly by bones rather than muscles.Hence horses could carry high loads with little energy consumption of leg muscles.
基金supported in part by the National Key R&D Program of China(Grant No.2022YFB4701200)the Ningbo Key Projects of Science and Technology Innovation 2025 Plan of China(Grant No.2022Z070)+2 种基金the Zhejiang Provincial Natural Science Foundation of China(Grant No.LD22E050011)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.T2121003)the National Natural Science Foundation of China(Grant No.52205003).
文摘The concept of remote center of motion(RCM)is pivotal in a myriad of robotic applications,encompa-ssing 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.
基金supported by the National Natural Science Foundation of China(Grant Nos.51975023 and 52322501).
文摘A key challenge is using bionic mechanisms to enhance aerodynamic performance of hover-capable flapping wing micro air vehicle(FWMAV).This paper presented a new lift system with high lift and aerodynamic efficiency,which use a hummingbird as a bionic object.This new lift system is able to effectively utilize the high lift mechanism of hummingbirds,and this study innovatively utilizes elastic energy storage elements and installs them at the wing root to help improve aerodynamic performance.A flapping angle of 154°is achieved through the optimization of the flapping mechanism parameters.An optimized wing shape and parameters are obtained through experimental studies on the wings.Consequently,the max net lift generated is 17.6%of the flapping wing vehicle’s weight.Moreover,energy is stored and released periodically during the flapping cycle,by imitating the musculoskeletal system at the wing roots of hummingbirds,thereby improving the energy utilization rate of the FWMAV and reducing power consumption by 4.5%under the same lift.Moreover,strength verification and modal analyses are conducted on the flapping mechanism,and the weight of the flapping mechanism is reduced through the analysis and testing of different materials.The results show that the lift system can generate a stable lift of 31.98 g with a wingspan of 175 mm,while the lift system weighs only 10.5 g,providing aerodynamic conditions suitable for high maneuverability flight of FWMAVs.
基金the National Natural Science Foundation of China(Grant Nos.U22B2080 and 51635002).
文摘The deployable telescopic boom,whose mass and stiffness play crucial roles,is extensively used in the design of space-deployable structures.However,the most existing optimal design that neglects the influence of the locking mechanisms in boom joints cannot raise the whole stiffness while reducing the boom mass.To tackle this challenge,a novel optimization model,which utilizes the arrangement of the locking mechanisms to achieve synchronous improvement of the stiffness and mass,is proposed.The proposed optimization model incorporates a novel joint stiffness model developed based on an equivalent parallel mechanism that enables the consideration of multiple internal stiffness factors of the locking mechanisms and tubes,resulting in more accurate representations of the joint stiffness behavior.Comparative analysis shows that the proposed stiffness model achieves more than at least 11% improved accuracy compared with existing models.Furthermore,case verification shows that the proposed optimization model can improve stiffness while effectively reducing mass,and it is applied in boom optimization design.
基金Supported by National Natural Science Foundation of China(Grant Nos.T2121003 and 91748201).
文摘In recent years,there has been a surge of interest in air-ground collaborative robotics technologies.Our research group designs a novel combination-separation air-ground robot(CSAGR),which exhibits rapid automatic combination and separation capabilities.During the combination process,contact effects between robots,as well as between robots and the environment,are unavoidable.Therefore,it is essential to conduct detailed and accurate modeling and analysis of the collision impact intensity and transmission pathways within the robotic system to ensure the successful execution of the combination procedure.This paper addresses the intricate surface geometries and multi-point contact challenges present in the contact regions of dual robots by making appropriate modifications to the traditional continuous contact force model and applying equivalent processing techniques.The validity of the developed model is confirmed through comparisons with results obtained from finite element analysis(FEA),which demonstrates its high fidelity.Additionally,the impact of this model on control performance is analyzed within the flight control system,thereby further ensuring the successful completion of the combination process.This research represents a pioneering application and validation of continuous contact theory in the dynamics of collisions within dual robot systems.
基金supported by the National Natural Science Foundation of China (Nos. 91748201 and 51505014)
文摘Small-scale rotorcraft unmanned robotic systems(SRURSs) are a kind of unmanned rotorcraft with manipulating devices. This review aims to provide an overview on aerial manipulation of SRURSs nowadays and promote relative research in the future. In the past decade, aerial manipulation of SRURSs has attracted the interest of researchers globally. This paper provides a literature review of the last 10 years(2008–2017) on SRURSs, and details achievements and challenges. Firstly, the definition, current state, development, classification, and challenges of SRURSs are introduced. Then, related papers are organized into two topical categories: mechanical structure design, and modeling and control. Following this, research groups involved in SRURS research and their major achievements are summarized and classified in the form of tables. The research groups are introduced in detail from seven parts. Finally, trends and challenges are compiled and presented to serve as a resource for researchers interested in aerial manipulation of SRURSs. The problem,trends, and challenges are described from three aspects. Conclusions of the paper are presented,and the future of SRURSs is discussed to enable further research interests.
基金supported by the National Natural Science Foundation of China (No.51635002) (Key Program) and No.51605011
文摘Accuracy of the fitted surface is of great importance to the performance of deployable antennas utilized in space.This paper proposes a stiffness analysis based fitting accuracy optimization method for achieving the optimal parameters of the parabolic cylindrical deployable antenna mechanism.The stiffness matrix of the proposed cylindrical antenna mechanism is established by assembling the stiffness of beams and tension cables.Structural deformations of the mechanism are calculated where the tensioned cable is substituted by a 2-node truss element and an equivalent force acting on the joint.Consideration of the tensity of tension cables,namely tensioned or slack,is transformed into a typical linear complementarity problem.Comparison between structural deformations of the mechanism fixed at different points is performed.Sensitivities of the geometric and structural parameters on fitting accuracy are investigated.Influence of force of the driven cable on structural deformations of antenna operated in different orbits is conducted.A fitting optimization method is proposed to minimize the structural deformations subject to constraints on volume and mass.Simulation result shows that the fitting accuracy of the antenna mechanism is improved significantly through the optimization.The proposed method can be utilized for the optimal design of other deployable mechanisms constructed by joining rigid links.
基金financially supported in-part by the Pre-research project on Civil Aerospace Technologies by CNSA(No.D020201)the National Natural Science Foundation of China(No.51905105,51775011,11932001,51635002,and U2013603)+2 种基金the Natural Science Foundation of Guangdong Province(No.2020A1515011262)the State Key Laboratory of Robotics and Systems(HIT)(No.SKLRS-2020-KF12)the Technology Innovation Strategic Special Funds of Guangdong Province(No.2019A050503011)。
文摘A 2 m class robotic drill was sent to the Moon and successfully collected and returned regolith samples in late 2020 by China.It was a typical thick wall spiral drill(TWSD)with a hollow auger containing a complex coring system to retain subsurface regolith samples.Before the robotic drill was launched,a series of laboratory tests were carried out to investigate and predict the possible drilling loads it may encounter in the lunar environment.This work presents how the sampling performance of the TWSD is affected by the regolith compressibility.Experiments and analysis during the drilling and sampling process in a simulated lunar regolith environment were conducted.The compressibility of a typical lunar regolith simulant(LRS)was measured through unidirectional compression tests to study the relationship between its inner regolith stress and bulk density.A theoretical model was established to elucidate the cutting discharge behavior by auger flights based on the aforementioned relationship.Experiments were conducted with the LRS,and the results show that the sampling performance is greatly affected by the flux of the drilled cuttings into the spiral flight channels.This work helped in scheduling reasonable drilling parameters to promote the sampling performance of the robotic drill in the Chinese Chang’E 5 mission.
基金This work was financially supported by the National Key R&D Program of China(Grant No.2019YFB1309600)the National Natural Science Foundation of China(Grant Nos.51775011 and 91748201).
文摘Many organisms have attachment organs with excellent functions,such as adhesion,clinging,and grasping,as a result of biological evolution to adapt to complex living environments.From nanoscale to macroscale,each type of adhesive organ has its own underlying mechanisms.Many biological adhesive mechanisms have been studied and can be incorporated into robot designs.This paper presents a systematic review of reversible biological adhesive methods and the bioinspired attachment devices that can be used in robotics.The study discussed how biological adhesive methods,such as dry adhesion,wet adhesion,mechanical adhesion,and sub-ambient pressure adhesion,progress in research.The morphology of typical adhesive organs,as well as the corresponding attachment models,is highlighted.The current state of bioinspired attachment device design and fabrication is discussed.Then,the design principles of attachment devices are summarized in this article.The following section provides a systematic overview of climbing robots with bioinspired attachment devices.Finally,the current challenges and opportunities in bioinspired attachment research in robotics are discussed.
基金the support from the National Natural Science Foundation of China(grant No.51575018)。
文摘Automated fibre placement(AFP) systems have successfully intensified the demand for high-quality composite component manufacturing in both the military and civilian fields. One of the main elements of these systems is the AFP mechanism for accomplishing individual fibre delivery,clamp/cut/restart(CCR) and the consolidation process, and it consists of several functional submechanisms presenting strong coupling relationships and motion sequences. This review aims to summarize the development of AFP mechanisms and the associated research achievements and provide insight into the research challenges in promoting innovative design in such mechanisms. The systematic development of AFP systems is reviewed in detail, and subsequently, engineering tendency and the general principle of AFP mechanisms are introduced. Focusing on the mechanism design of AFP sub-mechanisms, including the creel assembly CCR and compaction mechanisms,the mechanical schemes as well as the AFP process parameter control are discussed. To improve system reliability and fully optimise AFP mechanisms, the essential theoretical foundation for AFP mechanisms are provided. It is believed that this attempt will help to change the design and optimisation of similar complete mechanisms. Based on the reviewed research, overall remarks and perspectives are presented to serve as a guide for exploring the possibility of novel easy-to-use and cost-effective integrated AFP applications.
