MODELING AND CONTROLLING OF PARALLEL MANIPULATOR JOINT DRIVEN BY PNEUMATIC MUSCLES

A parallel manipulator joint driven by three pneumatic muscles and its posture control strategy are presented. Based on geometric constraints and dynamics, a system model is developed through which some influences on dynamic response and open-loop gain are analyzed including the supply pressure, the initial pressure and the volume of pneumatic muscle. A sliding-mode controller with a nonlinear switching function is applied to control posture, which adopts the combination of a main method that separates control of each muscle and an auxiliary method that postures error evaluation of multiple muscles, especially adopting the segmented and intelligent adjustments of sliding-mode parameters to fit different expected postures and initial states. Experimental results show that this control strategy not only amounts to the steady-state error of 0. 1° without overshoot, but also achieves good trajectory tracking.

Optimization Algorithm for Operation Comfortability of Master Manipulator of Minimally Invasive Surgery Robot

To evaluate the operation comfortability in the master-slave robotic minimally invasive surgery(MIS), an optimal function was built with two operation comfortability decided indices, i.e., the center distance and volume contact ratio. Two verifying experiments on Phantom Desktop and Micro Hand S were conducted. Experimental results show that the operation effect at the optimal relative location is better than that at the random location, which means that the optimal function constructed in this paper is effective in optimizing the operation comfortability.

Effect of Abnormal Posture on Quality of Life in Patients with Parkinson’s Disease

Background: Relationship between abnormal posture and QOL of Parkinson's disease is not clear. Objectives: To clarify the association between quality of life (QOL) and abnormal posture in patients with Parkinson’s disease (PD) and examine which QOL dimensions are involved. Methods: This study retrospectively examined PD patients (n = 57) who had undergone outpatient rehabilitation between January and March 2014. Evaluation items were Modified Hoehn Yahr (H-Y) stage, Unified Parkinson’s Disease Rating Scale (UPDRS)-Part III score, Timed Up and Go test (TUG, 3-m walking) result, Parkinson’s Disease Questionnaire (PDQ)-39 score, and the angle of forward and lateral trunk flexion in the standing position. Statistical analysis was performed to reveal the relationship between the total PDQ-39 score and individual evaluation items and which QOL dimensions were affected by abnormal posture due to forward or lateral flexion. Results: A total of 38 PD patients (17 men, 21 women;mean age, 73.2 ± 8.6 years) were enrolled. Among the evaluation items, lateral flexion angle showed a significant correlation with the total PDQ-39 score (r = 0.422, P = 0.008). PDQ-39 dimensions showing an association with forward flexion were activities of daily living (ADL) (P = 0.002) and communication (P = 0.007), whereas ADL (P = 0.004), communication (P = 0.021), and social support (P = 0.029) were associated with lateral flexion. Mobility was not associated with forward or lateral flexion. Conclusion: The present findings revealed a correlation between lateral flexion and QOL in PD patients. Among the PDQ-39 dimensions, ADL and communication were associated with abnormal posture.

An Adaptive Fuzzy Controller for Trajectory Tracking of Robot Manipulator

In this paper, an adaptive fuzzy control algorithm is proposed for trajectory tracking of an n-DOF robot manipulator subjected to parametric uncertainty and it is advantageous compared to the conventional nonlinear saturation controller. The asymptotic stability of the proposed controller has been derived based on Lyapunaov energy function. The design procedure is straightforward due to its simple fuzzy rules and control strategies. The simulation results show that the present control strategy effectively reduces the control effort with negligible chattering in control torque signals in comparison to the existing nonlinear saturation controller.

The relationship between intermittent limit cycles and postural instability associated with Parkinson’s disease

Background:Many disease-specific factors such as muscular weakness,increased muscle stiffness,varying postural strategies,and changes in postural reflexes have been shown to lead to postural instability and fall risk in people with Parkinson's disease(PD).Recently,analytical techniques,inspired by the dynamical systems perspective on movement control and coordination,have been used to examine the mechanisms underlying the dynamics of postural declines and the emergence of postural instabilities in people with PD.Methods:A wavelet-based technique was used to identify limit cycle oscillations(LCOs) in the anterior–posterior(AP) postural sway of people with mild PD(n = 10) compared to age-matched controls(n = 10).Participants stood on a foam and on a rigid surface while completing a dual task(speaking).Results:There was no significant difference in the root mean square of center of pressure between groups.Three out of 10 participants with PD demonstrated LCOs on the foam surface,while none in the control group demonstrated LCOs.An inverted pendulum model of bipedal stance was used to demonstrate that LCOs occur due to disease-specific changes associated with PD:time-delay and neuromuscular feedback gain.Conclusion:Overall,the LCO analysis and mathematical model appear to capture the subtle postural instabilities associated with mild PD.In addition,these findings provide insights into the mechanisms that lead to the emergence of unstable posture in patients with PD.

基于Sigmoid函数的非对称式S型曲线机械臂加减速控制方法

机械臂广泛应用于制造、装配、搬运、码垛等方面,对提高生产力起着重要作用。为减小机械臂在运动过程中的振动和冲击,提高机械臂轨迹执行效率,提出一种非对称式S型曲线加减速控制方法。该方法通过在双段Sigmoid函数中插入直线段,构成加加速度连续的运动学曲线。通过粒子群算法进行参数优化求解,无需反复确认每个时间段的存在性即可求出非对称约束下的曲线参数,并分别在关节空间和笛卡尔空间采用时间同步和位移同步方法使机械臂的运动轨迹更加协调自然。结果表明,相同条件下提出的方法比三角函数方法轨迹执行效率更高且加加速度仅为三角函数方法的55%。与梯形加加速度曲线相比,采用提出的方法规划的运动轨迹可减少35.7%的残余振动,验证了该方法的有效性。

Electroacupuncture Alleviates Memory Deficits in APP/PS1 Mice by Targeting Serotonergic Neurons in Dorsal Raphe Nucleus

Objective Alzheimer’s disease(AD)has become a significant global concern,but effective drugs able to slow down AD progression is still lacked.Electroacupuncture(EA)has been demonstrated to ameliorate cognitive impairment in individuals with AD.However,the underlying mechanisms remains poorly understood.This study aimed at examining the neuroprotective properties of EA and its potential mechanism of action against AD.Methods APP/PS1 transgenic mice were employed to evaluate the protective effects of EA on Shenshu(BL 23)and Baihui(GV 20).Chemogenetic manipulation was used to activate or inhibit serotonergic neurons within the dorsal raphe nucleus(DRN).Learning and memory abilities were assessed by the novel object recognition and Morris water maze tests.Golgi staining,western blot,and immunostaining were utilized to determine EA-induced neuroprotection.Results EA at Shenshu(BL 23)and Baihui(GV 20)effectively ameliorated learning and memory impairments in APP/PS1 mice.EA attenuated dendritic spine loss,increased the expression levels of PSD95,synaptophysin,and brain-derived neurotrophic factor in hippocampus.Activation of serotonergic neurons within the DRN can ameliorate cognitive deficits in AD by activating glutamatergic neurons mediated by 5-HT1B.Chemogenetic inhibition of serotonergic neurons in the DRN reversed the effects of EA on synaptic plasticity and memory.Conclusion EA can alleviate cognitive dysfunction in APP/PS1 mice by activating serotonergic neurons in the DRN.Further study is necessary to better understand how the serotonergic neurons-related neural circuits involves in EA-induced memory improvement in AD.

基于三次S型速度控制算法的移动机械臂末端振动研究

移动机械臂在实际工作环境中,受其自身柔性特征和外部因素的影响而引起机械臂末端的振动,而速度控制是实现机械臂末端抑振的有效手段之一。以UR10机械臂和Husky移动平台组成的移动机械臂为研究对象,针对梯形和S型速度控制算法的不足,提出一种三次S型速度控制算法,通过建立移动机械臂刚柔耦合动力学的理论和仿真模型得到移动机械臂末端的振动位移曲线和加速度变化曲线,验证了三次S型速度控制算法的正确性和抑振效果的有效性。

基于T-S模糊的欠驱动机械臂的平衡控制

针对欠驱动机械臂平衡控制精度低,鲁棒性差,抗干扰空间狭窄,起摆成功率低等问题,提出了一种基于T-S模糊结构和线性调节理论的欠驱动机械臂平衡控制策略,并实现了一种新的起摆-平衡控制方式。首先将系统设定的状态空间分为若干个模糊子空间,通过线性二次型最优理论和线性调节理论,在每个模糊子空间建立局部控制器,保证系统在每个局部子空间中平衡,并最终收敛于给定平衡点,然后使用隶属函数平滑的将各个局部控制器连接起来,最终得到非线性控制对象的模糊平衡控制器,实现了欠驱动机械臂在任意给定点的平衡控制。实验结果表明,所提出的控制策略控制精度高,抗干扰范围大,鲁棒性强,起摆成功率高,并且易于实现,具有较高的推广和应用价值。

位姿变化对6-SPS并联机器人精度的影响

通过对 6-SPS型并联机器人位置输入输出方程微分 ,获得机器人逆雅可比矩阵。研究机器人处于非奇异位姿即逆雅可比矩阵行列式不接近零时 ,位姿变化对机器人精度的影响。

柔性臂杆、柔性关节空间机械臂T-S模糊轨迹跟踪及双柔振动并行综合控制

针对存在参数不确定和外界干扰的柔性臂杆、柔性关节空间机械臂追踪期望运动的问题,设计了基于T-S模糊模型的滑模鲁棒控制方案和双柔性振动并行控制方案。首先,设计了关节柔性补偿器以提高系统的等效关节刚度。其次,利用反馈线性化技术建立了系统追踪期望轨迹的误差动力学方程,通过对系统Lyapunov稳定性证明来选择滑模控制参数;简化并改进T-S模糊推理规则,提出了模糊滑模鲁棒控制方法,可解决滑模控制的抖振问题并具有计算量少、控制力矩小的优点。再次,提出了柔性臂杆振动模态的直接反馈控制方案,解决了双柔性并行综合控制的问题。最后,运用逐步仿真的方法,对比仿真结果,证实了所设计轨迹跟踪、双柔性并行综合控制方案的有效性和稳定性。

柔性机械臂T-S模糊模型的辨识及其分析

针对柔性机械臂强非线性、强耦合性及不确定性等特点,利用Takagi-Sugeno模糊模型对柔性机械臂进行了建模。将模型的仿真结果和实验结果进行了对比分析,验证了模型的准确性。

基于Adams的6R选矸机械臂关节速度规划

设计了一种6R选矸机械臂并提出了一种三次S形加减速控制算法来提高其运动平稳性。首先建立梯形、7段S曲线加减速控制算法,通过分析这2种算法对机器人运动平稳性的影响,提出了一种三次S形加减速控制算法。利用Adams对3种算法进行仿真分析,结果表明新型的S形加减速控制算法在提高6R选矸机械臂的运动平稳性方面更具优势并为6R选矸机械臂后续的运动控制分析和优化奠定了基础。

软腔体柔性机械臂的T-S模糊建模与控制

针对柔性机械臂强非线性、强耦合性及不确定性的特点,利用Takagi-Sugeno模糊模型其规则前件是模糊变量,而规则后件的结论是输入输出线性函数的特点,对柔性机械臂进行了建模。在验证了模型准确性的基础上,进行了广义预测控制方法的研究,最后,对比分析了广义预测控制和传统PID控制,实验结果表明,基于T-S模糊模型的广义预测控制能很好的实现对柔性机械臂的控制。为柔性机械臂的模糊建模和进一步研究提供了理论指导及重要的前提条件。

激光四光束与PSD测量运动物体瞬时位置姿态系统的研究

介绍了一种新的光学非接触测量的方法。采用激光四光束与位敏元件 (PSD)测量物体的位置、角度 ,从而确定运动物体某一瞬时的位置姿态。对系统内部结构与信号处理进行了分析研究。实验证明 ,该测量系统具有测量精度高 ,重复稳定性好 ,系统响应速度快 ,测量范围宽等优点 ,且结构紧凑 ,制造成本低 ,应用前景相当广泛。

一种基于S-R-S构型特点的正交冗余机械臂避障规划方法

针对正交冗余机械臂避障规划问题,提出了一种基于S-R-S构型特点的避障规划新方法。该方法将正交7自由度冗余机械臂构型等效为S-R-S(球副-转动副-球副)构型,并依据S-R-S构型特点将避障规划分为肘部笛卡尔位置规划、第2根臂杆规划、末端工具规划3个部分。引入Bézier曲线完成肘部和末端工具在球面的避障规划,第2根臂杆的避障规划依据避障最大运动能力调整完成。通过Schunk-Lwa4D正交冗余机械臂避障规划实验,验证了提出的基于S-R-S构型特点的避障规划新方法的有效性和可行性。

推拿手法对家兔骨骼肌失神经支配后雪旺氏细胞S-100蛋白表达的影响

目的通过观察推拿家兔骨骼肌失神经支配后肌湿重、雪旺氏细胞S-100蛋白表达水平,探讨推拿手法对受损神经及失神经支配骨骼肌的影响。方法新西兰家兔120只,分为正常对照组、模型组、神经生长因子(NGF)治疗组、手法治疗组,每组30只,分别于手法干预2周、3周、1个月、2个月、4个月后,每组各取6只家兔,称量腓肠肌肌湿重,计算术侧与健侧的肌湿重比值;测定雪旺氏细胞S-100蛋白表达水平。结果(1)腓肠肌肌湿重比:与模型组比较,手法治疗组各时间点均增加[2周:(0.72±0.05)%比(0.53±0.01)%,3周:(0.55±0.04)%比(0.41±0.03)%,1个月:(0.55±0.99)%比(0.40±0.03)%,2个月:(0.49±0.03)%比(0.38±0.05)%,4个月:(0.50±0.03)%比(0.38±0.05)%,P均<0.05]。手法治疗组4个月时则显著高于NGF治疗组[(0.50±0.03)%比(0.42±0.02)%,P<0.05]。(2)雪旺氏细胞S-100蛋白表达:手法治疗组在各时期均高于模型组[2周:(27.00±6.29)比(10.33±1.51),3周:(33.17±5.27)比(20.83±3.87),1个月(51.00±4.56)比(21.17±4.62),2个月:(75.83±9.66)比(30.67±3.27),4个月:(116.67±3.10)比(53.17±7.52),P均<0.05]。手法治疗组在1个月、2个月均高于NGF治疗组[1个月:(51.00±4.56)比(32.83±4.12),2个月:(75.83±9.66)比(47.00±5.06),P均<0.05]。结论推拿手法可以延缓周围神经损伤后骨骼肌萎缩、变性,促进损伤神经的修复。

3SPS－PRPS并联型机器人机构位置正解分析

本文提出由三支ＳＰＳ和一支ＰＲＰＳ运动链连接上下平台的并联型机器人机构的位置正解分析方法．以上平台顶点坐标为输出变量建立起几何约束方程组，通过消元推导出一元八次多项式的输入输出方程．

软腔体柔性机械臂的T-S模糊建模方法的研究

提出一种利用T-S模糊模型的柔性机械臂建模方法;柔性机械臂是一个高度复杂、高度非线性、高度耦合的非线性时变系统,而模糊模型本质上是一种非线性模型,可以任意精度逼近任何非线性系统;利用减法聚类算法离线辨识了T-S模型的前件参数,同时利用最小二乘法求得了T-S模型的后件参数;最后将模型的仿真结果和实验结果进行了对比分析,验证了模型的准确性;由此表明,柔性机械臂T-S模糊建模方法是有效的,它具有模糊模型的特点,可以任意精度逼近任何非线性系统,为柔性机械臂的模糊建模和下一步研究提供了理论指导及重要的前提条件。

LSFP下的机器人视觉定位技术研究

针对当前点云的定位算法中,多平面分割效果差、误匹配以及定位精度不够高等问题,提出LSFP的定位思想和C-S分割算法,对目标物体进行定位。在深度相机场景下,利用点云处理算法初步获取目标的位姿,经手眼标定后,进行初步引导;再使用3D扫描仪进一步定位目标物体。结果表明:(1)C-S分割算法对多平面分割效果良好,能更准确地去除多余平面,减少点云数量。(2)在垂直于Z轴且Z轴坐标值为171 mm和-10 mm的平面上,仅PrimeSense的定位距离的均方根误差为7.3 mm和8.2 mm,LSFP下的定位距离的均方根误差为2.6 mm和3.2 mm。(3)LSFP定位思想能扩大场景定位的范围,提高物体的定位精度,具有良好的准确性。