Relationships between Racket Arm Joint Moments and Racket Head Speed during the Badminton Jump Smash Performed by Elite Male Malaysian Players

Three-dimensional position data of nineteen elite male Malaysian badminton players performing a series of maximal jump smashes were collected using a motion capture system. A ‘resultant moments’ inverse dynamics analysis was performed on the racket arm joints (shoulder, elbow and wrist). Relationships between racket head speed and peak joint moments were quantified using correlational analyses, inclusive of a Benjamini–Hochberg correction for multiple-hypothesis testing. The racket head centre speed at racket–shuttlecock contact was, on average, 61.2 m/s with a peak of 68.5 m/s which equated to average shuttlecock speeds of 95.2 m/s with a peak of 105.0 m/s. The correlational analysis revealed that a larger shoulder internal rotation moment (r = 0.737), backwards shoulder plane of elevation moment (r = 0.614) and wrist extension moment (r = −0.564) were associated with greater racket head centre speed at racket–shuttlecock contact. Coaches should consider strengthening the musculature associated with shoulder internal rotation, plane of elevation and wrist extension. This work provides a unique analysis of the joint moments of the racket arm during the badminton jump smash performed by an elite population and highlights significant relationships between racket head speed and peak resultant joint moments.

Design of a multi-resiliency exoskeleton and its physiologic cost evaluation in uphill walking and stair climbing locomotion

Background In recent years, as the large own weight of active exoskeleton brings some difficulty to energy-sustainable, studies have shown that passive lower extremity exoskeletons can also reduce the energy consumption of human locomotion, but the energy saving is still relatively small compared with the total consumption. Methods A passive lower limb exoskeleton named Multi-Resiliency was described, and design parameters were estimated based on inverse dynamics. Furthermore, a series of experiments was designed for assessing the assisting effect of the exoskeleton in uphill walking and upstairs activities. Results In the inverse dynamics analysis, the spring release angle θmax was confirmed to be 45° for increasing assist performance of the exoskeleton. In the exoskeleton wearing experiments, the energy expenditure of subjects were decreased by 14.3% in uphill walking test and 16.0% in stair climbing test respectively. Conclusion The results show that the design of Multi-Resiliency exoskeleton is reasonable and it may effectively improve walking efficiency during uphill walking and stair climbing activities.

Actuation-Coordinated Mobile Parallel Robots With Hybrid Mobile and Manipulation Function

Mobile robots with manipulation capability are a key technology that enables flexible robotic interactions, large area covering and remote exploration. This paper presents a novel class of actuation-coordinated mobile parallel robots (ACMPRs) that utilize parallel mechanism configurations and perform hybrid moving and manipulation functions through coordinated wheel actuators. The ACMPRs differ with existing mobile manipulators by their unique combination of the mobile wheel actuators and the parallel mechanism topology through prismatic joint connections. The common motion of the wheels will provide the mobile function while their differentiation will actuate the parallel manipulator function. This new concept reduces the actuation requirement and increases the manipulation accuracy and mobile motion stability through the coordinated and connected wheel actuators comparing with existing mobile parallel manipulators. The relative wheel location on the base frame also enables a reconfigurable base size with variable moving stability on the ground. The basic concept and general type synthesis are introduced and followed by the kinematics and inverse dynamics analysis of a selected three limb ACMPR. A numerical simulation also illustrates the dynamics model and the motion property of the new mobile parallel robot. The work provides a basis for introducing this new class of robots for potential applications in surveillance, industrial automation, construction, transportation, human assistance, medical applications and other operations in extreme environment such as nuclear plants, Mars, etc.

Hand Motion Capture from a 3D Leap Motion Controller for a Musculoskeletal Dynamic Simulation

The AnyBody Modeling System™ (AMS) is a musculoskeletal software simulation solution using inverse dynamics analysis. It enables the determination of muscle and joint forces for a given bodily motion. The recording of the individual movement and the transfer into the AMS is a complex and protracted process. Researches indicated that the contactless, visual Leap Motion Controller (LMC) provides clinically meaningful motion data for hand tracking. Therefore, the aim of this study was to integrate the LMC hand motion data into the AMS in order to improve the process of recording a hand movement. A Python-based interface between the LMC and the AMS, termed ROSE Motion, was developed. This solution records and saves the data of the movement as Biovision Hierarchy (BVH) data and AnyScript vector files that are imported into the AMS simulation. Setting simulation parameters, initiating the calculation automatically, and fetching results is implemented by using the AnyPyTools library from AnyBody. The proposed tool offers a rapid and easy-to-use recording solution for elbow, hand, and finger movements. Features include animation, cutting/editing, exporting the motion, and remote controlling the AMS for the analysis and presentation of musculoskeletal simulation results. Comparing the motion tracking results with previous studies, covering problems when using the LMC limit the correctness of the motion data. However, fast experimental setup and intuitive and rapid motion data editing strengthen the use of marker less systems as the herein presented compared to marker based motion capturing.

ANALYSIS OF MUSCLE STRENGTH EFFECTS ON EXERCISE PERFORMANCE USING DYNAMIC STABILIZATION EXERCISE DEVICE

Muscle strength may vary depending on the pathological issues and static life habits. These conditions lead to abnormal spinal loads and change muscle strength as well as activation patterns, thereby causing spinal disorders. In this study, the effects of muscle strength on the spine stabilization exercise were analyzed using a whole-body tilt device. Musculoskeletal modeling was performed and the results were validated through a comparison with the electromyography (EMG) analysis results. Based on the validated basic model, modeling was performed for the whole-body tilt device. To examine the exercise effect and muscle activation while the maximum muscle force capacity (MFC) was varied from 30[Formula: see text]N/cm2 to 60[Formula: see text]N/cm2 and 90[Formula: see text]N/cm2, the muscle force was predicted through inverse dynamics analysis. When MFC was 30[Formula: see text]N/cm2, the posterior direction of the tilt could not be analyzed (no solution found). When MFC was 60[Formula: see text]N/cm2, it could be analyzed, but the muscle force was predicted to be higher compared to when MFC was 90[Formula: see text]N/cm2. It was confirmed that muscle strength is a very important element for maintaining postural activities and performing exercise. Therefore, for rehabilitation patients and elderly people with weak muscle strength, hard or extreme exercise may cause musculoskeletal injuries.

COMPARING METHODS FOR 3D INVERSE DYNAMICS ANALYSIS OF SQUAT LIFTING USING A FULL BODY LINKED SEGMENT MODEL

Objective: The main objective of this study was to assess the accuracy of bottom-up solution for three-dimensional (3D) inverse dynamics analysis of squat lifting using a 3D full body linked segment model. Least squares solution was used in this study as reference for assessment of the accuracy of bottom-up solution. Findings of this study may clarify how much the bottom-up solution can be reliable for calculating the joint kinetics in 3D inverse dynamics problems. Methods: Ten healthy males volunteered to perform squat lifting of a box with a load of one-tenth of their body weights. The joint moments were calculated using 110 reflective passive markers (46 anatomical markers and 64 tracking markers) and a 3D full body linked segment model. Ground reaction forces and kinematics data were recorded using a Vicon system with two parallel Kistler force plates. Three-dimensional Newton–Euler equations of motion with bottom-up and least squares solutions were applied to calculate joint moments. The peak and mean values of the joint moments were determined to check the quantitative differences as well as the time-to-peak value of the moment curves was determined to check the temporal differences between the two inverse dynamics solutions. Results: Significant differences (all [Formula: see text]-[Formula: see text]) between the two inverse dynamics solutions were detected for the peak values of the hip (right and left sides) and L5–S1 joint moments in the lateral anatomical direction as well significant differences (all [Formula: see text]-[Formula: see text]) were detected for the peak and mean values of the L5–S1 joint moment in all anatomical directions. Moreover, small differences (all [Formula: see text]) were detected between the two inverse dynamic solutions for the calculated lower body joint moments. Conclusions: The findings of this study clarified the disadvantages of the straightforward solutions and demonstrated that the bottom-up solution may not be accurate for more distal measures from the force plate (for hip and S1–L5) but it may be accurate for more proximal joints (ankle and knee) in 3D inverse dynamics analysis.