Analysis of the musculoskeletal system of the hand and forearm during a cylinder grasping task

Musculoskeletal disorders of the hand are mostly due to repeated or awkward manual tasks in the work environment and are considered a public health issue. To prevent their development, it is necessary to understand and investigate the biomechanical behavior of the musculoskeletal system during the movement. In this study a biomechanical analysis of the upper extremity during a cylinder grasping task is conducted by using a parameterized musculoskeletal model of the hand and forearm. The proposed model is composed of 21 segments, 28 musculotendon units, and 20 joints providing 24 degrees of freedom. Boundary conditions of the model are defined by the three-dimensional coordinates of 43 external markers fixed to bony landmarks of the hand and forearm and tracked with an optoelectronic motion capture system. External marker positions from five healthy participants were used to test the model. A task consisting of closing and opening fingers around a cylinder 25 mm in diameter was investigated. Based on experimental kinematic data, an inverse dynamics process was performed to calculate output data of the model (joint angles, musculotendon unit shortening and lengthening patterns). Finally, based on an optimization procedure, joint loads and musculotendon forces were computed in a forward dynamics simulation. Results of this study assessed reproducibility and consistency of the biomechanical behavior of the musculoskeletal hand system.     

Planning manipulation movements of a dual-arm system considering obstacle removing

The paper deals with the problem of planning movements of two hand–arm robotic systems, considering the possibility of using the robot hands to remove potential obstacles in order to obtain a free access to grasp a desired object. The approach is based on a variation of a Probabilistic Road Map that does not rule out the samples implying collisions with removable objects but instead classifies them according to the collided obstacle(s), and allows the search of free paths with the indication of which objects must be removed from the work-space to make the path actually valid; we call it Probabilistic Road Map with Obstacles (PRMwO). The proposed system includes a task assignment system that distributes the task among the robots, using for that purpose a precedence graph built from the results of the PRMwO. The approach has been implemented for a real dual-arm robotic system, and some simulated and real running examples are presented in the paper.     

Motion detection using block based bi-directional optical flow method

Detecting moving objects from video frame sequences has a lot of useful applications in computer vision. This proposed method of moving object detection first estimates the bi-directional optical flow fields between (i) the current frame and the previous frame and between (ii) the current frame and the next frame. The bi-directional optical flow field is then subjected to normalization and enhancement. Each normalized and enhanced optical flow field is then divided into non-overlapping blocks. The moving objects are finally detected in the form of binary blobs by examining the histogram based thresholded values of such optical flow field of each block as well as the optical flow field of the candidate flow value. Our technique has been conceptualized, implemented and tested on real video data sets with complex background environment. The experimental results and quantitative evaluation establish that our technique achieves effective and efficient results than other existing methods.     

Arm motion analysis using genetic algorithm for rehabilitation and healthcare

The worlds population is quickly aging. With an aging society, an increase in patients with brain damage is predicted. In rehabilitation, the analysis of arm motion is vital as various day to day activities relate to arm movements. The therapeutic approach and evaluation method are generally selected by therapists based on his/her experience, which can be an issue for quantitative evaluation in any specific movement task. In this paper, we develop a measurement system for arm motion analysis using a 3D image sensor. The method of upper body posture estimation based on a steady-state genetic algorithm (SSGA) is proposed. A continuous model of generation for an adaptive search in dynamical environment using an adaptive penalty function and island model is applied. Experimental results indicate promising results as compared with the literature.     

台达20PM运动控制器在包装膜打孔机上的应用

台达20PM运动控制器及伺服驱动系统已被应用于食品包装膜打孔机。应用实例表明，采用基于非周期凸轮控制模式和CAMTABLE表的高速交流伺服驱动来代替快速气缸打孔是一种极佳的解决方案。该文简介了该打孔机控制系统的构成，着重分析了追剪和高速比较与捕捉功能这两个控制要素和部分应用程序。     

Incorporating motion analysis technology into modular arrangement of predetermined time standard (MODAPTS)

Implementing new strategies to achieve higher work efficiency is essential to improve productivity during a monotonous and exhausting work task. The Modular Arrangement of Predetermined Time Standard (MODAPTS) concept is widely used to achieve these goals in the field of human factors. However, MODAPTS is very complicated with regard to assisting engineers in understanding the system because it requires much learning time and even longer hours of effort during coding manual process. To help overcome the deficiency of the traditional method, a modern method for motion analysis, called PCA-based motion analysis, is proposed in this paper. Motion analysis has already been the main approach to analyze human motion in sports science and biometrics, but it is still unfamiliar for human factors analysts. This paper discusses a potential connection between motion analysis technology and MODAPTS analysis, which would help make MODAPTS more efficient and reliable. In the experiment, fifteen participants were asked to watch a motion sequence and then analyze the motion sequence using MODAPTS. Meanwhile, the motion-captured data were carefully segmented into motion elements with the PCA approach. A comparison of the motion segmentation contrast was made between MODAPTS analysis and automatic motion element segmentation using PCA. The accuracy rate of segmentation by the PCA approach was 80.08%, and the primitive frames of the two methods indicated that the segmentation is acceptable. In addition, the PCA-based motion analysis showed a substantial time-saving difference in the processing time, which was only approximately 3 min for motion analysis versus over 1 h for MODAPTS. Motion analysis provides high efficiency and reliability for motion segmentation and sufficient precision compared to the results using MODAPTS. Moreover, assessment of the operations’ rationality and optimization of the production line design instead of repetitive work on motion segmentation is the focus. Integrating motion analysis technology into traditional MODAPTS is a useful advancement that permits significant progress for human factors analysis. In the future, the accuracy of the automatic segmentation techniques should be improved.Relevance to industryIn recent years, motion analysis technology has become increasingly popular in various fields but not in the field of human factors. The automatic method presented in this paper may allow industrial workers to optimize unreasonable motion, remove unnecessary operations and formulate the standard working time more conveniently and accurately.     

Feasibility of tracking laparoscopic instruments in a box trainer using a Leap Motion Controller

Motion analysis is employed to assess minimally invasive surgical psychomotor skills in box trainers. Tracking of laparoscopic instruments requires sensor-based systems that can be expensive, limit movements and modify their ergonomic properties. We evaluate the feasibility of using Leap Motion as a cheap, unobtrusive alternative. Four experiments were performed to determine its precision while tracking a laparoscopic instrument inside and outside a box trainer. Static long and short term precision of the Leap Motion was <2.5 mm. Precision between 12 different positions within the box trainer was <0.7 mm for all measured distances between neighbors. Dynamic precision when moving the instrument for 200 mm ranged between 2 and 15 mm. Leap Motion presents acceptable precision values inside a box trainer. Improvements are still required (e.g.: multiple instruments’ tracking). Once solved, a validation study should verify the usefulness of Leap Motion to objectively measure skills of novices and residents during training.     

基于CPAC的数控转塔冲床系统的开发

介绍了计算机可编程自动化控制器(CPAC)的软硬件结构,分析了该控制器在数控领域的应用特点。提出了数控转塔冲床的结构方案和控制方案,采用"PC+运动控制器"的结构,以HMI为人机界面,IPC为控制系统核心,在windows CE操作系统上,用梯形图和顺序功能图两种开发语言,开发了数控转塔冲床系统。     

钢包回转台升降机构的运动仿真和有限元分析

采用SolidWorks软件对连杆式钢包回转台升降机构进行了运动仿真和整机有限元强度分析。通过运动仿真表明：该机构圆满地完成了工作,但运动时存在柔性冲击;通过整机有限元强度分析表明：最小安全系数为4.177,该机构具有足够的安全储备。     

Motion of a Rigid Body in a Newtonian Field of Force Exerted by Three Attracting Centers

In this paper, a nonsymmetric rigid body rotating around a fixed point under the action of a central Newtonian field of force exerted by three centers of attraction is considered. The angular momentum principle is applied to deduce the equations of motion of this body. These equations represent a simple autonomous system of twelve nonlinear ordinary differential equations, which describe the motion of the body. The first integrals for such a system are obtained. Euler, Lagrange, and the kinetic symmetry cases are obtained as special cases from this problem. The numerical solution for this system is obtained by using the fourth-order Runge-Kutta method. The aim is to find the influence of the characteristic parameters of the body on the motion. Two cases of study are given. The first occurs when the three attracting centers lie on the fixed axes OX, OY, and OZ, and the second occurs when these centers are reduced to one attracting center that lies on the vertical OZ-axis. A comparison between the solutions for the two previously-mentioned cases is given through computer programs.