The effect of handgrip span on isometric exercise performance

Fourteen male and eight female volunteers served as subjects in these experiments lo determine the effect of hand tool dimensions on isometric strength, endurance, the surface EMG above the active muscle, and the cardiovascular responses to isometric exercise. As reported by others, we found that for each individual, there existed one handgrip size at which he or she could exert the greatest isometric strength. Endurance was the same at any work load relative to the maximum strength for a given grip dimension. The EMG and blood pressure responses to isometric exercise were the same at any given grip span: however, the heart rate response was lowest when subjects worked with their muscles at the optimal grip span.     

Estimation of hand force in ergonomic job evaluations

The aims of the present study were: (1) to collect normative data of pinch and power grip strength with a newer digital dynamometer; (2) to study the ability of hand grip force matching using a hand dynamometer where the validity and reliability issues were studied; and (3) to study the relationship between hand grip force matching and muscle activities of three forearm and hand muscles. This study consisted of two experiments. One hundred and twenty subjects volunteered in the first experiment, where hand grip strength and hand force estimation data were collected. The second experiment had 14 volunteers, where muscle activities of the hand and forearm were collected during the tests of hand grip strength and hand force matching estimations. Results showed that the power grip and pinch grip strengths collected with a newer digital dynamometer were comparable to similar studies using older equipment. At the group level, the force matching method was largely accurate and consistent. Instructions to the subjects about force matching estimation were important to the accuracy and consistency of the estimated forces. Estimation in force matching might depend on perceptions of several major muscle activities.     

Estimation of hand force in ergonomic job evaluations

The aims of the present study were: (1) to collect normative data of pinch and power grip strength with a newer digital dynamometer; (2) to study the ability of hand grip force matching using a hand dynamometer where the validity and reliability issues were studied; and (3) to study the relationship between hand grip force matching and muscle activities of three forearm and hand muscles. This study consisted of two experiments. One hundred and twenty subjects volunteered in the first experiment, where hand grip strength and hand force estimation data were collected. The second experiment had 14 volunteers, where muscle activities of the hand and forearm were collected during the tests of hand grip strength and hand force matching estimations. Results showed that the power grip and pinch grip strengths collected with a newer digital dynamometer were comparable to similar studies using older equipment. At the group level, the force matching method was largely accurate and consistent. Instructions to the subjects about force matching estimation were important to the accuracy and consistency of the estimated forces. Estimation in force matching might depend on perceptions of several major muscle activities.     

Optimization of human-powered elastic mechanisms for endurance amplification

Throughout the human body hundreds of muscles exert forces to stiffen and move the limbs and torso. During heavy exercise, only a small portion of these muscles fatigue. We report here a new kind of human-powered mechanism which amplifies endurance by altering the distribution of work output between fatiguing and nonfatiguing muscles. During heavy exercise, springs within the mechanism are stretched by muscles which would not fatigue if the exercise were conducted without the mechanism. This stored energy is then used to assist those muscles which typically would fatigue, resulting in an increase in endurance. A mathematical model is used to predict the efficiency with which the body can perform mechanical work at various spring stiffnesses for a particular heavy-exercise activity and mechanism. The model results support the hypothesis that the spring stiffnesses which maximize endurance also maximize the efficiency with which the human body can perform work.     

基于BOA-ELM的混凝土抗压强度预测研究

为控制控制混凝土生产成本,在混凝土拌和期限制抗压强度不足的缺陷构建产出,可以有效降低原料的浪费,是节能降耗的关键方法之一。针对混凝土抗压强度的传统测量方法严重滞后的问题,提出了基于贝叶斯优化极限学习机(BOA-ELM)的混凝土抗压强度预测方法。首先,分析了混凝土拌和过程中对抗压强度预测值实时获得的需求。以各物料的用量为分析基础,28天标准养护后混凝土抗压强度值为预测目标,设计了基于极限学习机的强度预测模型。其次,为进一步提高模型的稳定性以及准确行,提出基于贝叶斯优化的极限学习机模型,根据模型超参数的分布特征,以高斯过程作为超参的先验分布,预测误差最小化作为目标,寻找最优的模型超参。最后,在实际施工产生的C50标号混凝土数据集上测试文中模型,并对比分析了其他预测模型和寻优算法。结果表明,结合了贝叶斯优化的极限学习机预测模型相较于经典算法具有更高的预测准确性和模型训练的高效性。     

Force control of twisted and coiled polymer actuators via active control of electrical heating and forced convective liquid cooling

For decades, numerous artificial muscles have been proposed in order to implement beneficial features of biological muscles into robotics. Unfortunately, traditional artificial muscles experienced difficulties in imitating properties of the biological muscles due to mechanical and control issues. Recently, twisted and coiled polymer actuators (TCP) have been shown to produce large mechanical power via thermal stimulations and strong linearity. In this paper, a high-performance TCP thermally cycled by electrical heating and forced convective liquid cooling is designed and associated control algorithms are presented. We elaborate the model of the TCP that is simple, yet provides insight into how the electrical heating and the forced convective liquid cooling contribute to the TCP actuation. The proposed model is verified by experimental studies. Based on the proposed model, we design a feedforward–feedback controller and switching laws, which actively control the TCP in both the heating and cooling cycles. Furthermore, we extend our control methodology to agonist–antagonist TCPs. From the experimental studies, the proposed method is shown to be effective in both single TCP and antagonistic TCPs.     

Changes in the force development characteristics of muscle following repeated maximum force and power exercise

There is some evidence to suggest that ability to develop force in skeletal muscle can be improved for a short period following repeated maximal strength exercise. Some studies have suggested the phenomenon known as post-activation potentiation (PAP) to explain this immediate response to such exercise. However, little is known about the physical and temporal characteristics of the changes in muscle function due to PAP when induced using whole-body maximal strength exercise. The purpose of this study was to establish the physical and temporal characteristics of PAP of muscle function in elite male athletes following maximum strength and power exercise. Fifteen participants performed one of repeated maximal strength exercise or maximal power exercise or a control protocol on separate occasions. Changes in maximum isometric voluntary force (iMF), maximum isometric rate of force development (iRFD) and maximum vertical counter-movement jump (CMJ) were assessed. Results suggest that post-activation potentiation of iRFD occurs but is preceded by an initial suppression of force development capability following repeated maximal strength exercise. Following repeated maximal power exercise, however, post-activation potentiation of iRFD occurs immediately but is not seen over as long a period as that observed following maximal strength exercise. These results suggest that post-activation potentiation does bring about increased force development capability following intense exercise and that the temporal profile of the post-activation potentiation changes with intensity of the exercise used to induce it.     

Nonlinear predictive control of smooth nonlinear systems based on Volterra models. Application to a pilot plant

There is a large demand to apply nonlinear algorithms to control nonlinear systems. With algorithms considering the process nonlinearities, better control performance is expected in the whole operating range than with linear control algorithms. Three predictive control algorithms based on a Volterra model are considered. The iterative predictive control algorithm to solve the complete nonlinear problem uses the non‐autoregressive Volterra model calculated from the identified autoregressive Volterra model. Two algorithms for a reduced nonlinear optimization problem are considered for the unconstrained case, where an analytic control expression can be given. The performance of the three algorithms is analyzed and compared for reference signal tracking and disturbance rejection. The algorithms are applied and compared in simulation to control a Wiener model, and are used for real‐time control of a chemical pilot plant. Copyright © 2009 John Wiley & Sons, Ltd.     

Improved Control Strategy of 2-Sliding Controls Applied to a Flexible Robot Arm

Controlling a flexible robot arm driven by McKibben artificial muscles with direct transmission is delicate. The usual PID controller rapidly reveals itself to be inadequate and robust control tools are unavoidable. Classical sliding control, although robust, generates chatter. Several solutions are available to attenuate this phenomenon, among them the twisting and super twisting algorithms, which belong to the 2-sliding control set. It will be shown when to use the equivalent control and the effect of a noised sensor signal on control performance. Also, the use of an additional discontinuous term that increases robustness, performance and stability is put forward. Experimental results are presented and discussed.     

Co-simulation research of a novel exoskeleton-human robot system on humanoid gaits with fuzzy-PID/PID algorithms

Legged exoskeletons supplement human intelligence with the strength and endurance of a pair of wearable mechanical legs that support heavy loads. The exoskeleton-type system is a nonlinear system with uncertainty of parameters, which is not easy to be identified with traditional mathematical model. This paper presents co-simulations of a novel exoskeleton-human robot system on humanoid gaits with fuzzy-PID/PID algorithms, which do not need the precise model. The lower extremity exoskeleton model with series–parallel topology was briefly described and the gait characteristics were analyzed. The co-simulation method integrates ADAMS and MATLAB/SIMULINK with fuzzy-PID/PID algorithms, which were used to develop the control schematic of the exoskeleton-human robot system. Finally, co-simulations of humanoid gaits and movements, which include level walking, stair ascent, stair descent, side kick, squatting down and standing up, were provided to confirm the performances and effectiveness of the proposed control approach.     

Predicting muscle forces measurements from kinematics data using kinect in stroke rehabilitation

Muscle strength is mostly measured by wearable devices. However, wearing such devices is a tedious, unpleasant, and sometimes impossible task for stroke patients. In this paper, a mathematical model is proposed to estimate the strength of the upper limb muscles of a stroke patient by using Microsoft Kinect sensor. A prototype exergame is designed and developed to mimic real post-stroke rehabilitation exercises. Least-square regression matrix is used to find the relation between the kinematics of the upper limb and the strength of the corresponding muscles. Kinect sensor is used along with a force sensing resistors (FSR) glove and two straps to collect both, real-time upper limb joints data and the strength of muscles of the subjects while they are performing the exercises. The prototype of this system is tested on five stroke patients and eight healthy subjects. Results show that there is no statistically significant difference between the measured and the estimated values of the upper-limb muscles of the stroke patients. Thus, the proposed method is useful in estimating the strength of the muscles of stroke patient without the need to wear any devices.     

Designing an exergaming system for exercise bikes using kinect sensors and Google Earth

This paper proposes an Exergaming system for exercise bikes. With the assistance of a Kinect device and the proposed body-movement-detection algorithm, exercise bike users are required to perform correct neck and shoulder movements to control the airplane trajectory in Google Earth. They can take a flying tour in the virtual reality provided by Google Earth while riding an exercise bike. According to the experimental results, 95 % of the users in the experiment considered the proposed Exergaming system to be very entertaining; more than 85 % of the users affirmed that the assigned neck and shoulder movements effectively help stretch the muscles in these body parts; the detection rate of the proposed body-movement algorithm was over 90 %. Therefore, the proposed Exergaming system is a good assisting system for exercise bikes.     

Person recognition by hand shape based on skeleton of hand image

A new approach to the biometrical identification of a person based on the analysis of his hand shape is suggested in this paper. The shape is compared for reference and test hands. The reference hand is a preset model of the hand, while the test hand is the binary image obtained using a web-camera. In comparing the hans, the model’s adjustment to the test image is carried out for the best coincidence of their silhouettes. In contrast to the existing algorithms, the propsed method allows one to compare hands with partly occluded fingers, which are often observed under real conditions. The paper also describes a prototype of the system which allows real-time person recognition.     

Effects of exercise on carpal tunnel syndrome symptoms

This is a study of whether participation in an exercise programme for increasing upper extremity flexibility, strength, and circulation has any effects on symptoms of carpal tunnel syndrome (CTS). Two groups (exercise and control) of seven participants each who did repetitive hand motion tasks were studied. The exercise group participated in daily arm, hand, and other upper-extremity exercises for 8 weeks. The control group did not participate in the exercise programme. Dependent (response) variables monitored were motor nerve conduction latency through the carpal tunnel, grip strength, and subjective comfort in the dominant hands of participants. Test results indicated no statistically significant differences in nerve conduction latency or subjective comfort between the two groups. Significant differences did develop in grip strengths over time, suggesting that the exercise group may have benefited physiologically from the exercise programme.     

Multi-loop control of liquid cooling garment systems

In this study the effects of multi-loop control of liquid cooling garments (LCGs) under exercise heat stress conditions were investigated by experiments and theoretical analysis. A triple-loop LCG, by which the torso, arms and legs could be independently cooled, was used in the two series of experiments carried out in a hot environment (35 degrees C/40% RH). The experiment consisted of rest, exercise on an ergometer at 70 W and exercise at 110 W. In the first experiment, each water inlet temperature (TWI) was adjusted according to the local thermal sensation. In the second experiment, TWI for the torso including arms and TWI for the legs were regulated by a skin temperature controller with set-point adjustment via heart rate. The experiments showed that a multi-loop LCG is more effective than a single-loop LCG in providing thermal sensation and comfort adjusted to the requirements of the different parts of the body, and that a skin temperature controller could be applied to a multi-loop system. The theoretical analysis was carried out using a mathematical model of thermoregulation. The results showed that a strong cooling of the surface over the working muscles (legs) provided the greatest thermoregulatory advantage during low body exercise, because most of the heat generated within the working muscles can be removed directly by heat conduction to the skin. Optimization of a human/LCG system could be attained by an optimal configuration and control. However, an optimal configuration always depends on the application purpose of an LCG system.     

Electromyographic investigation of abdominal exercises and the effects of fatigue

Abdominal exercises are widely used to develop the anterior muscles of the trunk. These exercises can be undertaken without the aid of equipment, but increasingly manufacturers are developing equipment which purportedly enhances the training effect for abdominal muscles. As there are many different products and exercises used for abdominal muscle development, it is likely that some are more effective than others. This study aimed to investigate the effectiveness of five commonly performed abdominal exercises. A second aim was to investigate the effects of fatigue on these exercises. Five different types of abdominal exercise [standard crunch (sit-up) with bent knees, gym ball crunch, crunch with 5 kg weight held behind the head, legs raised crunch and a commercially manufactured roller crunch] were examined using integrated surface electromyography (IEMG). The lower rectus abdominis (LRA), upper rectus abdominis (URA) and obliquus externus abdominis (EO) of 15 healthy male participants [age (mean +/- SD) 22.2 +/- 6.8 years; height 1.77 +/- 0.06 m; mass 79.3 +/- 10.7 kg] were monitored using a four-channel special purpose EMG data logger. Three trials of each exercise were performed in random order and normalized to enable comparisons between muscles and exercises. At a later date, ten participants were then re-tested when fresh and after a 30 min whole-body fatigue protocol that specifically targeted the abdominal muscles. Two exercises were evaluated, the abdominal roller crunch and legs raised crunch, which were judged to be the least and most effective, respectively, of the five exercises previously used. The normalized IEMG showed significant (p < 0.001) differences between exercises (gym ball crunch = 86.0 +/- 7.5%; legs raised crunch = 79.9 +/- 5.1%; 5 kg weight crunch = 65.1 +/- 13.4%; standard crunch = 56.2 +/- 3.2%; and roller crunch = 45.0 +/- 11.4%). Post-fatigue, the normalized mean IEMG for both exercises increased significantly (p < 0.05) for LRA and URA muscles but not for the EO (p > 0.05). It was concluded that exercises can be constructed to provide a greater challenge to abdominal muscles, commercially available roller-type equipment appears to be little different from the standard abdominal crunch with bent knees, and fatiguing exercise results in the LRA and URA being more highly activated. These findings provide more detailed knowledge and understanding of the effects of different forms of abdominal exercise.     

非结构化P2P网络副本一致性研究*

随着P2P应用的发展,由以往共享只读文件逐渐改变为共享可读写的文件,文件的频繁更新导致了数据副本之间的不一致性,因此确保其副本一致性是保证正确运行的关键。通过文献调研,对目前国内外研究的副本一致性算法进行了详细的介绍,分析了各种算法的优缺点,并在现有算法的基础上进行了展望,提出下一步研究的方向和重点。     

Real-time hand tracking using a mean shift embedded particle filter

Particle filtering and mean shift (MS) are two successful approaches to visual tracking. Both have their respective strengths and weaknesses. In this paper, we propose to integrate advantages of the two approaches for improved tracking. By incorporating the MS optimization into particle filtering to move particles to local peaks in the likelihood, the proposed mean shift embedded particle filter (MSEPF) improves the sampling efficiency considerably. Our work is conducted in the context of developing a hand control interface for a robotic wheelchair. We realize real-time hand tracking in dynamic environments of the wheelchair using MSEPF. Extensive experimental results demonstrate that MSEPF outperforms the MS tracker and the conventional particle filter in hand tracking. Our approach produces reliable tracking while effectively handling rapid motion and distraction with roughly 85% fewer particles. We also present a simple method for dynamic gesture recognition. The hand control interface based on the proposed algorithms works well in dynamic environments of the wheelchair.     

Novel soft bending actuator-based power augmentation hand exoskeleton controlled by human intention

This article presents the development of a soft material power augmentation wearable robot using novel bending soft artificial muscles. This soft exoskeleton was developed as a human hand power augmentation system for healthy or partially hand disabled individuals. The proposed prototype serves healthy manual workers by decreasing the muscular effort needed for grasping objects. Furthermore, it is a power augmentation wearable robot for partially hand disabled or post-stroke patients, supporting and augmenting the fingers’ grasping force with minimum muscular effort in most everyday activities. This wearable robot can fit any adult hand size without the need for any mechanical system changes or calibration. Novel bending soft actuators are developed to actuate this power augmentation device. The performance of these actuators has been experimentally assessed. A geometrical kinematic analysis and mathematical output force model have been developed for the novel actuators. The performance of this mathematical model has been proven experimentally with promising results. The control system of this exoskeleton is created by hybridization between cascaded position and force closed-loop intelligent controllers. The cascaded position controller is designed for the bending actuators to follow the fingers in their bending movements. The force controller is developed to control the grasping force augmentation. The operation of the control system with the exoskeleton has been experimentally validated. EMG signals were monitored during the experiments to determine that the proposed exoskeleton system decreased the muscular efforts of the wearer.