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Background: Impairments in gait and balance function are typical after concussion. There is evidence that these neuromuscular deficits persist past the typical time of symptom resolution. The ability to quantify these changes in gait and balance may provide useful information when making return to play decisions in clinical settings.Research Question: Are changes in gait function and postural control evident across the course of a concussion management program?Methods: A retrospective analysis of a convenience sample of 38 patients who were seen for concussion between October 2017 and May 2019 was performed. Gait and balance measures were assessed at their initial clinic visit post-injury and at their clearance visit using inertial measurement units. During dual-task walking trials, the medial-lateral motion of the center of mass and gait velocity were measured. Postural sway complexity and jerk index were measured during both eyes-open and eyes-closed balance trials.Results: Paired samples t-tests and Wilcoxon signed rank tests were used to determine whether statistically significant changes occurred for the gait and balance variables, respectively. Medial-lateral sway decreased (4.4 ± 1.3 cm to 4.0 ± 1.2 cm, p = 0.018) and gait velocity increased (0.78 ± 0.23 m/s to 0.91 ± 0.18 m/s, p <  0.001) from initial to clearance testing. Jerk index decreased (6.41 ± 11.06 m2/s5 to 5.73 ± 4.28 m2/s5, p = 0.031) and (11.87 ± 26.42 m2/s5 to 7.87 ± 8.38 m2/s5, p = 0.003) from initial to clearance testing for the eyes-open and eyes-closed conditions, respectively. Complexity index increased (2.38 ± 1.08-2.86 ± 0.72, p = 0.010) from initial to clearance testing for the eyes-closed condition. There was no change in complexity index for the eyes-open condition.Significance: These preliminary results support the potential use of measures of gait and postural control to assess recovery following a concussion in a clinical setting. [ABSTRACT FROM AUTHOR]

This paper presents methods for modelling and designing an ideal path trajectory between straight and bend track path segments for racing greyhounds. To do this, we numerically generate clothoid and algebraic curve segments for racing quadrupeds using a sequential vector transformation method as well as using a helper equation for approaching ideal clothoid segments that would respect greyhound kinematic parameters and boundary conditions of the track. Further, we look into the limitations of using a clothoid curve for racing dog track path design and propose a smooth composite curve for track transition design which roughly maintains G3 curvature continuity for smooth jerk to overcome limitations of a clothoid transition. Finally, we show results from race data modelling and past injury data, which provide a strong indication of clothoid curve segments improving the dynamics and safety of racing greyhounds while reducing injuries. [ABSTRACT FROM AUTHOR]

Abstract In this paper we propose an enhanced continuum model for traffic flow considering the effect of driver characteristics and traffic jerk. Based on the linear stability condition, the sufficient conditions of model stability is given. In the nonlinear stability analysis, we derive the KdV–Burger equation to describe the propagation characteristics of traffic density waves near the neutral stability curve. The simulation example verified that the driver characteristics and traffic jerk have a significant impact on the stability of the traffic flow and emissions. Highlights • An extension of continuum model considering explicitly both traffic jerk and driver characteristics is proposed. • The new continuum model's stability condition and KdV–Burgers equation are deduced. • The numerical simulation on energy consumption is carried out. • Distinctive types of drivers contribute differently to suppressing traffic jam. [ABSTRACT FROM AUTHOR]

Subjects in laboratory settings exhibit straight hand paths—typified by the minimum jerk path—even in the presence of a learned but disturbing force field. At the same time it is known that in this setting, visual feedback strongly influences reaches, biasing them to be straight. Here we examine whether or not this bias can account for the straightness of movements made in a force field. We ran three curl field experiments to investigate how the lack of visual feedback influences adapted reaches. In a first experiment, hand position was displayed at the beginning and at the end of each trial, but extinguished during movement, and the hand was passively brought back to the home location. In the second experiment, visual feedback of neither the hand nor the target was provided, and targets were haptically rendered as “dimples.” In order to provide extended practice, a third experiment was run with a single target and an active reach back to the home location. In all three cases we found minor changes in the adapted reaches relative to control groups that had full visual feedback. Our subjects adopted trajectories that were better explained by minimum jerk paths over those that minimize effort. The results indicate that for point-to-point reaching movements the visual feedback, or lack there of, cannot explain why reaches appear to be straight, even after adapting to a perturbing force field. [ABSTRACT FROM AUTHOR]

In this paper, we provide the noncommutative Sprott models. We demonstrate, that effectively, each of them is described by a system of three complex, ordinary and nonlinear differential equations. Apart from that, we find for such modified models the corresponding (noncommutative) jerk dynamics as well as we study numerically as an example, the deformed Sprott-A system. [ABSTRACT FROM AUTHOR]

Based on the two velocity difference model (TVDM), an extended car-following model is developed to investigate the effect of driver's memory and jerk on traffic flow in this paper. By using linear stability analysis, the stability conditions are derived. And through nonlinear analysis, the time-dependent Ginzburg-Landau (TDGL) equation and the modified Korteweg-de Vries (mKdV) equation are obtained, respectively. The mKdV equation is constructed to describe the traffic behavior near the critical point. The evolution of traffic congestion and the corresponding energy consumption are discussed. Numerical simulations show that the improved model is found not only to enhance the stability of traffic flow, but also to depress the energy consumption, which are consistent with the theoretical analysis. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency and smoothness of a robot and reduce its vibration, an algorithm called the augmented Lagrange constrained particle swarm optimization (ALCPSO), which combines constrained particle swarm optimization with the augmented Lagrange multiplier method to realize time-jerk (defined as the derivative of the acceleration) optimal trajectory planning is proposed. Kinematic constraints such as joint velocities, accelerations, jerks, and traveling time are considered. The ALCPSO algorithm is used to avoid local optimization because a new particle swarm is newly produced at each initial time process. Additionally, the best value obtained from the former generation is saved and delivered to the next generation during the iterative search for process. Thus, the final best value can be found more easily and more quickly. Finally, the proposed algorithm is tested on the 7-DOF robot that is presented in this paper. The simulation results indicate that the algorithm is effective and feasible. Hence, the algorithm presents a solution for the time-jerk optimal trajectory planning problem of a robot subject to nonlinear constraints. [ABSTRACT FROM AUTHOR]

A multistable system generated by Piecewise Linear (PWL) subsystems based on the jerk equation is presented. The system's behavior is characterized by means of the Nearest Integer or the function to control the switching events and to locate the corresponding equilibria on each of the commutation surfaces. These surfaces are generated through the switching function dividing the space into regions equally distributed along one axis. The trajectory of the system is governed by the eigenspectrum of the coefficient matrix, which can be adjusted by a bifurcation parameter. The behavior of the system can change from multiscroll oscillations in a mono-stable state into the coexistence of several single-scroll attractors in multistable states. The dynamics and bifurcation analysis are illustrated by numerical simulations to depict the multistable states. [ABSTRACT FROM AUTHOR]

In this paper, we have considered flat Friedmann-Lemaître-Robertson-Walker metric in the framework of perfect fluid models and modified f( G) gravity (where G is the Gauss Bonnet invariant). Particularly, we have considered particular realistic f( G) configurations that could be used to cure finite-time future singularities arising in the late-time cosmic accelerating epochs. We have then developed the viability bounds of these models induced by weak and null energy conditions, by using the recent estimated numerical figures of the deceleration, Hubble, snap and jerk parameters. [ABSTRACT FROM AUTHOR]

This paper investigated the characteristics of vehicle longitudinal jerk (change rate of acceleration with respect to time) by using vehicle sensor data from an existing naturalistic driving study. The main objective was to examine whether vehicle jerk contains useful information that could be potentially used to identify aggressive drivers. Initial investigation showed that there are unique characteristics of vehicle jerk in drivers’ gas and brake pedal operations. Thus two jerk-based metrics were examined: (1) driver’s frequency of using large positive jerk when pressing the gas pedal, and (2) driver’s frequency of using large negative jerk when pressing the brake pedal. To validate the performance of the two metrics, drivers were firstly divided into an aggressive group and a normal group using three classification methods (1) traveling at excessive speed (speeding), (2) following too closely to a front vehicle (tailgating), and (3) their association with crashes or near-crashes in the dataset. The results show that those aggressive drivers defined using any of the three methods above were associated with significantly higher values of the two jerk-based metrics. Between the two metrics the frequency of using large negative jerk seems to have better performance in identifying aggressive drivers. A sensitivity analysis shows the findings were largely consistent with varying parameters in the analysis. The potential applications of this work include developing quantitative surrogate safety measures to identify aggressive drivers and aggressive driving, which could be potentially used to, for example, provide real-time or post-ride performance feedback to the drivers, or warn the surrounding drivers or vehicles using the connected vehicle technologies. [ABSTRACT FROM AUTHOR]

Smoothness is a hallmark of healthy movement. Past research indicates that smoothness may be a side product of a control strategy that minimizes error. However, this is not the only reason for smooth movements. Our musculoskeletal system itself contributes to movement smoothness: the mechanical impedance (inertia, damping, and stiffness) of our limbs and joints resists sudden change, resulting in a natural smoothing effect. How the biomechanics and neural control interact to result in an observed level of smoothness is not clear. The purpose of this study is to 1) characterize the smoothness of wrist rotations, 2) compare it with the smoothness of planar shoulder-elbow (reaching) movements, and 3) determine the cause of observed differences in smoothness. Ten healthy subjects performed wrist and reaching movements involving different targets, directions, and speeds. We found wrist movements to be significantly less smooth than reaching movements and to vary in smoothness with movement direction. To identify the causes underlying these observations, we tested a number of hypotheses involving differences in bandwidth, signal-dependent noise, speed, impedance anisotropy, and movement duration. Our simulations revealed that proximal-distal differences in smoothness reflect proximal-distal differences in biomechanics: the greater impedance of the shoulderelbow filters neural noise more than the wrist. In contrast, differences in signal-dependent noise and speed were not sufficiently large to recreate the observed differences in smoothness. We also found that the variation in wrist movement smoothness with direction appear to be caused by, or at least correlated with, differences in movement duration, not impedance anisotropy. [ABSTRACT FROM AUTHOR]

In this paper, a new modified finite element method that can be used in the analysis of transverse and lateral vibrations of the thin beams under a point mass moving with a variable acceleration and constant jerk is presented. Jerk is the change in acceleration over time. In this method, the classical finite element of the beam is modified by the inclusion of the inertial effects of the moving mass. This modification is made using the relations between nodal forces and nodal deflections and shape functions of six DOF beam element. The mass, stiffness, and damping matrices of the modified finite element are determined by forces caused by the corresponding transverse and lateral accelerations and jerks, and transverse Coriolis and centripetal accelerations and jerks, respectively. This method was first applied on a simply supported beam plate to provide a comparison with the previous studies in literature, and it was proved that the results were within acceptable limits. Secondly, it was applied on a CNC type box-framed beam to analyse the dynamic response of the beam in terms of variable acceleration and jerk as well as constant velocity and mass ratios. [ABSTRACT FROM AUTHOR]

The main innovation of this paper is determining the dynamic load carrying capacity (DLCC) of a flexible joint manipulator (FJM) using a closed form nonlinear optimal control approach. The proposed method is compared with two closed loop nonlinear methods that are usually applied to robotic systems. As a new idea, DLCC of the manipulator is considered as a criterion to compare how well controllers perform point to point mission for the FJMs. The proposed method is compared with feedback linearization (FL) and robust sliding mode control (SMC) methods to show better performance of proposed nonlinear optimal control approach. An optimal controller is designed by solving a nonlinear partial differential equation named the Hamilton–Jacobi–Bellman (HJB) equation. This equation is complicated to solve exactly for complex dynamics so it is solved numerically using an iterative approximation combined with the Galerkin method. In the FL method, angular position, velocity, acceleration and jerk of links are considered as new states to linearize the dynamic equations. In the case of SMC, the dynamic equations of manipulator are changed to the standard form then the Slotine method is used to design the sliding mode controller. Two simulations are performed for a planar and a spatial Puma manipulator and performances of controllers are compared. Finally an experimental test is done on 6R manipulator and the Stereo vision method is used to determine the position and orientation of the end-effector. [ABSTRACT FROM AUTHOR]

Voluntary and reflexive muscle activation of the human elbow joint is investigated by both subject tests and numerical simulations. A jerk loading is applied to extend the elbow joint with different muscle tensing and pre-recognition conditions. Inter- and Intra-subject variations of the hand displacement are analyzed for an objective assessment of the active response at the elbow joint to the external perturbation. A finite element elbow model is developed using passive kinematic joint elements and active torques which have PID (Proportional-integral-derivative) close loop control. The simulation result from this FE model is compared with test results and shows a good correlation. [ABSTRACT FROM AUTHOR]

In this paper, a new optimization model of time optimal trajectory planning with limitation of operating task for the Tokamak inspecting manipulator is designed. The task of this manipulator is to inspect the components of Tokamak, the inspecting velocity of manipulator must be limited in the operating space in order to get the clear pictures. With the limitation of joint velocity, acceleration and jerk, this optimization model can not only get the minimum working time along a specific path, but also ensure the imaging quality of camera through the constraint of inspecting velocity. The upper bound of the scanning speed is not a constant but changes according to the observation distance of camera in real time. The relation between scanning velocity and observation distance is estimated by curve-fitting. Experiment has been carried out to verify the feasibility of optimization model, moreover, the Laplace image sharpness evaluation method is adopted to evaluate the quality of images obtained by the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a novel kinematic corner smoothing technique for high-speed CNC machine tools. Typically, reference tool-paths compromised of short G01 moves are geometrically smoothed by means of arcs and splines within the NC system. In this study, a continuous feed motion is generated by directly planning jerk limited velocity transitions for the drives in the vicinity of sharp corners of the tool-path. This approach completely eliminates the need for geometry based path smoothing and feed planning. Contouring errors at sharp corners are controlled analytically by accurately calculating cornering speed and duration. Since proposed approach bases on kinematically planning axis motion profiles, it exploits acceleration and jerk limits of the drives and delivers a near-time optimal motion. Experimental validation and comparisons are presented to show significant improvement in the cycle time and accuracy of contouring Cartesian tool-paths. [ABSTRACT FROM AUTHOR]

The problem of inverse kinematics is revisited in the present paper. The paper is focusing on the problem of solving the inverse kinematics problem while minimizing the jerk of the joint trajectories. Even though the conventional inverse kinematics algorithms have been proven to be efficient in many applications, it has been proven that constraints on the accelerations or the jerk cannot be guaranteed, and even yields to divergence or makes the problem unsolvable. The proposed algorithm yields smooth velocity and acceleration trajectories, which are highly desired features for industrial robots. The algorithm uses the joint jerk as the control parameter instead of the classical use of the joint velocity as result constraints on the jerk function can be easily incorporated. To validate the proposed approach, we have conducted several simulations scenarios. The simulation results have revealed that the proposed method can efficiently solve the inverse kinematics problem while considering constraints on the joint acceleration and jerk. [ABSTRACT FROM PUBLISHER]

Using an ecological dynamics framework, this study investigated the generality and specificity of skill transfer processes in organisation of perception and action using climbing as a task vehicle. Fluency of hip trajectory and orientation was assessed using normalized jerk coefficients exhibited by participants as they adapted perception and action under varying environmental constraints. Twelve recreational climbers were divided into two groups: one completing a 10-m high route on an indoor climbing wall; a second undertaking a 10-m high route on an icefall in a top-rope condition. We maintained the same level of difficulty between these two performance environments. An inertial measurement unit was attached each climber's hips to collect 3D acceleration and 3D orientation data to compute jerk coefficient values. Video footage was used to record the ratio of exploratory/performatory movements. Results showed higher jerk coefficient values and number of exploratory movements for performance on the icefall route, perhaps due to greater functional complexity in perception and action required when climbing icefalls, which involves use of specific tools for anchorage. Findings demonstrated how individuals solve different motor problems, exploiting positive general transfer processes enabling participants to explore the pick-up of information for the perception of affordances specific to icefall climbing. [ABSTRACT FROM AUTHOR]

In this paper, a novel autonomous RC chaotic jerk circuit is introduced and the corresponding dynamics is systematically investigated. The circuit consists of opamps, resistors, capacitors and a pair of semiconductor diodes connected in anti-parallel to synthesize the nonlinear component necessary for chaotic oscillations. The model is described by a continuous time three-dimensional autonomous system with hyperbolic sine nonlinearity, and may be viewed as a linear transformation of model MO15 previously introduced in [Sprott, 2010]. The structure of the equilibrium points and the discrete symmetries of the model equations are discussed. The bifurcation analysis indicates that chaos arises via the usual paths of period-doubling and symmetry restoring crisis. One of the key contributions of this work is the finding of a region in the parameter space in which the proposed ('elegant') jerk circuit exhibits the unusual and striking feature of multiple attractors (i.e. coexistence of four disconnected periodic and chaotic attractors). Laboratory experimental results are in good agreement with the theoretical predictions. [ABSTRACT FROM AUTHOR]

Removing the amplitude or polarity information in the feedback loop of a jerk structure shows that special nonlinearities with partial information in the variable can also lead to chaos. Some striking properties are found for this kind of hypogenetic chaotic jerk flow, including multistability of symmetric coexisting attractors from an asymmetric structure, hidden attractors with respect to equilibria but with global attraction, easy amplitude control, and phase reversal which is convenient for chaos applications. [ABSTRACT FROM AUTHOR]

We consider the correlation between seismicity, variations in the length of day, and geomagnetic jerks. We found that the jerks precede with in-phase variations in the number of strong earthquakes with М > 6.5 and the rate of the length of day in the range of periods of 5-8 years. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study some jerk motions considering some dynamic cases, other than the classical ones and extending the setting. We consider a special set of variations, finding a set of jerk motions, generalizing some cases known only in some particular forms till now. Finally we give a simple mechanical interpretation of these ideas. The subject is topical because we model a less studied type of movements that can lead to interesting new developments. [ABSTRACT FROM AUTHOR]

Repetitive loading of the upper limb due to wheelchair propulsion plays a leading role in the development of shoulder pain in manual wheelchair users (mWCUs). There has been minimal inquiry on understanding wheelchair propulsion kinematics from a human movement ergonomics perspective. This investigation employs an ergonomic metric, jerk, to characterize the recovery phase kinematics of two recommended manual wheelchair propulsion patterns: semi-circular and the double loop. Further it examines if jerk is related to shoulder pain in mWCUs. Data from 22 experienced adult mWCUs was analyzed for this study (semi-circular: n =12 (pain/without-pain:6/6); double-loop: n =10 (pain/without-pain:4/6)). Participants propelled their own wheelchair fitted with SMARTWheels on a roller dynamometer at 1.1 m/s for 3 min. Kinematic and kinetic data of the upper limbs were recorded. Three dimensional absolute jerk experienced at the shoulder, elbow and wrist joint during the recovery phase of wheelchair propulsion were computed. Two-way ANOVAs were conducted with the recovery pattern type and shoulder pain as between group factors. Findings: (1) Individuals using a semi-circular pattern experienced lower jerk at their arm joints than those using a double loop pattern ( P <0.05, η 2 =0.32) wrist ;( P =0.05, η 2 =0.19) elbow ;( P <0.05, η 2 =0.34) shoulder and (2) individuals with shoulder pain had lower peak jerk magnitude during the recovery phase ( P ≤0.05, η 2 =0.36) wrist ;( P ≤0.05, η 2 =0.30) elbow ;( P ≤0.05, η 2 =0.31) shoulder . Conclusions: Jerk during wheelchair propulsion was able to distinguish between pattern types (semi-circular and double loop) and the presence of shoulder pain. Jerk provides novel insights into wheelchair propulsion kinematics and in the future it may be beneficial to incorporate jerk based metric into rehabilitation practice. [ABSTRACT FROM AUTHOR]

SUMMARY This study proposes a variable dynamic threshold for a jerk signal for achieving contact detection in industrial robots. Sensorless force control is useful in applications in advanced industrial robots. The external torque of each joint is estimated accurately by using a disturbance observer and by inverse dynamics calculations. However, the phase lag of the disturbance observer and the dynamic parameter error create force estimation errors. These errors hamper quick and reliable contact detection in industrial robots. Therefore, this study proposes a useful approach to contact detection that uses a variable dynamic threshold for a jerk signal. The proposed variable dynamic threshold reduces contact detection failures caused by force estimation errors during the free motion of a robot. The proposed threshold is suitable for robot motion and improves the speed of contact detection. Numerical simulation results show that the proposed method is valid for the parameter variations in an actual industrial robot. In addition, experimental results show that the dynamic threshold is a useful technique for application to general robot systems as well. The dynamic threshold is useful in applications for any industrial sensorless force control system. [ABSTRACT FROM AUTHOR]

In this research work, a seven-term 3-D novel jerk chaotic system with two quadratic nonlinearities has been proposed. The basic qualitative properties of the novel jerk chaotic system have been described in detail. Next, an adaptive backstepping controller is designed to stabilize the novel jerk chaotic system with two unknown parameters. Moreover, an adaptive backstepping controller is designed to achieve complete chaos synchronization of the identical novel jerk chaotic systems with two unknown parameters. MATLAB simulations have been shown in detail to illustrate all the main results developed for the 3-D novel jerk chaotic system. [ABSTRACT FROM AUTHOR]

Based on optimal velocity car following model, a new model considering traffic jerk is proposed to describe the jamming transition in traffic flow on a highway. Traffic jerk means the sudden braking and acceleration of vehicles, which has a significant impact on traffic movement. The nature of the model is researched by using linear and nonlinear analysis method. A thermodynamic theory is formulated to describe the phase transition and critical phenomenon in traffic flow. The time-dependent Ginzburg–Landau (TDGL) equation and the modified Korteweg–de Vries (mKdV) equation are derived to describe the traffic flow near the critical point and the traffic jam. In addition, the connection between the TDGL and the mKdV equations are also given. [ABSTRACT FROM AUTHOR]

A theoretical framework is established for the control of higher-order nonholonomic systems, defined as systems that satisfy higher-order nonintegrable constraints. A model for such systems is developed in terms of differential–algebraic equations defined on a higher-order tangent bundle. A number of control-theoretic properties such as nonintegrability, controllability, and stabilizability are presented. Higher-order nonholonomic systems are shown to be strongly accessible and, under certain conditions, small time locally controllable at any equilibrium. The applicability of the theoretical development is illustrated through a third-order nonholonomic system example: a planar PPR robot manipulator subject to a jerk constraint. In particular, it is shown that although the system is not asymptotically stabilizable to a given equilibrium configuration using a time-invariant continuous feedback, it is strongly accessible and small-time locally controllable at any equilibrium. [ABSTRACT FROM AUTHOR]

Previously, a new control concept called ‘G-vectoring control (GVC)’ to improve vehicle agility and stability was developed. GVC is an automatic longitudinal acceleration control method that responds to vehicle lateral jerk caused by the driver's steering manoeuvres. In this paper, a new yaw-moment control method, which generates a stabilising moment during the GVC command and has positive acceleration value and the driver's accelerator pedal input is zero, was proposed. A new hybrid control, which comprises GVC, electric stability control and this new control, was constructed, and it was installed in a test vehicle and tested on a snowy surface. The very high potential for improvement in both agility and stability was confirmed. [ABSTRACT FROM PUBLISHER]

Abstract: This paper derives a jerk-shaped profile to address the vibration reduction of underdamped flexible dynamics of motion system. The jerk-limited profile is a widespread smooth command pattern used by modern motion systems. The ability of the jerk-limited profile to cancel the residual vibration of an undamped flexible mode is clearly explained using an equivalent continuous filter representation and the input shaping formalism. This motivates the design of a new jerk-shaped profile, named Damped-Jerk profile, to extend the previous result to the more common case of underdamped systems. Both simulations and experimental results demonstrate the effectiveness of the proposed Damped-Jerk profile to reduce damped vibration. [Copyright &y& Elsevier]

Abstract: For positioning servo-systems, this paper presents a jerk-constrained time- optimal control (JCTOC) scheme, augmented with an improved disturbance rejection method. In mechanical systems, the jerk that is the time derivative of acceleration may cause many unwanted results when too high. Thus, the JCTOC method is proposed to constrain the system׳s jerk and also obtain a time-optimal characteristic with the constrained jerk. However, because the JCTOC relies on the accuracy of the plant׳s model, system uncertainties and disturbances can adversely affect the output response. Thus, a disturbance observer (DOB) is added for compensation of the perturbation. The DOB used in this paper is in an integral form, and is thus referred to as an integral DOB (IDOB). The IDOB is further enhanced with a dynamic compensator to provide both better noise immunity and asymptotic compensation for disturbances of various orders. [Copyright &y& Elsevier]

In this paper, the dynamics of Chua's circuit in jerk form is presented. It is proved that two forms of Chua's circuit in jerk dynamics can be derived. The electronic circuit of the simpler dynamics has been implemented. The link between Chua's circuit and the search for simple jerk circuits has been established, therefore, proposing complex dynamics (like that of Chua's circuit) in jerk form. [ABSTRACT FROM AUTHOR]

Engineering applications are often handled by means of algorithms for constrained optimization. Currently, more frequently than in the past, the need for fast solvers that admit convergence times compatible with those of online applications is strongly felt. Such a need poses new additional implementation requirements, since the convergence of the mathematical programming algorithms is no longer sufficient to allow their use, but, conversely, such convergence must be achieved in very limited times. This article proposes an efficient approach for a constrained minimum-jerk online planning problem. In particular, the robotic application considered requires accounting for time, distance, velocity and acceleration constraints. The proposed approach returns good quality solutions by admitting execution times that meet the online requirements. Comparisons with a previously adopted strategy are proposed. [ABSTRACT FROM PUBLISHER]

Cerebral palsy (CP) of the spastic type is a neurological disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerks. Secondary to the spasticity, muscle adaptation is presumed to contribute to limitations in the passive range of joint motion. However, the mechanisms underlying these limitations are unknown. Using biopsies, we compared mechanical as well as histological properties of flexor carpi ulnaris muscle (FCU) from CP patients (n = 29) and healthy controls (n = 10). The sarcomere slack length (mean 2.5 µm, SEM 0.05) and slope of the normalized sarcomere length-tension characteristics of spastic fascicle segments and single myofibre segments were not different from those of control muscle. Fibre type distribution also showed no significant differences. Fibre size was significantly smaller (1933 µm2, SEM 190) in spastic muscle than in controls (2572 µm2, SEM 322). However, our statistical analyses indicate that the latter difference is likely to be explained by age, rather than by the affliction. Quantities of endomysial and perimysial networks within biopsies of control and spastic muscle were unchanged with one exception: a significant thickening of the tertiary perimysium (3-fold), i.e. the connective tissue reinforcement of neurovascular tissues penetrating the muscle. Note that this thickening in tertiary perimysium was shown in the majority of CP patients, however a small number of patients (n = 4 out of 23) did not have this feature. These results are taken as indications that enhanced myofascial loads on FCU is one among several factors contributing in a major way to the aetiology of limitation of movement at the wrist in CP and the characteristic wrist position of such patients. [ABSTRACT FROM AUTHOR]

The ability to maintain the body relative to the external environment is important for adaptation to altered gravity. However, the physiological limits for adaptation or the disruption of body orientation are not known. In this study, we analyzed postural changes in mice upon exposure to various low gravities. Male C57BL6/J mice (n = 6) were exposed to various gravity-deceleration conditions by customized parabolic flight-maneuvers targeting the partial-gravity levels of 0.60, 0.30, 0.15 and µg (<0.001 g). Video recordings of postural responses were analyzed frame-by-frame by high-definition cineradiography and with exact instantaneous values of gravity and jerk. As a result, the coordinated extension of the neck, spine and hindlimbs was observed during the initial phase of gravity deceleration. Joint angles widened to 120%-200% of the reference g level, and the magnitude of the thoracic-curvature stretching was correlated with gravity and jerk, i.e., the gravity deceleration rate. A certain range of jerk facilitated mouse skeletal stretching efficiently, and a jerk of -0.3~-0.4 j (g/s) induced the maximum extension of the thoracic-curvature. The postural response of animals to low gravity may undergo differential regulation by gravity and jerk. [ABSTRACT FROM AUTHOR]

In the literature, the length of a clothoid spiral usually is determined by three equations. These equations do not lead to the same length. As a result, all equations are applied and the maximum length is chosen. Of these three equations, two are based on actual and unbalanced superelevation with speed. These two equations are theoretically inaccurate. Thus, after selecting a spiral length, designers need to check the length against comfort criteria, even though these two equations are based on the same comfort criteria. Then, the length is adjusted. In fact, all parameters, such as jerk (g/s), actual superelevation runoff (mm/s), unbalanced superelevation runoff (mm/s), rotational runoff (deg/s), cant gradient, and twist (mm/min), are interrelated. Jerk criteria can fix the spiral length. In this paper, the writer presents spiral length equations that lead to equal spiral length by exploiting the interrelation between actual and unbalanced superelevation runoffs. With this process, the roll, superelevation gradient, and twist are internalized and designers need not recheck the comfort criteria. A single equation would replace the need for many, saving design time. This paper is a revised, improved version of an earlier, peer-reviewed conference paper by the writer. [ABSTRACT FROM AUTHOR]

In this study, cams were designed and manufactured for a homogenous charge compression ignition (HCCI) gasoline engine. Low lift cams were designed accordance with HCCI combustion characteristics for 38 mm base circular diameter, 124° dwell angle, 3.5, 5.5 and 7.5 mm valve lifts. Generic geometric models of cam profiles were obtained using circular arc curves. Obtained models were fitted with fourier series and circular arc curve was derived from the corresponding equations. Speed, acceleration and jerk effects of the follower were investigated for designed cam profiles. Obtained results were compared with cams obtained by 5th degree classical spline method. It has been shown that feature a single point of contact of cam into the follower has been lost and acceleration and jerk values of the follower increased so much as long as valve lift increase in the cam profiles obtained by classical spline functions. It has been shown that feature a single point of contact of cam into the follower has not been lost by fitting fourier series of obtained geometric model of cam profile even high valve lifts. Friction and inertia forces decreased due to the low speed and acceleration operation. [ABSTRACT FROM AUTHOR]

Dynamic models of a single-shaft parallel hybrid electric vehicle (HEV) equipped with automated mechanical transmission (AMT) were described in different working stages during a gear shifting process without disengaging clutch. Parameters affecting the gear shifting time, components life, and gear shifting jerk in different transient states during a gear shifting process were deeply analyzed. The mathematical models considering the detailed synchronizer working process which can explain the gear shifting failure, long time gear shifting, and frequent synchronizer failure phenomenon in HEV were derived. Dynamic coordinated control strategy of the engine, motor, and actuators in different transient states considering the detailed working stages of synchronizer in a gear shifting process of a HEV is for the first time innovatively proposed according to the state of art references. Bench test and real road test results show that the proposed control strategy can improve the gear shifting quality in all its evaluation indexes significantly. [ABSTRACT FROM AUTHOR]

This paper studies an assigned-time velocity-planning problem for robotic systems that are subject to velocity and acceleration constraints. The planning problem, which is justified by several robotic applications, poses feasibility issues that are investigated in this paper. In particular, this paper shows that feasible solutions exist if and only if proper interpolating conditions are assigned, and proposes an efficient planning strategy, that is suitable for online implementations. Available degrees of freedom are used to smooth the velocity function by minimizing its maximum jerk. [ABSTRACT FROM PUBLISHER]

Abstract: This paper introduces fully digital implementations of four different systems in the 3rd order jerk-equation based chaotic family using the Euler approximation. The digitization approach enables controllable chaotic systems that reliably provide sinusoidal or chaotic output based on a selection input. New systems are introduced, derived using logical and arithmetic operations between two system implementations of different bus widths, with up to 100× higher maximum Lyapunov exponent than the original jerk-equation based chaotic systems. The resulting chaotic output is shown to pass the NIST SP. 800-22 statistical test suite for pseudo-random number generators without post-processing by only eliminating the statistically defective bits. The systems are designed in Verilog HDL and experimentally verified on a Xilinx Virtex 4 FPGA for a maximum throughput of 15.59Gbits/s for the native chaotic output and 8.77Gbits/s for the resulting pseudo-random number generators. [Copyright &y& Elsevier]

A data-driven approach for analyzing faults in wind turbine gearbox is developed and tested. More specifically, faults in a ring gear are predicted in advance. Time-domain statistical metrics, such as jerk, root mean square (RMS), crest factor (CF), and kurtosis, are investigated to identify faulty components of a wind turbine. The components identified are validated with the fast Fourier transformation (FFT) of vibration data. Fifty neural networks (NNs) with different parameter settings are trained to obtain the best performing model. Models based on original vibration data, and transformed jerk data are constructed. The jerk model based on multisensor data outperforms the other models and therefore is used for testing and validation of previously unseen data. Short-term predictions of up to 15 time intervals, each representing 0.1 s, are performed. The prediction accuracy varies from 91.68% to 94.78%. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examined whether the smoothness of movement is related to the speed of movement. [•] Unconstrained head movements were completed at each of three different test speeds. [•] Slow head movements displayed higher normalized jerk cost than faster movements. [•] The smoothness of head movements was strongly related to the movement speed. [ABSTRACT FROM AUTHOR]

In this study, we propose a novel fractional-order Jerk system. Experiments show that, under some suitable parameters, the fractional-order Jerk system displays a chaotic phenomenon. In order to suppress the chaotic behavior of the fractional-order Jerk system, we design two control strategies. Firstly, we design an appropriate time delay feedback controller to suppress the chaos of the fractional-order Jerk system. The delay-independent stability and bifurcation conditions are established. Secondly, we design a suitable mixed controller, which includes a time delay feedback controller and a fractional-order PDσ controller, to eliminate the chaos of the fractional-order Jerk system. The sufficient condition ensuring the stability and the creation of Hopf bifurcation for the fractional-order controlled Jerk system is derived. Finally, computer simulations are executed to verify the feasibility of the designed controllers. The derived results of this study are absolutely new and possess potential application value in controlling chaos in physics. Moreover, the research approach also enriches the chaos control theory of fractional-order dynamical system. [ABSTRACT FROM AUTHOR]

In general, gearshift is related to change of acceleration due to the changing gear ratio. Modern double-clutch transmissions allow for shaping the acceleration transition by controlling the torques transmitted by the clutches. Thus, the question arises about an optimal transition law for the acceleration. The paper demonstrates that jerk and change of jerk may be considered as major sources of discomfort. Thus, a bi-criterion optimization problem is formulated for finding an optimal acceleration transition and an associated shift control. The problem is solved by analytical and polynomial approaches, and a theoretically optimal solution is shown. The latter is applied to a simple simulation model of a double-clutch transmission to demonstrate its applicability. [ABSTRACT FROM AUTHOR]

Single stepping a motor results in jerky movements of the motor, especially at lower speeds. Microstepping is used to achieve increased step resolution and smoother transitions between steps. In most applications, microstepping increases system performance while limiting noise and resonance problems. The paper presents a method for calculation the values of the phase currents for microstepping control of a 5 -- phase hybrid stepping motor. This method uses the standard control of the stepping motor with rated currents and only during the commutation the currents of the switched phases change their values in small steps so as the natural step is divided into several micro -- steps. The authors have developed a mathematical model and computer programs for simulation of the motor operation under investigated microstepping control. The paper contains also the results from simulations and corresponding conclusions. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate that the variation of acceleration, namely the jerk parameter j, could give hints for determining the dark energy equation of state (EoS). In particular, it is possible to show that a viable cosmological model is compatible with a constant jerk, here conventionally rewritten as j = 1+ϵ, with ϵ > 0 representing a departure from the ΛCDM model. This suggests that the cosmological constant could be seen as a limiting case of a more general dark energy model. We use the most recent union 2.1 compilation of supernovae Ia, showing at 1σ confidence level, that j is compatible with the condition j ≥ 1. In doing so, we infer a corresponding cosmological model, viable with a negative acceleration parameter, in the observed range -1 < q0 < 0. [ABSTRACT FROM AUTHOR]

Most mechanical systems have a functioning cycle consisting from 3 steps: accelerating period, constant speed period, and decelerating period. During these periods, the theoretical variation of acceleration and speed, represented by certain profiles, will determine significant jerk values as the system passes from one period to another, jerk that will cause transient vibration and will significantly increase settling time. In order to reduce this inconvenient, certain acceleration profiles can be designed to obtain a smooth motion, meaning to eliminate any corner from the speed profile .Different acceleration profiles will generate, by integration, certain profiles of speed and displacement, which also have an influence on dynamical power absorption. [ABSTRACT FROM AUTHOR]

The dependence of the intensity of geomagnetic field on the intensity of thermal convection in the liquid core of the Earth, which has been empirically derived by a number of the authors from the results of numerical modeling of convective dynamo, is substantiated theoretically. This dependence is used for estimating the characteristic time scale of jerk evolution. [ABSTRACT FROM AUTHOR]

In this work, the shock‐ and energy‐absorption capability of cold‐programmable shape memory polymers is evaluated. To this end, thin safety lines are prepared from different materials (critically cross‐linked syndiotactic polypropylene, shape memory natural rubber, natural rubber, and Dyneema) and tested by falling weight experiments to determine characteristic physical quantities such as maximum impact force, maximum jerk (first derivative of the deceleration), and energy absorption capability. Critically cross‐linked syndiotactic polypropylene is the best suited of all tested materials for cushioning the impact force, vibration, and chatter, which occur when a safety line abruptly tightens after the free fall in a falling weight experiment. Cold‐programmable shape memory polymers are evaluated regarding their suitability as shock‐ and energy absorber. Falling weight experiments with different deadweights from different drop heights demonstrate the excellent impact damping as well as kinetic energy absorption properties of syndiotactic polypropylene networks. [ABSTRACT FROM AUTHOR]

In this paper, two kinds of novel non-ideal voltage-controlled multi-piecewise cubic nonlinearity memristors and their mathematical models are presented. By adding the memristor to the circuit of a three-dimensional jerk system, a novel memristive multiscroll hyperchaotic jerk system is established without introducing any other ordinary nonlinear functions, from which 2N+2-scroll and 2M+1-scroll hyperchaotic attractors are achieved. It is exciting to note that this new memristive system can produce the extreme multistability phenomenon of coexisting infinitely multiple attractors. Furthermore, the dynamical behaviours of the proposed system are analysed by phase portraits, equilibrium points, Lyapunov exponents and bifurcation diagrams. The results indicate that the system exhibits hyperchaotic, chaotic and periodic dynamics. Especially, the phenomenon of transient chaos can also be found in this memristive multiscroll system. Additionally, the MULTISIM circuit simulations and the hardware experimental results are performed to verify numerical simulations. [ABSTRACT FROM AUTHOR]