Dear Editor,In this letter,a constrained networked predictive control strategy is proposed for the optimal control problem of complex nonlinear highorder fully actuated(HOFA)systems with noises.The method can effectiv...Dear Editor,In this letter,a constrained networked predictive control strategy is proposed for the optimal control problem of complex nonlinear highorder fully actuated(HOFA)systems with noises.The method can effectively deal with nonlinearities,constraints,and noises in the system,optimize the performance metric,and present an upper bound on the stable output of the system.展开更多
Precision actuation is a foundational technology in high-end equipment domains,where stroke,velocity,and accuracy are critical for processing and/or detection quality,precision in spacecraft flight trajectories,and ac...Precision actuation is a foundational technology in high-end equipment domains,where stroke,velocity,and accuracy are critical for processing and/or detection quality,precision in spacecraft flight trajectories,and accuracy in weapon system strikes.Piezoelectric actuators(PEAs),known for their nanometer-level precision,flexible stroke,resistance to electromagnetic interference,and scalable structure,have been widely adopted across various fields.Therefore,this study focuses on extreme scenarios involving ultra-high precision(micrometer and beyond),minuscule scales,and highly complex operational conditions.It provides a comprehensive overview of the types,working principles,advantages,and disadvantages of PEAs,along with their potential applications in piezo-actuated smart mechatronic systems(PSMSs).To address the demands of extreme scenarios in high-end equipment fields,we have identified five representative application areas:positioning and alignment,biomedical device configuration,advanced manufacturing and processing,vibration mitigation,micro robot system.Each area is further divided into specific subcategories,where we explore the underlying relationships,mechanisms,representative schemes,and characteristics.Finally,we discuss the challenges and future development trends related to PEAs and PSMSs.This work aims to showcase the latest advancements in the application of PEAs and provide valuable guidance for researchers in this field.展开更多
The introduction of wireless capsule endoscopy has brought a revolutionary change in the diagnostic procedures for gastrointestinal disorders.Biopsy,an essential procedure for disease diagnosis,has been integrated int...The introduction of wireless capsule endoscopy has brought a revolutionary change in the diagnostic procedures for gastrointestinal disorders.Biopsy,an essential procedure for disease diagnosis,has been integrated into robotic capsule endoscopy to augment diagnostic capabilities.In this study,we propose a magnetically driven biopsy robot based on a Kresling origami.Considering the bistable properties of Krelsing origami and the elasticity of the creases,a foldable structure of the robot with constant force characteristics is designed.The folding motion of the structure is used to deploy the needle into the target tissue.The robot is capable of performing rolling motion under the control of an external magnetic drive system,and a fine needle biopsy technique is used to collect deep tissue samples.We also conduct in vitro rolling experiments and sampling experiments on apple tissues and pork tissues,which verify the performance of the robot.展开更多
This paper introduces an innovative approach to the deployment of folding wings on cruise missiles,aiming to overcome the issues associated with explosive devices.The proposed solution involves employing NiTi shape me...This paper introduces an innovative approach to the deployment of folding wings on cruise missiles,aiming to overcome the issues associated with explosive devices.The proposed solution involves employing NiTi shape memory wires for a nonexplosive self-deploying wing mechanism.The fundamental concept of the design revolves around the utilization of NiTi wires,which contract upon electric heating.This contraction action severs the shear pin,consequently releasing the folded wings.The operational performance of the NiTi wire is thoroughly examined through a series of electro-thermo-mechanical tests,offering valuable insights for selecting the appropriate wire material.Moreover,the mechanical dynamics involved in the self-deploying process are elucidated through finite element simulations.The simulations highlight that the thermally-induced phase transformation within the NiTi wires generates substantial actuation forces,exceeding 700 N,and strokes of over 6 mm.These forces are deemed sufficient for breaking the aluminum shear pin and effecting wing deployment.The proposed mechanism’s practical viability is substantiated through prototype tests,which conclusively establish the superiority of the nonexplosive self-deploying wing mechanism when compared to conventional methods.The experimental outcomes underscore the mechanism’s capability to markedly reduce overload stress while remaining compliant with the designated requirements and constraints.展开更多
Laser direct imaging(LDI)machines are advantageous for the fabrication of printed circuit boards(PCBs).Before digital lithography,a vision-based measurement(VBM)system was used to calibrate PCBs.However,calibration ac...Laser direct imaging(LDI)machines are advantageous for the fabrication of printed circuit boards(PCBs).Before digital lithography,a vision-based measurement(VBM)system was used to calibrate PCBs.However,calibration accuracy and efficiency are affected by multiple disturbances.To improve the accuracy and enhance the robustness of the VBM system,we propose a piezoelectric-actuated kangaroo-inspired bionic compliant mechanism(BioCM)and a flyingfocusing VBM controller.A piezoelectric actuator(PEA)generates highly accurate motion.The CM transfers the motion without losing accuracy or producing couplings.The kangaroo-inspired bionic differential structure enlarges the magnification of the PEA-CM.A BioCM-based VBM system was also constructed.A static analysis of the BioCM was conducted using the compliance matrix approach,and dynamics results were obtained.To enhance the service performance of the PEA-BioCM,we developed a flying-focusing VBM controller.PEG-based flying,PEA-actuated focusing,and MEMF-enhanced RRHT algorithms were used.A BioCM prototype was fabricated.Several prototype tests were conducted on the statics and dynamics.The prototype test results verified the performance of the BioCM and flying-VBM controller.Service test results demonstrated the calibration accuracy and robustness of the PEA-BioCM-based flying-VBM system.The proposed BioCM and controller can contribute to the development of next-generation LDI machines for fabricating high-density PCBs.展开更多
This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theor...This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.展开更多
This paper investigates the adaptive fuzzy finite-time output-feedback fault-tolerant control (FTC) problemfor a class of nonlinear underactuated wheeled mobile robots (UWMRs) system with intermittent actuatorfaults. ...This paper investigates the adaptive fuzzy finite-time output-feedback fault-tolerant control (FTC) problemfor a class of nonlinear underactuated wheeled mobile robots (UWMRs) system with intermittent actuatorfaults. The UWMR system includes unknown nonlinear dynamics and immeasurable states. Fuzzy logic systems(FLSs) are utilized to work out immeasurable functions. Furthermore, with the support of the backsteppingcontrol technique and adaptive fuzzy state observer, a fuzzy adaptive finite-time output-feedback FTC scheme isdeveloped under the intermittent actuator faults. It is testifying the scheme can ensure the controlled nonlinearUWMRs is stable and the estimation errors are convergent. Finally, the comparison results and simulationvalidate the effectiveness of the proposed fuzzy adaptive finite-time FTC approach.展开更多
DC-DC converter-based multi-bus DC microgrids(MGs) in series have received much attention, where the conflict between voltage recovery and current balancing has been a hot topic. The lack of models that accurately por...DC-DC converter-based multi-bus DC microgrids(MGs) in series have received much attention, where the conflict between voltage recovery and current balancing has been a hot topic. The lack of models that accurately portray the electrical characteristics of actual MGs while is controller design-friendly has kept the issue active. To this end, this paper establishes a large-signal model containing the comprehensive dynamical behavior of the DC MGs based on the theory of high-order fully actuated systems, and proposes distributed optimal control based on this. The proposed secondary control method can achieve the two goals of voltage recovery and current sharing for multi-bus DC MGs. Additionally, the simple structure of the proposed approach is similar to one based on droop control, which allows this control technique to be easily implemented in a variety of modern microgrids with different configurations. In contrast to existing studies, the process of controller design in this paper is closely tied to the actual dynamics of the MGs. It is a prominent feature that enables engineers to customize the performance metrics of the system. In addition, the analysis of the stability of the closed-loop DC microgrid system, as well as the optimality and consensus of current sharing are given. Finally, a scaled-down solar and battery-based microgrid prototype with maximum power point tracking controller is developed in the laboratory to experimentally test the efficacy of the proposed control method.展开更多
The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sens...The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.展开更多
This paper introduces a self-sensing anthropomorphic robot hand driven by Twisted String Actuators(TSAs).The use of TSAs provides several advantages such as muscle-like structures,high transmission ratios,large output...This paper introduces a self-sensing anthropomorphic robot hand driven by Twisted String Actuators(TSAs).The use of TSAs provides several advantages such as muscle-like structures,high transmission ratios,large output forces,high efficiency,compactness,inherent compliance,and the ability to transmit power over distances.However,conventional sensors used in TSA-actuated robotic hands increase stiffness,mass,volume,and complexity,making feedback control challenging.To address this issue,a novel self-sensing approach is proposed using strain-sensing string based on Conductive Polymer Composite(CPC).By measuring the resistance changes in the strain-sensing string,the bending angle of the robot hand's fingers can be estimated,enabling closed-loop control without external sensors.The developed self-sensing anthropomorphic robot hand comprises a 3D-printed structure with five fingers,a palm,five self-sensing TSAs,and a 3D-printed forearm.Experimental studies validate the self-sensing properties of the TSA and the anthropomorphic robot hand.Additionally,a real-time Virtual Reality(VR)monitoring system is implemented for visualizing and monitoring the robot hand's movements using its self-sensing capabilities.This research contributes valuable insights and advancements to the field of intelligent prosthetics and robotic end grippers.展开更多
This paper presents a novel 1T2R three degrees of freedom redundantly actuated and overconstrained ■parallel machining head(■denotes the active prismatic joint), which can construct 5-axis hybrid machine to complete...This paper presents a novel 1T2R three degrees of freedom redundantly actuated and overconstrained ■parallel machining head(■denotes the active prismatic joint), which can construct 5-axis hybrid machine to complete high speed freedom surface milling for large complex structural components in aerospace. Firstly, based on the screw theory, the mobility of the proposed parallel manipulator is briefly analysed. Secondly, the kinematic inverse position and the parasitic motion of the parallel manipulator are explicitly expressed. Furthermore, motion-force transmission performance evaluation indices are derived in detail via an alternative approach based on the screw theory. More importantly, a simple method for quickly solving the maximum virtual power coefficient is proposed, and the motion-force transmission performance evaluation index is greatly improved. To evaluate the kinematic performance, its workspace is calculated. With numerical examples, performance distribution atlases of the manipulator are depicted visually. The corresponding results illustrate that the proposed parallel manipulator has better orientation workspace and superior motion-force transmission performance than the 2 PRU-PRS parallel manipulator, which proves the validity and applicability of applying this manipulator as a machining head.展开更多
The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getti...The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getting intersection and union to complete type synthesis.The number of redundant parallel mechanisms obtained by these two methods is limited.In this paper,based on Grassmann line geometry and Atlas method,a novel and effective method for type synthesis of redundant actuated parallel mechanisms(PMs)with closed-loop units is proposed.Firstly,the degree of freedom(DOF)and constraint line graph of the moving platform are determined successively,and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph,and a branch constraint allocation scheme is formulated based on the allocation criteria.Secondly,a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units.Finally,the branch chains that meet the requirements of branch chains configuration criteria and F&C(degree of freedom&constraint)line graph are assembled.In this paper,two types of 2 rotational and 1 translational(2R1T)redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational(2T1R)redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples,and 238,92 and 15 new configurations were synthesized.All the mechanisms contain closed-loop units,and the mechanisms and the actuators both have good symmetry.Therefore,all the mechanisms have excellent comprehensive performance,in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled.The instantaneous analysis shows that all mechanisms are not instantaneous,which proves the feasibility and practicability of the method.展开更多
This paper presents a redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator with two rotational and one translational coupling degrees of freedom.The kinematics analysis is firstly carried out and...This paper presents a redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator with two rotational and one translational coupling degrees of freedom.The kinematics analysis is firstly carried out and the mapping relationship of the velocity,acceleration and the independent parameters between the actuator joint and the moving platform are deduced by using the vector dot product and cross product operation.By employing d′Alembert′s principle and the principle of virtual work,the dynamics equilibrium equation is derived,and the simplified dynamics mathematical model of the parallel manipulator is further derived.Simultaneously,the generalized inertia matrix which can characterize the acceleration performance between joint space and operation space is further separated,and the performance indices including the dynamics dexterity,inertia coupling characteristics,energy transmission efficiency and driving force/torque balance are introduced.The analysis results show that the proposed redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator in comparison with the existing non-redundant one has better dynamic comprehensive performance,which can be demonstrated practically by the successful application of the parallel kinematic machine head module of the hybrid machine tool.展开更多
This paper investigates the effect of cutter clearance angle on variation of depth of cut and cutting process with an actuated disc cutting(ADC).ADC is a cyclic cutting method with two main characteristics:(i)a disk-s...This paper investigates the effect of cutter clearance angle on variation of depth of cut and cutting process with an actuated disc cutting(ADC).ADC is a cyclic cutting method with two main characteristics:(i)a disk-shape cutter is used to attack the rock in an undercutting mechanism;and(ii)the cutter is dynamically actuated as it is moved across the rock.Hence,the cutting process of such system is periodic,each recurrence known as actuation cycle.The first ADC model,developed in 2016,represented an idealization of the technology with a flat disc cutter,where no clearance angle was considered.The evolution of the contact between the disc and the rock was,therefore,computed only on horizontal x-y plane,ignoring the effect of normal component of the force acting on cartridge.This article reports on a study that incorporates the cutter inclination angle in derivation of cutter/rock interface laws.It extends the proposed kinematic and geometry based model to take into account the variable depth of cut in estimating the forces associated with cutting in one actuation cycle.Experiments were conducted using Wobble to test the predictions of the improved model at various operating conditions.The model predictions are matched with the experimental results and effects of various factors are analysed.展开更多
Redundantly actuated planar rotational parallel mechanisms（RAPRPMs） adapt to the requirements of robots under different working conditions by changing the antagonistic internal force to tune their stiffness.The geom...Redundantly actuated planar rotational parallel mechanisms（RAPRPMs） adapt to the requirements of robots under different working conditions by changing the antagonistic internal force to tune their stiffness.The geometrical parameters of the mechanism impact the performances of modulating stiffness.Analytical expressions relating stiffness and geometrical parameters of the mechanism were formulated to obtain the necessary conditions of variable stiffness.A novel method of variable stiffness design was presented to optimize the geometrical parameters of the mechanism.The stiffness variation with the internal force was maximized.The dynamic change of stiffness with the dynamic location of the mechanism was minimized,and the robustness of stiffness during the motion of the mechanism was ensured.This new approach to variable stiffness design can enable off-line planning of the internal force to avoid the difficulties of on-line control of the internal force.展开更多
This paper investigates fault tolerant attitude control theory and experiment for underactuated spacecraft with one reaction wheel completely broken and two others suffering actuator faults of partial loss of effectiv...This paper investigates fault tolerant attitude control theory and experiment for underactuated spacecraft with one reaction wheel completely broken and two others suffering actuator faults of partial loss of effectiveness or bias.A non-smooth robust adaptive fault tolerant control law is proposed under the zero-momentum and input saturation conditions.It shows that the available reaction wheels need to produce sufficient control torque for the fault tolerance.Such a new control method is implemented in a semi-physical simulation system of an air-bearing platform.Experimental results show the effectiveness of the proposed method in spacecraft practical engineering.展开更多
Capture is a key component for on?orbit service and space debris clean. The current research of capture on?orbit focuses on using special capture devices or full?actuated space arms to capture cooperative targets. How...Capture is a key component for on?orbit service and space debris clean. The current research of capture on?orbit focuses on using special capture devices or full?actuated space arms to capture cooperative targets. However, the structures of current capture devices are complex, and both space debris and abandoned spacecraft are non?cooperative targets. To capture non?cooperative targets in space, a lightweight, less driven under?actuated robotic hand is proposed in this paper, which composed by tendon?pulley transmission and double?stage mechanisms, and always driven by only one motor in process of closing finger. Because of the expandability, general grasping model is constructed. The equivalent joint driving forces and general grasping force are analyzed based on the model and the principle of virtual work. Which reveal the relationship among tendon driving force, joint driving forces and grasping force. In order to configure the number of knuckles of finger, a new analysis method which takes the maximum grasping space into account, is proposed. Supposing the maximum grasped object is an envelope circle with diameter of 2.5m. In the condition, a finger grasping maximum envelope circle with different knuckles is modeled. And the finger lengths with corresponding knuckles are calculated out. The finger length which consists of three knuckles is the shortest among under?actuated fingers consists of not more than five knuckles. Finally, the principle prototype and prototype robotic hand which consists of two dingers are designed and assembled. Experiments indicate that the under?actuated robotic hand can satisfy the grasp requirements.展开更多
Powered lower limb exoskeletons have traditionally used four or more powered joints to provide ambulation assistance for individuals with spinal cord injury.Exoskeletons with numerous powered joints commonly lost some...Powered lower limb exoskeletons have traditionally used four or more powered joints to provide ambulation assistance for individuals with spinal cord injury.Exoskeletons with numerous powered joints commonly lost some excellent features of passive orthoses and further decreased utility due to added weight and increased control complexity.This work adopts joints coupling mechanism to design a powered exoskeleton to minimize the number of actuated joints and control complexity.Unlike conventional powered exoskeletons,the joint-coupled-powered exoskeleton only has a single motor-actuated joint for each exoskeleton leg in conjunction with a unique knee coupled system to enable their users to walk,sit,and stand.And two types of joint coupled systems are designed,respectively,hip-knee coupled and knee-ankle coupled.The joint-coupled-powered exoskeleton system allows a single actuator to power the hip motion,and allows activate knee motion through the coupled motions of the hip or ankle.More specifically,when the mechanical coupled system is activated,the knee joint is unlocked,resulting in synchronized hip-knee or ankle-knee flexion and extension.The coupling mechanism is switched on and off at specific phases of the gait(the stance phase and the swing phase)to generate the desired motions.The research work proves that minimal actuated robotic systems with joint coupled could achieve safe and natural walking.展开更多
基金supported in part by the National Natural Science Foundation of China(62173255,62188101)Shenzhen Key Laboratory of Control Theory and Intelligent Systems(ZDSYS20220330161800001)
文摘Dear Editor,In this letter,a constrained networked predictive control strategy is proposed for the optimal control problem of complex nonlinear highorder fully actuated(HOFA)systems with noises.The method can effectively deal with nonlinearities,constraints,and noises in the system,optimize the performance metric,and present an upper bound on the stable output of the system.
基金financially supported by the National Key R&D Program of China(Grant No.2022YFC2204203)the National Natural Science Foundation of China(Grant No.52305107)。
文摘Precision actuation is a foundational technology in high-end equipment domains,where stroke,velocity,and accuracy are critical for processing and/or detection quality,precision in spacecraft flight trajectories,and accuracy in weapon system strikes.Piezoelectric actuators(PEAs),known for their nanometer-level precision,flexible stroke,resistance to electromagnetic interference,and scalable structure,have been widely adopted across various fields.Therefore,this study focuses on extreme scenarios involving ultra-high precision(micrometer and beyond),minuscule scales,and highly complex operational conditions.It provides a comprehensive overview of the types,working principles,advantages,and disadvantages of PEAs,along with their potential applications in piezo-actuated smart mechatronic systems(PSMSs).To address the demands of extreme scenarios in high-end equipment fields,we have identified five representative application areas:positioning and alignment,biomedical device configuration,advanced manufacturing and processing,vibration mitigation,micro robot system.Each area is further divided into specific subcategories,where we explore the underlying relationships,mechanisms,representative schemes,and characteristics.Finally,we discuss the challenges and future development trends related to PEAs and PSMSs.This work aims to showcase the latest advancements in the application of PEAs and provide valuable guidance for researchers in this field.
基金supported by the National Natural Science Foundation of China(Grant Nos.51805047 and 52175003)the Outstanding Youth Program of Hunan Education Department(Grant No.23B0335)the Natural Science Foundation of Hunan Province(Grant Nos.2023JJ30021 and 2023JJ50077).
文摘The introduction of wireless capsule endoscopy has brought a revolutionary change in the diagnostic procedures for gastrointestinal disorders.Biopsy,an essential procedure for disease diagnosis,has been integrated into robotic capsule endoscopy to augment diagnostic capabilities.In this study,we propose a magnetically driven biopsy robot based on a Kresling origami.Considering the bistable properties of Krelsing origami and the elasticity of the creases,a foldable structure of the robot with constant force characteristics is designed.The folding motion of the structure is used to deploy the needle into the target tissue.The robot is capable of performing rolling motion under the control of an external magnetic drive system,and a fine needle biopsy technique is used to collect deep tissue samples.We also conduct in vitro rolling experiments and sampling experiments on apple tissues and pork tissues,which verify the performance of the robot.
基金Supported by National Natural Science Foundation of China(Grant No.12372156).
文摘This paper introduces an innovative approach to the deployment of folding wings on cruise missiles,aiming to overcome the issues associated with explosive devices.The proposed solution involves employing NiTi shape memory wires for a nonexplosive self-deploying wing mechanism.The fundamental concept of the design revolves around the utilization of NiTi wires,which contract upon electric heating.This contraction action severs the shear pin,consequently releasing the folded wings.The operational performance of the NiTi wire is thoroughly examined through a series of electro-thermo-mechanical tests,offering valuable insights for selecting the appropriate wire material.Moreover,the mechanical dynamics involved in the self-deploying process are elucidated through finite element simulations.The simulations highlight that the thermally-induced phase transformation within the NiTi wires generates substantial actuation forces,exceeding 700 N,and strokes of over 6 mm.These forces are deemed sufficient for breaking the aluminum shear pin and effecting wing deployment.The proposed mechanism’s practical viability is substantiated through prototype tests,which conclusively establish the superiority of the nonexplosive self-deploying wing mechanism when compared to conventional methods.The experimental outcomes underscore the mechanism’s capability to markedly reduce overload stress while remaining compliant with the designated requirements and constraints.
基金Supported by Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515011189)Commissioned Project of Enterprise(Grant Nos.25HK0029,25HK0030,23HK0809)+2 种基金"Ganpo Plan"Talent Project of Jiangxi Province(Grant No.jxkjcytd2024001)National Natural Science Foundation of China(Grant Nos.U24A20108,51905106)Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201010398)。
文摘Laser direct imaging(LDI)machines are advantageous for the fabrication of printed circuit boards(PCBs).Before digital lithography,a vision-based measurement(VBM)system was used to calibrate PCBs.However,calibration accuracy and efficiency are affected by multiple disturbances.To improve the accuracy and enhance the robustness of the VBM system,we propose a piezoelectric-actuated kangaroo-inspired bionic compliant mechanism(BioCM)and a flyingfocusing VBM controller.A piezoelectric actuator(PEA)generates highly accurate motion.The CM transfers the motion without losing accuracy or producing couplings.The kangaroo-inspired bionic differential structure enlarges the magnification of the PEA-CM.A BioCM-based VBM system was also constructed.A static analysis of the BioCM was conducted using the compliance matrix approach,and dynamics results were obtained.To enhance the service performance of the PEA-BioCM,we developed a flying-focusing VBM controller.PEG-based flying,PEA-actuated focusing,and MEMF-enhanced RRHT algorithms were used.A BioCM prototype was fabricated.Several prototype tests were conducted on the statics and dynamics.The prototype test results verified the performance of the BioCM and flying-VBM controller.Service test results demonstrated the calibration accuracy and robustness of the PEA-BioCM-based flying-VBM system.The proposed BioCM and controller can contribute to the development of next-generation LDI machines for fabricating high-density PCBs.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272358 and 62103052)。
文摘This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.
基金the National Natural Science Foundation of China under Grant U22A2043.
文摘This paper investigates the adaptive fuzzy finite-time output-feedback fault-tolerant control (FTC) problemfor a class of nonlinear underactuated wheeled mobile robots (UWMRs) system with intermittent actuatorfaults. The UWMR system includes unknown nonlinear dynamics and immeasurable states. Fuzzy logic systems(FLSs) are utilized to work out immeasurable functions. Furthermore, with the support of the backsteppingcontrol technique and adaptive fuzzy state observer, a fuzzy adaptive finite-time output-feedback FTC scheme isdeveloped under the intermittent actuator faults. It is testifying the scheme can ensure the controlled nonlinearUWMRs is stable and the estimation errors are convergent. Finally, the comparison results and simulationvalidate the effectiveness of the proposed fuzzy adaptive finite-time FTC approach.
基金supported in part by the National Natural Science Foundation of China(62173255, 62188101)Shenzhen Key Laboratory of Control Theory and Intelligent Systems,(ZDSYS20220330161800001)。
文摘DC-DC converter-based multi-bus DC microgrids(MGs) in series have received much attention, where the conflict between voltage recovery and current balancing has been a hot topic. The lack of models that accurately portray the electrical characteristics of actual MGs while is controller design-friendly has kept the issue active. To this end, this paper establishes a large-signal model containing the comprehensive dynamical behavior of the DC MGs based on the theory of high-order fully actuated systems, and proposes distributed optimal control based on this. The proposed secondary control method can achieve the two goals of voltage recovery and current sharing for multi-bus DC MGs. Additionally, the simple structure of the proposed approach is similar to one based on droop control, which allows this control technique to be easily implemented in a variety of modern microgrids with different configurations. In contrast to existing studies, the process of controller design in this paper is closely tied to the actual dynamics of the MGs. It is a prominent feature that enables engineers to customize the performance metrics of the system. In addition, the analysis of the stability of the closed-loop DC microgrid system, as well as the optimality and consensus of current sharing are given. Finally, a scaled-down solar and battery-based microgrid prototype with maximum power point tracking controller is developed in the laboratory to experimentally test the efficacy of the proposed control method.
基金The financial support from the National Natural Science Foundation of China (32201179)Guangdong Basic and Applied Basic Research Foundation (2020A1515110126 and 2021A1515010130)+1 种基金the Fundamental Research Funds for the Central Universities (N2319005)Ningbo Science and Technology Major Project (2021Z027) is gratefully acknowledged。
文摘The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.
基金supported by the Anhui Provincial Key Research and Development Program No.2022f04020008National Natural Science Foundation of China No.62301522Anhui Provincial Nature Science Foundation No.1908085MF196.
文摘This paper introduces a self-sensing anthropomorphic robot hand driven by Twisted String Actuators(TSAs).The use of TSAs provides several advantages such as muscle-like structures,high transmission ratios,large output forces,high efficiency,compactness,inherent compliance,and the ability to transmit power over distances.However,conventional sensors used in TSA-actuated robotic hands increase stiffness,mass,volume,and complexity,making feedback control challenging.To address this issue,a novel self-sensing approach is proposed using strain-sensing string based on Conductive Polymer Composite(CPC).By measuring the resistance changes in the strain-sensing string,the bending angle of the robot hand's fingers can be estimated,enabling closed-loop control without external sensors.The developed self-sensing anthropomorphic robot hand comprises a 3D-printed structure with five fingers,a palm,five self-sensing TSAs,and a 3D-printed forearm.Experimental studies validate the self-sensing properties of the TSA and the anthropomorphic robot hand.Additionally,a real-time Virtual Reality(VR)monitoring system is implemented for visualizing and monitoring the robot hand's movements using its self-sensing capabilities.This research contributes valuable insights and advancements to the field of intelligent prosthetics and robotic end grippers.
基金supported by the Fundamental Research Funds for the Central Universities (Nos. 2018JBZ007, 2018YJS136 and 2017YJS158)China Scholarship Council (CSC) (No. 201807090079)National Natural Science Foundation of China (NSFC) (No. 51675037)
文摘This paper presents a novel 1T2R three degrees of freedom redundantly actuated and overconstrained ■parallel machining head(■denotes the active prismatic joint), which can construct 5-axis hybrid machine to complete high speed freedom surface milling for large complex structural components in aerospace. Firstly, based on the screw theory, the mobility of the proposed parallel manipulator is briefly analysed. Secondly, the kinematic inverse position and the parasitic motion of the parallel manipulator are explicitly expressed. Furthermore, motion-force transmission performance evaluation indices are derived in detail via an alternative approach based on the screw theory. More importantly, a simple method for quickly solving the maximum virtual power coefficient is proposed, and the motion-force transmission performance evaluation index is greatly improved. To evaluate the kinematic performance, its workspace is calculated. With numerical examples, performance distribution atlases of the manipulator are depicted visually. The corresponding results illustrate that the proposed parallel manipulator has better orientation workspace and superior motion-force transmission performance than the 2 PRU-PRS parallel manipulator, which proves the validity and applicability of applying this manipulator as a machining head.
基金Supported by National Natural Science Foundation of China(Grant No.51875499).
文摘The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getting intersection and union to complete type synthesis.The number of redundant parallel mechanisms obtained by these two methods is limited.In this paper,based on Grassmann line geometry and Atlas method,a novel and effective method for type synthesis of redundant actuated parallel mechanisms(PMs)with closed-loop units is proposed.Firstly,the degree of freedom(DOF)and constraint line graph of the moving platform are determined successively,and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph,and a branch constraint allocation scheme is formulated based on the allocation criteria.Secondly,a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units.Finally,the branch chains that meet the requirements of branch chains configuration criteria and F&C(degree of freedom&constraint)line graph are assembled.In this paper,two types of 2 rotational and 1 translational(2R1T)redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational(2T1R)redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples,and 238,92 and 15 new configurations were synthesized.All the mechanisms contain closed-loop units,and the mechanisms and the actuators both have good symmetry.Therefore,all the mechanisms have excellent comprehensive performance,in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled.The instantaneous analysis shows that all mechanisms are not instantaneous,which proves the feasibility and practicability of the method.
基金supported by the Fundamental Research Funds for the Central Universities (Nos. 2018JBZ007, 2018YJS136 and 2017YJS158)China Scholarship Council (CSC) (No. 201807090079)National Natural Science Foundation of China (No. 51675037)
文摘This paper presents a redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator with two rotational and one translational coupling degrees of freedom.The kinematics analysis is firstly carried out and the mapping relationship of the velocity,acceleration and the independent parameters between the actuator joint and the moving platform are deduced by using the vector dot product and cross product operation.By employing d′Alembert′s principle and the principle of virtual work,the dynamics equilibrium equation is derived,and the simplified dynamics mathematical model of the parallel manipulator is further derived.Simultaneously,the generalized inertia matrix which can characterize the acceleration performance between joint space and operation space is further separated,and the performance indices including the dynamics dexterity,inertia coupling characteristics,energy transmission efficiency and driving force/torque balance are introduced.The analysis results show that the proposed redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator in comparison with the existing non-redundant one has better dynamic comprehensive performance,which can be demonstrated practically by the successful application of the parallel kinematic machine head module of the hybrid machine tool.
基金Minerals Research Institute of Western Australia, Mining3 and CSIRO for funding this work
文摘This paper investigates the effect of cutter clearance angle on variation of depth of cut and cutting process with an actuated disc cutting(ADC).ADC is a cyclic cutting method with two main characteristics:(i)a disk-shape cutter is used to attack the rock in an undercutting mechanism;and(ii)the cutter is dynamically actuated as it is moved across the rock.Hence,the cutting process of such system is periodic,each recurrence known as actuation cycle.The first ADC model,developed in 2016,represented an idealization of the technology with a flat disc cutter,where no clearance angle was considered.The evolution of the contact between the disc and the rock was,therefore,computed only on horizontal x-y plane,ignoring the effect of normal component of the force acting on cartridge.This article reports on a study that incorporates the cutter inclination angle in derivation of cutter/rock interface laws.It extends the proposed kinematic and geometry based model to take into account the variable depth of cut in estimating the forces associated with cutting in one actuation cycle.Experiments were conducted using Wobble to test the predictions of the improved model at various operating conditions.The model predictions are matched with the experimental results and effects of various factors are analysed.
基金supported by the National Natural Science Foundation of China(No.51275127)
文摘Redundantly actuated planar rotational parallel mechanisms（RAPRPMs） adapt to the requirements of robots under different working conditions by changing the antagonistic internal force to tune their stiffness.The geometrical parameters of the mechanism impact the performances of modulating stiffness.Analytical expressions relating stiffness and geometrical parameters of the mechanism were formulated to obtain the necessary conditions of variable stiffness.A novel method of variable stiffness design was presented to optimize the geometrical parameters of the mechanism.The stiffness variation with the internal force was maximized.The dynamic change of stiffness with the dynamic location of the mechanism was minimized,and the robustness of stiffness during the motion of the mechanism was ensured.This new approach to variable stiffness design can enable off-line planning of the internal force to avoid the difficulties of on-line control of the internal force.
基金supported by the National Natural Science Foundation of China(Nos.62073165 and 62233009)the 111 Project,China(No.B20007).
文摘This paper investigates fault tolerant attitude control theory and experiment for underactuated spacecraft with one reaction wheel completely broken and two others suffering actuator faults of partial loss of effectiveness or bias.A non-smooth robust adaptive fault tolerant control law is proposed under the zero-momentum and input saturation conditions.It shows that the available reaction wheels need to produce sufficient control torque for the fault tolerance.Such a new control method is implemented in a semi-physical simulation system of an air-bearing platform.Experimental results show the effectiveness of the proposed method in spacecraft practical engineering.
基金Supported by Joint Funds of National Natural Science Foundation of China(Grant No.U1613201)Shenzhen Research Funds(JCYJ20170413104438332)
文摘Capture is a key component for on?orbit service and space debris clean. The current research of capture on?orbit focuses on using special capture devices or full?actuated space arms to capture cooperative targets. However, the structures of current capture devices are complex, and both space debris and abandoned spacecraft are non?cooperative targets. To capture non?cooperative targets in space, a lightweight, less driven under?actuated robotic hand is proposed in this paper, which composed by tendon?pulley transmission and double?stage mechanisms, and always driven by only one motor in process of closing finger. Because of the expandability, general grasping model is constructed. The equivalent joint driving forces and general grasping force are analyzed based on the model and the principle of virtual work. Which reveal the relationship among tendon driving force, joint driving forces and grasping force. In order to configure the number of knuckles of finger, a new analysis method which takes the maximum grasping space into account, is proposed. Supposing the maximum grasped object is an envelope circle with diameter of 2.5m. In the condition, a finger grasping maximum envelope circle with different knuckles is modeled. And the finger lengths with corresponding knuckles are calculated out. The finger length which consists of three knuckles is the shortest among under?actuated fingers consists of not more than five knuckles. Finally, the principle prototype and prototype robotic hand which consists of two dingers are designed and assembled. Experiments indicate that the under?actuated robotic hand can satisfy the grasp requirements.
基金supported in part by the National Natural Science Foundation of China(62073224)Shanghai Science and Technology Innovation Action Plan(19DZ2203600)National Key Research and Development Project(2018YFC2001501).
文摘Powered lower limb exoskeletons have traditionally used four or more powered joints to provide ambulation assistance for individuals with spinal cord injury.Exoskeletons with numerous powered joints commonly lost some excellent features of passive orthoses and further decreased utility due to added weight and increased control complexity.This work adopts joints coupling mechanism to design a powered exoskeleton to minimize the number of actuated joints and control complexity.Unlike conventional powered exoskeletons,the joint-coupled-powered exoskeleton only has a single motor-actuated joint for each exoskeleton leg in conjunction with a unique knee coupled system to enable their users to walk,sit,and stand.And two types of joint coupled systems are designed,respectively,hip-knee coupled and knee-ankle coupled.The joint-coupled-powered exoskeleton system allows a single actuator to power the hip motion,and allows activate knee motion through the coupled motions of the hip or ankle.More specifically,when the mechanical coupled system is activated,the knee joint is unlocked,resulting in synchronized hip-knee or ankle-knee flexion and extension.The coupling mechanism is switched on and off at specific phases of the gait(the stance phase and the swing phase)to generate the desired motions.The research work proves that minimal actuated robotic systems with joint coupled could achieve safe and natural walking.
