压电谐波电机位移放大机构的设计

压电谐波电机是一种基于谐波传动原理的新型低速电机，它由压电波发生器、柔轮、刚轮等组成。压电波发生器由八组以上压电驱动器及弹性铰链位移放大机构组合而成。该文在研究了杠杆、三角、压曲三种位移放大原理后，根据这三种放大原理设计出压电谐波电机的弹性铰链一体化位移放大机构。分析了影响放大机构性能的因素。介绍了放大机构的制造方法。     

Developing a linear piezomotor with nanometer resolution and high stiffness

A novel linear piezomotor was developed for machine tool applications. The design principles and methodology for this high stiffness linear piezomotor with nanometer resolution are presented. The linear piezomotor consists of three piezoelectric actuators and one monolithic flexure frame. The design strategy is to reduce the total number of mechanical elements and interfaces and to integrate all the elements into the frame. The finite element method is used in the design process. The principles and methodology are also applicable to other positioning systems where a high stiffness and high positioning resolution are required.     

压电谐波电机的控制系统设计

压电谐波电机是根据谐波传动和压电逆效应原理设计的一种新型电机；控制系统是使其运转及实现各种控制功能的关键。针对设计的由四相压电驱动器构成的压电谐波电机样机，通过分析其控制原理，提出了相应的控制方案。根据压电陶瓷为容性负载的条件，设计了可快速响应的压电驱动器驱动电路。简要叙述了使电机实现调速、换向、精确定位等各项功能的控制系统软件设计方案。     

The design and characterization of a novel piezoelectric transducer-based linear motor

Before microminiature robots can be realized, new direct drive micromotor systems must be developed. In this research, a linear motor system for a miniature jumping robot was desired. However, current systems must display better force/torque characteristics than is currently available. This paper deals with the design, construction, and testing, of a macro-scale, unidirectional, direct drive linear piezomotor that operates like an inchworm. It uses a parallel arrangement of unimorph piezoelectric transducers, in conjunction with passive mechanical latches, to perform work on a coil spring. Experimental results showed that the linear piezomotor achieved a maximum no-load velocity of 161 mm/s, and a blocked force of 14 N, at a drive signal frequency of 100 Hz. Thereafter, back slip in the latch assembly restricted the forward motion. Based on the results obtained with the macro-level linear piezomotor, it is concluded that smaller direct drive piezomotor designs based on unimorph piezoelectric transducers are achievable. System scalability will be addressed in a future publication.     

四足压电驱动装置的电源设计与研究

压电驱动装置具有纳米级/微米级定位的特性,被广泛应用于精密控制运动平台中,故对压电驱动装置的速度和精度的要求越来越高。根据步进式压电马达驱动原理,结合四足压电驱动装置动力学模型,设计了一种用于新型叠堆结构的四足压电驱动装置的驱动电源。该电源是高电压为±250 V和高频率为1.5 kHz的线性电源,且采用硬件阻抗补偿和信号切换两种策略,进一步解决了容性负载对信号频宽影响的问题,使四足压电驱动装置高精度恒速输出。同时应用硬件在环仿真与测试的方法搭建了实验平台。实验结果表明,在精度为1 nm分辨率的激光干涉仪采集设备中,实现了点对点50.7 nm的四足压电驱动装置的运动测试。     

Design of a linear piezomotor with ultra-high stiffness andnanoprecision

An ultra-stiff nanoprecision linear piezomotor was recently designed for grinding application. This piezomotor consists of three high-voltage piezoelectric actuators integrated by a monolithic flexure frame. This monolithic frame was designed to have multiple functions such as protecting and pre-loading three piezoelectric actuators and withstanding all the shearing forces during operation. The monolithic frame as a motion mechanism eliminates the backlash problem. The stiffness distributions in certain directions over the frame were designed using the finite-element method     

管道微机器人中压电执行器的研究

微执行器作为微机械系统的核心单元,一直是微机械发展关键。文章介绍了一种应用于管道微机器人的足式压电执行器。在交变电压作用下,该压电执行器将压电体的弯曲振动转化成其弹性足沿管壁的移动,从而实现执行器的运动。在分析其工作原理的基础上,研制了压电微执行器的驱动电源,并进行了简单的实验研究。研究表明该执行器具有结构简单,易于微型化,响应快,驱动方便等特点。     

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.     

Tracking position control of piezoelectric actuators for periodic reference inputs

The hysteresis characteristic is one of the major setbacks in precise tracking position control of piezoelectric actuators. In this paper, a position control method for a piezoelectric actuator is presented. The controller is based on PID control method augmented with feedback linearization loop. The feedback linearization loop uses a plant model drawn from the Maxwell slip model. The control strategy is then further extended to include a repetitive control algorithm for tracking periodic inputs. Experiments were performed on a 2-axis linear positioner driven by piezoelectric actuators. The experimental results show that the tracking performance is noticeably improved by augmenting a PID controller with both feedback linearization loop and a repetitive controller.     

An alternate drive method for improving the carrying load capacity and displacement smoothness of a vertical piezoelectric platform

Vertical piezoelectric platform is the key equipment in precision engineering fields, however, the characteristics of carrying load capacity and the smoothness of cross-scale motion in the vertical direction restrict their applications. In this work, an alternate drive method for a vertical piezoelectric platform is proposed to solve these challenges, and the characteristics of cross-scale motion, large carrying load capacity and smooth displacement output are achieved simultaneously. The working principle of the vertical positioning platform and the theoretical analysis for the alternate drive mode are introduced in detail. A series of experiments are performed, and the results show that the motion of the vertical piezoelectric platform has good smoothness in the cross-scale motion and carrying load capacity based on the alternate drive mode. The maximum upward and downward velocities are 4.44 and 7.43 mm/s under the voltage of 600 V_p-p and the frequency of 850 and 925 Hz, respectively. Finally, the point positioning, oblique and sine trajectory tracking experiments are performed, which demonstrate that the vertical piezoelectric platform has the capacity of automated precision positioning and tracking target. Therefore, the alternate drive-based vertical positioning platform has huge potential in precise applications, such as micro/nano machining and complex biological manipulation.     

尺蠖型压电驱动器结构及其特性

由于微纳米级精密定位技术在原位测试、精密光学、超精加工等领域的作用无可替代,因此具有精密定位功能的各种新型驱动器受到国内外学者的广泛关注,其中尺蠖型压电驱动器的研究尤为活跃。该类驱动器定位精度高,结构紧凑,输出力大,运动稳定,具备较大工作行程的同时拥有较高的运动分辨率,在各类驱动器中综合优势明显。首先,介绍了尺蠖型压电驱动器的原理和关键部件;其次,对直线型、旋转型和一体型三类代表性尺蠖驱动器的研究进展进行了总结和归纳,分析了各自的主要结构、动作原理、性能特点和适用场合。结果表明,实用性问题是未来研究重点,可从构型设计、控制系统、补偿算法以及温度控制等方面加以改进。     

Design and Fabrication of Hybrid Piezomotor Applied in Precision Positioning Devices

The motor＇s configuration is designed and the dynamic analysis equations based on its simplified model are deduced. A testing system utilizing grating is set up to test this new motor, and the theoretical movement principle for the motor is proved by experiments. The pulse waveforms are applied to drive the motor to move in steps. The motor has a displacement resolution of 10 nm and a maximum velocity of 0.6 mm/ s. It can drive a 200 g slider whose range is 20 mm. A one-dimensional precision positioning platform is fabricated by using the new hybrid piezoelectric motor. The prototype is made up of two servomotors and two piezoelectric motors, which are controlled automatically by a computer. The positioning range of the platform is 10 cm.     

Inverse kinematic modeling of a coupled flexure hinge mechanism

An inverse kinematic model of a micro-motion stage with three degrees-of-freedom motion is presented. The XYθ stage uses three piezoelectric actuators and a monolithic flexure hinge mechanism which is designed to provide large θ motion. The stage design has a coupled hinge mechanism which causes a difficulty in motion control. This paper describes a computer based inverse kinematic model of hinge mechanism and the experimental verification for the model. In particular, it presents a kinematic calibration procedure for improving the accuracy of the model. It is shown that the simulation and experimental results are very similar to each other and they also demonstrate that the inverse kinematic model can be used for open loop control of the stage within 5% error. The open loop control of the stage provides 7.6 and 8.2 nm positioning resolution over the total range of 41.5 and 47.8 μm along the X- and Y-axis, respectively, and 0.057 arcsec rotational resolution over the total range of 322.8 arcsec about the θ-axis.     

压电换能器并联谐振频率跟踪系统设计

分析了压电换能器夹持电容在线测量原理,提出了一种新的并联谐振频率跟踪方法。讨论了不同状态下并联谐振频率的变化规律。采用嵌入式芯片PSoC5为主控制器,结合数字合成技术,使激励信号分辨率达到0.5Hz。驱动直流电源采用软开关技术实现电压可调功能。对换能器的电压和电流进行检测并在此基础上实现扫频跟踪策略及自动解锁控制。在不同工作状态下的实验结果验证了设计方案的合理性。     

一种用于压电驱动微动工作台的测控系统

研究了压电陶瓷驱动器特有的迟滞和儒变特性，针对它的这些非线性特点，给出了一种有效消除这些非线性误差的闭环控制方案。采用高精度A／D和D／A转换芯片，设计了基于PC机并行增强口EPP协议的控制板。在自行设计高压驱动电路的基础上，研制出了用于纳米级定位的数字闭环控制器。测试结果表明，此控制器很好地克服压电陶瓷驱动器的非线性特性，系统定位精度优于10nm。     

基于H like模型的压电陶瓷作动器内模控制

针对压电陶瓷作动器的率相关特性降低应用端控制精度的问题,该文研究了基于Hammerstein like模型的内模控制策略。其中非线性部分由最小二乘支持向量机模型表示,动态线性部分由自回归历遍模型表示。在此基础上构建了系统逆模型,设计了内模控制器以实现对压电陶瓷作动器的跟踪控制,最后通过实验平台进行了验证。实验结果表明,实时跟踪100 Hz内的期望信号相对误差均小于10%,证明了所设计内模控制方案的有效性。     

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。     

Precision tracking control of a biaxial piezo stage using repetitive control and double-feedforward compensation

This article presents precision tracking control of an XY piezo stage using repetitive control and double-feedforward compensation. The XY piezo stage is composed of two piezoelectric actuators within a leaf spring mechanism. The study applies two feedback controllers, a Proportional-Integral-Derivative controller and a repetitive controller, to achieve precision trajectory tracking and evaluate performance against benchmarks. Moreover, the investigation applies a double-feedforward compensation approach that integrates a Zero-Phase-Error-Tracking-Controller and an adaptive plant inversion compensator adapted by a Least-Mean-Square algorithm, based on an inverse Prandtl-Ishlinskii model, to improve tracking control performance further. Performance analysis and comparison of the experimental results demonstrate that the proposed control structure improves dynamic tracking accuracy of the XY piezo stage.     

Sliding-Mode Control of a High-Speed Linear Axis Driven by Pneumatic Muscle Actuators

This paper presents a cascaded sliding-mode (SM) control scheme for a new pneumatic linear axis which could be seen as alternative to an electric direct linear drive. Its guided carriage is driven by a nonlinear mechanism consisting of a rocker with an antagonistic pair of pneumatic muscle actuators arranged at both sides. This innovative drive concept allows for both an increased workspace of approximately 1 m as well as higher carriage velocities of approximately 1.3 m/s as compared to a direct actuation. Modeling of the muscle-driven positioning system leads to a system of four nonlinear differential equations including polynomial approximations of the volume characteristic as well as the force characteristic of the pneumatic muscles. The differential flatness of the system is exploited in combination with SM techniques to stabilize the error dynamics in view of unmodeled dynamics. The internal pressure of each pneumatic muscle is controlled by a fast underlying control loop. Hence, the control design for the outer control loop can be simplified by considering these controlled muscle pressures as ideal control inputs. The control design of the outer control loop involves a decoupling of rocker angle as well as mean internal pressure of both pneumatic muscles as flat outputs. Additionally, model uncertainties in the equation of motion like nonlinear friction are directly counteracted by an observer-based disturbance compensation which reduces the chattering problem. Experimental results show an excellent control performance that outperforms alternative control approaches in a comparison.