Dynamics of Digital Force Control Applied in Rehabilitation Robotics

Controlled structures are often required to keep desired contact forces between some of its elements. A classical example is the controlled interaction of a robot with its environment when the control of the contact force between the robotic actuator and the workpiece is prescribed. Experiments often call the attention to the destabilising digital effects, like sampling, in these systems. In this paper the stability of a newly developed force based teaching-in method is analysed. The method is applied in rehabilitation robotics. The stability limits are presented in the parameter space of the sampling time, control gains and mechanical parameters of the robot. The least force error and the fastest settling force signal are calculated. The influence of the elasticity of the force sensor is analysed as well as the possible bifurcations. Real parameter case study confirms the analytical predictions.     

碘元素概念发展史及其教育价值

通过对碘元素概念发展历程的考证可知,1813年,盖·吕萨克首次提出碘元素概念,但当时碘元素和碘单质概念界定不清。至道尔顿提出原子论,赋予碘元素新的含义,首次将碘原子和碘元素结合在一起。20世纪40年代,碘同位素的发现完善了碘元素概念,形成现代碘元素观念。在化学教育中,须让学生认识到碘元素概念的发展史不仅是元素概念的发展史,也是科学思想的演进史和科学方法的发展史。     

Steering by transient destabilization in piecewise-holonomic models of legged locomotion

We study turning strategies in low-dimensional models of legged locomotion in the horizontal plane. Since the constraints due to foot placement switch from stride to stride, these models are piecewise-holonomic, and this can cause stride-to-stride changes in angular momentum and in the ratio of rotational to translational kinetic energy. Using phase plane analyses and parameter studies based on experimental observations of insects, we investigate how these changes can be harnessed to produce rapid turns, and compare the results with dynamical cockroach data. Qualitative similarities between the model and insect data suggest general strategies that could be implemented in legged robots.      

化学学科语义模型的研究

为了方便管理和有效使用各类教育资源,让计算机理解各门学科中概念的语义,本文采用了建立学科语义模型的方法,研究了化学学科的语义模型及其形式化描述.该模型可为实现化学类教育资源的语义分析、自动整合和重用奠定基础,也可为本领域其他学科的语义研究提供参照.     

Terrain classification using ToF sensors for the enhancement of agricultural machinery traversability

Ground properties influence various aspects of mobile machinery navigation including localization, mobility status or task execution. Excessive slipping, skidding or trapping situations can compromise the vehicle itself or other elements in the workspace. Thus, detecting the soil surface characteristics is an important issue for performing different activities in an efficient, safe and satisfactory manner. In agricultural applications, this point is specially important since activities such as seeding, fertilizing, or ploughing are carried on within off-road landscapes which contain a diversity of terrains that modify the navigation behaviour of the vehicle. Thus, the machinery requires a cognitive capability to understand the surrounding terrain type or its characteristics in order to take the proper guidance or control actions. This work is focused on the soil surface classification by implementing a visual system capable to distinguish between five usual types of off-road terrains. Computer vision and machine learning techniques are applied to characterize the texture and color of images acquired with a Microsoft Kinect V2 sensor. In a first stage, development tests showed that only infra-red and RGB streams are useful to obtain satisfactory accuracy rates (above 90%). The second stage included field trials with the sensor mounted on a mobile robot driving through various agricultural landscapes. These scenarios did not present illumination restrictions nor ideal driving roads; hence, conditions can resemble real agricultural operations. In such circumstances, the proposed approach showed robustness and reliability, obtaining an average of 85.20% of successful classifications when tested along 17 trials within agricultural landscapes.     

Interaction of intelligent and autonomous systems – part II: realization of cognitive technical systems

In this study, the application of a meta-modelling technique to structure complex environments is demonstrated with two examples. A special situation-operator model developed to model the human-machine-interaction is applied to automated supervision within the HMI context and to realize flexible and situated interaction of autonomous systems. A concept to automated monitoring of human operators is introduced to illustrate the structuring of complex environments as the first example. In the second example, this modelling technique is applied to a mobile robot to autonomously build and update a mental model of the interaction with the environment as an example of a cognitive technical system.     

布卢姆教育目标分类视角下的中美化学教材习题比较——以“氧化还原反应和电化学”为例

基于布卢姆教育目标分类学,从知识、认知过程2个评价维度对中美化学教材“氧化还原反应和电化学”主题的习题进行了比较研究,结果表明,在知识维度,2国教材均较为重视“概念性知识”和“程序性知识”,但中国教材侧重前者而美国教材侧重后者;在认知过程维度,美国教材对“理解”“运用”水平的考查均较多且尤为侧重“运用”,中国教材对“运用”“理解”“分析”水平的考查均较多,整体上较为均衡。教材习题编写应该关注习题的课程功能创生,注重对学生学科思维、解决实际问题能力的考查,充分发挥其对教与学尤其是学生学习方式的引导作用。     

物理电学实验仿真软件的设计

基于探究式学习的物理电学仿真软件以探究式学习的理论为软件设计的指导理念,利用仿真技术和统一的建模语言(UML)等一些软件工程的方法,以C 作为编程语言,运用VC 开发平台作为开发工具,编程开发了物理电学实验仿真软件.     

教育投资问题的表上作业法

教育投资问题的表上作业法使小规模情形下的手工操作变得十分方便、迅速,而且大规模情形下更有利于计算机的实现。本还就此算法给出了实例和复杂性分析。     

面向能力培养的分析化学混合式教学改革研究*

提出了MOOC建设中的关键点,开展了分析化学线上线下混合式教学的课前、课堂和课后教学设计与应用研究,建立了科学合理的教学综合评价方法,总结了面向能力培养的分析化学混合式教学改革与实践经验,并客观分析了混合式教学实践中遇到的问题且提出了切实可行的解决方法。实践证明,线上线下混合式教学模式能够提高教学效果,有效培养学生的分析问题和解决问题的能力。