Modular Organization of Muscle Synergies to Achieve Movement Behaviors

Muscle synergy has been applied to comprehend how the central nervous system (CNS) controls movements for decades. However, it is not clear about the motion control mechanism and the relationship between motions and muscle synergies. In this paper, we designed two experiments to corroborate the hypothesis: (1) motions can be decomposed to motion primitives, which are driven by muscle synergy primitives and (2) variations of motion primitives in direction and scale are modulated by activation coefficients rather than muscle synergy primitives. Surface electromyographic (EMG) signals were recorded from nine muscles of the upper limb. Nonnegative matrix factorization (NMF) was applied to extract muscle synergy vectors and corresponding activation coefficients. We found that synergy structures of different movement patterns were similar (α=0.05). The motion modulation indexes (MMI) among movement patterns in reaching movements showed apparent differences. Merging coefficients and reconstructed similarity of synergies between simple motions and complex motions were significant. This study revealed the motion control mechanism of the CNS and provided a rehabilitation and evaluation method for patients with motor dysfunction in exercise and neuroscience.

Study on an Interactive Truck Crane Simulation Platform Based on Virtual Reality Technology

The modern web-based distance education overcomes space-time restriction of the traditional teaching forms. However, being short of specifically observable and operable experimental equipment makes the web-based education lack advantages in the knowledge learning progress, which needs strong stereoscopic effect and operability. Truck crane is the most widely used crane installed on ordinary or tailor-made chassis with strong operability. This paper introduces a kind of interactive truck crane simulation platform based on the virtual reality technology, on which can complete the simulation experiment of the crane's movement. The framework and working principle of the interactive truck crane simulation platform are discussed in the paper, while landing leg and hook are used as an example to show the motion control mechanism of truck crane components. The interactive truck crane simulation platform uses the browser-based structure, Java3D, virtual reality and Java Applet, etc. to develop a Web3D virtual reality learning environment, which has the advantages of good interaction, strong sense of reality, simple update, less investment and so on. This learning environment can meet the needs that many students study online at the same time, so it has important application in the distance education of mechanical profession and remote training of vocational skills.

Study on an Interactive Truck Crane Simulation Platform Based on Virtual Reality Technology

The modern web-based distance education overcomes space-time restriction of the traditional teaching forms. However, being short of specifically observable and operable experimental equipment makes the web-based education lack advantages in the knowledge learning progress, which needs strong stereoscopic effect and operability. Truck crane is the most widely used crane installed on ordinary or tailor-made chassis with strong operability. This paper introduces a kind of interactive truck crane simulation platform based on the virtual reality technology, on which can complete the simulation experiment of the crane's movement. The framework and working principle of the interactive truck crane simulation platform are discussed in the paper, while landing leg and hook are used as an example to show the motion control mechanism of truck crane components. The interactive truck crane simulation platform uses the browser-based structure, Java3D, virtual reality and Java Applet, etc. to develop a Web3D virtual reality learning environment, which has the advantages of good interaction, strong sense of reality, simple update, less investment and so on. This learning environment can meet the needs that many students study online at the same time, so it has important application in the distance education of mechanical profession and remote training of vocational skills.

Finite element analysis of burr formation and an automatic online micro-deburring method in precise end-face grinding process

A new approach is presented in this article for modeling and analysis of precise end-face grinding burr formation. The aim of this approach is to develop an automatic online deburring method that utilizes a precision motion control mechanism and effective deburring tools. Servo valve cores widely used in aerospace industry were employed as the workpiece in this study. After precision external grinding process, as a rule, the way of end-face grinding is adopted to get qualified working edges; the precision of these edges are generally required to be micron level or higher. However, after end-face grinding, the outside circle of the working edges will have burrs whose heights range from a few to dozens of microns, and the manual offline burr removal method currently adopted is not only uneasy to control accuracy but also easy for the working edges of the workpiece to lose its integrity and lead to a high rejection rate. In this article, the burr modeling and analysis procedure were used to get the corresponding formation mechanism of burr, and the online precision burr removal equipment was designed reasonably. Therefore, the effective removal of arising micro-burr from end-face grinding and the accuracy of the working edges were very well guaranteed, so as to improve the production efficiency.