用复阻抗法分析纳米钛酸钡湿敏元件感湿机理

用复阻抗方法对硅衬底纳米钛酸钡湿敏元件的感湿机理进行了分析。实验测量了湿敏元件在不同相对湿度下的复阻抗特性曲线及阻抗、电容等参数随频率的变化曲线。分析出相应的等效电路,推导了等效电路有关参数,分析讨论了纳米钛酸钡湿敏元件的感湿机理。低湿时,感湿材料本身颗粒电阻和电容及吸附的少量水分子共同起作用;高湿时,吸附的水分子电离和极化起主要作用。     

Integrated Design of an Ionic Polymer–Metal Composite Actuator/Sensor

We are studying the robotic application of ionic polymer–metal composite (IPMC). The characteristics of IPMC greatly depend on the type of counterions, and it is considered that the performance of the actuators can be improved by combining the actuators with several types of counterions and applying an integrated control. IPMC also has a sensor function, as the IPMC film generates an electromotive force when it is deformed. It has the possibility to be integrated into an IPMC actuator with soft actuation. In this paper, we consider an integrated design of an IPMC actuator/sensor, and investigate control of the combined IPMC actuators using H _∞ control and the construction of an IPMC sensor system.     

A biomimetic underwater microrobot with multifunctional locomotion

Underwater microrobots are in urgent demand for applications such as pollution detection and video mapping in limited space. Compact structure, multi-functionality, and flexibility are normally considered incompatible characteristics for underwater microrobots. Nevertheless, to accomplish our objectives, we designed a novel inchworm-inspired biomimetic locomotion prototype with ionic polymer metal composite (IPMC) actuators, and conducted experiments to evaluate its crawling speed on a flat underwater surface. Based on this type of biomimetic locomotion, we introduced a new type of underwater microrobot, using ten IPMC actuators as legs or fingers to implement walking, rotating, floating, and grasping motions. We analysed the walking mechanism of the microrobot and calculated its theoretical walking speed. We then constructed a prototype of the microrobot, and carried out a series of experiments to evaluate its walking and floating speeds. Diving/surfacing experiments were also performed by electrolysing the water around the surfaces of the actuators. The microrobot used six of its actuators to grasp small objects while walking or floating. To implement closed-loop control, we employed three proximity sensors on the microrobot to detect an object or avoid an obstacle while walking.     

The sheer-contact MAGRES – a magnetic field sensor with minimal manufacturing complexity

This paper analyzes a solid state magnetic sensor called the “sheer-contact magnetic field sensitive resistor” (SC-MAGRES). The geometry of this device features no lateral insulation and is determined by the contacts only, thus, it can be manufactured with a minimal number of masking steps. Its applications are in the micro-electro-mechanical-systems (MEMS)-area with low-cost sensor-applications using non-standard processes. An equivalent circuit for use in circuit simulators as well as models of the device resistors and sensitivity are presented and compared to measurements which show a maximum sensitivity of 17 μA/VT. Other measurements show a maximum resolution of 120 nT as well as the offset of the device. A comparison to similar magnetic sensors concludes the analysis, together with an investigation of optimization strategies.     

Bending control of Nafion-based electroactive polymer actuator coated with multi-walled carbon nanotubes

Electrical bending control of Nafion-based ionic polymer-metal composite (IPMC) is quite difficult. Unlike a conventional fully hydrated noble metal-coated Nafion type IPMC, however, highly dehydrated silver-coated Nafion type IPMC exhibited better electrical bending controllability. Embedding of the multi-walled carbon nanotube (MWCNT) into Nafion surface promoted adsorption of a larger quantity of silver on the Nafion surface, since the MWCNT surface served as adsorption sites for silver. A MWCNT-embedded Nafion coated with such a large quantity of silver (SCNT-Naf) exhibited large bending curvature under an applied voltage when in a highly dehydrated state, because of large scale induction of silver redox reaction. We could even achieve autonomous bending curvature control of the highly dehydrated SCNT-Naf quantitatively by automatically monitoring total charge imposed on it.     

Electro-chemical operation of ionic polymer-metal composites

Currently, there is a major engineering challenge associated with ionic polymer-metal composites (IPMCs) that needs to be resolved before they can be vastly adopted in current and future engineering markets—relaxation of the IPMC actuator under a DC voltage. In this article, we rigorously discuss the potential origin of the relaxation phenomena of IPMCs that can be related to electro-chemically induced surface reactions with electrodes. Our measured voltammograms and deflection data of IPMCs revealed that the relaxation phenomena of the IPMC actuators are primarily caused by the overpotential of the surface electrodes. The overpotential values of ca. +1 V were clearly noted for many IPMC samples. We believe that the relaxation of IPMCs originate from the platinum oxide formation during actuation—a key surface reaction. The IPMC solvated with a typical ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) as a solvent, showed a larger bending, but there was no relaxation during actuation because there was no platinum oxide formation.     

接触式传感器测量软体驱动器角度的数据融合

现有用于软体驱动器角度测量的接触式传感器主要包括惯性传感器与曲率传感器,但惯性传感器的测量精度易受软体驱动器内嵌气道膨胀的影响,曲率传感器测量则存在迟滞和漂移等问题。为进一步提高接触式传感器测量软体驱动器角度的准确性,结合模糊推理与卡尔曼滤波结合的算法实现惯性传感器和曲率传感器数据融合。基于BP神经网络和长短时记忆网络分别融合曲率传感器和惯性传感器,减少接触式传感器测量软体驱动器角度时迟滞和气道膨胀的影响。实验结果显示,采用长短时记忆网络、BP神经网络和模糊推理与卡尔曼滤波相结合的数据融合结果均方根误差精度分别为0.51°、0.63°和1.59°,表明长短时记忆网络能够更好地提高接触式传感器对软体驱动器角度的测量精度。     

Multiphysics modeling of an IPMC microfluidic control device

A microfluidic control device that uses an electroactive polymer for actuation has been recently proposed. This design has potential to control temperature sensitive particle-laden liquids. The electro-mechanical characteristics of ionic polymer metal composite (IPMC) actuators have been studied both theoretically and empirically. However, very little data has been published on the thermal behavior of IPMC actuators. To realize the proposed fluidic control device, it is essential to understand the thermal properties of the device under actuation conditions. This paper discusses the theoretical basis for developing a multiphysics model describing electroactive polymer actuation. In addition, experimental results are presented that give insight to the thermal characteristics of IPMC actuation.     

Design and control of an IPMC wormlike robot.

This paper presents an innovative wormlike robot controlled by cellular neural networks (CNNs) and made of an ionic polymer-metal composite (IPMC) self-actuated skeleton. The IPMC actuators, from which it is made of, are new materials that behave similarly to biological muscles. The idea that inspired the work is the possibility of using IPMCs to design autonomous moving structures. CNNs have already demonstrated their powerfulness as new structures for bio-inspired locomotion generation and control. The control scheme for the proposed IPMC moving structure is based on CNNs. The wormlike robot is totally made of IPMCs, and each actuator has to carry its own weight. All the actuators are connected together without using any other additional part, thereby constituting the robot structure itself. Worm locomotion is performed by bending the actuators sequentially from "tail" to "head," imitating the traveling wave observed in real-world undulatory locomotion. The activation signals are generated by a CNN. In the authors' opinion, the proposed strategy represents a promising solution in the field of autonomous and light structures that are capable of reconfiguring and moving in line with spatial-temporal dynamics generated by CNNs.     

Exponential Stabilization of a Rayleigh Beam Using Collocated Control

We consider a hinged elastic beam described by the Rayleigh beam equation on the interval [0,pi]. We assume the presence of two sensors: one measures the angular velocity of the beam at a point xi epsiv [0,pi] and the other measures the bending (curvature) of the beam at the same point. (If xi = 0 or xi = pi, then the second output is not needed.) The corresponding operator semigroup is unitary on a suitable Hilbert state space. These two measurements are advantageous because they make the open-loop system exactly observable, regardless of the point xi. We design the actuators and the feedback law in order to exponentially stabilize this system. Using the theory of collocated static output feedback developed in our recent paper , we design the actuators such that they are collocated, meaning that B = C*, where B is the control operator and C is the observation operator. It turns out that if xi epsiv [0,pi], then the actuators cause a discontinuity of the bending exactly at (this is the price, in this example, of having collocated actuators and sensors). This obliges us to use an extension of to define the output signal in terms of the left and right limit of the bending at xi. We prove that, for all static output feedback gains in a suitable finite range, the closed-loop system is well posed and exponentially stable. This follows from the general theory in our paper, whose main points are recalled here.     

基于V-F变换的硅压阻压力传感器的处理电路

针对硅压阻压力传感器提出了一种基于电桥本身参数的温度自补偿方法,并设计了一种差分输入、双参数输出的高精度处理电路用以获得电桥参数。该电路用简单元件搭建差分输入的电荷平衡式V/F转换器,根据不同组态的频率输出解算电桥参数。该电路巧妙地利用差分输入方式消除了共模电压引起的误差,巧妙借用参考电阻消除了基准频率的影响,最终的输出频率只与被测量和参考电阻有关。经实验验证,电桥电阻的测量精度能达到0.0068%,经补偿后的压力传感器精度可达0.039%,相比补偿之前提高了一个数量级。     

AMT控制器产品自动测试系统设计

为了使机械式自动变速器（AMT）的控制器产品测试摆脱在传统测试方法中需要实物传感器和笨重机构的限制,根据AMT控制器的控制原理,利用嵌入式系统开发方法设计开发了一套自动测试系统。测试系统主要基于电子电路原理,利用各种电子元器件来模拟AMT的各种传感器信号和机构的响应,并通过程序实现自动检测。另外基于LabWindows/CVI的平台开发了测试监控软件,使测试结果一目了然。试验结果表明,利用该测试系统可快速、自动完成对AMT控制器的测试,并可快速定位控制器的潜在故障。     

A bio-inspired multi degree of freedom actuator based on a novel cylindrical ionic polymer–metal composite material

In this work, we explore a promising electroactive polymer (EAP), called ionic polymer–metal composite (IPMC) as a material to use as a multi degree of freedom actuator. Configuration of our interest is a cylindrical IPMC with 2-DOF electromechanical actuation capability. The desired functionality was achieved by fabricating unique inter-digitated electrodes. First, a 3D finite element (FE) model was introduced as a design tool to validate if the concept of cylindrical actuators would work. The FE model is based upon the physical transport processes—field induced migration and diffusion of ions. Second, based upon the FE modeling we fabricated a prototype exhibiting desired electromechanical output. The prototype of cylindrical IPMC has a diameter of 1 mm and a 20 mm length. We have successfully demonstrated that the 2-DOF bending of the fabricated cylindrical IPMCs is feasible. Furthermore, the experimental results have given new insight into the physics that is behind the actuation phenomenon of IPMC.     

An electrical model with equivalent elements in a time-variant environment for an ionic-polymer-metal-composite system

Ionic polymer metal composite (IPMC) is a kind of ionic electroactive polymer (EAP) smart material that can exhibit conspicuous deflection with low external voltages (~ 5 V). It can be cut in various sizes and shapes, and used and applied in robots and artificial muscles with the capability in aquatic operation. An IPMC strip can be modeled as a cantilever beam with a loading distribution on the surface. Nevertheless, the loading distribution is non-uniform due to the imperfect surface conductivity that causes four different imaginary loading distributions employed in our structural model. The difference can be up to 5 times (3:8 mm to 19 mm). In this paper, a novel linear time-variant (LTV) model is introduced and applied to model an IPMC system. This modeling method is different from previous linear time-invariant (LTI) models because the internal environment of IPMC may be unsteady due to mobile cations with water molecules. In addition, the influence of surface conductivity is simulated and proven based on this model. Finally, by applying this novel modeling method, hysteresis that exists in IPMC and affects the relationship between the output deflection and the corresponding input voltage, such as 0:1-, 0:2-, and 0:3-rad/s sinusoidal waves, has been shown and simulated.     

Direct interface circuit to linearise resistive sensor bridges

This paper proposes the direct connection of different configurations of resistive sensor bridges to a microcontroller without any intermediate active component. Such a direct interface circuit relies on measuring the discharging time of a RC network that includes the resistances of the sensor bridge. For quarter-, half-, and full-bridge circuits, we combine the discharging times to estimate the fractional resistance change x of the bridge arms. Experimental results for half- and full-bridge circuits emulated by resistors yield a nonlinearity error below 0.3%FSR (full-scale range) for x between 0 and 0.1 and an effective resolution of 11 bit. Measurements on two commercial magnetoresistive sensors yield higher nonlinearity errors: 1.8%FSR for an AMR (Anisotropic Magnetoresistive) sensor and 5.8%FSR for a GMR (Giant Magnetoresistive) sensor, which are mainly due to the nonlinearity of the sensors themselves. Therefore, the nonlinearity of the measurement is limited by the sensors, not by the proposed interface circuit and linearisation algorithm.     

Doping effects on robotic systems with ionic polymer–metal composite actuators

Ionic polymer–metal composite (IPMC) materials are one of the most promising electro-active polymer actuators for applications, and have good properties of response and durability. The characteristics of IPMC materials depend on the type of counter-ion. When applied to mechanical systems such as a robot, there exist possibilities to change the properties of the system dynamics by changing the counter-ions and system parameters according to the environment or purpose. We focus on this 'doping effect' property of the system and will verify the effect on robotic applications. In this paper, we consider dynamic walking of a small-sized biped robot and swimming motion of a snake-like robot, and demonstrate the doping effects by numerical simulations and experiments.     

Development and evaluation of a Venus flytrap-inspired microrobot

Nature has provided the inspiration for many robots, leading to the development of biomimetic machines based on stick insects, jellyfish, butterflies, lobsters, and inchworms. Some carnivorous plants are capable of rapid motion, including mimosa, Venus flytraps, telegraph plants, sundews, and bladderworts, all of which are of interest in the design of biomimetic robots that can be activated in a controlled manner to capture prey using trigger hairs. Here, we describe a biomimetic robotic inspired by a Venus flytrap and fabricated using two ionic polymer metal composite (IPMC) actuators. First, we describe the structure of the robotic flytrap, which consists of two IPMC lobes and a proximity sensor, and discuss the design of the control circuitry. We then evaluate the deformation and bending force of the IPMC actuator with various applied signal voltages. We describe a prototype robotic flytrap utilising a proximity sensor to imitate the trigger hairs of the Venus flytrap. We conducted an experiment to assess the feasibility of the biomimetic flytrap. To evaluate grasping ability, we measured the maximum grasping payload with different applied voltages. To enlarge the working area, we integrated biomimetic walking and rotating motion into the robotic Venus flytrap. This paper describes a prototype movable robotic Venus flytrap and evaluates its walking and rotating speeds.     

Encapsulated micro mechanical sensors

Encapsulated micro mechanical sensors were fabricated using glass-silicon anodic bonding and an electrical feedthrough structure. Two parallel plates which can be used not only for capacitive sensors but also electrostatic actuators are adopted for integrated sensors as capacitive pressure sensors, accelerometers and resonating sensors. Micromachining technologies were developed for these packaged micro sensors. These include silicon etching technologies as laser assisted etching, deep RIE and in-process thickness monitoring during wet etching. Anodic bonding technologies which enable to incorporate a circuit inside the package and to keep a sealed cavity at a high vacuum are also developed.This work has been supported by the Japanese Ministry of Education Science and Culture under a Grand-in Aid No. 03102001     

基于曲度特征的三维模型检索算法

针对如何提高复杂曲面的三维模型的检索精度的问题,提出了一种基于曲度特征的三维模型检索算法。首先,在模型表面选取随机采样点,计算点所在局部曲面的高斯曲率和平均曲率,通过高斯曲率和平均曲率求出随机点的曲度值,曲度值表明了曲面的凹凸属性。然后,以模型的质心为球心,以随机点与质心距离和曲度值为坐标轴建立坐标系,统计出一定距离范围内曲度值分布的概率,构建距离与曲度的分布矩阵,以此分布矩阵作为三维模型特征描述符。该特征描述符具有旋转不变性和平移不变性,能够很好地反映复杂曲面的几何特征。最后,通过比较分布矩阵给出不同模型间的相似度。实验结果表明,该方法相比形状分布算法的检索性能有较大提高,尤其适用于具有复杂曲面的三维模型检索。