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This study estimated the contribution of the midfoot joint complex (MJC) kinematics to the pelvis anterior–posterior positions during the stance phase of walking and investigated whether the MJC is functionally coordinated with the lower limb joints to maintain similar pelvic positions across steps. Hip, knee, ankle, and MJC sagittal angles were measured in 11 nondisabled participants during walking. The joints' contributions to pelvic positions were computed through equations derived from a link-segment model. Functional coordination across steps was identified when the MJC contribution to pelvic position varied and the summed contributions of other joints varied in the opposite direction (strong negative covariations [r ≤ −.7] in stance phase instants). We observed that the MJC plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. The MJC was the second joint that contributed most to the pelvis positions (around 18% of all joints' contributions), after the ankle joint. The MJC and ankle were the joints that were most frequently coordinated with the other joints (≅70% of the stance phase duration). The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints. [ABSTRACT FROM AUTHOR]

The strong dynamic coupling effects among kinematic chains are not beneficial to the control of parallel mechanisms. This paper deals with the chain position optimization of a 4UPS−UPU parallel mechanism to reduce dynamic coupling effects among kinematic chains. Using the kinematic model, the Jacobian matrix is derived, and a method is proposed to transform it into a non-dimensional form and being independent of scaling factors. A singularity index is formulated based on the normalized determinant of the modified Jacobian matrix, guiding the optimization of chain positions at the base platform. Subsequently, the dynamic model is derived by using the principle of virtual work and a novel dynamic coupling index is proposed by taking both the inertia and centrifugal terms in the dynamic model into account. The neural network is then employed to enhance the calculation efficiency of the dynamic coupling index. Finally, the chain positions at the moving platform are optimized using Particle Swarm Optimization algorithm. This optimization process significantly reduces the dynamic coupling effects among kinematic chains in the parallel mechanism, thereby conferring advantageous benefits to its overall control. [ABSTRACT FROM AUTHOR]

Isomorphism identification of kinematic chains or topological graphs is a crucial issue in structural synthesis and innovative mechanism design. In this paper, a new method of isomorphism identification is proposed based on loop theory and hopfield neural networks. A program is written in Python to execute the method. First, the combination of maximum loops in a graph is generated by graph depth-first traversal algorithm. Then, the maximum loop is determined by its link degree sequence, and the maximum-loop matrix is also ensured by the selected maximum loop. Based on the iteration processes in hopfield neural networks, the maximum-loop matrix is changed from original low-ranking matrix to high-ranking matrix. Finally, some kinematic chains and topological graphs are introduced to justify the effectiveness of the proposed method. Results show that the proposed method applies to isomorphism identification of kinematic chains and topological graphs. And the proposed method is efficient and accurate. It enriches the application of loop theory and neural network for isomorphism identification. [ABSTRACT FROM AUTHOR]

It is a very important process to determine whether there is a rigid sub-chain in the type synthesis for kinematic chains. In this paper, a new method for identifying and eliminating rigid sub-chains of kinematic chains with multiple joints is proposed. Firstly, the properties of the mesh loop set and independent loop set in loop combination were introduced. Properties determine that testing the degrees of freedom (DOF) of all independent loop sets and the combined loops can verify the existence of a rigid sub-chain. Secondly, representation methods and properties of the joint-joint adjacent matrix and loop matrix were explained and the operation method of the loop matrix was explained. A method of obtaining some loop matrices, which represents an independent loop set, by joint-joint adjacency matrix is proposed. Then, the DOF of all independent loop sets and the combined loops of independent loop sets were obtained by the operation method of loop matrix to identify and eliminate the rigid sub-chain. Finally, a large number of cases have proved the feasibility and effectiveness of this method. [ABSTRACT FROM AUTHOR]

With the help of plane geometric algebra, we see volumetric errors as pure geometric objects. We use this identification to expand errors with respect to Abbe's principle into the whole working space with respect to some additional conditions. We show that geometric algebra helps us to understand errors in kinematics chains. We demonstrate our approach on a model example. [ABSTRACT FROM AUTHOR]

Background: Pes Planus (flatfoot) only becomes a medical issue when symptoms appear. This disease occurs in both young children and adults. When the medial longitudinal arch (MLA) has raised to the point where it cannot be maintained, the flatfoot changes form. This condition causes over pronation of the foot in contrast to normal feet, resulting in heel eversion and moving the weight load inward to compress the MLA.1-2 Purpose: To compare the effectiveness of kinematic chain exercise and TheraBand exercise session among the young adults with flat foot. Materials and Methods: 30 subjects participated and were taken from Saveetha college of physiotherapy based on specific criteria and assigned to two groups. Pre and post assessment was taken using Numerical Pain Rating Scale [NPRS] and Foot Functional Index Scale [FFI]. The interventions were given for 2 Weeks and the study was conducted from November 2022 to April 2023. Results: The study's results revealed that both groups exhibited significant improvements in flat foot, with a p-value < 0.001. However, Group A showed more statistical significance than Group B. Conclusion: In conclusion, the commencement of two- week intervention plan, kinematic chain exercise showed a marked outcome on pain subjects with flat foot [ABSTRACT FROM AUTHOR]

This article overviews known parallel mechanisms with a circular guide. The considered mechanisms are systemized in terms of kinematic chains and the motion pattern. The structural analysis of these mechanisms is performed using the mobility equations of kinematic chains. [ABSTRACT FROM AUTHOR]

While mechanical tracking is commonly seen in robot-assisted surgery, contactless gesture control leads to a more intuitive approach. Magnetic localization systems might be able to provide an untethered access to the necessary hand movement data. A model-based system exploiting a priori knowledge to improve the accuracy and robustness can be beneficial in this context. We present a proof of concept, in which the index finger of a digital twin of a hand is tracked with three simulated sensors. Based on the physiological composition, the finger is modeled as a kinematic chain with rotational degrees of freedom between the segments according to the corresponding finger joints. We applied an extended Kalman filter using this description to enhance position and rotation estimates for the sensors on the finger segments. We achieved mean absolute errors < 1 cm for the positions and < 10 for the local rotations with first simulations of a bending motion.

While mechanical tracking is commonly seen in robot-assisted surgery, contactless gesture control leads to a more intuitive approach. Magnetic localization systems might be able to provide an untethered access to the necessary hand movement data. A model-based system exploiting a priori knowledge to improve the accuracy and robustness can be beneficial in this context. We present a proof of concept, in which the index finger of a digital twin of a hand is tracked with three simulated sensors. Based on the physiological composition, the finger is modeled as a kinematic chain with rotational degrees of freedom between the segments according to the corresponding finger joints. We applied an extended Kalman filter using this description to enhance position and rotation estimates for the sensors on the finger segments. We achieved mean absolute errors < 1 cm for the positions and < 10 for the local rotations with first simulations of a bending motion. [ABSTRACT FROM AUTHOR]

Purpose: The hindfoot is believed to compensate varus and valgus deformities of the knee by eversion and inversion movements. But these mechanisms were merely found in static radiologic measurements. The aim of this study was, therefore, to assess dynamic foot posture during gait using pressure-sensitive wireless insoles in patients with osteoarthritis of the knee and frontal knee deformities. Methods: Patients with osteoarthritis of the knee were prospectively included in this study. Patients were clinically and radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), and talar tilt (TT)) exa mined. Gait line analysis was conducted using pressure-sensitive digital shoe insoles. Results: Eighty-two patients (varus n = 52, valgus n = 30) were included in this prospective clinical study. Radiologically, the mTFA significantly correlated with the HAVA (cor = −0.72, p < 0.001) and with the TT (Pearson's cor = 0.32, p < 0.006). Gait analysis revealed that the gait lines in varus knee osteoarthritis were lateralized, despite the hindfoot valgus. In valgus knee osteoarthritis, gait lines were medialized, although the hindfoot compensated by varization. Conclusions: Functional dynamic gait analysis could demonstrate that the hindfoot is not able to sufficiently compensate for frontal malalignments of the knee joint, contrary to static radiologic findings. This led to a narrowing of the joint space of the ankle medially in varus and laterally in valgus knee osteoarthritis. [ABSTRACT FROM AUTHOR]

Purpose: Varus or valgus deformities in knee osteoarthritis may have a crucial impact on ankle subtalar range of motion (ROM) and ligamentous stability. The purpose of this study was to assess whether the grade of ankle eversion and inversion rotation stability was influenced by frontal deformities of the knee joint. Methods: Patients who were planned to undergo total knee arthroplasty (TKA) were prospectively included in this study. Patients were examined radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), anterior distal tibia angle (ADTA)) and clinically (ROM of the knee and ankle joint, foot function index, knee osteoarthritis outcome score). Ankle stability was assessed using an ankle arthrometer (AA) to test inversion/eversion (ie) rotation and anterior/posterior (ap) displacement stability of the ankle joint. Correlations were calculated using Pearson's coefficient, and differences between two independent groups of nonparametric data were calculated using a two-sided Wilcoxon signed rank test. Results: Eighty-two (varus n = 52, valgus n = 30) patients were included. The preoperative mTFA significantly correlated with the HAVA (Pearson's correlation = − 0.72, p < 0.001). Laxity testing of the ankle demonstrated that in both varus and valgus knee osteoarthritis, higher grades of mTFA did not correlate with the inversion or eversion capacity of the ankle joint. The ADTA significantly correlated with the posterior displacement of the ankle joint (cor = 0.24, p = 0.049). Conclusions: This study could not confirm that higher degrees of frontal knee deformities in osteoarthritis were associated with increasing grades of ligamentous ankle instabilities or a reduced ROM of the subtalar joint. Level of evidence: II. [ABSTRACT FROM AUTHOR]

New challenges in engineering design are about resilience, frugality and sustainability. Nature offers remarkable examples of successful mechanical designs that respond to those constraints. Therefore, biological systems deserve to be explored from a design perspective. The study of design features of biological locomotor systems would allow engineers to get inspiration for solving technological problems. The ant Messor barbarus is specialized in load bearing; hence the interest of studying their skeletal structure from an engineering perspective. In this work, we propose a topological architecture of the ant exoskeleton for kinematic analysis. The proposed architecture is obtained by a geometrical analysis of the articular surfaces of the exoskeleton joints. In this analysis, the mobility as well as the geometrical parameters of the joints are estimated from a 3D geometrical model of the ant exoskeleton. This model was obtained from X-ray micro-computed tomography. The proposed topological architecture was implemented in a multibody model and evaluated by means of inverse kinematic simulations. The results of these simulations, in terms of the root mean square errors (RMSE) regarding the input kinematic data, suggest that the proposed topological architecture is able to reproduce well the kinematic during walking of this ant. This study is one step toward a better understanding of the locomotor performance features of ants. [ABSTRACT FROM AUTHOR]

In this paper, an original mathematical model and experimental results for the vibration generator and the magnetic spring prototype that converts mechanical energy to electrical energy are proposed. The magnetic spring model is developed by a robotic approach based on Denavit–Hartenberg's notation and designed by the 2-degrees of freedom kinematic chain for determination of its motion and estimation of several resonance frequencies useful in many energy harvesting applications. The vibration generator that moves the magnetic spring is modeled by neural networks and the magnetic spring potential energy is calculated by the finite elements method (FEM). Furthermore, the magnetic spring and the vibration generator are designed by the Simulink block diagram. Testing results of the magnetic spring and vibration generator displacement conducted in laboratory have shown good agreement with simulation results. [ABSTRACT FROM AUTHOR]

The study of humanoid robots is still a challenge for the scientific community, although there are several related works in this area, several limitations have been found in the literature that drive the need to develop an inverse kinematic modeling of biped robots. This paper presents a research proposal for the Bioloid Premium robot. The objective is to propose a complete solution to the inverse kinematics model for a 18 DOF (Degrees Of Freedom) biped robot. This model will serve as a starting point to obtain the dynamic model of the robot in a subsequent work. The proposed methodology can be extended to other biped robots. [ABSTRACT FROM AUTHOR]

The article presents novel foldable mechanisms designed by integrating spatial kinematic chains on a planar four-bar linkage. At the same time, the integrated chains do not add imposed constraints; therefore, the synthesized mechanisms have one degree of freedom. Two-bar chains are accepted as the integrated chains, in which the central joint is a two-degree of freedom pin spherical joint or toroidal joint, and the outermost joints are either cylindrical or spherical and rotational joints. The article presents a solution to the kinematics problem of a foldable mechanism, in which the integrated chains are formed by spherical, pin spherical and rotational joints. [ABSTRACT FROM AUTHOR]

Every machine needs a suitable mechanism to impart motion and transmit power. Hence, it becomes necessary to study the various aspects of a mechanism in terms of synthesis and structural analysis of kinematic chain. In past few decades, a lot of researchers had put their efforts in identifying distinct kinematic chain with a given degree of freedom, tested them for isomorphism and identified the distinct number of mechanisms (inversions) that can be obtained by fixing a link in a particular kinematic chain. All those methods are solely dependent on the study and analysis of two basic factors of any kinematic chain i.e links and joints. However, the presence of loops and its effect in driving a mechanism is somehow neglected. The complete analysis of the structure of a kinematic chain depends on the study of all the three factors i.e. links, joints and loops. This paper approaches with a new method based on matrix composition to identify the accurate number of distinct mechanisms which can be obtained in a particular kinematic chain. The method adopted is quite simple and reliable as it considers the presence of loop among the kinematic chain along with the links and the joints hence uses link-joint-loop adjacency. [ABSTRACT FROM AUTHOR]

In the creative design of mechanical devices，the isomorphic kinematic chains should be eliminated to reduce the mechanism scheme for subsequent design and improve the design efficiency of mechanical device. A new method for isomorphism recognition of kinematic chains is proposed based on the Hamming matrix. Firstly，the Hamming matrix of kinematic chains is educed from the link adjacency matrix，then the square matrix of Hamming matrix and the cubic matrix of link adjacency matrix are integrable to obtain the product matrix of kinematic chains. Secondly，the elements of each row in the product matrix are ordered in descending to get the row sequences of the product matrix. Finally，the isomorphism recognition code (IRC) of the kinematic chain is obtained by the sum of the product of the element in the row sequence with the defined topological factor. The isomorphism recognition code does not change with the link labels，so if the isomorphism recognition codes of the kinematic chains are the same，they are isomorphic，otherwise they are not. The effectiveness of this method is proved by a large number of examples. Because of its simplicity，efficiency and convenience for computer execution，it can be considered as a new option for isomorphism screening.

Background and Study Aim. Students are often injured while playing sports. The main condition for preventing injuries is the correct technique of movements. In the literature, rock climbing has not been analyzed in terms of prevention of student injuries. Therefore, the development of programs to prevent injuries of students-rock climbers is relevant. Aim: to determine the impact of the use of exercises in a closed kinematic chain on the technical skill and the number of injuries to the elbows of student-rock climbers based on the analysis of the one-arm hang technique. Material and methods. First, to substantiate the correct technique in rock climbing, the technique of performing one-arm hang was analyzed by 20 leading male climbers of Ukraine and 20 students - novice male climbers. Then a randomized control study was conducted. The participants in the randomized control study were 40 male students-climbers in the intervention group and 44 male students-climbers in the control group aged 18-19 years. The one-arm hang technique was determined based on the angles between the shoulder and the collarbone during the movement. The experiment lasted 1 year. At the beginning and at the end of the experiment, the analysis of the one-arm hang technique was carried out. The number of elbow injuries in both groups was also recorded. Results. The main parameters of the one-arm hang technique for qualified and unskilled climbers have been substantiated. For qualified climbers, one-arm hang involves the muscles of the shoulder girdle, torso, and legs. In unskilled climbers, one-arm hang is provided only by the muscles of the arm. In a control randomized study, there was a significant improvement in the results of biomechanical analysis of the hang technique in athletes in the intervention group (p

BackgroundBaseball pitching performance can be mechanically explained by the summation of speed principle and the principle of optimal coordination of partial momenta. Impeding optimal energy generation or transfer by or between the pelvis and trunk segments could provide valuable insight into possible compensation or catch-up mechanisms that may manifest themselves based on these principles.AimThe aim of the present study was to explore the effects of experimentally impeding the mobility of and between the pelvis and trunk segments (1) on ball speed and mechanical peak joint power, and (2) on mechanical peak load of the elbow and shoulder joints at maximal external rotation (MER) during fastball pitching.MethodsEleven elite baseball pitchers (mean age 17.4, SD 2.2 years; mean pitching experience 8.9, SD 3.0 years) were instructed to throw at least 15 fastballs as fast and accurately as possible under two conditions. One condition involved impeding the mobility of the pelvis and trunk segments to hamper their ability to rotate independently, which consequently should affect the separation time, defined as the time interval between the pelvis and trunk peak angular velocities. In the other condition, pitchers threw unimpeded. Ball speed, mechanical peak joint power and peak net moment of the elbow and shoulder at MER were compared between conditions using Generalized Estimating Equations (GEE).ResultsIn the impeded pitching condition, the mean difference of the separation time was 12.4 milliseconds [95% CI (4.0, 20.7)] and for ball speed 0.6 mph [95% CI (0.2, 0.9)] lower compared to the unimpeded condition. Only the peak pelvic angular velocity, in addition to the trunk, upper arm and forearm, was 45 deg/s [95% CI (24, 66)] higher impeded condition. The mean differences of the joint power and net moments at the shoulder and elbow did not reach statistical significance.ConclusionIn elite adolescent baseball, the observed pitching performance after experimentally impeding pelvic and trunk mobility undermines a potential distal catch-up strategy based on the summation of speed principle. The increased peak pelvic angular velocity may indicate a compensation strategy following the optimal coordination of partial momenta principle to practically maintain pitching performance.

Exploring a general and effective method of isomorphism identification is an arduous task. For this aim, some new concepts such as binary link path and link-assortment adjacency matrix are introduced in this paper. On this basis, a new method is proposed to improve the operability of isomorphism identification and relieve the computational pressure. By generating new elements from structural features and connection relations among links or vertices in the graph, it transforms traditional high-ranking adjacency matrix into new low-ranking adjacency matrix. Some typical graphs including kinematic chains, topological graphs, and planetary gear trains are used to verify the effectiveness of the proposed method. As shown by a comparison with results in the cited references, the proposed method is available in isomorphism identification. [ABSTRACT FROM AUTHOR]

Inadequate hip active range of motion (AROM) may stifle the energy flow through the kinematic chain and decrease pitching performance while increasing the risk for pitcher injury. To examine the relationship between hip AROM and pitching biomechanics during a fastball pitch in adolescent baseball pitchers. Cross-sectional study. Biomechanics laboratory. A sample of 21 adolescent male baseball pitchers (age = 16.1 ± 0.8 years, height = 183.9 ± 5.2 cm, mass = 77.9 ± 8.3 kg). Bilateral hip external-rotation (ER), internal-rotation, flexion, abduction, and extension AROM were measured. Three-dimensional biomechanics were assessed as participants threw from an indoor pitching mound to a strike-zone net at regulation distance. Pearson product moment correlation coefficients were used to determine relationships between hip AROM and biomechanical metrics. Negative correlations were found at foot contact between back-hip ER AROM and torso-rotation angle (r = −0.468, P =.03), back-hip ER AROM and back-hip abduction angle (r = −0.474, P =.03), and back-hip abduction AROM and lead-hip abduction angle (r = −0.458, P =.04). Back-hip extension AROM was positively correlated with increased stride length (r = 0.446, P =.043). Lead-hip abduction AROM was also positively correlated with normalized elbow-varus torque (r = 0.464, P =.03). We observed several relationships between hip AROM and biomechanical variables during the pitching motion. These findings support the influence that hip AROM can have on pitching biomechanics. Overall, greater movement at the hips allows the kinematic chain to work at maximal efficiency, increasing the pitch velocity potential. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the upper limb kinematic chain of tennis players using either an eastern or continental non-dominant grip position during the forward swing of the double-handed backhand stroke. Sixteen right-handed tennis players performed backhands using two non-dominant grip positions (eastern and continental), aiming for two cross-court zones (deep and short). Trajectory data were captured using sixty reflective markers attached to the upper limb and racket using a 12-camera Vicon motion capture system (250 Hz). Peak angular velocity was significantly greater for multiple joint rotations at the dominant shoulder and entire non-dominant limb in the eastern grip. Subsequently, greater peak racket head angular velocity and post-impact ball speed were generated by the eastern grip, while shot accuracy was similar between grip types. There was delayed dominant shoulder peak adduction angular velocity for the continental grip, possibly due to a lack of skill familiarity causing changes in coordinative patterns. Collectively, the non-dominant grip position appears to influence proximal and distal upper limb movement. Future research should explore upper limb segment coordination comparing preferred and non-preferred double-handed backhand techniques and complete inter-disciplinary investigations to understand what grip positions are most effective for individuals to learn double-handed backhands. [ABSTRACT FROM AUTHOR]

The aim of this article is the mathematical modeling of the car wheel with an energy harvester. The car wheel will be represented as a 3-DoF robotic kinematic chain. The Matlab program has been used to simulate the movement of the car wheel and the movement of the electromagnetic energy harvester located on the tire of the wheel. Simulation of the movement of the energy harvesting element allows us to compute the energy harvested in such a system. [ABSTRACT FROM AUTHOR]

The paper deals with linkages used to actuate the retractable top of convertible passenger car, which are either a simple articulated 4-bar mechanism or a stacking multi-contour n-bar mechanism. The car top that can fold or unfold is consisting of two or three hard components. The folding linkage of the hard top is a planar kinematic chain with articulated bars which allows the two or three top parts to be stacked into the trunk room. To be observed that the first hard component of the kinematic chain is the car rear screen and the second hard part is actually the retractable top. In order to fold the car top and the rear screen, the door trunk is actuated by means of a simple hinge pair or a 4-bar mechanism. In the case of a larger passenger car, the top consists of two parts and together with the rear screen form the open kinematic chain which can be closed by means of some stacked kinematic chains. Using CAD modeling and kinematic simulation of the retractable textile car top linkage used on convertibles, the mechanism efficiency regarding its operation can be improved. Through Inventor® software the user can modify any part or subassembly of the mechanism at any moment. This can be done by means of the parametric design which allows that any changing on a component to be instantaneous reflected on the assembly which that part belongs to.

The displacement graphs (d-graphs) are the final form of planetary gear trains (PGTs) synthesis. The existing configuration synthesis methods for the d-graphs of PGTs need rotation graphs (r-graphs) as the intermediate step and produce a large amount of isomorphic KCs. This paper proposes a method to obtain d-graphs directly from the geared graph. Meanwhile, a uniform isomorphism identification method suitable for parent graphs, geared graphs, and d-graphs is presented. Finally, a fully automatic method based on parent graphs is tested on synthesizing 1-DOF PGTs with up to nine links. Our synthesis results and those in the literature are comparatively analyzed, and the reasons for contradictory synthesis results are analyzed. [ABSTRACT FROM AUTHOR]

The article reviews various designs of parallel robots with a circular guide, which provide the output link with an unlimited rotation around one of the axes. The paper considers familiar methods and algorithms for type and dimensional synthesis and mobility analysis, singularity determination, and workspace construction for such robots. The performed study presents the current state of the problems mentioned above and shows the directions for future research in this field. [ABSTRACT FROM AUTHOR]

Isomorphism identification plays an important role in structural design and innovative design. Based on the adjacency matrix and loop theory, a new method is proposed in this paper to identify the isomorphic kinematic chains. It enriches the application of loop-based theory for isomorphism identification. In the kinematic chain, links and joints are connected alternatively and every link corresponds to a fixed link degree. Due to the inherent characteristics, the labeled sequence of links can be random, which does not affect the result of isomorphism identification. By the programming software MATLAB, some examples with 6-, 8-, 10-, 11-, 12-link kinematic chains, and 15-vertex topological graphs are presented. Results show that the proposed method applies to topology graphs and kinematic chains with one or multiple joints. Compared with other methods, the proposed method is confirmed correctly. And there is no counterexample. It lays a solid foundation for structural synthesis in the future. [ABSTRACT FROM AUTHOR]

A method to compensate the influence of geometric deviations on tool center point (TCP) for a multi-tasking machine tool is proposed in this paper. Some methods to compensate geometric deviations of a rotary axis in five-axis machining centers have been proposed. However, due to the special topological structure of multi-tasking machine tools, the identification and compensation methods for geometric deviations are different from those of the five-axis machining centers, which have been seldom researched until now. In this paper, the main attention is paid to analyze the eccentricities of the trajectories measured by a ball bar under simultaneous three-axis motions and to reduce the influence of the identified geometric deviations on the position error of TCP by the compensation method. It is divided into two sequential subtasks. At first, the geometric deviations are identified by using the eccentricities of measured trajectories. A simple and practical measuring procedure is proposed to identify geometric deviations of rotary axes existing in a multi-tasking machine tool. For the second step, a method is proposed by modifying the original NC code according to the kinematic chain model of the targeted machine tool to compensate the influence of the existing geometric deviations on TCP. An experiment is conducted on a multi-tasking machine tool with a swivel tool spindle head in the horizontal position. The repeatability of the measured eccentricities based on three experimental results is also investigated to reduce the influence of measuring error on the identified results. As a result, the corresponding values of geometric deviations after the compensation are less than 2.2 arcseconds or 2.4 μm. It is concluded that the influence of geometric deviations on TCP is compensated effectively, and the position error of TCP is reduced significantly. • A measuring procedure using a ball bar is designed to identify eight geometric deviations of a multi-tasking machine tool. • According to the kinematic chain model, a method is proposed to compensate the influence of geometric deviations on TCP. • From the experimental results, the position error of TCP is reduced significantly after the compensation. [ABSTRACT FROM AUTHOR]

The paper presents the generalized and parametrized 3D geometric modelling of the lower limb bone system. The research subscribes to ampler interests within the specialty literature, objectified through analytical, geometrical, numerical or experimental models regarding the human gait. The study of the previously mentioned models presents high interest for the further development of treatment strategies, implants or prosthesis of the specific human body element. After the thorough study of the anatomy, kinematics and biomechanics, a parametrized 3D modelling of the lower limb assembly has been developed. The resulted product assures generating the 3D model of the foot within all gait phases, through changing of the parameter values, and further, it can be associated to the existing variable loading states. By using the Skeleton system method within the relevant joint areas, it is provided the facile possibility of simulations and analyses of both healthy subjects, along with subjects affected by diverse pathological conditions, such as axial deviations of the bones. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this work to determine the influence of a program containing exercises in a closed kinematic chain, eccentric and strength exercises on injuries of students - rock climbers. Methods: Participants in this study were 84 male amateur climbing students, aged 18-19, 40 athletes were in the intervention group and 44 in the control group. In the intervention group, the program for the injuries prevention has been stalled. The program included exercises that are performed in a closed kinematic chain in combination with exercises that are performed in eccentric mode and strength exercises. We determined the Incidence rate ratio and confidence intervals. The Incidence rate ratio was determined by the by Fisher exact test. Results: The significant influence of the developed program on the reduction of injuries among the athletes of the intervention group was revealed. Injury rate per 1000 AEs recorded of all shoulder injuries in the control group was 3.182, in the intervention group was 0.5, P < 0.001. The incidence rate ratio for mild shoulder injuries was 0.861 (0.737; 1.007). The incidence rate ratio for moderate shoulder injuries was 0.862 (0.751; 0.990; P = 0.039). The incidence rate ratio for severe shoulder injuries was 0.864 (0.768; 0.971; P = 0.017). Conclusions: The use of exercises in a closed kinematic chain and exercises in an eccentric mode reduces the Incidence rate ratio of shoulders among students - amateur climbers. The incidence rate ratio decreases in the intervention group for mild, moderate, and severe shoulder injuries. [ABSTRACT FROM AUTHOR]

• A general method for dynamics modeling of open-loop system with auxiliary subchains. • The method is applied to analyze dynamics of the mobile crane and load hanged on. • Kinetic energy and positioning indicators are proposed to evaluate the crane model. • Influence of the load geometry and rope sling system on the crane dynamics is examined. In the paper, the authors present a general mathematical model of an open-loop kinematic chain with auxiliary sub-chains in application to the dynamics analysis of an exemplary boom crane. The developed model takes into account the influence of the load geometry (with particular attention to all its inertial moments), the rope sling system, and the flexibility of the drives and the selected link of the crane on the dynamic response of the crane and the load. The dynamics equations are derived using a formalism of joint coordinates, homogeneous transformation matrices, and Lagrange equations of the second kind. The mathematical model has been successfully validated using the commercial MSC.Adams program and the ANSYS-MSC.Adams program interface and then the influence of the aforementioned factors on the behavior of the load and the crane drives is assessed using the kinetic energy, positioning, and RMS indicators. [ABSTRACT FROM AUTHOR]

Multiplanar kinematic and kinetic sequencing from different approach angles can highlight how soccer players perform fast and accurate kicks. This study therefore aimed to a) determine multiplanar torso, pelvis and kick leg sequencing during instep kicks and b) highlight the effect of different approach angles on these sequencing patterns. Twenty male soccer players (mass 77.9 ± 6.5 kg, height 1.71 ± 0.09 m, age 23.2 ± 3.7 years) performed kicks from self-selected (∼30−45°), straight (0°) and wide (67.5°) approaches and multiplanar lumbo-pelvic, hip and knee angular velocities, moments and powers were derived from 3D motion analysis. The results suggest tension arc release between the upper and lower body functions as a two-stage mechanism. The first phase of arc release was characterised by increases in concentric hip flexion and transverse lumbo-pelvic velocities towards the ball. The second phase was characterised by increasing concentric lumbo-pelvic flexion and knee extension work to angularly accelerate the kicking knee towards foot-to-ball contact. Further, alterations in kinematic and kinetic sequencing helped maintain performance (ball and foot velocities at ball contact) and accuracy at approach angles other than self-selected. These findings can help coaches and practitioners design effective training practices. [ABSTRACT FROM AUTHOR]