Determination method for power-saved driving motions of manipulators by heuristic algorithms (in case of PTP control)

This study proposed a method for suppressing torques and consumed energy of manipulators considering an effect of inertial forces in order to achieve power-saved drive. The present paper describes the case that the start and end points of a work path of a manipulator are specified and the path between the points can be determined arbitrarily, which is so-called point-to-point (PTP) control. The proposed method determines both the initial pose of a manipulator and input motions of its joints so that the torque or consumed energy is suppressed. The input motion of the joint is expressed by a motion curve that indicates the time profiles of input displacements, velocities and accelerations. The proposed method determines the motion curve as a polynomial with appropriate coefficients. Those coefficients and their values are decided by a heuristic algorithm in order to suppress the input torques or consumed energy of a manipulator. The paper actually determines the power-saved drive motion of “PUMA560” by the proposed method and reveals its effectiveness.     

优秀女子短道速度滑冰运动员下肢肌力特征及与500米成绩的回归分析

摘要：目的：探讨短道速度滑冰运动员下肢肌力特征以及与500米成绩的回归分析,增强训练的优化性和对项目规律的认识。方法：运用ISOMED 2000多关节等速测力系统对我国10名女子短道速度滑冰国家队队员膝、踝关节肌肉力量进行测试。结果：1）相对峰力矩和总功指标角随速度增加而下降,各速度间呈显著性差异;而膝、踝关节屈伸比指标低于国际和国内标准;运动员的膝关节爆发能力较好,踝关节在高速度下表现不足。2）左右腿同名肌群除膝关节屈伸比、踝关节平均功率两项指标,均呈显著性差异（p<0.05）,多个指标超过10%的推荐值膝关节差值在4.5%～12.9%之间,踝关节差值在5.5%～14.5%之间。3）膝伸肌群峰力矩角度（240°/s）、膝屈肌群相对峰力矩（240°/s）和膝伸肌群平均功率（180°/s）3组指标进入与500 m成绩的逐步回归方程,相关系数为0.94,决定系数为0.90,方差检验p<0.05,方程有效。结论：优秀女子短道运动员下肢膝、踝关节屈伸力量符合生物力学特征,对于短道速度滑冰项目高速度区比低速度区的力量能力更重要,膝关节肌群相对踝关节在500 m项目中起到更大作用,短道运动员的膝、踝屈伸肌群比例较低,或具有项目特点,与技术相关的力量指标与成绩的相关性更高,训练中应加强两腿同名肌群力量的平衡性,减少由于肌群不平衡所引起的伤病和技术缺陷。     

地面煤流201G皮带机改造方案

文章对地面煤流系统进行了改造,并提出了皮带机改造的方案及对策,对提高皮带机系统的可靠性,保证矿井安全、经济、稳定运行有重要的参考价值。     

临吹门控制方式改进

在电源点新建项目中,必须对锅炉过热汽,再热汽等管道进行蒸汽吹扫,已达到国家标准要求及机组运行要求,从而较好的保护机组设备。临吹门就是控制蒸汽吹扫过程的主要设备。这就要求临吹门具有较高的可靠性,动作灵活,控制方式安全、可靠,以适应吹管过程中的恶劣环境,保证吹管过程安全可靠的进行。     

Acute effects of static stretching on characteristics of the isokinetic angle – torque relationship,surface electromyography,and mechanomyography

Abstract

The aims of this study were to examine the acute effects of static stretching on peak torque, work, the joint angle at peak torque, acceleration time, isokinetic range of motion, mechanomyographic amplitude, and electromyographic amplitude of the rectus femoris during maximal concentric isokinetic leg extensions at 1.04 and 5.23 rad · s^?1 in men and women. Ten women (mean ± s: age 23.0 ± 2.9 years, stature 1.61 ± 0.12 m, mass 63.3 ± 9.9 kg) and eight men (age 21.4 ± 3.0 years, stature 1.83 ± 0.11 m, mass 83.1 ± 15.2 kg) performed maximal voluntary concentric isokinetic leg extensions at 1.04 and 5.23 rad · s^?1. Following the initial isokinetic tests, the dominant leg extensors were stretched using four static stretching exercises. After the stretching, the isokinetic tests were repeated. Peak torque, acceleration time, and electromyographic amplitude decreased (P≤ 0.05) from pre- to post-stretching at 1.04 and 5.23 rad · s^?1; there were no changes (P > 0.05) in work, joint angle at peak torque, isokinetic range of motion, or mechanomyographic amplitude. These findings indicate no stretching-related changes in the area under the angle – torque curve (work), but a significant decrease in peak torque, which suggests that static stretching may cause a “flattening” of the angle – torque curve that reduces peak strength but allows for greater force production at other joint angles. These findings, in conjunction with the increased limb acceleration rates (decreased acceleration time) observed in the present study, provide tentative support for the hypothesis that static stretching alters the angle – torque relationship and/or sarcomere shortening velocity.     

Determining the minimum number of passive stretches necessary to alter musculotendinous stiffness

Abstract

In this study, we examined the minimum number of constant-torque passive stretches necessary to reduce musculotendinous stiffness. Thirteen healthy individuals (mean age 22 years, s = 3; stature 1.67 m, s = 0.1; mass 66 kg, s = 13 kg) volunteered to participate in the investigation and underwent four 30-s constant-torque passive stretches of the plantar flexor muscles. Musculotendinous stiffness was examined from the angle–torque curves generated prior to the passive stretches, at the beginning of each 30-s stretch, and immediately following the four 30-s passive stretches. The results indicated that musculotendinous stiffness of the plantar flexors was reduced following two 30-s constant-torque passive stretches (P < 0.05) compared with the pre- musculotendinous stiffness assessment. Musculotendinous stiffness remained depressed following the third and fourth stretches, but did not decrease further. These findings suggest that two 30-s bouts of constant-torque passive stretching may be necessary to cause a significant decrease in musculotendinous stiffness of the plantar flexor muscles.     

Size–strength relationships of the elbow flexors and extensors are not affected by age or gender

Abstract

In the present study, we examined the relationships between muscle volume and joint torque for the elbow flexors and extensors in young and elderly individuals, with the aim of evaluating age effects on these relationships. The participants were 45 young (27 men and 18 women aged 20–37 years) and 51 elderly (19 men and 32 women aged 60–77 years) individuals. The joint torques developed during isometric maximal voluntary elbow flexion and extension were measured using a torque meter. The muscle volumes of the elbow flexors and extensors were determined by magnetic resonance imaging. For the elbow flexors, joint torque was significantly correlated with muscle volume in both young and elderly individuals (r=0.564–0.872). There were also significant correlations between muscle volume and joint torque for the elbow extensors in elderly men and women as well as in young men and women (r=0.715–0.826). None of the y-intercepts of the regression lines between muscle volume and joint torque were significantly different from zero. Furthermore, no significant age or gender effects on the joint torque per muscle volume of the elbow flexors and extensors were observed. The present results suggest that muscle volume is a main determinant of joint torque regardless of age and gender, for both muscle groups.     

Inter-session Reliability of Glenohumeral Internal and External Rotation Range-of-motion Measurements is Unaffected by Use of Applied Load Feedback

ABSTRACT

This study evaluated whether real-time applied load feedback and a predefined applied load limit improved inter-session reliability and measurement error of passive glenohumeral rotation range-of-motion measurements. Twenty-one male recreational overhead athletes completed two data collection sessions, approximately 1-week apart. Measurements of internal and external rotation range-of-motion and clinician-applied loads were obtained and side-to-side differences were calculated. A load limit of 4 Nm was used for feedback trials. Perception of a capsular end-feel was used for no-feedback trials. Intraclass correlation coefficients (ICCs), standard errors of measurement (SEMs) and minimal detectable changes (MDCs) were derived. ICCs from single trials with and without feedback ranged from 0.72–0.93 and 0.63–0.89, respectively. SEMs ranged from 2.6°-6.1° with feedback and 3.3°-6.0° without feedback. MDCs from single trials with and without feedback ranged from 7.2°-16.8° and 9.1°-16.7°, respectively. Applied load feedback did not improve, already moderate to excellent, inter-session reliability and SEM for passive glenohumeral rotation range-of-motion measurements.     

振动力量训练对跨栏跑运动员髋关节肌力变化影响的实验研究

运用对比实验方法,采用JETVIBE(ETS-900N模式)振动训练台,对首都体育学院跨栏跑专项二级运动员进行振动刺激力量训练,振动频率为25～40Hz。经过8周系统的力量训练,在60°/s和300°/s测试条件下,利用ISOMED2000等速测试训练仪器分别对2组受试者髋关节屈伸肌群进行等速力量测试。研究结果:实验后,Ⅰ组和Ⅱ组受试者髋关节屈伸肌群相对峰值力矩、总功都有显著性提高(P<0.05),最大做功有非常显著性提高;组间比较,Ⅱ组受试者髋关节屈伸肌群相对峰值力矩、最大功和总功的增长率均高于Ⅰ组,差异具有显著性(P<0.05)。研究结论:在传统力量训练中附加振动刺激,能更有效地达到提高髋关节力量训练的目的;振动刺激能更好地提高髋关节的最大力量和耐力水平;振动力量训练在前4周使髋关节屈伸肌群肌力保持相同的速度增长,而后4周髋关节伸肌肌群肌力的增长速度明显高于屈肌肌群肌力增长速度。     

Research and industrial application of a novel compound permanent magnet synchronous machine

We propose a novel kind of compound permanent magnet synchronous machine （CPMSM）, which is applicable in low-speed and high-torque situations. We first explain the structure of the CPMSM. Based on theoretically deducing the calculation formulae of the CPMSM electromagnetic parameters, we analyze the operating characteristics of the CPMSM, and obtain the power-angle curves and working curves. The no-load magnetic field distribution and the cogging torque are analyzed by applying the finite element method of three-dimensional （3D） magnetic fields, to determine the no-load leakage coefficient and the waveform of the cogging torque. Furthermore, the optimal parameters of the permanent magnet for reducing the cogging torque are determined. An important application target of the CPMSM is in direct-drive pumping units. We have installed and tested a directdrive pumping unit in an existing oil well. Test results show that the power consUmption of the direct-drive pumping unit driven by CPMSM is 61.1% of that of the beam-pumping unit, and that the floor space and weight are only 50% of those of a beam-pumping unit. The noise output does not exceed 58 dB in a range of 1 m around the machine when the machine is 1.5 m from the ground.