Part Of Actuator Research Articles

Behavior Learning of Swarm Robot System using Bluetooth Network

With the development of techniques, robots are getting smaller, and the number of robots needed for application is greater and greater. How to coordinate large number of autonomous robots through local interactions has becoming an important research issue in robot community. Swarm Robot Systems (SRS) is a system that independent autonomous robots in the restricted environments infer their status from pre-assigned conditions and operate their jobs through the cooperation with each other. In the SRS, a robot contains sensor part to percept the situation around them, communication part to exchange information, and actuator part to do a work. Especially, in order to cooperate with other robots, communicating with other robots is one of the essential elements. Because Bluetooth has many advantages such as low power consumption, small size module package, and various standard protocols, it is rated as one of the efficient communicating technologies which can apply to small-sized robot system. In this paper, we will develop Bluetooth communicating system for autonomous robots. And we will discuss how to construct and what kind of procedure to develop the communicating system for group behavior of the SRS under intelligent space.

2A2-L03 磁気駆動Robot-on-a-chipに関する研究 : その1: 2自由度磁気駆動マイクロツールによるオンチップ微粒子操作

We proposed a two-degree-freedom magnetically driven microtool (2DOF-MMT) which can directly manipulate cells on a chip with high accuracy. The classified actuation method of MMT showed that using of the permanent magnet has an advantage over micro-electromagnetic coil in microscale in terms of the magnetic interference of MMT and actuation part. A fundamental experiment was carried out to confirm the displacement of the 2DOF-MMT actuated by a permanent magnet mounted below it. The displacement was in the range of 400-600 μm in x-direction and 250-400μm in y-direction, and the hybrid 2DOF-MMT which contain the Nickel plate show far larger displacement (30% in x-direction and 60% in y-direction). The 2DOF-MMT has potential to be used as micro-nano-robot on a chip which can be defined as Magnetically Driven Robot-on-a-Chip (MDRoC).

等温化した空気圧ゴム人工筋の体積からの収縮率推定

The applications of pneumatic artificial muscles (PARM) are increasing in the power assist and manipulator systems, because of its advantages such as high power-to-weight ratio and flexibility. Usually, we have to measure the contract ratio of PARM using a displacement sensor installed near the actuator which is not easy to make dust and water proof. In this paper, we propose an estimation method of the contract ratio from the volume change of the PARM which can make the actuator part sensor-less. The air charged and discharge to the PARM is measured by a quick response laminar flow meter. Then, the volume of the PARM is estimated from the flow rate and the pressure measured by a pressure sensor. In order to estimate the contract ratio accurately, thin copper wires are stuffed to the PARM to produce an almost isothermal condition during the charge and discharge. The effectiveness of the proposed method was confirmed experimentally.

Development of a Peristaltic Micropump for Bio-Medical Applications Based on Mini LIPCA

This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from Polydimethylsiloxane (PDMS) material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two Polymethyl Methacrylate (PMMA) plates, which help increase the stiffness of the micropump. A maximum flow rate of 900 μL·min −1 and a maximum backpressure of 1.8 kPa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a promising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.

Thermal effect on piezoelectric stick-slip actuator systems

The piezoelectric stick-slip (PZT-SS) actuator is known to achieve motion with a theoretically unlimited range yet high resolution (several nanometers). In this type of actuator, friction plays an active role in producing a meaningful stick-slip motion. However, friction is a source of heat which may cause significant temperature rise, affecting the dynamic performance of the actuator. Our study aimed to measure temperature rise in the stick-slip motion and to understand whether such a rise could significantly affect the displacement of the stick-slip motion. In this study, a temperature measurement system was developed using the off-the-shelf components, with which the temperature rise up to 0.436 degrees C was successfully measured on a proprietary PZT-SS actuator. The experiment further shows that the temperature rise affects the displacement of the actuator when operating voltage is at the low end (approximately 6 V). Therefore, one of the design recommendations for such an actuator system is that the operating voltage should be at the high end (approximately 30 V). The study also measured the temperature rise (approximately 0.263 degrees C after the system worked for 6300 s) at the friction interface due to the piezoelectric element which is a part of the whole PZT-SS actuator. This means that temperature rise is due to both the friction at two interacting surface and the operation of the piezoelectric element.

A mechanical model of a non-uniform ionomeric polymer metal composite actuator

This paper describes a mechanical model of an IPMC (ionomeric polymer metal composite)actuator in a cantilever beam configuration. The main contribution of our model is that itgives the most detailed description reported so far of the quasistatic mechanical behaviourof the actuator with non-uniform bending at large deflections. We also investigate a casewhere part of an IPMC actuator is replaced with a rigid elongation and demonstrate thatthis configuration would make the actuator behave more linearly. The model isexperimentally validated with MuscleSheet™ IPMCs, purchased from BioMimeticsInc.

RF MEMS Extended Tuning Range Varactor and Varactor Based True Time Delay Line Design

MEMS varactors are one of the important passive MEMS devices. Their applica- tions include use in VCOs, tunable impedance matching networks, tunable fllters, phase shifters, and true time delay lines. The shunt capacitive structure has been employed in most of the conventional MEMS varactor designs because of its simplicity. However, the capacitance ratio of this conventional shunt capacitive MEMS varactor is limited to 1.5 because of the MEMS Pull- In efiect, which happens when the de∞ection between the MEMS top and bottom metal plates increase beyond 1/3 of the airgap between the two metal plates. At that time, the top metal plate will quickly snap down. This efiect is the major limitation in MEMS varactor designs and can cause nonlinearity and mechanically instability. In order to eliminate this Pull-In efiect, the author employed the so-called MEMS extended tuning range structure. This structure utilizes a variable height top metal beam with separate actuation parts. The airgap between the center part of the top beam and the bottom plate has been designed to be less than 1/3 of the airgap between the top beam and the bottom actuation pads. When DC bias is applied to the actuation parts, the entire top beam will move down together. Consequently, before the Pull-In efiect happens at the actuation parts, the center part has already traveled through its entire tuning range, which means that the capacitive ratio of this kind of MEMS varactor can go to inflnity. A fabrication process employing a GaAs substrate has been designed based on surface micro- machining technology. The maximum capacitance ratio of the designed MEMS extended tuning range varactor is 5.39 with a Cmax value of 167fF. Based on this MEMS varactor design, a Ka-band MEMS varactor based distributed true time delay line has been designed. This dis- tributed true time delay line includes a high impedance CPW transmission line with 70› un- loaded impedance at 28GHz and eight MEMS extended tuning range varactors based on the varactor design periodically loaded on the CPW line. The testing results show that a 56 - phase delay variation has been achieved at 28GHz. The measured insertion loss at 28GHz is i1:07dB at the up-state and i2:36dB at the down-state. The measured return losses, S11 and S22, are both below i15dB at 28GHz and below i10dB over the entire tested frequency range of 5GHz to 40GHz.

Reliable Adaptive Control for Switched Fuzzy Systems

A model of a kind of uncertain switched fuzzy systems is presented first, in which each subsystem is an uncertain fuzzy system. Then the robust stabilization problem to the system is studied and a solution proposed. When the upper bounds of the disturbances are unknown, and the actuator is serious failure and the residual part of actuator can not make original system stable, a reliable robust adaptive controller is constructed to guarantee the closed-loop system is uniformly ultimately bounded via using switching technique and multiple Lyapunov function approach. The switching strategy achieving system uniformly ultimately bounded of the uncertain switched fuzzy system is given. An illustrative example is given that demonstrates the feasibility and the effectiveness of the proposed method.

Design and fabrication of in-plane resonant microcantilevers

An in-plane resonant bimetal microcantilever based on thermal actuation mechanism was developed utilizing the photolithography technique. The microcantilever structure consists of a platform, a long narrow anchor, and a U-shape actuation loop. Niobium and gold are used as materials for fabrication of the microcantilever. In the cantilever design the shortcoming of low actuation frequency was overcome by separating the thermal actuator part and the microcantilever part. According to the dynamic property tests, the in-plane resonant frequency of our microcantilevers is one order of magnitude higher than the out-of-plane one. With further optimizing the design, our microcantilevers may have applications as actuators and biosensors.

Output Feedback Sliding Mode Control for a Linear Focusing Actuator in Digital Video Cameras

The output feedback sliding mode control offers an effective positioning method by robustness to parameter variation and disturbance rejection. This paper presents the output feedback sliding mode control based on a position estimation algorithm written in the microprocessor for use in the focusing control system of a digital video camera to achieve fast focusing response and accurate positioning despite vibration and friction of the movable part of the linear focusing actuator. The focusing performance by utilizing the output feedback sliding mode control includes a 60-ms setting time and 7-m steady-state error, respectively, which are only half and one-third of those in proportional-integral-derivative control when the movable part of the linear focusing actuator moves at a 5-mm stroke.

Photocontrolled wettability changes in polymer microchannels doped with photochromic molecules

The authors demonstrate the possibility to control the fluid flow inside microfluidic networks by photoresponsive capillaries. The approach relies on the use of photochromic molecules undergoing reversible changes in their polarity when irradiated with light of specific wavelength, thus varying the wettability of cyclic olefin copolymer microchannels. The realized photoresponsive elements exhibit a decrease up to 20° between the water contact angles of the native and the irradiated surfaces, which could be exploited for enhancing the penetration flow rate of fluids inside microfluidic channels up to 25%. The photocontrollable microfluidic circuitry presents on-off valve behavior, allowing or blocking liquid filling processes on the base of optical control, thus allowing one to manipulate liquid flow within microfluidic networks without mechanical actuation parts.

Nanoenergetic Materials for MEMS: A Review

New energetic materials (EMs) are the key to great advances in microscale energy-demanding systems as actuation part, igniter, propulsion unit, and power. Nanoscale EMs (nEMs) particularly offer the promise of much higher energy densities, faster rate of energy release, greater stability, and more security (sensitivity to unwanted initiation). nEMs could therefore give response to microenergetics challenges. This paper provides a comprehensive review of current research activities in nEMs for microenergetics application. While thermodynamic calculations of flame temperature and reaction enthalpies are tools to choose desirable EMs, they are not sufficient for the choice of good material for microscale application where thermal losses are very penalizing. A strategy to select nEM is therefore proposed based on an analysis of the material diffusivity and heat of reaction. Finally, after a description of the different nEMs synthesis approaches, some guidelines for future investigations are provided.

Miniature bending manipulator for fetoscopic intrauterine laser therapy to treat twin-to-twin transfusion syndrome

Recent typical therapy for twin-to-twin transfusion syndrome (TTTS) is selective laser photocoagulation of anastomotic communicating vessels on the placenta using the fetoscopic approach. The difficulty of a conventional laser device approach for this procedure depends significantly on the placental location, so a new robotized device is required to bend the direction of laser irradiation flexibly within the narrow uterus. The authors designed a miniature bending mechanism impelled by a wire-guided linkage driving method that provides a stable procedure for bending laser irradiation from -90 degrees to 90 degrees . Using this bending mechanism, the authors developed a bending manipulator with a diameter of 3.5 mm and a hollow central channel with a diameter of 0.8 mm for passing a glass fiber for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser photocoagulation. The bending mechanism is motorized by an electrical actuator and controlled by a grip-type interface with a small joystick. The robotized tip's part and the actuator's part are easily separable for cleaning and sterilization. In performance evaluations of the manipulator, the bending characteristics with a glass fiber were examined. The bending range was -52.6 degrees to 80 degrees, with a very small hysteresis error, and the bending repeatability error was 0.5 degrees +/- 0.2 degrees, which corresponds with the high accuracy of 0.2 +/- 0.1-mm positioning error at the glass fiber's tip. In the evaluation of Nd:YAG laser photocoagulation, the study confirmed that the manipulator performed effective laser photocoagulation of the placental phantom surface (underwater chicken liver). The large bending range, reaching 80 degrees, enabled a flexible approach from various directions with a high irradiation efficiency of no less than 96.6%. The authors' original miniature bending manipulator can change the laser irradiating direction with highly repeatable positioning accuracy for speedy, safe, and effective vessel occlusion in clinical practice.

Theoretical analysis and optimization of electromagnetic actuation in a valveless microimpedance pump

The construction of a novel valveless microimpedance pump is proposed and the utilized electromagnetic actuator is designed and optimized in this study. The actuating mechanism comprises an electroplated permanent magnet mounted on a flexible PDMS diaphragm and electroplated Cu coils located on a glass substrate. The electromagnetic force between the magnet and the Cu coils causes the diaphragm to deflect and then creates the accumulative effects of wave propagation and reflection at the junction of the compressible and rigid sections. The resulting pressure gradient in the fluid drives the flow from the inlet to the outlet of the micropump. The constituent parts of the electromagnetic actuator, namely the diaphragm, the microcoils, and the magnet are modeled and analyzed in order to optimize the actuator design. The design models are verified both theoretically and numerically and the relationships between the magnetic force, diaphragm displacement, and diaphragm strength are established. The magnitude of the magnetic force acting on the flexible diaphragm are calculated using Ansoft/Maxwell3D FEA software and the resulting diaphragm deflection simulated by ANSYS FEA software are found to agree with the theoretical predictions. Different diaphragm shapes are investigated and their relative strength and flexibility are compared. It is found that a circular PDMS diaphragm represents the most appropriate choice for the actuating mechanism in the micropump. The desired diaphragm deflection of 15μm is obtained using a compression force of 16μN, generated by a coil input current of 0.9A. The diaphragm deflection can be regulated by varying the current passed through the microcoil and hence the flow rate can be controlled. The valveless microimpedance pump proposed in this study is easily fabricated and can be readily integrated with existing biomedical chips due to its plane structure. The results of the present study provide a valuable contribution to the ongoing development of Lab-on-a Chip systems.

Modelling approaches for an ultrasonic percussion drill

This work deals with a novel piezoelectrically driven vibro-impact drilling tool which is designed to drill holes and take rock samples in NASA's future space missions. The drilling device consists of an ultrasonic transducer with a piezoelectric stack, a free flying mass and a drill stem. Excited by the high-frequency vibration of the transducer the free mass oscillates between the horn tip of the transducer and the drill stem. The shock waves in the drill stem caused by the impacts with the free mass affect hard and brittle materials so effectively that small holes can be performed with extremely low additional downforce and low power consumption. This paper provides measurements with a modified actuator which show an irregular motion of the free mass. For further optimization two model approaches are investigated: the finite element method and a discrete lumped parameter model. Each model is capable of predicting actuator's parts motion similar to measurements.

Mechanical Characteristics of FIB Deposited Carbon Nanowires Using an Electrostatic Actuated Nano Tensile Testing Device

This research is directed at the development of Electrostatic Actuated NAno Tensile testing devices (EANATs) for measuring mechanical properties of carbon nanowires, deposited by focused ion beam-assisted chemical vapor deposition (FIB-CVD) using phenanthrene gas. The EANATs were composed of the specimen part, actuator part and measurement part. 1000, 3000 and 5000 pairs of comb drive actuators were prepared within the actuator part for stretching the nanowires. The measurement part had a cantilever used as a lever motion amplification system for measuring tensile displacement of the nanowires. A theoretical resolution of 0.17 nm in tensile displacement was achieved using the amplification system and imaging analysis. The uniaxial tensile force was derived from the total spring constant of suspended beams built within the EANATs, with the theoretical resolutions ranging from 108 to 113 nN. This research was therefore successful in obtaining accurate load-displacement curves for carbon nanowires. The Young's modulus observed for the nanowires provided the scatter in absolute values ranging from 42.6 to 80.7 GPa. The fracture stress and strain of the nanowires exhibited larger values of 4.3 GPa and 0.08 strain, respectively. Discussion of the deformation behaviors and failure mechanisms of the nanowires is made from FE-SEM observations of the nanowires before and after tensile failure

Microscale and nanoscale robotics systems [Grand Challenges of Robotics

Depending on their overall size, sensing and actuation precision, part or tool size, and task space, robotic systems can be classified as microrobotics or nanorobotics, respectively. Micro/nanorobotics represents these two different scale robotics areas jointly while keeping their clear scale differences in mind. At its current early infancy, the field of micro/nanorobotics has two major research thrust areas. Analogous to the manipulation area in macroscale robotics, the first area explores new methods for programmable manipulation and assembly of micro- and nanoscale entities. Here, the overall micro/nanorobotic system size can be very large, while only the manipulation tools, manipulated objects, and sensing, actuation, and manipulation precision are required to be at the micro/nanoscale. On the other hand, the second research area focuses on overall miniaturization of mobile robots down to mum overall sizes with various locomotion capabilities such as flying, swimming, walking, hopping, rolling, and climbing. In these mobile robotic systems, overall system size is very limited, which induces severe constraints in utilized actuators, sensors, motion mechanisms, power sources, computing power, and wireless communication capability. These two research thrusts are described in detail in the following sections

Bluetooth Network for Group Behavior of Multi-Agent Robotic System

Multi-Agent Robotic System (MARS) is a system that independent autonomous robots in the restricted environments infer their status from pre-assigned conditions and operate their jobs through the cooperation with each other. In the MARS, a robot contains sensor part to percept the situation around themselves, communication part to exchange information, and actuator part to do given work. Especially, in order to cooperate with other robots, communicating with other robots is one of the essential elements. Because Bluetooth has many advantages such as low power consumption, small size module package, and various standard protocols, Bluetooth is rated as one of the efficient communicating technologies which can apply to small-sized robot system. In this paper, we will develop Bluetooth communicating system for autonomous robots. For the purpose, the communication system must have several features-separated module, flexible interface. We will discuss how to construct and what kind of procedure to develop the communicating system.

Technology and application of electro-depositable photo resists to create uniform coatings needed for complex 3D micro actuators and sensors

Electro-depositable photo resists, which have been developed for printed circuit board industry (PCB), are recently receiving great attention in MEMS technology. This paper reports on the technology needed and its application for patterning 3D microstructures with high aspect ratios and large structure heights. Adapted equipment for coating structured and non-structured wafers is introduced. The optimized process technology obtained by a multitude of parameter variations is described—providing the application engineer with a means to produce pin hole free uniform coatings on arbitrary geometries, which may be structured with high resolution and allow high aspect ratios. The technology was adapted to several applications, which show the big potential for the development of micro actuators and sensors. This paper focuses on the utilization for electroplating conductors, which are part of a micro actuator based on a helical coil.

Characterization of stiction effects of an electrostatic micro positioner for probe storage

We start by presenting a short explanation of the micro actuator working principle. The main contribution of this paper is the characterization of the coefficient of stiction between two silicon nitride parts of a MEMS actuator. Having one flat contact surface while the other is composed of many relatively sharp circular bumps, has the advantage that the effective contact area is drastically reduced. The stiction coefficient varies between 0-0.53 for the device configuration presented. The exact value depends closely on the electrostatically applied force which presses the textured part on to the smooth one. Individual measurements used are highly accurate (typically within 5 nm noise band) and identical measurements for the characterization of stiction show only a small variation, typically under 25nm on a range of 11.8µm.