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Über dieses Buch

Advanced Mechatronics and MEMS Devicesdescribes state-of-the-art MEMS devices and introduces the latest technology in electrical and mechanical microsystems. The evolution of design in microfabrication, as well as emerging issues in nanomaterials, micromachining, micromanufacturing and microassembly are all discussed at length in this volume. Advanced Mechatronics also provides a reader with knowledge of MEMS sensors array, MEMS multidimensional accelerometer, artificial skin with imbedded tactile components, as well as other topics in MEMS sensors and transducers. The book also presents a number of topics in advanced robotics and an abundance of applications of MEMS in robotics, like reconfigurable modular snake robots, magnetic MEMS robots for drug delivery and flying robots with adjustable wings, to name a few.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Experience from the Development of a Silicon-Based MEMS Six-DOF Force–Torque Sensor

A six-DOF (Degrees Of Freedom) forcetorque sensor was developed to be used for interactive robot programming by so-called lead through. The main goal of the development was to find a sensor concept that could drastically reduce the cost of force sensors for robot applications. Therefore, a sensor based on MEMS (Micro Electro Mechanical System) technology was developed, using a transducer to adapt the measuring range needed in the applications to the limited measuring range of the silicon MEMS sensor structure. The MEMS chip was glued with selected epoxy adhesive on a planar transducer, which was cut by water jet guided laser technology. The transducer structure consists of one rigid cross and one cross with four arms connected to the rigid cross by springs, all in the same plane. For this transducer a German utility patent [Weiß M, Eichholz J Sensoranordnung. Pending German utility patent] is pending. The MEMS structure consists of one outer part and one inner part, connected to each other with beams obtained by DRIE (Deep Reactive Ion Etching) etching. On each beam four piezoresistors are integrated to measure the stress changes used to calculate the forces and torques applied between the outer and inner part of the MEMS structure. The inner part was glued to the mentioned rigid cross of the transducer and the outer part was glued to the four arms including the transducer springs. FEM (Finite Element Modeling) was used to design both the MEMS- and transducer part of the sensor and experimental tests were made of sensitivity, temperature compensation, and glue performance. Prototypes were manufactured, calibrated, and tested, and the concept looks very promising, even if more work is still needed in order to get optimal selectivity of the sensor.
Jörg Eichholz, Torgny Brogårdh

Chapter 2. Piezoelectrically Actuated Robotic End-Effector with Strain Amplification Mechanisms

This chapter describes a nested rhombus multilayer mechanism for large effective-strain piezoelectric actuators. This hierarchical nested architecture encloses smaller flextensional actuators with larger amplifying structures so that a large amplification gain on the order of several hundreds can be obtained. A prototype nested PZT cellular actuator that weighs only 15 g produces 21% effective strain (2.53 mm displacement from 12 mm actuator length and 30 mm width) and 1.69 N blocking force. A lumped parameter model is proposed to represent the mechanical compliance of the nested strain amplifier. This chapter also describes the minimum switching discrete switching vibration suppression (MSDSVS) approach for flexible robotic systems with redundancy in actuation. The MSDSVS method reduces the amplitude of oscillation when applied to the redundant, flexible actuator units. A tweezer-style end-effector is developed based on the rhombus multilayer mechanism. The dimensions of the end-effector are determined by taking the structural compliance into account. The assembled robotic end-effector produces 1.0 N of force and 8.8 mm of displacement at the tip.
Jun Ueda

Chapter 3. Autocalibration of MEMS Accelerometers

In this chapter, we analyze the critical aspects of the widely diffused calibration and autocalibration procedures for MEMS accelerometers. After providing a review of the main applications of this kind of sensors, we introduce the different sensor models proposed in literature, highlighting the role of the axis misalignments in the sensor sensitivity matrix. We derive a principled noise model and discuss how noise affects the norm of the measured acceleration vector. Since autocalibration procedures are based on the assumption that the norm of the measured acceleration vector, in static condition, equals the gravity acceleration, we introduce the international gravity formula, which provides a reliable estimate of the gravity acceleration as a function of the local latitude and altitude. We derive then the autocalibration procedure in the context of maximum likelihood estimate and we provide examples of calibrations. For each calibrated sensor, we also illustrate how to derive the accuracy on the estimated parameters through the covariance analysis and how to compute the angles between the sensing axes of the sensor. In the conclusion, we summarize the main aspects involved in the autocalibration of MEMS accelerometers.
Iuri Frosio, Federico Pedersini, N. Alberto Borghese

Chapter 4. Miniaturization of Micromanipulation Tools

To enable the manipulation of objects below micrometers, miniaturization of MEMS tools is crucial. The process of device miniaturization, however, poses several challenges that are yet to be overcome. Due to force scaling, the significant increase in surface forces also demands the development of new manipulation strategies. This chapter provides a summary of the difficulties associated with this miniaturization process as well as an up-to-date review on recent progress.
Brandon K. Chen, Yu Sun

Chapter 5. Digital Microrobotics Using MEMS Technology

Microrobotics deals with the design, fabrication, and control of microrobots to perform tasks in the microworld (i.e., the world of submillimetric objects). While end-effectors experienced considerable developments, few works concerned the development of microrobot architectures adapted to the microworld. Most of the current robots are bulky and are based on the miniaturization of traditional architectures and kinematics. In this chapter, we introduce a new approach for the design of microrobot architectures based on elementary mechanical bistable modules. This bottom-up approach called “digital microrobotics” takes advantage of MEMS technology and open-loop (sensorless) digital control to offer a flexible way to experiment various kinematics adapted to the microworld. A microfabricated bistable module is proposed and a complete digital microrobot is designed, modeled and fabricated. Digital microrobotics opens new perspectives in microrobots design and micromanipulation tasks.
Yassine Haddab, Vincent Chalvet, Qiao Chen, Philippe Lutz

Chapter 6. Flexure-Based Parallel-Kinematics Stages for Passive Assembly of MEMS Optical Switches

A key operation in assembly of MEMS optical switches is to insert fibers into U-grooves on a silicon substrate. Due to the limited positioning accuracy of the handling tool, heavy collision often occurs between fibers and the edges of U-grooves during the insertion operation. Such collisions will not only damage fibers and U-grooves but also sometimes make the fiber skidding from the handling tool. Conventional solutions to the problem involve determining misalignment using machine vision or force sensors, and then positioning fibers accurately by virtue of high precision multiaxis positioning systems (with submicron repeatability). However, such approaches are costly and difficult to implement. In this chapter, we present a cost-effective passive assembly method to solve the problem. It utilizes a specially designed passive flexure-based fixture (stage) to regulate high contact forces and accommodate assembly errors. To determine the design conditions for a successful insertion, the major problems encountered during the fiber insertion are analyzed. A systematic design method is then proposed for a 3-legged Flexure-based Parallel-Kinematics Stage (FPKS) for passive assembly applications. Experimental results show that such a passive assembly approach can effectively and automatically reduce the contact force and accommodate the assembly errors.
Wenjie Chen, Guilin Yang, Wei Lin

Chapter 7. Micro-Tactile Sensors for In Vivo Measurements of Elasticity

In this chapter, a sensing approach for the measurement of both contact force and elasticity is introduced and discussed. By using the developed method, the elasticity of various objects (e.g., tissue) can be measured by simply touching the targeted object with the sensor. Each developed sensor consists of a pair of contact elements that have different values of stiffness. During contact, the relative deformation of the two sensing components can be used to calculate the Young’s modulus of elasticity. Several prototypes of tactile sensors have been fabricated through various MEMS processes. One of the prototypes developed through a polymer MEMS process has a favorable flexible structure, which enables the sensor to be integrated on end-effectors for robotic or biomedical applications. Finally, the tactile sensor has been attached on a touch probe and tested in a handheld mode. An estimation algorithm for this handheld device, which employs a recursive least squares method with adaptive forgetting factors, has also been developed. Experimental results show that this sensor can differentiate between a variety of rubber specimens and has the potential to provide reliable in vivo measurement of tissue elasticity.
Peng Peng, Rajesh Rajamani

Chapter 8. Devices and Techniques for Contact Microgripping

The gripping and manipulation of microparts significantly differs from the handling and assembly of macroscopic components. In the macroworld gravity dominates, whereas in the microdomain, it becomes negligible, and superficial forces dominate pick and place operations. Releasing a part from the grasp of a microgripper is not a simple task as the part may stick to the gripper due to the presence of these adhesive forces. For this reason, beside the numerous attempts of downscaling traditional grippers also innovative actuation strategies have been proposed. The chapter critically reviews some of the most widely used micromanipulation techniques with contact, highlighting their advantages and disadvantages and describing some innovative solutions based on capillary forces.
Claudia Pagano, Irene Fassi

Chapter 9. A Wall-Climbing Robot with Biomimetic Adhesive Pedrail

A prototype of a wall-climbing robot with gecko-mimic adhesive pedrails was developed to demonstrate the adhesive ability of micron adhesive arrays. The robot has two parallel pedrails driven by a DC motor. The outside surfaces of the pedrails were covered by gecko-mimic adhesive hair arrays made by polydimethylsiloxane (PDMS). A two-step template method was used to fabricate gecko-mimic adhesive array in which the hair density, diameter, and length could be adjusted independently. A tail was fixed at the rear of the robot to provide preload for adhesion. Experiment results show that the robot has the ability to climb on vertical wall.
Xuan Wu, Dapeng Wang, Aiwu Zhao, Da Li, Tao Mei

Chapter 10. Development of Bioinspired Artificial Sensory Cilia

Given inspiration from the natural hair receptors of animals, sensors based on micro/nanofibers are considered as a significant and promising solution for improving the intelligence and automation of microrobots in the future. Thus, we introduce in this chapter the concept and design of some novel artificial hair receptors for the sensing system of microintelligent robots. The natural hair receptor of animals, also called cilium or filiform hair by different research groups, is usually used as a sensitive element for slight disturbance by insects, mammals and fishes, such as a detector for ambient vibration, flow or tactile information. At first, focusing on the development of biomimetic sensory abilities for an undulatory soft-body lamprey-like robot, piezoresistive sensory elements based on highly soft silicone rubber matrix are presented. On the other hand, micro-artificial hair receptor based on suspended PVDF (polyvinylidene fluoride) microfibers is also designed to address useful applications for microrobots working in unstructured environments. Both these cilia shaped sensors show a reliable response with good sensibility to external disturbance, as well as a good prospect in the application on sensing system of mini/microbiorobots.
Weiting Liu, Fei Li, Xin Fu, Cesare Stefanini, Paolo Dario

Chapter 11. Jumping Like an Insect: From Biomimetic Inspiration to a Jumping Minirobot Design

Locomotion is a key issue for autonomous robots, moreover if we consider gait efficiency in exploration and monitoring application. Despite the implicit mechanical and kinematic complication, legged locomotion is often preferred to the simpler wheeled version in unstructured environment, e.g., difficult terrains. Focusing on microrobot, lessons from nature often provide us a good insight of profitable solutions and suggest bioinspired design for small legged robots.
According to the biological observation experiment, it was found that a specific leg configuration maps the nonlinear muscle-like force into a constant force at feet–ground interface so as to minimize the risk of both leg ruptures and tarsus slippage, which represents an optimum design of jumping insects. That gives us the bionic inspiration to optimize the saltatorial legs by reproducing the dynamic characteristics of insect jumping. Based on this idea, jumping robot prototype GRILLO is designed and tested with different ways.
In this chapter, we present the bioinspired design of such a jumping mini robot including the dynamically optimized saltatorial leg which is designed to imitate the characteristics of a real jumping insect, kinematically and dynamically, and proposed to mitigate the peak contact force at tarsus–ground interface during jumping acceleration; the overall design of the jumping robot prototype; and as a part of the biomimetic research, the measuring and comparing of the jumping characteristics between the robot and animal so as to show the dynamic similarity and optimization results between them. The finally energy integrated jumping robot prototype is able to move by continuous jumping, of which a single one reaches 100 mm high and 200 mm long, about twice and four times of its body length respectively.
Weiting Liu, Fei Li, Xin Fu, Cesare Stefanini, Gabriella Bonsignori, Umberto Scarfogliero, Paolo Dario

Chapter 12. Modeling and H ∞ PID Plus Feedforward Controller Design for an Electrohydraulic Actuator System

This work studies the modeling and design of a proportional-integral-derivative (PID) plus feedforward controller for a high precision electrohydraulic actuator (EHA) system. The high precision positioning EHA system is capable of achieving a very high accuracy positioning performance. Many sophisticated control schemes have been developed to address these problems. However, in industrial applications, PID control is still the most popular control strategy used. Therefore, the main objective of this work is to design a PID controller for the EHA system, improving its performance while maintaining and enjoying the simple structure of the PID controller. An extra feedforward term is introduced into the PID controller to compensate for the tracking error especially during the transient period. The PID plus feedforward control design is augmented into a static output feedback (SOF) control design problem and the SOF controller is designed by solving an H optimization problem with bilinear matrix inequalities (BMIs).
Yang Lin, Yang Shi, Richard Burton

Backmatter

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