Clearance angle and evolution of depth of cut in actuated disc cutting

This paper investigates the effect of cutter clearance angle on variation of depth of cut and cutting process with an actuated disc cutting(ADC). ADC is a cyclic cutting method with two main characteristics:(i) a disk-shape cutter is used to attack the rock in an undercutting mechanism; and(ii) the cutter is dynamically actuated as it is moved across the rock. Hence, the cutting process of such system is periodic, each recurrence known as actuation cycle. The first ADC model, developed in 2016, represented an idealization of the technology with a flat disc cutter, where no clearance angle was considered. The evolution of the contact between the disc and the rock was, therefore, computed only on horizontal x-y plane, ignoring the effect of normal component of the force acting on cartridge. This article reports on a study that incorporates the cutter inclination angle in derivation of cutter/rock interface laws. It extends the proposed kinematic and geometry based model to take into account the variable depth of cut in estimating the forces associated with cutting in one actuation cycle. Experiments were conducted using Wobble to test the predictions of the improved model at various operating conditions. The model predictions are matched with the experimental results and effects of various factors are analysed.     

面向并联机器人驱动器故障的容错纠错方法研究

基于机构类型演化提出了一种具有驱动器故障容错功能的1TP+3TPRS型并联机器人的新结构;研究了机器人的机械系统容错重构策略;在位置反解的基础上导出了机器人的重构规划算法;对于退化机器人容错性能指标的研究,定义了容错空间影响因子,可以用来衡量机器人在发生故障后的容错操作能力;基于这个指标,提出容错并联机器人的结构参数优设计方法;通过模拟动平台按预期轨迹运动时某驱动器在不同时刻发生故障的情况,比较了退化机器人的工作状况,结果表明基于容错空间影响因子的结构参数优设计方法对于提高容错性能具有重要的意义。     

Powered orthosis for lower limb movements assistance and rehabilitation

This paper presents two rehabilitation approaches of the lower limb: passive and active. The passive one ensures repetitive motions of the limb without any effort delivered by the wearer. Within the active one, a human–exoskeleton interaction approach is proposed. It allows us to provide a knee joint torque support, adapted according to the intention and ability of the wearer, for assistance-as-needed. The wearer׳s intention is estimated using a realistic model of the muscles actuating the knee joint. The identification process concerns the inertial parameters of the shank-foot-exoskeleton and the musculotendinous parameters. Experiments were conducted online on a healthy subject and have shown satisfactory results in terms of tracking error, intention detection and passive-rehabilitation/active-assistance.     

静电致动硅膜板的宏模型建立方法

器件宏模型技术是MEMS系统设计和系统级仿真的关键技术。为了建立静电致动硅膜板的宏模型,在模态有限元分析的基础上,利用多维非线性函数拟合方法,将由数值计算得到的板的动能、弹性能和电容写成以模态广义坐标表示的解析式。导出双模态坐标下的静电微板的动力学特性方程,即宏模型。利用该宏模型研究了器件的静态、动态特性,并与有限元计算结果比较。表明,用模态坐标表达的动态宏模型能够考虑残余应力、大变形、静电力等非线性因素的影响,大大地减少了计算费用,而且具有足够的仿真精度。     

Adaptive control of an actuated ankle foot orthosis for paretic patients

This paper deals with the control of an active ankle foot orthosis (AAFO) to assist the gait of paretic patients. The AAFO system is driven by both, the residual human torque delivered by the muscles spanning the ankle joint and the AAFO’s actuator’s torque. A model reference adaptive control is proposed to assist dorsiflexion and plantar-flexion movements of the ankle joint during level walking. Unlike most classical model-based controllers, the proposed one does not require any prior estimation of the system’s (AAFO-wearer) parameters. The ankle reference trajectory is updated online based on the main gait cycle events and is adapted with respect to the self-selected speed of the wearer. The adaptive desired ankle trajectory is estimated using cubic spline interpolations between the different key events of the gait cycle. The closed-loop input-to-state stability of the AAFO-wearer system with respect to a bounded human muscular torque is proved by a Lyapunov analysis. Experimental results obtained from three healthy subjects and one paretic patient, show satisfactory results in terms of tracking performance and ankle assistance throughout the full gait cycle. The experiments also show good performance at different walking speeds and with different gait sub-phase duration proportions.     

静电无阀微泵两种仿真模型的比较研究

为提高无阀微泵性能,分别采用全耦合模型(FCM)和预先定义泵膜位移的模型(PDM)对基于扩散/收缩单元的静电无阀微泵的动态特性进行计算仿真.对泵膜变形形状、泵膜中点位移、泵腔内压力以及进出口处流量等的变化历程进行比较.结果表明:PDM模型计算费用较低,但无法以较高精度近似泵膜变形的动态特性,进而导致错误的瞬态流场结果.要准确仿真微泵的动态特性,必须考虑电-结构-流场之间的相互作用.     

静电悬浮加速度计与真空有关的噪声分析

从麦克斯韦速率分布函数和克努曾的"吸附层"假说出发,推导出静电悬浮加速度计核心部分因辐射计效应和残余气体平衡态阻尼引入的加速度热噪声表达式。指出辐射计效应是加速度计噪声的一个重要来源,气体阻尼的影响相对较小;加速度计长期保持优良的高真空是控制这两项噪声水平的必要措施;认为出气效应比辐射计效应大一到两个数量级是错误的。     

静电自组装技术及其应用

静电自组装技术有许多优点：工艺简单，能精确控制膜厚，每层膜厚都能控制在分子级水平，膜的稳定性较传统方法有较大提高，适用于制造大面积的薄膜器件。本文综述了静电自组装技术的特点，注意事项及其应用前景。     

Mechanisms for actuated assistive hip orthoses

Mobility is often a central problem for people having muscle weaknesses. The need for new devices to assist walking and walk related activities is therefore growing. Lower limb actuated orthoses have already proven their positive impact with paraplegic patients and are potentially promising for assisting people with weak muscles. However, the transfer from the existing systems of mobilization towards assistance implies several technical challenges as the seamless integration and the reduction of power consumption. In this paper two assistive orthoses which use different types of actuation mechanisms are presented and discussed. The first one is based on a ball screw and an excavator-like mechanism while the second one is based on a double differential actuation. Their technical capabilities are compared and contextualized for diverse activities. Objective characteristics such as the range of motion of the devices, the transparency, the maximal torque that they can provide or the RMS torque during cyclic trajectories are compared to point out which device is better adapted for specific situations.     

球,柱面变间隙电容传感器的精密测量研究

本文对球、柱面间隙电容传感器进行了分类，定义了几个重要参数，将误差分为电路和机械的，并完成了理论与实验研究。文章以精密的静电陀螺为例，研制了转子位移电容分辨率标定装置，使陀螺转子相对位移分辨率、零点稳定度可标定到０．０１μｍ量级