基于SolidWorks六自由度机械臂的逆解求解与仿真

借助SolidWorks完善的二次开发功能,结合六自由度机械手臂的运动学逆解求解的理论研究,开发一种适用于大多数六自由度的机械手臂的逆解求解和运动仿真软件。首先运用基于三轴相交于一点的Pieper's solution解法来对机械手臂的运动学逆解进行求解,对于求解需要的矩阵则通过SolidWorks API中的矩阵相关函数来获取、计算;然后将求得的结果赋值给机械手臂模型中对应的角度来完成验证,对于一条连续的路径,则通过对路径上的每一点的计算、赋值,来验证规划所求得的路径的合理性。     

Effect of chiropractic manipulations on the kinematics of back and limbs in horses with clinically diagnosed back problems

REASON FOR PERFORMING STUDY: Although there is anecdotal evidence of clinical effectiveness of chiropractic in treatment of equine back pain, little scientific work has been reported on the subject. OBJECTIVES: To quantify the effect of chiropractic manipulations on back and limb kinematics in horse locomotion. METHODS: Kinematics of 10 Warmblood horses were measured over ground at walk and trot at their own, preferred speed before, and one hour and 3 weeks after chiropractic treatment that consisted of manipulations of the back, neck and pelvic area. Speed was the same during all measurements for each horse. RESULTS: Chiropractic manipulations resulted in increased flexion-extension range of motion (ROM) (P<0.05) at trot in the vertebral angular segments: T10-T13-T17 (0.3 degrees ) and T13-T17-L1 (0.8 degrees ) one hour after treatment, but decreased ROM after 3 weeks. The angular motion patterns (AMPs) of the same segments showed increased flexion at both gaits one hour after treatment (both angles 0.2 degrees at walk and 0.3 degrees at trot, P<0.05) and 3 weeks after treatment (1.0 degrees and 2.4 degrees at walk and 1.9 degrees and 2.9 degrees at trot, P<0.05). The lumbar (L3 and L5) area showed increased flexion after one hour (both angles 0.3 degrees at walk and 0.4 degrees at trot P<0.05), but increased extension after 3 weeks (1.4 degrees and 1.2 degrees , at trot only, P<0.05). There were no detectable changes in lateral bending AMPs. The inclination of the pelvis was reduced at trot one hour (1.6 degrees ) and 3 weeks (3 degrees ) after treatment (P<0.05). The mean axial rotation of the pelvis was more symmetrical 3 weeks after the treatment at both gaits (P<0.05). There were no changes in limb angles at walk and almost no changes at trot. CONCLUSIONS: The main overall effect of the chiropractic manipulations was a less extended thoracic back, a reduced inclination of the pelvis and improvement of the symmetry of the pelvic motion pattern. POTENTIAL RELEVANCE: Chiropractic manipulations elicit slight but significant changes in thoracolumbar and pelvic kinematics. Some of the changes are likely to be beneficial, but clinical trials with increased numbers of horses and longer follow-up are needed.     

What can we learn from visual and objective assessment of non-lame and lame horses in straight lines,on the lunge and ridden?

Traditionally and when using objective gait analysis, horses with and without lameness are most frequently assessed trotting in straight lines in hand. Valuable information can be gained from assessment on the lunge and ridden in walk, trot and canter. No studies have quantified lameness during all aforementioned conditions and gaits at once, despite the rapid recent development in equine gait analysis methods. Objective methodologies, previously confined to gait laboratories, are currently being expanded to field technologies using accelerometers and inertial measurement units (IMUs). This publication aims to describe normal gait and the spectrum of pain-related gait abnormalities and other musculoskeletal adaptations to pain that can be observed in walk, trot and canter during in hand and ridden assessment in straight lines and on a circle on hard and soft surfaces. In addition, it aims to describe briefly how IMUs have been used and areas for further research in the light of what we know from subjective lameness examinations and what is possible with IMUs.     

Kinetics and kinematics of the horse comparing left and right rising trot

Reasons for performing study: At rising trot the rider sits alternately down on one diagonal pair of limbs and rises up on the other. The possible effects on asymmetry of locomotion induced by rising trot have rarely been studied. Objectives: To demonstrate whether, and if so to what extent, rising trot causes asymmetrical loading in the vertical ground reaction force (VGRF) and/or asymmetrical effects on the locomotion pattern, comparing left and right side. Methods: Seven elite horses were ridden in left and right rising trot on a treadmill, while VGRF and kinematics were measured, with the horses' neck raised, the poll high and the bridge of the nose slightly in front of the vertical. Results: Force loading was generally increased in the limbs of the sitting diagonal. The lumbar back was lower between mid‐stances of the sitting and nonsitting stance, pelvic roll was limited and the tuber coxae heights were lower on the sitting side. Maximal hindlimb protraction was decreased. Forelimb retraction was increased and the T6 height decreased. Conclusion: The rider movement induces an uneven biphasic load that affects the back, pelvis and limb kinematics and VGRF. Potential relevance: The generally advocated technique of alternating limbs when riding in rising trot is supported. The VGRF changes between rising on the left or right diagonal were distinct, but minor in absolute terms and therefore unlikely to have direct impact on the occurrence of locomotor injuries. Knowledge of an increase of asymmetry in rising trot is potentially useful for riders/trainers.     

Biomechanics of the Distal Interphalangeal Joint

This article summarizes the kinematics of the distal interphalangeal (DIP) joint during locomotion at walk and trot. The patterns and ranges of motion in flexion and extension are very similar at walk (range of motion: 46±40) and trot (range of motion: 47±40). In both gaits there is a cucle of flexion that peaks in the first half of stance. The joint is extended through the remainder of stance in opposition to a palmar moment generated by the deep digital flexor tendon and its accessory ligament and the navicular ligaments. During locomotion in a straight line, small amounts of abduction/adduction (∼50) and internal/external rotation (5-60) occur, especially around the times of contact and breakover. Extra-sagittal motions increase as a consequence of hoof imbalance, during turning or when the horse moves over uneven terrain.     

基于倍四元数和Groebner基的6R机械手的位置反解

提出了一般6R机械手的位置反解的新算法,该算法是把齐次变换矩阵转以倍四元数形式表示,建立了倍四元数形式的串联6R机械手运动学方程,再通过线性消元和两次应用分次字典序Groebner基消去5个变元,得到一个一元16次方程.此方法没有增根,是一种对空间任意尺寸6R机械手进行建模和求解的新算法.其中求解Groebner基采用了计算机代数系统进行有理数运算,目前的求解速度尚不是很高,需进一步改进.     

6-3-3并联机构逆动力学分析与仿真

建立了6自由度6-3-3并联机构逆运动学模型,基于刚体动力学牛顿-欧拉法推导出了该机构逆动力学方程组,并用矩阵QR分解方法求解了该动力学方程组,给出了逆动力学仿真程序开发思路并通过Matlab软件加以实现,通过空载和有载荷作用条件下的算例仿真和分析比较,验证了该动力学模型的正确性.     

福建省东部近海地区冬季坡地逆温分析

山坡地果树在冬季强低温下会表现出不同的冻害特征,研究坡地逆温特征、选择适宜的坡位种植果树对避免或减轻低温给果树造成的损失具有重要意义。为研究山坡地逆温特征,2007／2008年度在永泰县境内山坡的不同坡位上布点进行最低温度考察,结果显示,在相对高差近300m的山坡上,相对坡位约7／10附近晴天的最低温度常出现最高,与坡底的最大逆温差达1．9℃。结合福建省东部4个市县10个山坡地的考察资料,分析得出坡地逆温具有以下特征：最大逆温出现的坡位与山坡的总高度差成反相关,随着总高度差的增加,最大逆温差出现的坡位呈下降趋势;随着排汇比（可排泄的方位角与360°之比）的减小,最大逆温差出现的坡位呈升高的趋势。最大逆温差值与山坡的排汇比、坡度和总高度差有关,最大逆温差值随着排汇比的减小呈增大的趋势、随坡度的增大呈增大的趋势;当排汇比和坡度相同时,最大逆温差值随山坡的总高度差的增大而减小。