Kinematic Coupling Research Articles

Kinetic coupling in distal foot joints during walking

BackgroundKinematic coupling between the first metatarsophalangeal (MTP) and midtarsal joints is evident during gait and other movement tasks, however kinetic foot coupling during walking has not been examined. Furthermore, contributing factors to foot coupling are still unclear. Therefore, the purpose of this study was to investigate kinematic and kinetic coupling within the foot by restricting MTP motion during overground walking. We hypothesized that when the MTP joint was prevented from fully extending, the midtarsal joint would achieve less peak motion and generate less positive work compared to walking with normal MTP motion.MethodsTwenty-six individuals participated in this randomized cross-over study. Using motion capture to track motion, participants walked at 1.3 m/s while wearing a brace that restricted MTP motion in a neutral (BR_NT) or extended (BR_EX) position. Additionally, participants walked while wearing the brace in a freely moveable setting (BR_UN) and with no brace (CON). A pressure/shear sensing device was used to capture forces under each foot segment. During stance, peak joint motion and work were calculated for the MTP and midtarsal joints using inverse dynamics. A series of ANOVAs and Holm post hoc tests were performed for all metrics (alpha = 0.05).ResultsThe brace successfully decreased peak MTP motion by 19% compared to BR_UN and CON. This was coupled with 9.8% less midtarsal motion. Kinetically, the work absorbed by the MTP joint (26–51%) and generated by the midtarsal joint (30–38%) were both less in BR_EX and BR_NT compared to BR_UN.ConclusionImplications and sources of coupling between the MTP and midtarsal joints are discussed within the context of center of pressure shifts and changes to segmental foot forces. Our results suggest that interventions aimed at modulating MTP negative work (such as footwear or assistive device design) should not ignore the midtarsal joint.

Balanced Standing on One Foot of Biped Robot Based on Three-Particle Model Predictive Control.

Balancing is a fundamental task in the motion control of bipedal robots. Compared to two-foot balancing, one-foot balancing introduces new challenges, such as a smaller supporting polygon and control difficulty coming from the kinematic coupling between the center of mass (CoM) and the swinging leg. Although nonlinear model predictive control (NMPC) may solve this problem, it is not feasible to implement it on the actual robot because of its large amount of calculation. This paper proposes the three-particle model predictive control (TP-MPC) approach. It combines with the hierarchical whole-body control (WBC) to solve the one-leg balancing problem in real time. The bipedal robot's torso and two legs are modeled as three separate particles without inertia. The TP-MPC generates feasible swing leg trajectories, followed by the WBC to adjust the robot's center of mass. Since the three-particle model is linear, the TP-MPC requires less computational cost, which implies real-time execution on an actual robot. The proposed method is verified in simulation. Simulation results show that our method can resist much larger external disturbance than the WBC-only control scheme.

Lateral attitude control of solar-powered UAV with high aspect ratio

A solar-powered UAV usually has a high-aspect-ratio and flexible structural design. Its aerodynamic and mass characteristics are different from those of a conventional aircraft. This paper compares the differences in lateral aerodynamic data with those of Class I and Class III aircrafts. Based on the rigid-body dynamics theory, the effects of flexible wing deformation on the stability of the UAV are analyzed. Then, by combining the structural deformation, inertia variation and aerodynamic derivative, the solar-powered UAV's lateral stability is analyzed based on the root locus method. The variation of eigenvalues with wing deformation is also investigated. The rolling moment equation is combined with the kinematic equation to reveal the roll attitude limitation envelope constrained by the kinematic coupling and aileron effects. Taking into account the aerodynamic characteristics of the solar-powered UAV, its wing deformation and roll attitude limitation problem, this paper proposes an adaptive back-stepping control method with strong robustness to achieve the accurate control of the roll attitude of the solar-powered UAV.

Kinematic coupling‐based trajectory planning for rotary crane system with double‐pendulum effects and output constraints

AbstractWhen the payload is too large or the hook mass cannot be ignored, the double‐pendulum phenomenon may happen in rotary cranes practical applications. The increase in dynamic complexity makes it more difficult to fast and accurate positioning while suppressing swing during cargo transportation. Moreover, output constraints should be considered in actual crane systems. In this paper, a novel kinematic coupling‐based trajectory planning method is proposed for double‐pendulum rotary cranes with the constraints on angular acceleration and velocity of the boom. The proposed trajectory consists of two parts: a positioning reference component and a swing‐eliminating component. The positioning reference trajectory takes into account the physical constraints of the actuator. The swing‐eliminating trajectory is designed based on the kinematic coupling relationship among the boom luffing, the hook swing and the payload swing. Lyapunov techniques and Barbalat lemma are used for stability analysis. Numerical simulation and real experiments verify the superior control performance and robustness of the proposed control method.

Experimental delineation of gas-particle coupling regimes in explosive volcanic eruptions

The kinematic and thermal coupling between pyroclasts and gas is one of the main controlling factors in the dynamics of explosive volcanic eruptions. Here, we performed rapid decompression experiments in a shock-tube apparatus at eruptive pressures (2–11 MPa) using monodisperse volcanic particles (grain-size 0.063–1.4 mm). We systematically investigated the coupling of these particles with the gas phase by measuring the rarefaction speed and the ejection velocity of the particles front in each experiment. The results are consistent with a theoretical model derived from the pseudogas approximation (i.e. perfect coupling) only for particles smaller than a certain size: ∼ 0.125 mm for rarefaction speed and ∼ 0.5 mm for the particles front ejection velocity, whereas larger particles are significantly decoupled. We present an experimental parameterization to calculate the kinematic Stokes number (Stk). We show that: 1) for the ejection process the particles are coupled with the gas if Stk < 1, whereas for the rarefaction speed the particles are fully coupled when Stk < 0.2; 2) for the rarefaction speed there is a transition when 0.2 < Stk < 1; and 3) in both processes particles are decoupled when Stk > 1. Furthermore, where the Reynolds number based on the relative velocity between gas and particles (Rep) is larger than 103, the ratio between the timescales required for thermal and kinematic equilibration increases with Rep, such that some particles are coupled with the gas but decoupled from it thermally. These findings represent the first experimental delineation of kinematic and thermal coupling regimes between volcanic particles and gas and contribute thereby to a more robust basis for multiphase explosive eruptive models.

Structural modeling and dynamic analysis of the two-segment deployable beam system

The structural modeling and dynamic analysis of the two-segment deployable beam system are carried out with considering complicated influential factors like base elasticity, complete extension, twist and 2-D translational deformations, as well as distinct structural and kinematic couplings. The model is considered as an improved one relative to the traditional model which mostly considers extension and 1-D transverse deformations. The Lagrange-form method is proposed to derive the dynamic equation by virtue of finite element method and a special time-varying deformation compatibility condition, and the frequency and time domain solutions for dynamical analyses are developed by iteration method and Newmark-beta method. The effectiveness of the present method is verified by comparisons with the traditional Euler method, and whereby the modal and dynamic properties of the system are studied. Two typical motion modes are constructed to explore the influence of motion velocity and acceleration on the coupling mechanisms among structural deformations. Based on that, the implication of friction between the segments is further evaluated.

Full‐state prescribed performance pose tracking of space proximity operations with input saturation

AbstractThis paper investigates the relative position tracking and attitude synchronization control for spacecraft close‐range proximity missions with input saturation and model uncertainties. A robust saturated relative motion controller is proposed for this purpose. Prescribed performance functions are designed to guarantee the transient and steady‐state response of the system and the full‐state constraints. Then, a nonlinear disturbance observer is developed to estimate the lumped disturbance that comprises the effects of parametric uncertainties and kinematic couplings. At the same time, a linear compensator system is incorporated into the controller design to deal with the control input saturation. Finally, it can be proved via the Lyapunov theory that the closed‐loop system is uniformly ultimately bounded stable. Simulation results on the spacecraft close‐range rendezvous and docking mission validate the effectiveness of the proposed control approach.

Geometry, kinematics and mechanism of growth unconformities in the Biertuokuoyi piggy-back basin: implications for episodic growth of the Pamir frontal thrust

Piggy-back basins are characterized by growth stratigraphic sequences bounded by growth unconformities and record the complete deformational history of the related structures. The Biertuokuoyi piggy-back basin, located in the hanging wall of the Pamir frontal thrust (PFT), provides a remarkable example documenting the geometry, kinematics and mechanism of growth unconformities. High-resolution seismic data reveal that multiple growth sequences were folded with constant-dip kink band migration and their dips are equal to the change in the fault-bend angle of the PFT, indicating their kinematic coupling. Divided by a basal Cenozoic detachment, the PFT system contains five lower thrust ramps that cut Paleozoic–Mesozoic strata and an upper thrust ramp that cuts Cenozoic strata. The growth strata and unconformities record c. 4425 m of dip-slip and six stages of episodic thrusting for the PFT. We propose a coeval thrusting style for the five lower thrust ramps. The present seismic section reveals at least 31.1 km of total shortening at the northeastern Pamir front. In particular, the latest shortening of c. 8.0 km is recorded by the Biertuokuoyi Basin and the Mushi anticline. Our results show that multiple growth sequences bounded by growth unconformities are powerful resources for documenting the evolution of deformation. Supplementary material: Supporting figures and data, including seismic profiles and kinematic simulation results, are available at https://doi.org/10.17605/OSF.IO/DNQBS . Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts

Finite-Time Prescribed Performance Control for Space Circumnavigation Mission With Input Constraints and Measurement Uncertainties

This article presents a 6-DOF attitude-orbit synchronous control problem for the space circumnavigation (SCN) mission with parameter uncertainties, time-varying uncertainties, and input constraints. In particular, from the perspective of engineering application, time-varying measurement uncertainties are taken into account of the 6-DOF attitude–orbit coupling kinematics and dynamics, and the analytical solution of the desired attitude is derived based on the measured relative orbit information with measurement uncertainties. To drive the active spacecraft approach to the faulty target safely, a time-varying exponential prescribed convergence boundary is introduced into the sliding surface. A finite-time disturbance observer is involved in equivalent tracking errors for compensating the mismatched uncertainties. In addition, an auxiliary system is designed to overcome the instability danger caused by input constraints. The stability of the controlled system is discussed in the nonautonomous finite-time stable framework, which is proved via Lyapunov analysis that the attitude-orbit tracking errors converge to the equilibrium within finite time. The simulation experiment with mismatched uncertainties and prescribed constraints shows the superiority of the designed control scheme.

Gesture-vocal coupling in Karnatak music performance: A neuro-bodily distributed aesthetic entanglement.

In many musical styles, vocalists manually gesture while they sing. Coupling between gesture kinematics and vocalization has been examined in speech contexts, but it is an open question how these couple in music making. We examine this in a corpus of South Indian, Karnatak vocal music that includes motion-capture data. Through peak magnitude analysis (linear mixed regression) and continuous time-series analyses (generalized additive modeling), we assessed whether vocal trajectories around peaks in vertical velocity, speed, or acceleration were coupling with changes in vocal acoustics (namely, F0 and amplitude). Kinematic coupling was stronger for F0 change versus amplitude, pointing to F0's musical significance. Acceleration was the most predictive for F0 change and had the most reliable magnitude coupling, showing a one-third power relation. That acceleration, rather than other kinematics, is maximally predictive for vocalization is interesting because acceleration entails force transfers onto the body. As a theoretical contribution, we argue that gesturing in musical contexts should be understood in relation to the physical connections between gesturing and vocal production that are brought into harmony with the vocalists' (enculturated) performance goals. Gesture-vocal coupling should, therefore, be viewed as a neuro-bodily distributed aesthetic entanglement.

Cross-flow oscillations of a circular cylinder with mechanically coupled rotation

Flow-induced vibrations (FIV) of an elastically mounted circular cylinder are investigated by means of two-dimensional simulations. A mechanical coupling between cross-flow translation and rotation provides a single degree-of-freedom system in which the coupled rotational oscillations affect the fluid–structure dynamics. The structural response of this system is investigated exploring the design space spanned by reduced velocity, coupling radius and phase density ratio. The kinematic coupling introduces the rotation-induced shear layer modifications, as well as an equivalent inertia effect connected to the coupling force. Such a computational campaign is carried out by means of direct numerical simulations with immersed boundary forcing at a Reynolds number equal to 100. The investigated system exhibits the wake-body synchronisation features typical of lock-in for non-rotating cylinders. However, the kinematic coupling provides a novel FIV scenario, in which the oscillation amplitude is magnified in the locked configurations with respect to the forced rotation case. Furthermore, it is found that there a significant widening of the reduced velocity domain where the lock-in condition takes place. In view of the proposed analyses, it is determined that the coupled rotation guarantees the phase alignment between lift and displacement necessary to sustain the lock-in condition, making the oscillation amplitude grow indefinitely with the reduced velocity. This is inherently achieved due to the rotational shear layer and the added mass contribution, which prevent the exact match between oscillation frequency and system natural frequency in vacuum. The outcomes of this study might potentially lead to an innovative water energy harvester offering larger power outputs and extended optimal operating regions.

Research on Design, Simulation, and Experiment of Separation Mechanism for Micro-Nano Satellites

The separation mechanism is a critical device that transports and releases satellites during launch and on-orbit. However, as satellites become smaller and more compact, the traditional belt-locking device or pyrotechnic release and separation device cannot meet the micro-nano satellite’s separation requirements. A novel separation mechanism kinematic system was designed, analyzed, and experimentally verified to achieve non-interference and non-pyrotechnic separation of the satellites from the launch vehicle while maintaining the initial separation attitude. First, an overall structural strategy for the kinematics system was proposed based on the MF (product code of the satellite) satellite’s structural properties. The structural characteristics of the separation mechanism were also confirmed by the principle of energy conservation. Then, a finite element model and a dynamic model of the kinematic coupling system between the MF satellite and the separation mechanism during launch and deployment were constructed, along with an analysis of the mechanical characteristics and a kinematic simulation. Finally, the mechanical characteristics and dependability of the separation mechanism were verified using a ground vibration test and a separation test. The prototype test results demonstrate that the separation process is essentially identical to the numerical simulation results and that the MF satellite can be deployed successfully without interference, with the MF satellite’s initial separation attitude fully satisfying the designed technical indexes.

Fuzzy adaptive sliding mode fault estimation and fixed-time fault-tolerant control for coupled spacecraft based on SE(3)

The goal of this study is to develop fault estimation (FE) and fault tolerant control (FTC) techniques for rigidly coupled spacecraft. A fuzzy adaptive sliding mode fault estimation approach is proposed to address fault tolerance against a large scale of disturbances, including inertia parametric uncertainties, space disturbances, actuator faults and saturation constraints. Firstly, a six-degrees of freedom (6-DOF) fault tolerant control architecture is established on the Lie group SE(3), which combined rotation and translation coupling kinematics and dynamics together. Then, a nonlinear fault estimator is used to deal with controllability loss of the fault actuator and the fuzzy logic system (FLS) is presented to solve the lumped disturbance. Next, in order to reduce the number of control parameters, the exponential parameters of the fast double-power sliding mode surface and the reaching law are set to be the same, which are nested with the estimated value of actuator effectiveness and combined with the pseudo inverse control allocation method to form the control algorithm in this paper. Finally, the stability and fixed-time convergence of the proposed method are proved theoretically by Lyapunov function, and the effectiveness of the scheme is verified by numerical simulation.

Passive mold alignment for the fabrication of polymer through-holes using punching and double-sided hot embossing

Aligning two mold inserts is one of the most important steps in the punching of through-holes for polymer microfluidic devices. Significant misalignment of the mold inserts could reduce device functionality or allow for interference between mold inserts. Active and iterative methods require repetitive experiments, characterization, and mold adjustments making the process tedious. Passive set-up alignment using a temporary kinematic coupling can be an alternative to the active and iterative methods. To do this, the three v-grooves on the primary mold insert mate with the three spheres set in dimples on the complementary mold insert. Once the mold inserts are aligned and secured, the spheres are removed, and face-to-face contact between the mold inserts can be achieved for the molding operation. This aligns the primary and complementary mold inserts without any repeated measurements or adjustments. To validate the proposed design, primary and complementary mold inserts were fabricated with alignment joints and features to conduct a punching process. Prior to assembling the mold inserts to the thermal press for punching, they were pre-assembled to inspect the innate misalignment due to the machining of the mold inserts. Along the X-Axis, the X-magnitude (∆Xi) of the mean misalignment ranged from 2 to 7 µm and the Y-magnitude (∆Yi,) of the mean misalignment were from 7 to 13 µm. The X- and Y-magnitude (∆Xj and ∆Yj) of mean misalignment along the Y-Axis ranged from 1 to 4 µm, and 5–12 µm, respectively. The mold inserts were aligned and subsequently mounted to the thermal press. Punching was conducted on a polymer substrate Misalignment was the displacement of the center-point of a die hole impression from the center point of a through-hole. The X- and Y-magnitudes of the mean misalignment (∆Xk and ∆Yk) along the X-Axis ranged from 12 to 82 µm and 32–72 µm, respectively. The X- and Y-magnitudes of the misalignment (∆Xl and ∆Yl) along Y-Axis were 11–71 µm and 32–70 µm, respectively. The results of experiments showed that the proposed passive alignment method is applicable to the punching of through-holes for polymer microfluidic devices.

A nonlocal interface approach to peridynamics exemplified by continuum‐kinematics‐inspired peridynamics

AbstractIn this contribution, we present a novel approach on how to treat material interfaces in nonlocal models based on peridynamics (PD) and in particular continuum‐kinematics‐inspired peridynamics (CPD), a novel variationally consistent peridynamic formulation. Our method relies on a nonlocal interface where the material subdomains overlap. Within this region, a kinematic coupling of the two constituents is enforced. The contact is purely geometrical as interaction forces act only between points of the same material. We provide a detailed description of the computational implementation within the framework of CPD, that is in principle applicable to all formulations of PD. A variety of numerical examples for modeling bimaterial interfaces illustrate the utility of the technique for both two‐dimensional and three‐dimensional problems, including examples at large deformations. Our model approaches a local model when the nonlocality parameter, the horizon size, is decreased. The proposed methodology offers a viable alternative to previous approaches in PD, which are essentially imposing mixture rules for the interfacial material parameters.

Non-Linear Device Head Coupling and Temporal Delays in Large Animal Acceleration Models of Traumatic Brain Injury

Accurate characterization of head kinematics following an external blow represents a fundamental aspect of traumatic brain injury (TBI) research. The majority of previous large animal studies have assumed an equivalent relationship between the device delivering the impulsive load and subsequent head kinematics rather than performing direct measurement (sensors or videography). The current study therefore examined factors affecting device/head coupling kinematics in an acceleration TBI model. Experiment 1 indicated ~ 50% reduction in peak angular velocity for swine head relative to the device, with an approximate doubling in temporal duration. The peak angular velocity for the head was not significantly altered by variations in restraint device (straps vs. cables), animal positioning or body mass. In Experiment 2, reducing the impulsive load by 32% resulted in only a 14% reduction in angular velocity of the head (approximately 69% head/device coupling ratio), with more pronounced differences qualitatively observed for angular momentum. A temporal delay was identified in initial device/head coupling, potentially a result of soft tissue deformation. Finally, similar head kinematics were obtained regardless of mounting the sensor directly to the skull or through the scalp (Experiment 3). Current findings highlight the importance of direct measurement of head kinematics for future studies.

Kinematic coupling of the glenohumeral and scapulothoracic joints generates humeral axial rotation

Glenohumeral and scapulothoracic motion combine to generate humerothoracic motion, but their discrete contributions towards humerothoracic axial rotation have not been investigated. Understanding their contributions to axial rotation is important to judge the effects of pathology, surgical intervention, and physiotherapy. Therefore, the purpose of this study was to investigate the kinematic coupling between glenohumeral and scapulothoracic motion and determine their relative contributions towards axial rotation. Twenty healthy subjects (10 M/10F, ages 22–66) were previously recorded using biplane fluoroscopy while performing arm elevation in the coronal, scapular, and sagittal planes, and external rotation in 0° and 90° of abduction. Glenohumeral and scapulothoracic contributions towards axial rotation were computed by integrating the projection of glenohumeral and scapulothoracic angular velocity onto the humeral longitudinal axis, and analyzed using one dimensional statistical parametric mapping and linear regression. During arm elevation, scapulothoracic motion supplied 13–20° (76–94%) of axial rotation, mainly via scapulothoracic upward rotation. The contribution of scapulothoracic motion towards axial rotation was strongly correlated with glenohumeral plane of elevation during arm elevation. During external rotation, scapulothoracic motion contributed 10° (8%) towards axial rotation in 0° of abduction and 15° (15%) in 90° of abduction. The contribution of scapulothoracic motion towards humerothoracic axial rotation could explain the simultaneous changes in glenohumeral plane of elevation and axial rotation associated with some pathologies and surgeries. Understanding how humerothoracic motion results from the functional coupling of scapulothoracic and glenohumeral motions may inform diagnostic and treatment strategies by targeting the source of movement impairments in clinical populations.

Young females with hallux valgus show lower foot joint movement stability compared to controls: An investigation of coordination patterns and variability

BackgroundA kinematic coupling relationship exists between foot joints during gait. In individuals with hallux valgus, forefoot or hallux kinematics may be affected by adjacent or nonadjacent joint motion. Thus, this study aimed to investigate the foot joint coordination pattern and variability during gait in young females with hallux valgus. MethodsTwenty-five young females with hallux valgus and 25 healthy young females without hallux valgus were enrolled. Reflective markers were attached according to a multisegment foot model. Kinematic data were obtained using a three-dimensional motion analysis system. Joint angles between distal and proximal segments were calculated using analysis software. Foot joint coordination pattern and variability were assessed using a vector-coding technique. FindingsIndividuals with hallux valgus had a larger rearfoot relative to shank eversion and forefoot relative to midfoot dorsiflexion during terminal stance and pre-swing compared with those without hallux valgus. There were no significant differences in coordination patterns, but the consistency of coordination between the rearfoot relative to shank motion in the frontal plane and forefoot relative to midfoot motion in the sagittal plane during terminal stance was greater in the hallux valgus group than in the control group. InterpretationThe soft tissue composing the first ray might suffer from more severe stress due to the large motion that occurred with low variability in individuals with hallux valgus. This finding may suggest that the altered kinematics and coordination variability in foot joints are related to hallux valgus biomechanical etiology.

A miniature kinematic coupling device for mouse head fixation

• Development of a kinematic clamp for mice for precise repositioning in chronic studies. • Headplate and clamp provide stability for cellular resolution imaging during behavior. • Ruby contact features enable submicron registration repeatability.

Warping-Inclusive Kinematic Coupling in Mixed-Dimension Macro Models for Steel Wide Flange Beam Columns

A warping-inclusive kinematic coupling method to be used in finite-element analysis of members featuring wide-flange cross sections is proposed in this paper. This coupling method is used in mixed-dimension macromodels that combine continuum and beam-column elements to reduce the computational cost of purely continuum finite-element models. The proposed coupling method, utilizing either linear or nonlinear constraint equations, is implemented and validated in a commercial finite-element software; the source code is made publicly available. Case studies indicate that including warping in the coupling formulation is critical for components that may experience coupled local and lateral-torsional buckling. Also highlighted is the potential of macromodels to reduce the total degrees of freedom by up-to about 60%, and computational memory use by up to around 80%, while retaining solution fidelity for beam, column, and panel zone components in steel moment-resting frames. The case studies show that the linear constraint equation formulation may not be suitable for all problems; however, it may still yield acceptable results as long as the level of twisting is insignificant and lateral-torsional buckling is not critical.