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The principle of organization of strap-down inertial navigation systems is based on numerical integration of angular velocities and accelerations. The purpose of numerical integration algorithms is to approximate the behavior of a dynamic system (unmanned aerial vehicle – UAV) with continuous time using a digital computer. The efficiency of numerical integration is determined by the accuracy and stability of the computational process. The integration algorithm may have a small integration error, but at the same time be inefficient due to the instability of the numerical method when the step or conditions of integration change. The standard way to test integration algorithms for stability is to test them under control operating conditions (when performing a typical UAV flight along the route and canonical movement). The article presents the results of simulation modeling of traditional numerical integration algorithms in the conditions of rectilinear and conical UAV motion, when calculating the values of angular velocities by various methods. The analysis of the obtained research results is carried out, which allows us to choose an algorithm that has an advantage with respect to accuracy and computational simplicity, depending on the flight conditions. For a UAV that has no or minimal undampened angular harmonic oscillations of its body, when performing a typical flight along the route, the best, in terms of accuracy and volume of calculations, is a second-order accuracy algorithm implementing the average speed method. Its average error in calculating angles ranges from 3.6 to 43%, which is approximately equal to the errors values when using the considered algorithms (an algorithm implementing a second approximation to the average speed method, a one-step algorithm of the thirdorder of accuracy), with a three-fold smaller amount of mathematical calculations.

Purpose: Kinematic variables identify movement patterns and are used to compare successful versus unsuccessful performances that cause to better understanding of performance optimization techniques. Therefore, the aim of this study was to compare the angular kinematic variables in successful and unsuccessful performances in gymnastic somersault for identifying the optimization performance of this technique. Materials and methods: Eleven skillful male gymnasts (Avg. age 11.5 ± 3.7 years, height 123 ± 38.9 cm, weight 36.5 ± 16.9 kg and experience 4.64 ± 3.7 years) participated in this study. They were required to perform somersault and their performances were labeled as successful and unsuccessful performances according to referees' scores. Then, the recorded performances were analyzed and the desired kinematic parameters were calculated. Results: The results showed that the average of ankle angles at two instances of initial contact and toe off were higher in successful performances than unsuccessful ones. Besides, the minimum values of hip and knee angles and also the maximum values of knee angles were significantly higher in successful performances. The shoulder angles at two instances of initial contact and toe off in successful performances were also found to be less than unsuccessful ones, but, the range of shoulder motion in successful performances were greater than unsuccessful performances. Conclusions: According to the results of this study, the maximum and minimum values of the major joints involved in this technique, range of their motions, and angular velocities of them are identified as the effective factors in this technique. [ABSTRACT FROM AUTHOR]

Canoe polo is an increasingly popular discipline requiring both kayaking and ball-handling skills. While the kinematics of the upper body during throw has been investigated for several overhead sports, the canoe polo throw has still to be studied. Therefore, the aim of this study is to analyze the canoe polo throw kinematics in terms of angles and inter-articular sequencing to understand its specificity. A secondary aim was to investigate whether adding pelvis mobility has an impact. Nineteen male players of canoe polo were equipped with reflective body markers for the throw analysis. They performed 5 throws with the pelvis fixed and 5 throws with additional pelvic mobility in rotation around a vertical axis. Inverse kinematics was performed with OpenSim providing pelvis, trunk, and glenohumeral rotations. Angular velocities were calculated to build the inter-articular sequences relative to these throws. Statistical parametric mapping was used to assess the effect of pelvis mobility on the throwing kinematics. Similar kinematics patterns as in other overhead sports were observed, however, a different inter-articular sequence was found for the canoe polo throw with a maximal angular velocity occurring sooner for the thorax in axial rotation than for the pelvis in rotation. While the limitation of rotation of the pelvis around a vertical axis has an influence on the pelvis and trunk kinematics, it did not modify the kinematic sequence.

INTRODUCTION: The aim of this study was the analysis of human musculoskeletal system energy costs of normal walking and walking under reduced weight loading. METHODS: There were 15 subjects who participated in the study. We analyzed the biomechanical parameters of walking under different musculoskeletal system loads. The subjects walked on a treadmill at a pace of 90 steps/min under various loading conditions: 1) 100% bodyweight loading, corresponding to the terrestrial surface; 2) 38% bodyweight loading, corresponding to the surface of Mars; and 3) 17% bodyweight loading, corresponding to the surface of the Moon. Joint angles and angular velocities were recorded from the hip, knee, and ankle. RESULTS: We analyzed changes in joint phase trajectories and the ratio of kinetic extension energy to kinetic flexion energy in the joints. We observed changes in kinetic energy parameters associated with both flexion and extension motions in the joints of the feet while walking under various loads. In terrestrial conditions (walking under 100% bodyweight), flexion kinetic energy in the hip joint prevailed over extension kinetic energy by 90%, with a small variation equal to 22%. If weight loading decreased up to 17% (lunar conditions), the difference between flexion and extension kinetic energies diminished, and eventually reached only 9%. The ratio of flexion energy and extension energy in the ankle joint equalized under lower loading conditions. Thus, 38% bodyweight loading was sufficient for approximation of flexion and extension energy values. DISCUSSION: Our results revealed that phase trajectories shifted toward smaller joint angles and a decreased ratio between extension kinetic energy and flexion kinetic energy in the knee joint of all subjects. However, significant differences in the ratio of flexion and extension kinetic energy in the knee joint under bodyweight support were not found. The methods used for musculoskeletal system assessments that were proposed in our work can be used in clinical practice to evaluate the effectiveness of rehabilitation measures in a patient's musculoskeletal system disorders. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the existence of rotational waves in deforming thermoelastic non-classical solid continua in which the conservation and balance laws consider internal rotations due to the deformation gradient tensor (Jacobian of deformation) as well as their time varying rates. In this non-classical continuum theory, time dependent deformation of solid continua results in time dependent varying rotations, angular velocities and angular accelerations at material points. Resistance to these by deforming continua results in additional moments due to rotations, angular momenta due to rotation rates and rotational inertial effects due to angular accelerations at the material points. Currently this physics is neither considered in classical continuum mechanics (CCM) nor in non-classical continuum mechanics (NCCM) based on internal and/or Cosserat rotations. In this paper, we present derivation of conservation and balance laws in Lagrangian description: conservation of mass, balance of linear momentum, balance of angular momentum, balance of moment of moments, first and second laws of thermodynamics that include: (i) physics due to internal rotations resulting from the displacement gradient tensor (ii) new physics associated with rotation rates (angular velocities) and angular accelerations resulting from the varying, time dependent internal rotations at the material points. The balance laws derived here are compared with those that only consider internal rotations and their rates in the absence of rotational inertial effects (Surana et al. in J Therm Eng 1(6):446–459, 2015; Int J Eng Res Ind Appl 8(2):77–106, 2015) to demonstrate the influence of new physics. Constitutive variables and their argument tensors are established using the conjugate pairs in the entropy inequality, additional desired physics and the principle of equipresence. The constitutive theories are derived using Helmholtz free energy density as well as representation theorem and integrity. It is shown that the mathematical model consisting of the conservation and balance laws and the constitutive theories has closure. Existence of rotational waves is demonstrated due to the presence of angular velocities and angular accelerations arising from the time varying rotations and their rates when deforming solid continua offer rotational inertial resistance. In this paper, we only consider isotropic and homogeneous solid continua with small strain, small deformation physics and reversible mechanical deformation. Model problem studies are presented in a follow up paper. [ABSTRACT FROM AUTHOR]

Purpose: The aims of the present study were: (1) to compare the differences in the ball release speed and throwing accuracy between the ABOVE and SIDE throw; (2) to analyze kinematic differences of these two throwing techniques; and (3) togive practical applications to team handball coaches and players. Methods: Ball release speed, throwing accuracy, and kinematics were measured via the Vicon MX 13 (Vicon Peak, Oxford, UK) from 12 male elite right-handed team handballplayers. Results: Results of our study suggest that the two throwing techniques differ significantly (P < .0073) in the angles and/or angular velocities of the trunk (flexion, left tilt and rotation) and shoulder (flexion and abduction) of the throwingarm that result in a significantly different ball release speed (1.4 ± 0.8 m/s; P < .001) and that throwing accuracy was not significantly different. Conclusion: Our results indicated that the different position of the hand at ball release of the ABOVE and SIDE throws is primarily caused by different trunk flexion and tilt angles that lead to differences in ball release speed but not in throwing accuracy, and that the participants try to move their throwing arm similarly in both throwing techniques. [ABSTRACT FROM AUTHOR]

Hand shaping during prehension involves intricate coordination of a complex system of bones, joints, and muscles. It is widely hypothesized that the motor system uses strategies to reduce the degrees of independent control. Both biomechanical constraints that result in coupling of the fingers and joints and neural synergies act to simplify the control problem. Synergies in hand shaping are typically defined using principal component-like analyses to define orthogonal patterns of movement. Although much less examined, joint angle velocities are also important parameters governing prehension. The primary goal of this study was to evaluate joint angles and joint angle velocities during prehension in monkeys. Fourteen joint angles and angular velocities were measured as monkeys reached to and grasped a set of objects designed to systematically vary hand shapes. Hand shaping patterns in joint angles and velocities were examined using singular value decomposition (SVD). Highly correlated patterns of movements were observed in both joint angles and joint angle velocities, but there was little correlation between the two, suggesting that velocities are controlled separately. Joint angles and velocities can be defined by a small number of eigenvectors by SVD. The unresolved question of the functional relevance of higher-order eigenvectors was also evaluated. Results support that higher-order components are not easily distinguished from noise and are likely not of physiological significance. [ABSTRACT FROM AUTHOR]

The main focus of this paper is to compensate the steady state offset error of the 6D IMU which provides the measurements that include the vehicle linear accelerations and angular rates of all three axes. Additionally, the sensor compensation algorithm exploits the wheel speed data and the steering angle information, since they are already available in most of the modern mass production vehicles. These inputs are combined with the inverse vehicle kinematics to estimate the steady state offset error of each sensor inputs as it is done in a disturbance observer, and the raw sensor measurements are compensated by the estimated offset errors. The stability of the error dynamics regarding the integrated signal processing system is verified, and finally, the performance of the system is tested via experiments based on a real production SUV. [ABSTRACT FROM AUTHOR]

The penalty corner is one of the most important game situations in field hockey. Women use the drag flick less than men. The objectives of this paper were to describe the kinematic parameters of the drag flick in specialist players and discover the variables determining the performance of this technical strike by hockey players. We analysed fifteen flicks by five players using 6 VICON automatic capture system cameras recording at 250 Hz. To compare means we used nonparametric one-way Kruskal Wallis analysis (subject). Those parameters in which significant differences were found were compared in pairs using a Mann Whitney U test. Players 1 (22.5 ? .9 m/s) and 3 (22.6 ? 0.7 m/s) recorded higher ball speeds from the stick (p < 0.001) than all the other players (19.1 ? 0.7 m/s player 2; 20.5 ? 0.4 m/s player 4 and 19.9 ? 0.4 m/s player 5). Player 1 bases their final acceleration on a long double support, with a sequence of speeds and distance travelled as extensive as possible. However, player 3 bases their speed on the prior swing and on a sequence of explosive movements. The individual characteristics of each player play an important role in the choice of technical strategy when flicking the ball. [ABSTRACT FROM AUTHOR]

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Abstract: The aim of this study was the fine tuning of a Kalman filter with the intent to provide optimal estimates of lower trunk orientation in the frontal and sagittal planes during treadmill walking at different speeds using measured linear acceleration and angular velocity components represented in a local system of reference. Data were simultaneously collected using both an inertial measurement unit (IMU) and a stereophotogrammetric system from three healthy subjects walking on a treadmill at natural, slow and fast speeds. These data were used to estimate the parameters of the Kalman filter that minimized the difference between the trunk orientations provided by the filter and those obtained through stereophotogrammetry. The optimized parameters were then used to process the data collected from a further 15 healthy subjects of both genders and different anthropometry performing the same walking tasks with the aim of determining the robustness of the filter set up. The filter proved to be very robust. The root mean square values of the differences between the angles estimated through the IMU and through stereophotogrammetry were lower than 1.0° and the correlation coefficients between the corresponding curves were greater than 0.91. The proposed filter design can be used to reliably estimate trunk lateral and frontal bending during walking from inertial sensor data. Further studies are needed to determine the filter parameters that are most suitable for other motor tasks. [Copyright &y& Elsevier]

It is presented an integral approach for the velocity analysis of complex gear systems. Due to the intrinsic nature of the method, it can be systematically applied for gear trains with arbitrary architecture, including bevel gears with non-parallel motion axes. As a result, not only velocity ratios can be computed, but also angular velocities of any body composing the gear system. Several application examples are presented to prove the feasibility and the validity of the proposed method. [ABSTRACT FROM AUTHOR]

The badminton, in respect to shuttle velocity, is one of the fastest racket sports along with tennis. The ability to respond quickly and effectively to a constant changing environment is a key factor to successful performance in addition to service, plays a vital role in winning a point. Thus, the study was proposed to analyse cut and drop shot in badminton of six male university players. The data were collected during competition situation. The biomechanical variables and segmental angle and segment angular velocities of upper extremities were- shuttle velocity. The mean age, height and body weight were reported as 22± 1.78 years; 1.66±0.05 m and 62.16±7.11 kg, respectively. Legaria Canon SF-tO, 8.1 Mp video camera in a field setting operation at 60 Hz was used to record the movement. The identified clips were analyzed with the help of "Silicon Coach Pro7" motion analysis software. The statistical analysis t-test revealed that there is significant difference in the shuttle velocity between cut and drop shot, however no significant differences were found in body kinematics at pO.Ol as well as at pO.OS level of significance. Hence it is concluded that the increase in segmental angular velocities enhances shuffle velocities. [ABSTRACT FROM AUTHOR]

In this paper an algorithm based on [1] [2] are numerical simulations, achieving generalized coordinates of motion, positions, speeds of a rigid rotating kinematic coupling with big clearance in joint, case without friction [ABSTRACT FROM AUTHOR]

Canoe polo is an increasingly popular discipline requiring both kayaking and ball-handling skills. While the kinematics of the upper body during throw has been investigated for several overhead sports, the canoe polo throw has still to be studied. Therefore, the aim of this study is to analyze the canoe polo throw kinematics in terms of angles and inter-articular sequencing to understand its specificity. A secondary aim was to investigate whether adding pelvis mobility has an impact. Nineteen male players of canoe polo were equipped with reflective body markers for the throw analysis. They performed 5 throws with the pelvis fixed and 5 throws with additional pelvic mobility in rotation around a vertical axis. Inverse kinematics was performed with OpenSim providing pelvis, trunk, and glenohumeral rotations. Angular velocities were calculated to build the inter-articular sequences relative to these throws. Statistical parametric mapping was used to assess the effect of pelvis mobility on the throwing kinematics. Similar kinematics patterns as in other overhead sports were observed, however, a different inter-articular sequence was found for the canoe polo throw with a maximal angular velocity occurring sooner for the thorax in axial rotation than for the pelvis in rotation. While the limitation of rotation of the pelvis around a vertical axis has an influence on the pelvis and trunk kinematics, it did not modify the kinematic sequence., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Assila, Delavallade, Blache, Berger-Vachon, Collotte and Duprey.)