BACKGROUND Medial dished(MD)liner designs for cruciate-retaining(CR)total knee arthroplasty(TKA)are a relatively novel development.MD tibial inserts have a more constraining medial side,which allows for more similar k...BACKGROUND Medial dished(MD)liner designs for cruciate-retaining(CR)total knee arthroplasty(TKA)are a relatively novel development.MD tibial inserts have a more constraining medial side,which allows for more similar kinematics and function to a native knee.AIM To evaluate the clinical results and patient-reported outcomes after CR TKA procedures utilizing a kinematically designed medial dish system.METHODS A multicenter,retrospective cohort review of 139 primary elective TKAs utilizing a kinematically designed CR Knee System(JOURNEY™II CR MD;Smith and Nephew,Memphis,TN,United States)at three different institutions with a minimum of two years of follow-up.Demographic information,clinical outcomes,and patient-reported outcome measures were collected and analyzed.RESULTS With up to 3.7 years from surgery,overall implant survivorship was 98.6%.There were significant postoperative increases in the average Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores(17.4 at 6 months,26.1 points at two years or more,P<0.001).CONCLUSION The combination of high implant survivorship and substantial improvements in patient-reported outcome measures suggests that the medial dish tibial insert represents a safe and effective option within TKA.Additional investigation is necessary to evaluate the long-term survivorship of this design.展开更多
The increasing global prevalence of mild cognitive impairment(MCI)necessitates a paradigm shift in early detection strategies.Conventional neuropsychological assessment methods,predominantly paper-and-pencil tests suc...The increasing global prevalence of mild cognitive impairment(MCI)necessitates a paradigm shift in early detection strategies.Conventional neuropsychological assessment methods,predominantly paper-and-pencil tests such as the Mini-Mental State Examination and the Montreal Cognitive Assessment,exhibit inherent limitations with respect to accessibility,administration burden,and sensitivity to subtle cognitive decline,particularly among diverse populations.This commentary critically examines a recent study that champions a novel approach:The integration of gait and handwriting kinematic parameters analyzed via machine learning for MCI screening.The present study positions itself within the broader landscape of MCI detection,with a view to comparing its advantages against established neuropsychological batteries,advanced neuroimaging(e.g.,positron emission tomography,magnetic resonance imaging),and emerging fluid biomarkers(e.g.,cerebrospinal fluid,blood-based assays).While the study demonstrates promising accuracy(74.44%area under the curve 0.74 with gait and graphic handwriting)and addresses key unmet needs in accessibility and objectivity,we highlight its cross-sectional nature,limited sample diversity,and lack of dual-task assessment as areas for future refinement.This commentary posits that kinematic biomarkers offer a distinctive,scalable,and ecologically valid approach to widespread MCI screening,thereby complementing existing methods by providing real-world functional insights.Future research should prioritize longitudinal validation,expansion to diverse cohorts,integration with multimodal data including dual-tasking,and the development of highly portable,artificial intelligence-driven solutions to achieve the democratization of early MCI detection and enable timely interventions.展开更多
To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method...To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method for a class of parallel platforms with 3-RE structure after locking the actuated joints is proposed in this paper.Given that the angle between specific joint axes of limbs remains constant,a set of geometric constraints for the forward kinematics of parallel mechanisms(PM)are determined.After translating unit direction vectors of these joint axes to the common starting point,the geometric constraints of the angle between the vectors are transformed into the distances between the endpoints of the vectors,making them easier to handle.Under the framework of CGA,the positions of key points that determine the position and orientation of the moving platform can be intuitively determined by the intersection,division,and duality of basic geometric entities.By employing the tangent half-angle substitution,the forward kinematic analysis of the parallel mechanisms leads to a high-order univariate polynomial equation without the need for any complex algebraic elimination operations.After solving this equation and back substitution,the position and pose of the MP can be obtained indirectly.A numerical case is utilized to confirm the effectiveness of the proposed method.展开更多
Background China is seeing a growing demand for rehabilitation treatments for post-stroke upper limb spastic paresis(PSSP-UL).Although acupuncture is known to be effective for PSSP-UL,there is room to enhance its effi...Background China is seeing a growing demand for rehabilitation treatments for post-stroke upper limb spastic paresis(PSSP-UL).Although acupuncture is known to be effective for PSSP-UL,there is room to enhance its efficacy.Objective This study explored a semi-personalized acupuncture approach for PSSP-UL that used three-dimensional kinematic analysis(3DKA)results to select additional acupoints,and investigated the feasibility,efficacy and safety of this approach.Design,setting,participants and interventions This single-blind,single-center,randomized,controlled trial involved 74 participants who experienced a first-ever ischemic or hemorrhagic stroke with spastic upper limb paresis.The participants were then randomly assigned to the intervention group or the control group in a 1:1 ratio.Both groups received conventional treatments and acupuncture treatment 5 days a week for 4 weeks.The main acupoints in both groups were the same,while participants in the intervention group received additional acupoints selected on the basis of 3DKA results.Follow-up assessments were conducted for 8 weeks after the treatment.Main outcome measures The primary outcome was the Fugl-Meyer Assessment for Upper Extremity(FMA-UE)response rate(≥6-point change)at week 4.Secondary outcomes included changes in motor function(FMA-UE),Brunnstrom recovery stage(BRS),manual muscle test(MMT),spasticity(Modified Ashworth Scale,MAS),and activities of daily life(Modified Barthel Index,MBI)at week 4 and week 12.Results Sixty-four participants completed the trial and underwent analyses.Compared with control group,the intervention group exhibited a significantly higher FMA-UE response rate at week 4(χ^(2)=5.479,P=0.019)and greater improvements in FMA-UE at both week 4 and week 12(both P<0.001).The intervention group also showed bigger improvements from baseline in the MMT grades for shoulder adduction and elbow flexion at weeks 4 and 12 as well as thumb adduction at week 4(P=0.007,P=0.049,P=0.019,P=0.008,P=0.029,respectively).The intervention group showed a better change in the MBI at both week 4 and week 12(P=0.004 and P=0.010,respectively).Although the intervention group had a higher BRS for the hand at week 12(P=0.041),no intergroup differences were observed at week 4(all P>0.05).The two groups showed no differences in MAS grades as well as in BRS for the arm at weeks 4 and 12(all P>0.05).Conclusion Semi-personalized acupuncture prescription based on 3DKA results significantly improved motor function,muscle strength,and activities of daily living in patients with PSSP-UL.展开更多
Serial-parallel manipulators are of great interest to academic community in recent years,especially those composed of classical parallel mechanisms.There have been many studies around 2(3RPS)and 2(3SPR)S-PMs,but unfor...Serial-parallel manipulators are of great interest to academic community in recent years,especially those composed of classical parallel mechanisms.There have been many studies around 2(3RPS)and 2(3SPR)S-PMs,but unfortunately their inverse kinematics have not yet been resolved.This paper discovers that the unknown kinematic parameters of middle platform are responsible for the unresolvable of inverse kinematics,meanwhile the unknown kinematic parameters of middle platform also have huge coupling relationships.Therefore,to break through this challenges,the huge coupling relationships are decoupled layer by layer,the kinematic parameters of middle platform are solved by combining Sylvester's elimination method,and the inverse displacements of 2(3RPS)and 2(3SPR)S-PMs are obtained subsequently.This paper not only solves the inverse kinematics of classical 2(3RPS)and 2(3SPR)S-PMs,but also reveals the essence of the inverse kinematics of general(3-DOF)+(3-DOF)6-DOF S-PMs and proposes a corresponding solution.展开更多
Backswimmers exhibit a high degree of mobility in water,and their different motion patterns have important implications for the design of micro-biomimetic underwater robots.This paper used three-dimensional high-speed...Backswimmers exhibit a high degree of mobility in water,and their different motion patterns have important implications for the design of micro-biomimetic underwater robots.This paper used three-dimensional high-speed cameras to extract the key points on the hind legs.The hind leg motion laws and the deformation laws of the setae were obtained in four motion patterns:rapid forward,cruising,in-motion turning,and in-place turning.The motion laws of each joint on the hind leg are modeled using a Fourier series.A kinematic model of hind legs was established based on the DH method,and the motion characteristics of hind legs under different motion patterns were analyzed.This paper provides basic data and theoretical models for micro-biomimetic robots.展开更多
The design and analysis of continuum robots have consistently been a prominent research focus in the field of mechanics.However,portable continuum robots with minimal spatial occupancy,which have great potential for a...The design and analysis of continuum robots have consistently been a prominent research focus in the field of mechanics.However,portable continuum robots with minimal spatial occupancy,which have great potential for applications such as search and rescue,are scarcely available.This paper presents a novel helical-coiled multi-segment flexible continuum robot featuring helical deployment and compact design,with an integrated framework for structural design,kinematic modeling,and experimental validation.The design of the helical-coiled multi-segment flexible continuum robot for unstructured environment detection,including a flexible body,an actuation module,a feed module,and a sensing module,is presented systematically.Kinematic models of both single-and multisegment continuum robots were established based on the constant curvature model to analyze the parameter mapping relationship from the end-effector position and orientation to the driving inputs.Furthermore,the feedforward motion of the robot was examined,and an uncoiling strategy based on S-curve compensation was employed to complete the kinematic analysis.Finally,the accuracy of the kinematic model considering the active uncoiling feed motion was validated through experimental analysis,demonstrating the motion characteristics of the continuum robot.Altogether,this study provides a framework for the design and analysis of helical-coiled continuum robots.展开更多
Rockfall kinematic characteristics exhibit significant randomness and are influenced by factors such as rock mass properties,slope morphology,impact angle,and slope materials.Accurately determining the key parameters ...Rockfall kinematic characteristics exhibit significant randomness and are influenced by factors such as rock mass properties,slope morphology,impact angle,and slope materials.Accurately determining the key parameters of rockfall movement is critical for understanding motion patterns and effectively preventing and controlling rockfall hazards.In this study,a monitoring system consisting of selfdeveloped inertial navigation equipment,high-speed cameras,and an unmanned aerial vehicle was used to conduct onsite motion tests involving four differently shaped rock specimens on three types of slopes(bedrock,detritus,and clast bedding).The selfdeveloped inertial navigation system integrated a highdynamic-range accelerometer(±400 g)and a shockresistant gyroscope(±4000°/s),capable of robustly collecting data during the test.The data collected from these tests were processed to extract key kinematic parameters such as velocity,trajectory,restitution coefficients,and friction coefficients.The test results demonstrated that the inertial navigation system accurately recorded the acceleration and angular velocity of the rocks during motion,with these measurements closely aligning with the field data.The normal and tangential restitution coefficients were found to be influenced primarily by the slope material and impact angle,with higher normal restitution coefficients observed for low-angle impacts.The normal restitution coefficients ranged from 0.35 to 0.86,whereas the tangential restitution coefficients ranged from 0.46 to 0.91,depending on the slope materials.Additionally,the sliding friction coefficient was calculated to be between 0.66 and 0.78,whereas the rolling friction coefficient for the slab-shaped specimen was determined to be 0.53.These findings provide valuable data for improving the accuracy of rockfall trajectory predictions and the design of protective structures.展开更多
Cable-driven parallel robots(CDPRs)have advantages of larger workspace and load capacity than conventional parallel robots while existing interference problems among cables,workpieces and the end-effector.In order to ...Cable-driven parallel robots(CDPRs)have advantages of larger workspace and load capacity than conventional parallel robots while existing interference problems among cables,workpieces and the end-effector.In order to avoid collision and improve the flexibility of the robots,this study proposes a reconfigurable cable-driven parallel robot(RCDPR)having characteristics of large load-to-weight ratio,easy modularity and variable stiffness.Adjustable brackets are connected to the moving platform to adjust the position of the pull-out point with the movement of the end-effector.In addition,a variable stiffness actuator(VSA)accompanied by finite element analysis is designed to optimize the cable tension to adapt different task requirements.Firstly,a new idea of reconfiguration is given,and an inverse kinematic model is established using the vector closure principle to derive its inverse kinematic expressions focusing on one of the configurations.Second,the VSA is attached to each cable to achieve stiffness adjustment,and the system stiffness is derived in detail.Finally,the rationality and accuracy of the robot are verified through numerical analysis,providing a reference for subsequent trajectory planning with implications.展开更多
Flip-flow screens offer unique advantages in grading fine-grained materials.To address inaccuracies caused by sensor vibra-tions in traditional contact measurement methods,we constructed a non-invasive measurement sys...Flip-flow screens offer unique advantages in grading fine-grained materials.To address inaccuracies caused by sensor vibra-tions in traditional contact measurement methods,we constructed a non-invasive measurement system based on electrical and optical sig-nals.A trajectory tracking algorithm for the screen-body was developed to visually measure the kinematics.Employing the principle oflaser reflection for distance measurement,optical techniques were performed to capture the kinematic information of the screen-plate.Ad-ditionally,by using Wi-Fi and Bluetooth transmission of electrical signals,tracer particle tracking technology was implemented to elec-trically measure the kinematic information of mineral particles.Consequently,intelligent fusion and perception of the kinematic informa-tion for the screen-body,screen-plate,and particles in the screening system have been achieved.展开更多
We apply methods of algebraic integral geometry to prove a special case of the Gaussian kinematic formula of Adler-Taylor.The idea,suggested already by Adler and Taylor,is to view the GKF as the limit of spherical kin...We apply methods of algebraic integral geometry to prove a special case of the Gaussian kinematic formula of Adler-Taylor.The idea,suggested already by Adler and Taylor,is to view the GKF as the limit of spherical kinematic formulas for spheres of large dimension N and curvature1/N.展开更多
Based on the updated M giant star catalog selected from Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR9,we identify substructures within the integrals-of-motion space through the Friends-of-Friends clust...Based on the updated M giant star catalog selected from Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR9,we identify substructures within the integrals-of-motion space through the Friends-of-Friends clustering algorithm.We obtain members belonging to several known substructures:the Sagittarius stream,Galactic Anticenter Substructure(GASS),Gaia-Enceladus-Sausage(GES),Splash,and the high-αdisk.Furthermore,we also identify two groups which cannot be clearly associated with previously known substructures.Our findings confirm the existence of metal-rich constituents within the GES,representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved.Additionally,this study further expands the sample of GASS,high-αdisk,and Splash stars.Analysis of these metal-rich M giant stars as members of the GES,Splash,and high-αdisk components supports an evolution scenario for the early Milky Way,as proposed by previous studies.In this scenario,stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event(GES).This process redistributed stellar orbits,creating the Splash population,while the undisturbed portion of the primordial disk persisted as the present-day high-αdisk component.展开更多
Accurate kinematic calibration is the very foundation for robots'application in industry demanding high precision such as machining.Considering the complex error characteristic and severe ill-posed identification ...Accurate kinematic calibration is the very foundation for robots'application in industry demanding high precision such as machining.Considering the complex error characteristic and severe ill-posed identification issues of a 5-DoF parallel machining robot,this paper proposes an adaptive and weighted identification method to achieve high-precision kinematic calibration while maintaining reliable stability.First,a kinematic error propagation mechanism model considering the non-ideal constraints and the screw self-rotation is formulated by incorporating the intricate structure of multiple chains and a unique driven screw arrangement of the robot.To address the challenge of accurately identifying such a sophisticated error model,a novel adaptive and weighted identification method based on generalized cross validation(GCV)is proposed.Specifically,this approach innovatively introduces Gauss-Markov estimation into the GCV algorithm and utilizes prior physical information to construct both a weighted identification model and a weighted cross-validation function,thus eliminating the inaccuracy caused by significant differences in dimensional magnitudes of pose errors and achieving accurate identification with flexible numerical stability.Finally,the kinematic calibration experiment is conducted.The comparative experimental results demonstrate that the presented approach is effective and has enhanced accuracy performance over typical least squares methods,with maximum position and orientation errors reduced from 2.279 mm to 0.028 mm and from 0.206°to 0.017°,respectively.展开更多
To efficiently search out the optimal cam contour,a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented,and its effectiveness was demonstrated by a ...To efficiently search out the optimal cam contour,a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented,and its effectiveness was demonstrated by a case study of the cam contour optimization for an offset press open-close gripper mechanism.The acceleration curve and the residual vibration model of the follower were separately studied.A symmetric harmonic trapezoidal curve was designed to control the follower’s acceleration,and single-DOF lumped parameter torsional vibration model was proposed to describe the follower’s residual vibration.Accordingly,corresponding motion curve design software and Simulink vibration model of the follower were developed respectively,and they were integrated into an automatic optimization platform with iSIGHT.The multi-objective optimization with objectives of minimizing both the acceleration and the residual vibration of the follower was completed within the platform by using NSGA-II algorithm.An appropriate point with lower acceleration and residual vibration was chosen from Pareto front as an optimal solution of the follower’s motion curve.Based on the follower’s new motion curve,the actual cam contour was generated by inverse kinematic simulation in COSMOSMotion.The offset press that installed our new designed cam exhibited a lower vibration than the previous machine,and the maximum measured acceleration of the offset press at a printing speed of 15000 r/h is reduced by 7.7%.展开更多
Parallel mechanisms with fewer degrees of freedom that incorporate two or more SPR limbs have been widely adopted in industrial applications in recent years.However,notable theoretical gaps persist,particularly in the...Parallel mechanisms with fewer degrees of freedom that incorporate two or more SPR limbs have been widely adopted in industrial applications in recent years.However,notable theoretical gaps persist,particularly in the field of analytical solutions for forward kinematics.To address this,this paper proposes an innovative forward kinematics analysis method based on Conformal Geometric Algebra(CGA)for complex hybrid mechanisms formed by serial concatenation of such parallel mechanisms.The method efficiently represents geometric elements and their operational relationships by defining appropriate unknown parameters.It constructs fundamental geometric objects such as spheres and planes,derives vertex expressions through intersection and dual operations,and establishes univariate high-order equations via inner product operations,ultimately obtaining complete analytical solutions for the forward kinematics of hybrid mechanisms.Using the(2-SPR+RPS)+(3-SPR)serial-parallel hybrid mechanism as a validation case,three configuration tests implemented in Mathematica demonstrate that:for each configuration,the upper 3-SPR mechanism yields 15 mathematical solutions,while the lower 2-SPR+RPS mechanism yields 4 mathematical solutions.After geometric constraint filtering,a unique physically valid solution is obtained for each mechanism.SolidWorks simulations further verify the correctness and reliability of the model.This research provides a reliable analytical method for forward kinematics of hybrid mechanisms,holding significant implications for advancing their applications in high-precision scenarios.展开更多
The human thumb plays a crucial role in performing coordinated hand movements for precise tool use.However,quantifying and interpreting the kinematics and couplings of the six degrees of freedom(6DOF)between the inter...The human thumb plays a crucial role in performing coordinated hand movements for precise tool use.However,quantifying and interpreting the kinematics and couplings of the six degrees of freedom(6DOF)between the interphalangeal(IP)and metacarpophalangeal(MCP)joints during hand functional tasks remains challenging.To address this issue,advanced dynamic biplane radiography combined with a model-based 2D–3D tracking technique was employed to decode the inherent kinematics of the thumb IP and MCP joints during key pinch,tip pinch,palmar pinch and wide grasp.The results indicate that the functional tasks of the thumb are intricately modulated by the 3D rotational and translational motions of the IP and MCP joints.The IP joint exhibited the greatest flexion/extension range of motion during the tip pinch task(67.2°±8.4°),compared to smaller ranges in key pinch(27.6°±3.8°)and wide grasp(16.2°±7.1°)tasks.In the wide grasp task,the IP joint showed more movement in the radius/ulna direction(3.4±1.2 mm)compared to tip pinch(3.1±0.8 mm).Furthermore,the kinematic data of the IP joint challenge the traditional notion that the IP joint normally acts as a hinge mechanism.The results of this study help to elucidate the kinematics of human thumb IP and MCP joints and may provide new inspiration for the design of high-performance bionic hands or thumb prosthetics as well as for evaluating the outcomes of thumb therapeutic interventions and surgical procedures.展开更多
Let Gq(R_(n))be the Grassmannian of all linear q dimensional subspaces of R_(n)and I an integral invariant of p+q−n dimensional submanifolds of R_(n).Then we give methods of evaluating Crofton type integral∫G_(q)(R^(...Let Gq(R_(n))be the Grassmannian of all linear q dimensional subspaces of R_(n)and I an integral invariant of p+q−n dimensional submanifolds of R_(n).Then we give methods of evaluating Crofton type integral∫G_(q)(R^(n))I(M∩L)dL The methods also work for various generalizations of Gq(R_(n))such as complex Grassmannians.展开更多
Aiming at the innovative design requirements of rehabilitation robots with multiple kinematically coupled components and the current absence of systematic processes in the design of such mechanisms,this paper presents...Aiming at the innovative design requirements of rehabilitation robots with multiple kinematically coupled components and the current absence of systematic processes in the design of such mechanisms,this paper presents the concept of a multi-output component mechanism(MOCM).A classification methodology for the MOCM is proposed based on the operational coupling between the actuators and the output components within closedloop mechanisms.Building on the classification results,a design methodology for a kinematically coupled MOCM(KCMOCM)is proposed based on the actuation distribution within the closed-loop sub-mechanisms.First,the number and relative kinematic characteristics of the output components are determined based on the application environment of the mechanism.These components are then grouped and classified according to motion similarity principles,followed by the design of closed-loop sub-mechanisms with actuators for each group,ultimately forming a complete KCMOCM.Taking the sit-stand-lie-bed mechanism in a spinal cord injury lower-limb rehabilitation robot as an example,this study comprehensively considers the multi-posture transition task requirements and spatial constraint characteristics of lower-limb rehabilitation training to design the mechanism.By applying the mechanism design methodology,six practical novel configurations are developed with established evaluation criteria,and kinematic analysis and experimental validation are performed on the optimized configuration.The results demonstrate that the optimized configuration satisfies the multi-posture rehabilitation training requirements for lower limbs.This validates the efficacy of the design methodology.Furthermore,the scalability of the design methodology is validated through the development of a robotic finger rehabilitation mechanism.展开更多
Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce t...Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce the number of the generalized coordinates and constraint functions. By solving the nonlinear equations, the motion of any points in the whole suspension and wheel system can be predicted, including the spatial changes of the wheel alignment parameters which are of great importance to the car performances.展开更多
Based on the multi-body kinematics principle, the topological structure and restriction relation among parts of machine tool and 3D multi-body model are constructed, the kinematics simulation system of machine tool is...Based on the multi-body kinematics principle, the topological structure and restriction relation among parts of machine tool and 3D multi-body model are constructed, the kinematics simulation system of machine tool is developed. The designer can observe the movement and machining course of the whole machine tool and understand accurately the kinematics parameters of components such as position, velocity and acceleration. Also the designer can estimate the pose of components in the virtual circumstance and forecast accurately and correct problems which may appear during the design before the prototype is manufactured to assure the feasibility of design scheme, shorten period of product design and reduce product cost. The simulation system is used during the design of CK1416 high speed and precision numerical control lathe. The curves of ball screw angular velocity and carriage displacement agree well with the results of theoretical calculation and the constructed model is correct.展开更多
文摘BACKGROUND Medial dished(MD)liner designs for cruciate-retaining(CR)total knee arthroplasty(TKA)are a relatively novel development.MD tibial inserts have a more constraining medial side,which allows for more similar kinematics and function to a native knee.AIM To evaluate the clinical results and patient-reported outcomes after CR TKA procedures utilizing a kinematically designed medial dish system.METHODS A multicenter,retrospective cohort review of 139 primary elective TKAs utilizing a kinematically designed CR Knee System(JOURNEY™II CR MD;Smith and Nephew,Memphis,TN,United States)at three different institutions with a minimum of two years of follow-up.Demographic information,clinical outcomes,and patient-reported outcome measures were collected and analyzed.RESULTS With up to 3.7 years from surgery,overall implant survivorship was 98.6%.There were significant postoperative increases in the average Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores(17.4 at 6 months,26.1 points at two years or more,P<0.001).CONCLUSION The combination of high implant survivorship and substantial improvements in patient-reported outcome measures suggests that the medial dish tibial insert represents a safe and effective option within TKA.Additional investigation is necessary to evaluate the long-term survivorship of this design.
文摘The increasing global prevalence of mild cognitive impairment(MCI)necessitates a paradigm shift in early detection strategies.Conventional neuropsychological assessment methods,predominantly paper-and-pencil tests such as the Mini-Mental State Examination and the Montreal Cognitive Assessment,exhibit inherent limitations with respect to accessibility,administration burden,and sensitivity to subtle cognitive decline,particularly among diverse populations.This commentary critically examines a recent study that champions a novel approach:The integration of gait and handwriting kinematic parameters analyzed via machine learning for MCI screening.The present study positions itself within the broader landscape of MCI detection,with a view to comparing its advantages against established neuropsychological batteries,advanced neuroimaging(e.g.,positron emission tomography,magnetic resonance imaging),and emerging fluid biomarkers(e.g.,cerebrospinal fluid,blood-based assays).While the study demonstrates promising accuracy(74.44%area under the curve 0.74 with gait and graphic handwriting)and addresses key unmet needs in accessibility and objectivity,we highlight its cross-sectional nature,limited sample diversity,and lack of dual-task assessment as areas for future refinement.This commentary posits that kinematic biomarkers offer a distinctive,scalable,and ecologically valid approach to widespread MCI screening,thereby complementing existing methods by providing real-world functional insights.Future research should prioritize longitudinal validation,expansion to diverse cohorts,integration with multimodal data including dual-tasking,and the development of highly portable,artificial intelligence-driven solutions to achieve the democratization of early MCI detection and enable timely interventions.
基金Supported by National Natural Science Foundation of China (Grant No. 52175019)Beijing Municipal Natural Science Foundation of China (Grant No. L222038)+3 种基金Beijing Nova Programme Interdisciplinary Cooperation Project of China (Grant No. 20240484699)Joint Funds of Industry-University-Research of Shanghai Academy of Spaceflight Technology of China (Grant No. SAST2022-017)Beijing Municipal Key Laboratory of Space-ground Interconnection and Convergence of ChinaKey Laboratory of IoT Monitoring and Early Warning,Ministry of Emergency Management of China
文摘To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method for a class of parallel platforms with 3-RE structure after locking the actuated joints is proposed in this paper.Given that the angle between specific joint axes of limbs remains constant,a set of geometric constraints for the forward kinematics of parallel mechanisms(PM)are determined.After translating unit direction vectors of these joint axes to the common starting point,the geometric constraints of the angle between the vectors are transformed into the distances between the endpoints of the vectors,making them easier to handle.Under the framework of CGA,the positions of key points that determine the position and orientation of the moving platform can be intuitively determined by the intersection,division,and duality of basic geometric entities.By employing the tangent half-angle substitution,the forward kinematic analysis of the parallel mechanisms leads to a high-order univariate polynomial equation without the need for any complex algebraic elimination operations.After solving this equation and back substitution,the position and pose of the MP can be obtained indirectly.A numerical case is utilized to confirm the effectiveness of the proposed method.
基金funded by Science Foundation for Youth supported by Shanghai Municipal Health Commission(No.20204Y0313)Sailing Program with the support of Science and Technology Commission of Shanghai Municipality(No.21YF1443800).
文摘Background China is seeing a growing demand for rehabilitation treatments for post-stroke upper limb spastic paresis(PSSP-UL).Although acupuncture is known to be effective for PSSP-UL,there is room to enhance its efficacy.Objective This study explored a semi-personalized acupuncture approach for PSSP-UL that used three-dimensional kinematic analysis(3DKA)results to select additional acupoints,and investigated the feasibility,efficacy and safety of this approach.Design,setting,participants and interventions This single-blind,single-center,randomized,controlled trial involved 74 participants who experienced a first-ever ischemic or hemorrhagic stroke with spastic upper limb paresis.The participants were then randomly assigned to the intervention group or the control group in a 1:1 ratio.Both groups received conventional treatments and acupuncture treatment 5 days a week for 4 weeks.The main acupoints in both groups were the same,while participants in the intervention group received additional acupoints selected on the basis of 3DKA results.Follow-up assessments were conducted for 8 weeks after the treatment.Main outcome measures The primary outcome was the Fugl-Meyer Assessment for Upper Extremity(FMA-UE)response rate(≥6-point change)at week 4.Secondary outcomes included changes in motor function(FMA-UE),Brunnstrom recovery stage(BRS),manual muscle test(MMT),spasticity(Modified Ashworth Scale,MAS),and activities of daily life(Modified Barthel Index,MBI)at week 4 and week 12.Results Sixty-four participants completed the trial and underwent analyses.Compared with control group,the intervention group exhibited a significantly higher FMA-UE response rate at week 4(χ^(2)=5.479,P=0.019)and greater improvements in FMA-UE at both week 4 and week 12(both P<0.001).The intervention group also showed bigger improvements from baseline in the MMT grades for shoulder adduction and elbow flexion at weeks 4 and 12 as well as thumb adduction at week 4(P=0.007,P=0.049,P=0.019,P=0.008,P=0.029,respectively).The intervention group showed a better change in the MBI at both week 4 and week 12(P=0.004 and P=0.010,respectively).Although the intervention group had a higher BRS for the hand at week 12(P=0.041),no intergroup differences were observed at week 4(all P>0.05).The two groups showed no differences in MAS grades as well as in BRS for the arm at weeks 4 and 12(all P>0.05).Conclusion Semi-personalized acupuncture prescription based on 3DKA results significantly improved motor function,muscle strength,and activities of daily living in patients with PSSP-UL.
基金Supported by National Natural Science Foundation of China(Grant No.52275033)National Natural Science Youth Foundation of China(Grant No.52205033)Hebei Provincial Natural Science Foundation of China(Grant No.E2021203019)。
文摘Serial-parallel manipulators are of great interest to academic community in recent years,especially those composed of classical parallel mechanisms.There have been many studies around 2(3RPS)and 2(3SPR)S-PMs,but unfortunately their inverse kinematics have not yet been resolved.This paper discovers that the unknown kinematic parameters of middle platform are responsible for the unresolvable of inverse kinematics,meanwhile the unknown kinematic parameters of middle platform also have huge coupling relationships.Therefore,to break through this challenges,the huge coupling relationships are decoupled layer by layer,the kinematic parameters of middle platform are solved by combining Sylvester's elimination method,and the inverse displacements of 2(3RPS)and 2(3SPR)S-PMs are obtained subsequently.This paper not only solves the inverse kinematics of classical 2(3RPS)and 2(3SPR)S-PMs,but also reveals the essence of the inverse kinematics of general(3-DOF)+(3-DOF)6-DOF S-PMs and proposes a corresponding solution.
基金supported by the National Natural Science Foundation of China(52475307)the Shandong Provincial Natural Science Foundation(ZR2023ME041).
文摘Backswimmers exhibit a high degree of mobility in water,and their different motion patterns have important implications for the design of micro-biomimetic underwater robots.This paper used three-dimensional high-speed cameras to extract the key points on the hind legs.The hind leg motion laws and the deformation laws of the setae were obtained in four motion patterns:rapid forward,cruising,in-motion turning,and in-place turning.The motion laws of each joint on the hind leg are modeled using a Fourier series.A kinematic model of hind legs was established based on the DH method,and the motion characteristics of hind legs under different motion patterns were analyzed.This paper provides basic data and theoretical models for micro-biomimetic robots.
基金Supported by National Natural Science Foundation of China(Grant Nos.52305003,52175019)National Key R&D Program of China(Grant No.2023YFD2001100)+2 种基金Beijing Natural Science Foundation(Grant No.L222038)Beijing Nova Programme Interdisciplinary Cooperation Project(Grant No.20240484699)Project“Vice President of Science and Technology”of Changping District of Beijing.
文摘The design and analysis of continuum robots have consistently been a prominent research focus in the field of mechanics.However,portable continuum robots with minimal spatial occupancy,which have great potential for applications such as search and rescue,are scarcely available.This paper presents a novel helical-coiled multi-segment flexible continuum robot featuring helical deployment and compact design,with an integrated framework for structural design,kinematic modeling,and experimental validation.The design of the helical-coiled multi-segment flexible continuum robot for unstructured environment detection,including a flexible body,an actuation module,a feed module,and a sensing module,is presented systematically.Kinematic models of both single-and multisegment continuum robots were established based on the constant curvature model to analyze the parameter mapping relationship from the end-effector position and orientation to the driving inputs.Furthermore,the feedforward motion of the robot was examined,and an uncoiling strategy based on S-curve compensation was employed to complete the kinematic analysis.Finally,the accuracy of the kinematic model considering the active uncoiling feed motion was validated through experimental analysis,demonstrating the motion characteristics of the continuum robot.Altogether,this study provides a framework for the design and analysis of helical-coiled continuum robots.
基金supported by Guizhou Provincial Basic Research Program(Natural Science,Grant No.QKHJC-ZK[2022]YB075)the National Natural Science Foundation of China(Grant No.42067046)+2 种基金the Guizhou Provincial Program on Commercialization of Scientific and Technological Achievements(N0.QKHCG-LH2024-ZD025)the Science and Technology Planning Project of Guiyang City(Grant No.ZKHT[2023]13-10)Undergraduate Training Program for Innovation and Entrepreneurship of Guizhou Province(Project No.S202110657053)。
文摘Rockfall kinematic characteristics exhibit significant randomness and are influenced by factors such as rock mass properties,slope morphology,impact angle,and slope materials.Accurately determining the key parameters of rockfall movement is critical for understanding motion patterns and effectively preventing and controlling rockfall hazards.In this study,a monitoring system consisting of selfdeveloped inertial navigation equipment,high-speed cameras,and an unmanned aerial vehicle was used to conduct onsite motion tests involving four differently shaped rock specimens on three types of slopes(bedrock,detritus,and clast bedding).The selfdeveloped inertial navigation system integrated a highdynamic-range accelerometer(±400 g)and a shockresistant gyroscope(±4000°/s),capable of robustly collecting data during the test.The data collected from these tests were processed to extract key kinematic parameters such as velocity,trajectory,restitution coefficients,and friction coefficients.The test results demonstrated that the inertial navigation system accurately recorded the acceleration and angular velocity of the rocks during motion,with these measurements closely aligning with the field data.The normal and tangential restitution coefficients were found to be influenced primarily by the slope material and impact angle,with higher normal restitution coefficients observed for low-angle impacts.The normal restitution coefficients ranged from 0.35 to 0.86,whereas the tangential restitution coefficients ranged from 0.46 to 0.91,depending on the slope materials.Additionally,the sliding friction coefficient was calculated to be between 0.66 and 0.78,whereas the rolling friction coefficient for the slab-shaped specimen was determined to be 0.53.These findings provide valuable data for improving the accuracy of rockfall trajectory predictions and the design of protective structures.
基金Supported by National Natural Science Foundation of China(Grant Nos.52335002,52205014,52275033)the Fundamental Research Funds for the Central Universities(Grant No.JZ2024HGTB0245).
文摘Cable-driven parallel robots(CDPRs)have advantages of larger workspace and load capacity than conventional parallel robots while existing interference problems among cables,workpieces and the end-effector.In order to avoid collision and improve the flexibility of the robots,this study proposes a reconfigurable cable-driven parallel robot(RCDPR)having characteristics of large load-to-weight ratio,easy modularity and variable stiffness.Adjustable brackets are connected to the moving platform to adjust the position of the pull-out point with the movement of the end-effector.In addition,a variable stiffness actuator(VSA)accompanied by finite element analysis is designed to optimize the cable tension to adapt different task requirements.Firstly,a new idea of reconfiguration is given,and an inverse kinematic model is established using the vector closure principle to derive its inverse kinematic expressions focusing on one of the configurations.Second,the VSA is attached to each cable to achieve stiffness adjustment,and the system stiffness is derived in detail.Finally,the rationality and accuracy of the robot are verified through numerical analysis,providing a reference for subsequent trajectory planning with implications.
基金financially supported by ChinaNational Funds for Distinguished Young Scientists(No.52125403)National Natural Science Foundation of China(Nos.52261135540 and 52404303)Science and Tech-nology Plan Special Fund Project of Jiangsu Province,China(No.BZ2024046)。
文摘Flip-flow screens offer unique advantages in grading fine-grained materials.To address inaccuracies caused by sensor vibra-tions in traditional contact measurement methods,we constructed a non-invasive measurement system based on electrical and optical sig-nals.A trajectory tracking algorithm for the screen-body was developed to visually measure the kinematics.Employing the principle oflaser reflection for distance measurement,optical techniques were performed to capture the kinematic information of the screen-plate.Ad-ditionally,by using Wi-Fi and Bluetooth transmission of electrical signals,tracer particle tracking technology was implemented to elec-trically measure the kinematic information of mineral particles.Consequently,intelligent fusion and perception of the kinematic informa-tion for the screen-body,screen-plate,and particles in the screening system have been achieved.
文摘We apply methods of algebraic integral geometry to prove a special case of the Gaussian kinematic formula of Adler-Taylor.The idea,suggested already by Adler and Taylor,is to view the GKF as the limit of spherical kinematic formulas for spheres of large dimension N and curvature1/N.
基金supported by the National Key Research and Development Program of China No.2024YFA1611902the National Natural Science Foundation of China(NSFC)under grants Nos.12273027 and 12588202+3 种基金the Innovation Team Funds of China West Normal University under grant No.KCXTD2022-6CAS Project for Young Scientists in Basic Research under grants Nos.YSBR-062 and YSBR-092the Strategic Priority Research Program of Chinese Academy of Sciences under grant No.XDB1160102the science research grant from the China Manned Space Project with No.CMS-CSST-2025-A11.
文摘Based on the updated M giant star catalog selected from Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR9,we identify substructures within the integrals-of-motion space through the Friends-of-Friends clustering algorithm.We obtain members belonging to several known substructures:the Sagittarius stream,Galactic Anticenter Substructure(GASS),Gaia-Enceladus-Sausage(GES),Splash,and the high-αdisk.Furthermore,we also identify two groups which cannot be clearly associated with previously known substructures.Our findings confirm the existence of metal-rich constituents within the GES,representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved.Additionally,this study further expands the sample of GASS,high-αdisk,and Splash stars.Analysis of these metal-rich M giant stars as members of the GES,Splash,and high-αdisk components supports an evolution scenario for the early Milky Way,as proposed by previous studies.In this scenario,stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event(GES).This process redistributed stellar orbits,creating the Splash population,while the undisturbed portion of the primordial disk persisted as the present-day high-αdisk component.
基金Supported by National Key R&D Program of China(Grant No.2022YFB3404101)National Natural Science Foundation of China(Grant Nos.52375018,92148301)。
文摘Accurate kinematic calibration is the very foundation for robots'application in industry demanding high precision such as machining.Considering the complex error characteristic and severe ill-posed identification issues of a 5-DoF parallel machining robot,this paper proposes an adaptive and weighted identification method to achieve high-precision kinematic calibration while maintaining reliable stability.First,a kinematic error propagation mechanism model considering the non-ideal constraints and the screw self-rotation is formulated by incorporating the intricate structure of multiple chains and a unique driven screw arrangement of the robot.To address the challenge of accurately identifying such a sophisticated error model,a novel adaptive and weighted identification method based on generalized cross validation(GCV)is proposed.Specifically,this approach innovatively introduces Gauss-Markov estimation into the GCV algorithm and utilizes prior physical information to construct both a weighted identification model and a weighted cross-validation function,thus eliminating the inaccuracy caused by significant differences in dimensional magnitudes of pose errors and achieving accurate identification with flexible numerical stability.Finally,the kinematic calibration experiment is conducted.The comparative experimental results demonstrate that the presented approach is effective and has enhanced accuracy performance over typical least squares methods,with maximum position and orientation errors reduced from 2.279 mm to 0.028 mm and from 0.206°to 0.017°,respectively.
基金the Foshan Science and Technology Innovation Team Project(No.FS0AA-KJ919-4402-0060)the National Natural Science Foundation of China(No.62263018)。
文摘To efficiently search out the optimal cam contour,a software integrated optimization method considering cam mechanism’s kinematic and dynamic characteristics was presented,and its effectiveness was demonstrated by a case study of the cam contour optimization for an offset press open-close gripper mechanism.The acceleration curve and the residual vibration model of the follower were separately studied.A symmetric harmonic trapezoidal curve was designed to control the follower’s acceleration,and single-DOF lumped parameter torsional vibration model was proposed to describe the follower’s residual vibration.Accordingly,corresponding motion curve design software and Simulink vibration model of the follower were developed respectively,and they were integrated into an automatic optimization platform with iSIGHT.The multi-objective optimization with objectives of minimizing both the acceleration and the residual vibration of the follower was completed within the platform by using NSGA-II algorithm.An appropriate point with lower acceleration and residual vibration was chosen from Pareto front as an optimal solution of the follower’s motion curve.Based on the follower’s new motion curve,the actual cam contour was generated by inverse kinematic simulation in COSMOSMotion.The offset press that installed our new designed cam exhibited a lower vibration than the previous machine,and the maximum measured acceleration of the offset press at a printing speed of 15000 r/h is reduced by 7.7%.
基金Supported by Hebei Provincial Natural Science Foundation(Grant No.F2024202052)National Natural Science Foundation of China(Grant No.52175019)+3 种基金Beijing Municipal Natural Science Foundation(Grant No.L222038)Beijing Nova Programme Interdisciplinary Cooperation Project(Grant No.20240484699)Joint Funds of Industry-University-Research of Shanghai Academy of Spaceflight Technology(Grant No.SAST2022-017)Beijing Municipal Key Laboratory of Space-ground Interconnection and Convergence of China and Key Laboratory of IoT Monitoring and Early Warning,Ministry of Emergency Management。
文摘Parallel mechanisms with fewer degrees of freedom that incorporate two or more SPR limbs have been widely adopted in industrial applications in recent years.However,notable theoretical gaps persist,particularly in the field of analytical solutions for forward kinematics.To address this,this paper proposes an innovative forward kinematics analysis method based on Conformal Geometric Algebra(CGA)for complex hybrid mechanisms formed by serial concatenation of such parallel mechanisms.The method efficiently represents geometric elements and their operational relationships by defining appropriate unknown parameters.It constructs fundamental geometric objects such as spheres and planes,derives vertex expressions through intersection and dual operations,and establishes univariate high-order equations via inner product operations,ultimately obtaining complete analytical solutions for the forward kinematics of hybrid mechanisms.Using the(2-SPR+RPS)+(3-SPR)serial-parallel hybrid mechanism as a validation case,three configuration tests implemented in Mathematica demonstrate that:for each configuration,the upper 3-SPR mechanism yields 15 mathematical solutions,while the lower 2-SPR+RPS mechanism yields 4 mathematical solutions.After geometric constraint filtering,a unique physically valid solution is obtained for each mechanism.SolidWorks simulations further verify the correctness and reliability of the model.This research provides a reliable analytical method for forward kinematics of hybrid mechanisms,holding significant implications for advancing their applications in high-precision scenarios.
基金supported by the National Natural Science Foundation of China(No.52175270)the Project of Scientific and Technological Development Plan of Jilin Province(No.20220508130RC).
文摘The human thumb plays a crucial role in performing coordinated hand movements for precise tool use.However,quantifying and interpreting the kinematics and couplings of the six degrees of freedom(6DOF)between the interphalangeal(IP)and metacarpophalangeal(MCP)joints during hand functional tasks remains challenging.To address this issue,advanced dynamic biplane radiography combined with a model-based 2D–3D tracking technique was employed to decode the inherent kinematics of the thumb IP and MCP joints during key pinch,tip pinch,palmar pinch and wide grasp.The results indicate that the functional tasks of the thumb are intricately modulated by the 3D rotational and translational motions of the IP and MCP joints.The IP joint exhibited the greatest flexion/extension range of motion during the tip pinch task(67.2°±8.4°),compared to smaller ranges in key pinch(27.6°±3.8°)and wide grasp(16.2°±7.1°)tasks.In the wide grasp task,the IP joint showed more movement in the radius/ulna direction(3.4±1.2 mm)compared to tip pinch(3.1±0.8 mm).Furthermore,the kinematic data of the IP joint challenge the traditional notion that the IP joint normally acts as a hinge mechanism.The results of this study help to elucidate the kinematics of human thumb IP and MCP joints and may provide new inspiration for the design of high-performance bionic hands or thumb prosthetics as well as for evaluating the outcomes of thumb therapeutic interventions and surgical procedures.
文摘Let Gq(R_(n))be the Grassmannian of all linear q dimensional subspaces of R_(n)and I an integral invariant of p+q−n dimensional submanifolds of R_(n).Then we give methods of evaluating Crofton type integral∫G_(q)(R^(n))I(M∩L)dL The methods also work for various generalizations of Gq(R_(n))such as complex Grassmannians.
基金Supported by National Key Research and Development Program of China(Grant No.2019YFB1312500)。
文摘Aiming at the innovative design requirements of rehabilitation robots with multiple kinematically coupled components and the current absence of systematic processes in the design of such mechanisms,this paper presents the concept of a multi-output component mechanism(MOCM).A classification methodology for the MOCM is proposed based on the operational coupling between the actuators and the output components within closedloop mechanisms.Building on the classification results,a design methodology for a kinematically coupled MOCM(KCMOCM)is proposed based on the actuation distribution within the closed-loop sub-mechanisms.First,the number and relative kinematic characteristics of the output components are determined based on the application environment of the mechanism.These components are then grouped and classified according to motion similarity principles,followed by the design of closed-loop sub-mechanisms with actuators for each group,ultimately forming a complete KCMOCM.Taking the sit-stand-lie-bed mechanism in a spinal cord injury lower-limb rehabilitation robot as an example,this study comprehensively considers the multi-posture transition task requirements and spatial constraint characteristics of lower-limb rehabilitation training to design the mechanism.By applying the mechanism design methodology,six practical novel configurations are developed with established evaluation criteria,and kinematic analysis and experimental validation are performed on the optimized configuration.The results demonstrate that the optimized configuration satisfies the multi-posture rehabilitation training requirements for lower limbs.This validates the efficacy of the design methodology.Furthermore,the scalability of the design methodology is validated through the development of a robotic finger rehabilitation mechanism.
文摘Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce the number of the generalized coordinates and constraint functions. By solving the nonlinear equations, the motion of any points in the whole suspension and wheel system can be predicted, including the spatial changes of the wheel alignment parameters which are of great importance to the car performances.
文摘Based on the multi-body kinematics principle, the topological structure and restriction relation among parts of machine tool and 3D multi-body model are constructed, the kinematics simulation system of machine tool is developed. The designer can observe the movement and machining course of the whole machine tool and understand accurately the kinematics parameters of components such as position, velocity and acceleration. Also the designer can estimate the pose of components in the virtual circumstance and forecast accurately and correct problems which may appear during the design before the prototype is manufactured to assure the feasibility of design scheme, shorten period of product design and reduce product cost. The simulation system is used during the design of CK1416 high speed and precision numerical control lathe. The curves of ball screw angular velocity and carriage displacement agree well with the results of theoretical calculation and the constructed model is correct.
