Design enhancement of a chevron electrothermally actuated microgripper for improved gripping performance

In this paper design modifications are proposed in microgripper design using two in-plane chevron electrothermal actuators. The design modifications are, converting free–free gripping arm into a clamped-free gripping arm and inclusion of the heat sinks in the shuttle. The modified design provides reduced temperature at the gripping jaws and higher gripping force. The proposed microgripper is modelled analytically and numerically using MEMS CAD tool CoventorWare. The performance of the microgripper such as displacement, force and temperature for the voltage range of 0–1.2 V is evaluated through numerical and analytical simulation. The results demonstrate the feasibility of fabrication. Further the gripper is made of polysilicon which allows operating the gripper at lower voltage.     

Design,modeling and test of a novel compliant orthogonal displacement amplification mechanism for the compact micro-grasping system

In the compact micro-grasping system, the combination of precisely orthogonal movement transformation, displacement amplification and simple structure is important. The typical solution of the combination issue requires bidirectional symmetric input forces/displacements. However, under a certain driving condition, numerous actuators used in micro-manipulation only supply unidirectional input froce/displacement for the driven mechanism, which makes the typical solution infeasible. In this study, a novel compliant orthogonal displacement amplification mechanism (DAM) is proposed to solve the combination issue for numerous actuators used in micro-grasping. The proposed mechanism is a triangulation amplification-based mechanism with undetermined structural parameters. The number of the undetermined parameters and the solution principle are analyzed. The design process is presented. Finite element analysis (FEA) is used to verify the design method. The FEA results show that, for the design examples, the errors evaluating the orthogonal movement transformation are smaller than 0.56 % and 0.15 % respectively, and the displacement amplification ratios are larger than 4.6. The orthogonal displacement amplification is realized. A precise model of the displacement amplification ratio is derived. The dynamic performances of the proposed orthogonal DAM are modeled and FEA verified. Furthermore, a microgripper utilizing the proposed mechanism is presented. The performances of the gripper, including the displacement amplification and the parallel movement of the jaws, are verified by FEA and experiments.

     

Design and analysis of a novel piezoelectric inertial actuator with large stepping displacement amplified by compliant mechanism

Microsystem Technologies - A novel piezoelectric inertial actuator is developed in this paper, to realize the requirements of large stroke and high output displacement accuracy. This proposed...     

Development of a transformable wheel actuated by soft pneumatic actuators

Small mobile robots with transformable wheels have recently emerged thanks to their increased mobility and maneuverability. When a high payload is applied to these robots, however, wheel transformation becomes difficult because they must directly overcome the payload’s weight. In this paper, we propose a wheel that can be transformed from its starting circular shape (radius, 56 mm) to a wheel with three legs (radius, 99 mm) under a high payload with low operating force. The key design principle of this wheel is to kinematically decoupled legs and passive locking. Its legs are kinematically decoupled but operated by a single air pump using a pneumatic channel connected to soft pneumatic actuators installed at each leg. Application of pressure causes the legs to behave like a coupled system through the pneumatic channel. With pressurization, the two legs that are not in contact with the ground easily emerge from body, and the leg in contact with the ground emerges once the wheel rotates. Once emerged, each leg is supported by a rigid pawl instead of by the soft pneumatic actuators. This setup enables the legs to be transformed independently with low air pressure, even under high payloads. It reduces system weight and the energy required to maintain the transformed shape. This legged wheel can overcome obstacles up to 2.9 times the radius of the wheel in its circular form, and wheel transformation can be accomplished with 85 kPa air pressure for payloads up to 1115 g.     

Design,analysis and validation of the bridge-type displacement amplification mechanism with circular-axis leaf-type flexure hinges for micro-grasping system

Microsystem Technologies - For stable and flexible manipulation, realizing parallel grasping and large output stroke simultaneously has become a key issue in the researches on micro-grasping...     

Dynamics modeling and analysis of a biped walking robot actuated by a closed-chain mechanism

We developed a new type of human-sized biped walking robot (BWR) driven by the closed-chain type of joint actuator. Each leg of the robot is composed of three pitch joints and one roll joint. In all, a 15 degree-of-freedom robot including four arm joints and three joints for the head was developed. The BWR was developed to walk autonomously such that all leg joints are actuated by small 90 W dc motors/drivers and dc batteries and controllers which are boarded. The joint actuator for the BWR is composed of the four-bar-link mechanism driven by the ball screw which has high strength and high gear ratio. A dynamics modeling of the developed BWR for forward walking is presented in which the revolute joint dynamics are transformed into the prismatic joint dynamics of the ball screw. Also, an analysis on the four-bar-link mechanism applied to the joint actuator and on the structure of the BWR is shown. The design specification of the actuating motor for the BWR is analyzed through the torque analysis of the four-bar-link actuator. Through walking experiments of the BWR, the walking performance and trajectory tracking ability is shown. © 2004 Wiley Periodicals, Inc.     

Design of swing arm type actuators considering thermal and dynamic characteristics

The present state of the design of swing arm actuators for optical disc drives is to obtain the highly efficient dynamic characteristics within a very compact volume. As a necessary consequence, the need of the small form factor (SFF) storage device has arisen as a major interest in the information storage technology. Due to the size constraint, the thermal stability of the optical pick-up head is important: therefore, the actuator is designed to emit the heat, which is generated by the optical pick-up, along the structural body easily. In this paper, we suggest the miniaturized swing arm type actuator that has effective heat emission quality as well as satisfies the dynamic requirements for the SFF optical disk drive (ODD). The actuator is targeted to be installed in CF-II card size drive to be competitive with flash memory or mini hard disk drive used in mobile electric devices; therefore the dimension of the actuator is required as 11.0 mm × 2.5 mm × 25.0 mm (width × height × length). Because of its small size, the dynamic requirements are severe to ensure the enough gain-margin for the system control together with satisfying the DC/AC sensitivity conditions. Moreover, due to the small size, the maximum pick-up temperature is critical in design because the system has high possibility to reach the shut-down temperature. For the operating mechanism, it uses a tracking electromagnetic (EM) circuit for the focusing motion together and the initial model is designed and promoted by the design of experiments (DOE) only considering the dynamic characteristics. New concept design is suggested based on the topology optimization method considering the thermal conductivity. Furthermore, the new design is modified by DOE to maintain the high sensitivity and to have wide control bandwidth and decreasing mass and inertia. The final design of a swing arm type actuator for SFF ODD is suggested and its dynamic characteristics are verified.     

基于集成电子设备的微小飞行器热控设计及分析

随着航天器轻量化以及微型化发展趋势,微小飞行器作为一种高功能性、低成本的航天器得到了广泛的关注,同时微小飞行器电子设备集成化以及轻量化会给热控系统带来设计难度。针对某微小飞行器的轨道参数和结构性能,提出了采取等温化以及机-电-热一体化的热设计方案,并通过Thermal Desktop软件建立飞行器在轨状态的热模型,仿真分析飞行器的高温和低温极端外热流工况以及瞬态温度分布。仿真结果表明,采取的热控方案能够解决该类微小飞行器的热设计难题。     

基于STM32的微位移检测系统设计

研制了一种基于STM32的微位移检测系统设计方案.通过抑制直流漂移的电路处理模块得到直流稳定的两路光电信号.根据两路光电信号的相位特点,采用STM32同步采样两路光电信号,并利用椭圆拟合、最小二乘法、相位解包裹法对采集的数据进行处理运算,计算出微位移.现场测试结果表明:该系统满足微位移测量要求.     

Design and fabrication of novel micro electromagnetic actuator

This study designs, fabricates, and characterizes a novel micro electromagnetic actuator comprising a PDMS diaphragm, a polyimide-coated copper micro coil, and a permanent magnet. When an electrical current is passed through the micro coil, a magnetic force is induced between the coil and the magnet which causes the diaphragm to deflect, thereby creating an actuation effect. The experimental results demonstrate that the diaphragm deflection can be accurately controlled by regulating the current passed through the micro coil. It is shown that the maximum diaphragm deflection within elastic limits is 150 μm; obtained by passing a current of 0.6 A through a micro coil with a line width of 100 μm. The micro actuator proposed in this study is easily fabricated and is readily integrated with existing bio-medical chips due to its planar structure.     

Optimal displacement amplification ratio of bridge-type compliant mechanism flexure hinge using the Taguchi method with grey relational analysis

Microsystem Technologies - The compliant mechanism flexure hinge has been frequently utilized in precision enginering in recent years, such as the bridge-type and rhombus-type compliant mechanisms....     

Design of novel deformable mirror with large displacement

A stabilized zoom system with deformable mirrors (DMs) was designed for continuous optical zoom. In order to adjust the focal length and expand the field angle, the characteristic surface shapes of the DMs composed of the low-order and high-order Zernike polynomials were provided. The maximum peak-to-valley (PV) value at the center of the surface shape is 80 μm. This work presents a piezoelectrically-actuated deformable mirror (PADM) with large displacement for a stabilized zoom system. The COMSOL simulation was conducted to obtain the desired design by matching and optimizing structural parameters. The maximum displacement of PADM was more than 80 μm. The fitting results by the steepest descent algorithm (SD) showed that the RMS values of the residual surface shapes were 1 of 7 to 1 of 4 of their PV values, and the PV values of the residual surface shapes were less than 1 of 10 of the PV values of the target surface shapes.     

扫描隧道显微镜微动台的有限元分析与实验研究

设计了一种以基于尺蠖运动原理的微动台为核心的扫描隧道显微镜(STM)机械机构,利用有限元方法对微动台部分的结构进行分析,对其静态、模态特性进行了实验研究。结果表明:微动台具有较大的行程和较好的稳定性,载物力可以达到16.7 N,最小步距约8.8 nm,行程14mm。     

Piezoelectric thin films formed by MOD on cantilever beams for micro sensors and actuators

Novel piezoelectric cantilever beams for micro sensors and actuators based on PZT thin films have been batch fabricated by surface micromachining. Lead zirconate titanate (PZT) thin film is formed by metalorganic deposition (MOD) on Pt/Ti/SiO₂/Si (1 0 0) substrates and Pt/Ti/LTO/Si₃N₄ cantilever beams and then annealed at 700 °C in air. The PZT thin film is 0.5 m thick and has dielectric permittivity of 1698, remanent polarization of 13.66 C/cm², and coercive field of 44.5 kV/cm. The influence of deposition temperatures on PZT thin film stress has been investigated. When continuously controlling the deposition temperatures, the stress of the thin film is reduced from 0.313 × 10⁸ to 0.269 × 10⁸ N/m, that is 16.4% decrease. With the total 120 designed devices on 4-inch wafers, the number of functional devices is increased from 82 to 97, that is 12.47%.Tianhong Cui joined the faculty of Institute for Micromanufacturing at Louisisana Tech University in 1999. He received his B.S. from Nanjing University of Aeronautics & Astronautics in 1991, and his Ph.D. from Chinese Academy of Sciences in 1995. He has conducted research and development work for the realization of microsensors and microactuators since 1992. Prior to joining the IfM in 1999, he was at the National Laboratory of Metrology in Japan as a Research Fellow under STA fellowship, and previous to that, served as a Postdoctoral Research Associate at the University of Minnesota. His current research interests include MEMS, polymer micro/nanoelectronics, and nanotechnology.     

二维微载荷传感器的设计与分析

设计了一种二维微载荷传感器。用于仿生粘性材料的力学性能测试,也可用于一般的摩擦试验。利用应力集中原则对平行梁弹性体局部削弱,结合材料力学理论和有限元软件ANSYS对弹性体进行仿真设计。利用ANSYS后处理器中提供的路径映射技术,在弹性体应变最大的区域,确定弹性体应变计的最佳贴片位置。对传感器进行静态标定,得出其静态性能指标,其垂直方向的最大量程为3.0 N,分辨力为0.008 N;水平方向的最大量程为3.5 N,分辨力为0.01 N。     

Simulation and experimental analysis for hysteresis behavior of a piezoelectric actuated micro stage using modified charge system search

The main goal of this study is to investigate the hysteresis behavior of a piezoelectric actuated micro stage. The hysteresis of piezoelectric actuators (PA) is formulated using the generalized Duhem model (GDM) and a modified charge system search (CSS) is proposed to identify the hysteresis model. Different from the present CSS method, the proposed method applies a construction factor to prevent converging to a local optimum. The modified CSS is used to evaluate the parameters of the GDM to compare with the particle swarm optimization (PSO). The use of MCSS-based optimization is superior to the CSS and the PSO for identification of the GDM. The experimental result also validated the modeling correctness using the proposed method.     

Design and analysis of MEMS based piezoelectric micro pump integrated with micro needle

Microsystem Technologies - This paper presents the design and simulation of piezoelectric micro pump integrated with micro needle. The proposed micro pump adopted rectangular piezoelectric vibrator...     

Design and mechanism analysis of a novel type compact single mirror laser scanner

A novel type of laser scanner employing a permanent magnetic suspension and spherical hinges has been developed. It consists of a single mirror based on linear electromagnetic actuators. This system has design features of playing the role of a two-dimensional tilt actuator by means of driving the electromagnetic actuators, and it provides good mechanical characteristics such as low distortion and damping, high optical angular deflection, and high dynamical performance (more than 1 kHz). This paper describes the configuration of the device and presents experimental results to demonstrate its performance and effectiveness.