Optimized friction drive controller for a multi-DOF ultrasonic nanopositioner

This paper presents a new generation of compliant multi-degrees-of-freedom piezoelectric nanopositioner for positioning, transport, alignment of micro-objects under the field of view of a microscope. It is based on the cooperation of arrayed direct-drive standing-wave ultrasonic actuators (microSWUMs). A number of nonlinearities exist in the actuator due to its macro- and microdynamics. An optimized friction drive multidimensional controller is proposed based on a closed-loop electromagnetic field-based preload controller ensuring optimal preload, and a feedforward pulsewidth modulation (PWM) controller with input shaping for driving force control. These techniques are applied to reduce the effects of low-speed-low-force instabilities due to stick-slip and friction pairs which lead to output oscillations during nanometric stepping motion. The closed-loop positioning system designed with microSWUMs produced 10-nm resolution and 5% displacement repeatability in a low-speed-low-force region; unlimited travel with velocities of 0.3 m.s/sup -1/ and driving forces around 2 mN in a high-speed-high-force region.     

A high-efficiency magnetic suspension actuator with reluctance-balanced permanent magnet biasing and flux-based control

To reduce power consumption of active magnetic bearings (AMBs), permanent magnets (PMs) may be employed to generate a bias flux through the magnetic circuits connecting the actuators with the rotor. In this way, control algorithms based on zero-current operating points and linearized models may be used. This paper describes a new modular design of PM-biased AMB actuator involving a balanced-reluctance topology where the bias flux is set by an auxiliary air gap within the magnetic circuit. A theoretical model and design methodology for achieving a specified range of actuation forces are also defined. Each actuator unit within an AMB suspension system may by positioned freely and operated independently because, unlike many previous PM-biased designs, there is no flux linkage between actuators. To improve the robustness of the actuator control to uncertainty in material properties and air gap sizes, a feedback control scheme is proposed based on inductive sensing of the mean flux density at the actuator pole faces. Testing of the actuator with a current-cancelling flux-based control scheme shows that stable suspension with very low power consumption can be achieved over a range of operating conditions involving both static loading and unbalance excitation.     

Inversion-free force tracking control of piezoelectric actuators using fast finite-time integral terminal sliding-mode

The major hurdles to control the force created by piezoelectric actuators (PEAs) are originated from its strong nonlinear behaviors which include hysteresis, creep, and vibration dynamics. To achieve an accurate, fast and robust force tracking performance without using complicated modeling and parameter identification of PEAs, this paper presents a practical direct force control scheme. The proposed controller is based on two core approaches: 1) fast finite-time integral terminal sliding mode (FFI-TSM) which allows fast convergence and high accuracy to the closed-loop system without control chattering; and 2) an inverse-model-free compensation, named force-based time-delayed estimation (FBTDE) which offers significant robustness with minimum use of plant dynamics information. The finite-time stability of the overall closed-loop system is proven through the Lyapunov’s method. The proposed force tracking controller is implemented on the PEA system driving a variable physical damping actuator mechanism. The overall accuracy, convergence speed, and robustness of the proposed controller are validated under various experimental scenarios. Comparative experimental results are particularly presented to verify the effectiveness of the FFI-TSM term and the FBTDE term.     

Micro mechatronics and micro actuators

Micro mechatronics is the synergetic integration of both mechanical and electronic systems based on scaling effects in the micro world. A micro mechatronics system is expected to be the key component of the mechanical system, such as in electronic automotive technologies. Micro mechatronics requires the organic combination of micro devices such as micro processor, micro sensor, and micro actuator. Among the micro devices, the micro processor and micro sensor have been widely employed in advanced mechatronics products, but not the micro actuator. This paper surveys the state of the art of micro mechatronics and deals with micro actuators as new devices for micro mechatronics and advanced mechatronics, which play an important role in today's integrated mechanical products. Since micro actuators are still under development, the authors focus on micro actuators for further research and development in this paper.     

An 80-V integrated boost converter for piezoelectric actuators in smartphones

A boost converter for piezoelectric actuator driving system in haptic smartphones is proposed and implemented using a 0.35 μm BCDMOS process. The designed boost converter generates extremely high output voltage from a low-voltage battery supply. The boost converter provides stable power for the piezoelectric actuator with the peak-current control technique. The minimum variation of the output ripple variation can be achieved by the designed current-sensing and peak-current control circuits. The supply voltage of the boost converter is 2.7–4.2 V and the maximum output voltage is up to 80 V. The complete piezoelectric actuator driving system consists of a serial interface, SRAM, and signal-shaping logic as well as the boost converter. It also includes the resistor-string digital-to-analog converter and high voltage piezoelectric actuator driver (PZ driver). The fabricated chip size is 2,100 × 2,200 μm, including bonding pads.     

Closed-loop class E transcutaneous power and data link for microimplants.

Magnetic transcutaneous coupling is frequently used for power and data transfer to implanted electronic devices. The proposed development of MicroImplants, small enough to be injected through a hypodermic needle suggest the need for a high-efficiency magnetic transcutaneous link. This paper describes the use of a multifrequency transmitter coil driver based upon the Class E topology. The development of a "high-Q approximation" which simplifies the design procedure is presented. A closed-loop controller to compensate for transmitter and receiver variations, and a method of data modulation, using synchronous frequency shifting are described. The closed-loop Class E circuit shows great promise, especially for circuits with unusually low coefficients of coupling. Currents of several amperes, at radio frequencies, can easily and efficiently be obtained.     

压电双晶片阵列式直线驱动器的设计与研究

基于压电双晶片提出一种新型准静态直线压电驱动器,可通过阵列的方式获得所需机械输出力,结构简单,性能稳定,可控性强。利用有限元软件对驱动器结构进行设计与分析,并加工制造了该驱动器的物理样机。最后通过实验发现,当驱动频率为500~2 100Hz时,驱动器可直接输出直线运动。当驱动频率为1 100Hz,驱动电压峰-峰值为200V,预紧力为1.5N时,该驱动器最大输出速度可达95mm/s,最大输出力为0.7N。     

Integrated micromechanical sensors and actuators in silicon

The integrated silicon microsensor and microactuator field is a rapidly developing branch of the microelectronic technology research. The vast potential of these sensors lies in the compatibility with conventional microelectronic circuits in silicon. Special efforts are often required to maintain this fundamental material compatibility, while enabling the fabrication of versatile sensors and actuators. Sensors in silicon are possible for the measurement of many different non-electrical quantities. This overview is focussed on micromechanical sensors and actuators. The basic technologies used for the fabrication of micromechanical structures in silicon are presented with a special emphasis on their compatibility with integrated electronic readout circuits. The performance and the limitations are outlined using several successfully-fabricated integrated sensor and actuator structures.     

Laser‐Induced Rapid Carbon Nanotube Micro‐Actuators

Laser‐induced rapid actuating microstructures made of aligned carbon nanotube (CNT) arrays are achieved. Desirable operational features of the CNT micro‐actuators include low laser power activation, rapid response, elastic and reversible motion, and robust durability. Experimental evidence suggests a laser‐induced electrostatic interaction mechanism as the primary cause of the optomechanical phenomenon. Oscillating CNT micro‐actuators up to 40 kHz are achieved by driving them with a modulated laser beam. The micro‐actuators are utilized in exerting a sub‐micro‐Newton force to bend nanowires. Electrical coupling of the micro‐actuator and feasibilities of multi‐actuator systems made entirely out of CNTs are also demonstrated.     

精密直线压电驱动器的设计与研究

针对现有直线驱动器精度及输出位移受限等问题,该文基于改进的尺蠖原理,以压电陶瓷堆为动力源设计了一种新型精密直线驱动器。首先介绍该驱动器的结构原理、运行过程及实现方式,然后对该驱动器所用压电陶瓷的特性进行分析,并采用ANSYS对主要部件进行有限元分析。本驱动器采用特有柔性铰链结构和柔性箝位片设计结构,可实现双向移动和输出位移不受限,有效弥补了现有驱动器的一些不足,实用价值较高,有望在微驱动领域推广与应用。     

Electrical and Mechanical Self‐Healing in High‐Performance Dielectric Elastomer Actuator Materials

Dielectric elastomers are of interest for actuator applications due to their large actuation strain, high bandwidth, high energy density, and their flexible nature. If future dielectric elastomers are to be used reliably in applications that include soft robotics, medical devices, artificial muscles, and electronic skins, there is a need to design devices that are tolerant to electrical and mechanical damage. In this paper, the first report of self‐healing of both electrical breakdown and mechanical damage in dielectric actuators using a thermoplastic methyl thioglycolate–modified styrene–butadiene–styrene (MGSBS) elastomer is provided. The self‐healing functions are examined from the material to device level by detailed examination of the healing process, and characterization of electrical properties and actuator response before and after healing. It is demonstrated that after dielectric breakdown, the initial dielectric strength can be recovered by up to 67%, and after mechanical damage, a 39% recovery can be achieved with no degradation of the strain–voltage response of the actuators. The elastomer can also heal a combination of mechanical and electrical failures. This work provides a route to create robust and damage tolerant dielectric elastomers for soft robotic and other applications related to actuator and energy‐harvesting systems.     

Coordination mechanism based on mobile actuator design for wireless sensor and actuator networks

Wireless sensor and actuator networks combine a large number of sensors and a lower number of actuators that are connected with wireless medium, providing distributed sensing and executing appropriate tasks in a special region of interest. To accomplish effective sensing and acting tasks, efficient coordination mechanism among the nodes is required. As an attempt in this direction, this paper develops a collaborative control and estimation mechanism, which addresses the nodes coordination in a distributed manner. First, we propose a regional controllability‐based virtual force algorithm as an actuator deployment strategy to enhance area coverage after an initial random placement of actuators. During this process, a dynamic coordination mechanism is adopted to control nodes. This mechanism incorporates two components, namely, proportional‐integral‐derivative neural network and recursive least squares‐based Kalman filter algorithms. Taking advantage of feedback control and online learning technology, the proposed coordination mechanism schedules the corresponding nodes on the basis of the characteristics of current events, utilizes proportional‐integral‐derivative neural network controller inside each actuator to improve system transient and steady‐state responses, and deals with system state/parameter estimation problems according to the recursive least squares‐based Kalman filter algorithm, so as to achieve better control accuracy. Simulations demonstrate the effectiveness of our proposed methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Polymer MEMS actuators for underwater micromanipulation

Conventional MEMS actuators are not suitable for underwater applications such as cell grasping due to two main reasons: 1) their required actuation voltage are typically higher than 2 V, which would cause electrolysis in water and 2) they have small displacement/deflection due to their inherent driving principles. In this paper, three-different types of novel polymer-based MEMS underwater actuators developed in our laboratory are discussed: 1) ionic conducting polymer films (ICPF) actuator, which actuates by stress gradient induced by ionic movement due to electric field; 2) parylene thermal actuator, which actuates due to the induced stress gradient across a structure made of different layers of materials with different thermal expansion coefficients; and 3) polyaniline (PANI) actuator, which actuates due to its volumetric change caused by a reversible electrochemical oxidation-reduction (redox) reaction. All these polymer micro actuators can be actuated underwater with large deflections and require less power input than conventional MEMS actuators. The experimental results from characterizing these prototype actuators are presented in this paper.     

用于挠性驱动的双足压电作动器的研究

为了进一步拓展压电式挠性驱动的研究和大包角挠性驱动机理,该文提出了一种用于挠性驱动的双足压电作动器.压电作动器结构为带有两圆柱驱动足的方形截面梁,在驱动足外圆柱面加工螺旋槽,既保证了挠性丝与驱动足的充分接触,又使挠性丝缠绕多圈时不会相互影响.根据设计思路,使用ANSYS有限元分析软件建立压电作动器的有限元模型,并确定其...     

Control of ionic polymer metal composites

Robotic devices are traditionally actuated by hydraulic systems or electric motors. However, with the desire to make robotic systems more compact and versatile, new actuator technologies are required. In this paper, the control of ionic polymer metal composite actuators is investigated from a practical perspective. The actuator characteristics are examined through the unblocked maximum displacement and blocked force output. An open-loop position control and closed-loop position proportional-integral-derivative (PID) control are then applied to a strip of actuators. Finally, the performance of the polymer is investigated when implementing an impedance controller (force/position control).     

Pulse drive and capacitance measurement circuit for MEMS electrostatic actuators

In this paper we present an electronic circuit for position or capacitance estimation of MEMS electrostatic actuators based on a switched capacitor technique. The circuit uses a capacitive divider configuration composed by a fixed capacitor and the variable capacitance of the electrostatic actuator for generating an output signal that is a function of the input voltage and capacitive ratio. The proposed circuit can be used to simultaneously actuate and sense position of an electrostatic MEMS actuator without extra sensing elements. This approach is compatible with the requirements of most analog feedback systems and the circuit topology of pulsed digital oscillators.     

The effect of actuator saturation on the performance of PD-controlled servo systems

Perhaps the most often utilized means of closed-loop control of a servo system is proportional-derivative (PD) control. Linear analysis methods suggest the best tracking performance is achieved at maximum possible proportional and derivative gains. Maximum gains, however, drive the actuators into saturation, which renders the system nonlinear and the linear analysis invalid. This paper investigates the effect of actuator saturation on servo system tracking performance by formulating a frequency-based tracking performance measure roughly equivalent to the linear system −3 dB bandwidth. The proposed measure utilizes a series of band-limited pseudo-random tracking inputs to characterize the ‘bandwidth’ of the (nonlinear) saturating system. Numerical simulations based on this measure show that, for a servo system that exhibits actuator saturation, the best tracking performance is not achieved at maximum gain. Instead, performance improves up to a given gain, then begins to recede as the gain is increased further. The simulations also show that avoiding actuator saturation to ensure linear behavior significantly sacrifices tracking performance. The measure of tracking performance is compared with the −3 dB bandwidth utilized in linear analysis techniques, and the two are shown to be well correlated.     

Switching-behavior improvement of insulated gate-controlled devices

MOSFETs and insulated gate bipolar transistor (IGBT) devices are increasingly used in electronic circuits due to both their easy driving and ability to handle high currents and voltages at high-switching frequencies. This paper deals with a new driver technique that allows optimization of the switching speed, reduction of the energy losses during the switching time, and limitation of the electromagnetic interference (EMI). First, an analysis of voltage- and current-switching waveforms of gate-insulated devices is performed. Then, a method of controlling voltage and current slopes independently is shown using the “one-cycle” method or a suitable adaptive-driving technique based on a phase-locked loop (PLL) approach. These techniques were adopted in order to allow correct generation of the gate signals regardless of the operating conditions. Finally, practical results of the proposed driving circuit obtained using a single IGBT switch chopper are presented     

Stimulating Acrylic Elastomers by a Triboelectric Nanogenerator – Toward Self‐Powered Electronic Skin and Artificial Muscle

Dielectric elastomers are a type of actuator materials that exhibit excellent performance as artificial muscles, but a high driving voltage is required for their operation. By using the amazingly high output voltage generated from a triboelectric nanogenerator (TENG), a thin film dielectric elastomer actuator (DEA) can be directly driven by the contact‐separation motion of TENG, demonstrating a self‐powered actuation system. A TENG with a tribo surface area of 100 cm² can induce an expansion strain of 14.5% for the DEA samples (electrode diameter of 0.6 cm) when the system works stably within the contact‐separation velocity ranging from 0.1 to 10 cm s^?1. Finally, two simple prototypes of an intelligent switch and a self‐powered clamper based on the TENG and DEA are demonstrated. These results prove that the dielectric elastomer is an ideal material to work together with TENG and thereby the fabricated actuation system can potentially be applied to the field of electronic skin and soft robotics.     

TFT-LCD驱动芯片的二级驱动电路

针对单芯片集成的TFT-LCD驱动芯片的特性,提出了在γ校正电路中加入两级驱动Buffef的驱动电路结构,以及提高其驱动能力的有效措施.对于具有13个驱动buffer的二级驱动电路,当由一个灰度电压驱动全部396个像素单元时,驱动电压的最大安定时间约为19.2μs;静态消耗电流为518μA,与传统的64个驱动buffer电路相比,其功耗减小了77%.本文的设计结果已成功应用于132RGB×176分辨率、26万色彩色显示手机用TFT-LCD驱动芯片中,其也可用于PDA、数码相机等其他便携电子设备的显示驱动.