Quantification of dance movement by simultaneous measurement of body motion and biophysical information

The purpose of this research is a quantitative analysis of movement patterns of dance,which cannot be analyzed with a motion capture system alone,using simultaneous measurement of body motion and biophysical information.In this research,two kinds of same leg movement are captured by simultaneous measurement;one is a leg movement with given strength,the other is a leg movement without strength on condition of basic experiment using optical motion capture and electromyography (EMG) equipment in order to quantitatively analyze characteristics of leg movement.Also,we measured the motion of the traditional Japanese dance using the constructed system.We can visualize leg movement of Japanese dance by displaying a 3D CG character animation with motion data and EMG data.In addition,we expect that our research will help dancers and researchers on dance through giving new information on dance movement which cannot be analyzed with only motion capture.     

Analyzing motoric and physiological data in describing upper extremity movement in the aged

Cognitive functions, motoric expression, and changes in physiology are often studied separately, with little attention to the relationships or correlations among them. The study presented in this paper implements an integrated approach by combining motion capture (action) and EMG (physiological) parameters as synchronized data streams resulting from the action and associated physiological data. The reported experiments were designed to measure the preparatory movement capabilities of the upper extremities. In particular, measurement of changes in preparatory activity during the aging process is of interest in this context, as the attempt is to develop means to compensate for loss of adaptive capabilities that aging entails. To achieve this goal, it is necessary to quantify preparation phases (timing and intensity). Motion capture and EMG parameters were measured when subjects raised their arms without constraint (condition one) and raised their arms while holding a ball (second condition). Furthermore, on comparing aging and young participants, it was confirmed that with aging the temporal relationships between actual movement and the preceding EMG signal change.     

仿人足底肌电特征的机器人行走规划

模仿人类行走规律是规划双足机器人运动的基础.以往模仿人类步态主要通过视觉方法或惯性模块测量(Inertia measurement unit, IMU)方法捕捉人体特征点轨迹.这些方法不考虑零力矩点(Zero moment point, ZMP)的相似性.为解决该问题,本文提出了一种基于足底肌电信号(Electromyography, EMG)和惯性模块测量信号的混合运动规划方法.该方法通过测量足底肌电信号计算出足底压力中心的位置以及踝关节扭矩,结合惯性模块所测量的人体躯干和双足轨迹,来规划双足机器人的步态.首先,用肌电仪测量足底肌电信号,用惯性测量模块测量人体各肢体部分的姿态轨迹,经数据标定后作为仿人机器人的运动参考; 然后,通过预观控制输出稳定的步态.为确保仿人行走的效果,基于人体相似性对运动数据进行了步态优化.实验验证和分析表明, EMG信号超前ZMP约160ms,利用这个特性实现了对压力点位置的有效预测,提高了机器人在线模仿人类行走的稳定性.     

Stroke Survivors' Gait Adaptations to a Powered Ankle–Foot Orthosis

Stroke is the leading cause of long-term disability in the US, and for many it causes loss of gait function. The purpose of this research is to examine stroke survivors' gait adaptations to training on the powered ankle–foot orthosis (PAFO). Of particular interest is the stroke survivors' ability to learn how to store and release energy properly while using the device. The PAFO utilizes robotic tendon technology and supports motion with a single degree of freedom — ankle rotation in the sagittal plane. This actuator comprises a motor and series spring. The user interacts with the output side of the spring while the robot controls the input side of the spring such that typical able-body ankle moments would be generated, assuming able-body ankle kinematics are seen at the output side of the spring. Three individuals post-stroke participated in a 3-week training protocol. Outcome measures (temporal, kinematic and kinetic) were derived from robot sensors and recorded for every step. These data are used to evaluate each stroke survivor's adaptations to robotic gait assistance. The robot was worn only on the paretic ankle. For validation of the kinematic results, motion capture data were collected on the third subject. All subjects showed increased cadence, ankle range of motion and power generation capabilities. Additionally, all subjects were able to achieve a larger power output than power input from the robot. Motion capture data collected from Subject 3 validated the robot sensor kinematic data on the affected side, but also demonstrated an unexpected gait adaptation on the unaffected ankle. Sensors on the gait-assisting robot provide large volumes of valuable information on how gait parameters change over time. We have developed key gait evaluation metrics based on the available robot sensor information that may be useful to future researchers. All subjects adapted their gait to the robotic assistance and many of their key metrics moved closer to typical able-body values. This suggests that each subject learned to utilize the assistive moments generated by the robot, despite having no predefined ankle trajectory input from the robot. The security of being harnessed on the treadmill led to more dramatic and favorable results.     

Towards an application of interactive sonification for the forces applied on the pedals during cycling on the Wattbike ergometer

Cyclists aim to improve pedaling technique to increase pedal force effectiveness. Therefore, biomechanical feedback about how the force is applied on the pedal stroke throughout the cycle is valuable. This information is typically presented visually on a display mounted on the handlebars. However, challenges associated with visual information presentation motivate movement researchers to display the information acoustically via parameter-mapping sonification that has shown potential for improving motor skills. This paper describes initial considerations for an application of interactive sonification for the forces applied on the pedals during cycling on the Wattbike ergometer. It was aimed to examine if the characteristics of the pedal stroke are represented in the sound to create congruency between sound, action and reaction. The primary focus is on describing the design followed by a brief summary of evaluation and practical effectiveness which was conducted on twenty-four master students (25.9 ± 3.0 years) and tested in a pilot study with four recreational cyclists (35.3 ± 0.9 years).The results of both requests indicate that sonification of the Wattbike data as an acoustic presentation of the force applied throughout the pedal stroke cycle is directly and intuitively understandable. Individual statements from testing revealed that participants became aware of characteristics within the cycling movement which they have not explicitly noticed before. The feeling for specific periods throughout the cycle was improved (pushing and pulling), and the differences in applying force on the legs (symmetry) became evident. Listening to the sound allowed cyclists to hear fluctuations in the forces applied on the pedals and thus try to adapt their muscle activation pattern. Thus, the approach presented here could serve as a helpful training tool for cyclists to optimize their cycling movement.     

Development of a motion analysis system using acceleration sensors for tennis and its evaluations

The term biological motion is often used by researchers studying the patterns of movement generated by living forms and in sports. We studied a pattern recognition system of motion in sport using biological motion data. Biological motion data are acquired using a 3D motion capture system. However, 3D motion capture systems are very expensive. In this article, a biological motion capture system was built using acceleration sensors. Our proposed system uses the technique of Gaussian fitting and regression analysis. We tested our proposed system in pattern recognition of outdoor tennis and its evaluations.     

Experimental investigation and biomechanical analysis of lower limb movements for clutch pedal operation

Lower limb movements for clutch-pedal operations were investigated and the influence of four parameters (seat height, pedal travel, pedal travel inclination, pedal resistance) was studied using a multi-adjustable experimental seat. Fifteen subjects participated in the experiment: five short females, five average height males and five tall males. A biomechanical model has been proposed to explain how pedal force direction could be controlled. The experimental observations show that the lower limb movement of clutch pedal operation is mainly guided by the geometric constraints imposed by the task and its environment, especially during the depression phase. The results support the hypothesis that movements obey the principle of minimum work and minimum discomfort. Furthermore, it seems that a functional segmentation exists between the distal joint (ankle) and the proximal joints (knee and hip), thus simplifying the control problem, which is due to the redundancy of the human body. It appears that the depression movement is controlled by proprioceptive feedback related to foot displacement and pedal force, from the fact that the deceleration duration during the depression phase increases with the pedal resistance and pedal travel. The minimum pedal resistance and pedal travel are discussed.     

Experimental investigation and biomechanical analysis of lower limb movements for clutch pedal operation

Lower limb movements for clutch-pedal operations were investigated and the influence of four parameters (seat height, pedal travel, pedal travel inclination, pedal resistance) was studied using a multi-adjustable experimental seat. Fifteen subjects participated in the experiment: five short females, five average height males and five tall males. A biomechanical model has been proposed to explain how pedal force direction could be controlled. The experimental observations show that the lower limb movement of clutch pedal operation is mainly guided by the geometric constraints imposed by the task and its environment, especially during the depression phase. The results support the hypothesis that movements obey the principle of minimum work and minimum discomfort. Furthermore, it seems that a functional segmentation exists between the distal joint (ankle) and the proximal joints (knee and hip), thus simplifying the control problem, which is due to the redundancy of the human body. It appears that the depression movement is controlled by proprioceptive feedback related to foot displacement and pedal force, from the fact that the deceleration duration during the depression phase increases with the pedal resistance and pedal travel. The minimum pedal resistance and pedal travel are discussed.     

A comparison of clutching movements of freely adjusted and imposed pedal configurations for identifying discomfort assessment criteria

This paper focuses on the effects of the free pedal position adjustment on clutching movements of the left lower limb as well as on the perceived discomfort. Six automotive clutch pedal configurations were tested by 20 subjects (5 young females, 5 young males, 5 older females, 5 older males) using a multi-adjustable experimental mock-up. Results showed that the pedal position was adjusted to ensure a good starting pedal position allowing a less flexed ankle and avoiding unnecessary leg displacement from the foot rest to the position at start depression. Pedal position adjustment seemed not motivated by reducing joint torque though discomfort ratings were found significantly correlated with knee and ankle torques at the end of depression. The present work also illustrates that the less-constrained motion concept is helpful for a better understanding of people preference and useful for identifying motion-related biomechanical parameters to be considered for defining assessment criteria.     

Design optimization of a pedaling mechanism for paraplegics

The design optimization of a pedaling mechanism for use by paraplegic persons through functional electric stimulation of paralyzed muscles is described. The objective of the optimization is to enable paraplegics to pedal by use of the limited number of leg muscles accessible to surface stimulation. This is obtained by optimization of a four-bar pedaling mechanism with no dead points. As a beneficial side effect of the optimization, an indication of the best stimulation pattern for the muscles is obtained. A prototype of the mechanism is built, and its attractive behavior is explained. It is concluded that the mechanism has indisputable advantages compared with conventional cranks. The next step will be experimental verification with fit people and subsequently with paraplegics.     

Muscular fatigue measurements for push‐down tasks in ground demolitions

Demolition hammering tasks are physically demanding tasks that could cause muscle fatigue and musculoskeletal disorders. Electromyography (EMG) data have been adopted to assess levels of muscular activity and onset of muscular fatigue for both industrial tasks and physical activities. An experiment simulating a manual demolition task on the ground was performed on 23 healthy male participants. The objectives were to test the hypotheses that the handle height and the force applied to affect the EMG amplitude, the increase of the EMG amplitude, and the decline of the mean power frequency (MPF) of the EMG for performing the tasks. This study also aimed at finding the most fatigued muscles which dominate the end of the sustained push‐down tasks in ground demolitions. The results showed that the EMG amplitude required to perform the tasks was significantly affected by the handle height and force applied. Significant increases in EMG amplitude and decreases in MPF were found. Bicep brachii, tricep brachii, and pectoralis major muscles were the most fatigued muscles that dominated the termination of the tasks. Pushing with body leaning forward to utilize partial body weight was less fatiguing than the other two postures. Elbow flexion is undesirable and should be avoided when performing such tasks.     

A passive movement method for parameter estimation of a musculo-skeletal arm model incorporating a modified hill muscle model

In this paper we present an experimental method of parameterising the passive mechanical characteristics of the bicep and tricep muscles in vivo, by fitting the dynamics of a two muscle arm model incorporating anatomically meaningful and structurally identifiable modified Hill muscle models to measured elbow movements. Measurements of the passive flexion and extension of the elbow joint were obtained using 3D motion capture, from which the elbow angle trajectories were determined and used to obtain the spring constants and damping coefficients in the model through parameter estimation. Four healthy subjects were used in the experiments. Anatomical lengths and moment of inertia values of the subjects were determined by direct measurement and calculation. There was good reproducibility in the measured arm movement between trials, and similar joint angle trajectory characteristics were seen between subjects. Each subject had their own set of fitted parameter values determined and the results showed good agreement between measured and simulated data. The average fitted muscle parallel spring constant across all subjects was 143 N/m and the average fitted muscle parallel damping constant was 1.73 Ns/m. The passive movement method was proven to be successful, and can be applied to other joints in the human body, where muscles with similar actions are grouped together.     

Pneumatic-driven jumping robot with anthropomorphic muscular skeleton structure

Human muscular skeleton structure plays an important role for adaptive locomotion. Understanding of its mechanism is expected to be used for realizing adaptive locomotion of a humanoid robot as well. In this paper, a jumping robot driven by pneumatic artificial muscles is designed to duplicate human leg structure and function. It has three joints and nine muscles, three of them are biarticular muscles. For controlling such a redundant robot, we take biomechanical findings into account: biarticular muscles mainly contribute to joint coordination whereas monoarticular muscles contribute to provide power. Through experiments, we find (1) the biarticular muscles realize coordinated movement of joints when knee and/or hip is extended, (2) the extension of the ankle does not lead to coordinated movement, and (3) we can superpose extension of the knee with that of the hip without losing the joint coordination. The obtained knowledge can be used not only for robots, but may also contribute to understanding of adaptive human mechanism.     

Data-driven facial expression synthesis via Laplacian deformation

Realistic talking heads have important use in interactive multimedia applications. This paper presents a novel framework to synthesize realistic facial animations driven by motion capture data using Laplacian deformation. We first capture the facial expression from a performer, then decompose the motion data into two components: the rigid movement of the head and the change of the facial expression. By making use of the local-detail preserving property of the Laplacian coordinate, we clone the captured facial expression onto a neutral 3D facial model using Laplacian deformation. We choose some expression “independent points” in the facial model as the fixed points when solving the Laplacian deformation equations. Experimental results show that our approach can synthesize realistic facial expressions in real time while preserving the facial details. We compare our method with the state-of-the-art facial expression synthesis methods to verify the advantages of our method. Our approach can be applied in real-time multimedia systems.     

Relationship between limb movement speed and associated contraction of the trunk muscles

Rapid shoulder movement is preceded by contraction of the abdominal muscles to prepare the body for the expected disturbance to postural equilibrium and spinal stability provoked by the reactive forces resulting from the movement. The magnitude of the reactive forces is proportional to the inertia of the limb. The aim of the study was to investigate if changes in the reaction time latency of the abdominal muscles was associated with variation in the magnitude of the reactive forces resulting from variation in limb speed. Fifteen participants performed shoulder flexion at three different speeds (fast, natural and slow). The onset of EMG of the abdominal muscles, erector spinae and anterior deltoid (AD) was recorded using a combination of fine-wire and surface electrodes. Mean and peak velocity was recorded for each limb movement speed for five participants. The onset of transversus abdominis (TrA) EMG preceded the onset of AD in only the fast movement condition. No significant difference in reaction time latency was recorded between the fast and natural speed conditions for all muscles. The reaction time of each of the abdominal muscles relative to AD was significantly delayed with the slow movement compared to the other two speeds. The results indicate that the reaction time latency of the trunk muscles is influenced by limb inertia only with limb movement below a threshold velocity.     

Examining kinematics and muscle activity of the upper extremity while performing cleaning tasks: A pre-post shift evaluation

Custodians engage in strenuous manual labour throughout their workday. Uncertainty exists on whether kinematics or muscle activation changes as workers progress through their shift. The purpose of this study was to examine muscle activation and upper extremity kinematics during typical custodial tasks performed at the start and end of the work shift. Electromyography (EMG) of 8 torso and upper extremity muscles and motion capture of the corresponding region were collected for 10 custodial participants while they completed garbage removal, dry mopping, and vacuuming tasks at the start and end of a work shift. The start of shift assessment demonstrated larger anterior deltoid, posterior deltoid and extensor digitorum activation by up to 12.6 %maximal voluntary contraction (%MVC) (p < 0.001–0.023). Task affected mean and peak EMG in all muscles except flexor digitorum (p < 0.001–0.0293), and the greatest activation was found during vacuuming (peak <55%MVC in anterior and middle deltoid) and the heaviest garbage removal task (84% MVC peak in upper trapezius). Mopping created the lowest amounts of activation for almost all muscles. Joint range of motion (p < 0.001–0.031) in the shoulder was highest in vacuuming, while trunk flexion was largest in garbage removal tasks. This work replicated common custodial tasks in a laboratory, using actual custodial workers at times relevant to their typical work shifts. The information presented is useful for ergonomists, work tasks designers and custodial administration staff to develop guidelines for injury prevention.     

Ankle angle effects on endurance time,median frequency and mean power of gastrocnemius EMG power spectrum: a comparison between individual and group analysis

Surface EMG of the gastrocnemius medialis muscle during sustained submaximal isometric contraction was recorded for eight subjects at two ankle angles (at a fixed knee angle). Power spectral median frequency and mean power was examined by means of Fourier analysed EMG and related to plantar flexion exertion time. A longer endurance time was found at the smaller ankle angle, for six of eight subjects. This is probably related to significantly smaller mean spectral power found for those subjects in that condition, indicating decreased voluntary excitation of the muscle despite equal net moment exertion relative to maximal voluntary contraction (60%) at both ankle angles. At exhaustion a significant decrease of spectral median frequency of 10% with respect to initial values was shown for the group of subjects at both ankle angles. However not every individual subject showed a significant decrease of median frequency. In fact such a decrease was only shown for 7 out of 16 experiments. An influence of ankle angle was found on initial median frequency. It is concluded that ankle angle may affect voluntary excitation of gastrocnemius and that the use of EMG spectral median frequency as an indicator of muscle fatigue is not valid for individual analysis.     

Using extension method for health analysis system of a fitness device

This paper used foot-operated fitness equipment, a power generation system and a biomedical measurement system to construct a fitness system for fitness exercise, energy storage and diagnosing the user’s movement conditions. The diagnostic mode is that the rotation speed and output power of pedal-dynamo are converted into the mileage and calorie consumption of the user’s pedaling movement. Second, the biomedical measurement module can diagnose the user’s movement health status timely according to the heartbeat signals and the consumed calories while the user is in exercise. The diagnostic data were integrated using touch tablet PC and LabVIEW software for the image controlled man-machine interface. The user can observe the real-time motion state through the virtual instrument interface. The built-in program can diagnose the health status, and count the total generation and movement process after exercise.     

EMG onset detection and upper limb movements identification algorithm

Electromyography (EMG) consists of the measurement and recording of the electrical potential generated by the activation of muscle fibers when performing voluntary or involuntary movements. Therefore, electromyography signals (EMGs) are directly linked to the movement performed by a person. Hence, the study of surface EMGs to determine the movement a person is performing to control exoskeletons for post-stroke rehabilitation has become increasingly popular in recent years; particularly towards bilateral rehabilitation (BLR). Bilateral rehabilitation provides the patient the opportunity to control the intensity and frequency of the rehabilitation exercises. This paper introduces an onset detection method and a movement identification algorithm to differentiate (identify) among five different movements of the upper limb; abduction (AB), adduction (AD), flexion of the upper limb (FUL), extension of the upper limb (EUL) and AB followed by arm to the front (ABF). The movement identification algorithm focuses on the activation of muscle fibers within a single muscle when performing different movements; rather than a comparison between flexor and extensor muscles. This algorithm was evaluated using surface EMG recordings measured on healthy subjects at the Deltoid Muscle. Prior to the movement identification, the proper EMG preprocessing, feature extraction and onset detection of each EMGs recording was performed using Matlab. Two features were extracted from each channel, the root mean square (RMS) and the contractility characteristic of the muscle. An algorithm is then followed to identify the movement performed by a person. Results have shown a highly percentage of accuracy for both, the onset detection and movement identification algorithms.     

Net shoulder joint moment and muscular activity during light weight-handling at different displacements and frequencies.

The purpose of this study was to calculate net shoulder (gleno-humeral) joint moments from inverse dynamics and to measure muscular activity from six shoulder muscles (supraspinatus, infraspinatus, middle deltoid, anterior deltoid, trapezius, and pectoralis major) during light weight-handling at two different displacements (horizontal and vertical) and frequencies (40 and 60 cycles/min), to simulate an occupational cervicobrachial working task (light weight displacement). Ten normal adult male subjects were asked to move a known weight, representing 15% of the maximal lifted weight, in both horizontal and vertical conditions at frequencies of 40 cycles/min and 60 cycles/min. Raw EMG signals from six shoulder muscles were recorded and synchronized with the cinematographic data during three trials of 6 s each. The raw EMG signals of each muscle were full wave rectified and filtered at 3 Hz. The linear envelope (LE EMG) signals were normalized by time (% cycle) and by amplitude (% MVC), and for the analysis of variance, the normalized LE EMG signals were integrated (IN LE EMG). The average shoulder angular velocities, joint moments, and moment powers were computed from cinematographical data. No significant differences were observed between both tasks for the supraspinatus, infraspinatus, and pectoralis major IN LE EMG data as well as for integrated normalized shoulder joint moment for the whole cycle of movement. IN LE EMG data from middle deltoid, anterior deltoid, and trapezius muscles were significantly higher (p less than 0.05) when performing the vertical displacement task for the whole cycle of movement. This muscular activity difference between vertical and horizontal tasks indicated that the vertical displacement conditions induced higher muscular loads on the shoulder than the horizontal weight displacement conditions, although the vertical displacements were approximately 15% longer than the horizontal displacements. The non-significant difference of IN LE EMG between frequencies obtained for all muscles indicated that neither frequencies induced more muscular activity.