Development of an Ultrasonic Motor That Uses an Inchworm Shaped Deformation of a Metallic Plate

At the present time, ultrasonic motors have been developed for a variety of purposes such as linear motion drives and rotational drives. The elaboration of an ultrasonic motor is time-consuming, because it is developed adapting on its application. In this study, a new ultrasonic motor structure that combines a piezoelectric element and a metallic plate is elaborated. The driving principle of this motor is that the metal plate is bent to an inchworm shape and rotates the rotor when the piezoelectric element is stretched. The objective of this study is to verify the functioning of the new motor experimentally.

Unilateral self-locking mechanism for inchworm in-pipe robot

A unilateral self-locking mechanism(USM) was proposed to increase the tractive ability of the inchworm in-pipe robots for pipeline inspection.The USM was basically composed of a cam,a torsional spring and an axis.The self-locking and virtual work principles were applied to studying the basic self-locking condition of the USM.In order to make the cooperation between the crutch and telescopic mechanism more harmonical,the unlocking time of the USM was calculated.A set of parameters were selected to build a virtual model and fabricate a prototype.Both the simulation and performance experiments were carried out in a pipe with a nominal inside diameter of 160 mm.The results show that USM enables the robot to move quickly in one way,and in the other way it helps the robot get self-locking with the pipe wall.The traction of the inchworm robot can rise to 1.2 kN,beyond the limitation of friction of 0.497 kN.

Design and experiments of a small resonant inchworm piezoelectric robot

A small resonant inchworm piezoelectric robot with six driving feet which are set evenly along the circumference is proposed and tested.A bonded-type structure is adopted to realize a small size.The radial bending vibration mode and longitudinal vibration mode are excited at the same frequency.The superposition of these two vibration modes makes the driving feet produce elliptical motions.And the driving force can be generated by friction coupling between the driving foot and the operating plane.The structure of the robot is designed by finite element simulation.The geometric parameters are adjusted to make the resonant frequencies of the vibration modes as close as possible.The elliptical trajectories generated at the driving feet are discussed in detail.The vibration and motion characteristics of the prototype are tested,and the resonant frequencies of the radial bending mode and the longitudinal vibration mode are degenerated successfully.The optimal working frequency of the prototype is 21.5 kHz.The maximum speed of the prototype is 200 mm/s,and the displacement resolution is 0.71μm.The measured results show that the resonant inchworm piezoelectric robot can be used for fast and high-precision transportation in narrow space.

Clawed Miniature Inchworm Robot Driven by Electromagnetic Oscillatory Actuator

In this research we propose a novel inchworm robot, which is composed of an Electromagnetic Oscillatory Actuator （EOA） and claws. The EOA consists of a yoke, a magnet, and a coil. The overall robot size is 12.2 mm x 11 mm x 9 mm （length x height ~ width）. The locomotion of the robot is achieved by different amounts of slips when the robot stretches and contracts its front leg. To realize locomotion, the working conditions were calculated theoretically and the calculated input signal was applied to the robot. The performance of the inchworm robot was evaluated experimentally with varying input voltages and frequencies. A simple op-amps based driving circuit was used to provide a square-wave input. Travel speed, average distance per step of the robot, and moving distance of the leg and body at each step were measured. The maximum travel speed was 36 mm-s-1 at 30 Hz, which validates our simple locomotion strategy experimentally.

An Inchworm-inspired Robot Based on Modular Body, Electronics and Passive Friction Pads Performing the Two-anchor Crawl Gait

We have created an inchworm robot capable of the two-anchor crawl gait on level ground and inclined plane. The main novelty is in the design of the inchworm： （1） three-part body that is 3D printed and actuated by two servo motors to allow a looping and lengthening action, （2） passive friction pads to anchor the feet, each of which may be disengaged using a servo motor actuated lever arm, and （3） modular body and electronics. The robot is about 2 feet （61 cm） in length, has a mass of about 4 kg, and uses an open-loop controller to achieve steady crawling gait. The inchworm robot achieved a speed of 2.54 em.sI on level ground as well as on an incline plane of 19~. The energy usage as measured by the Mechanical Cost of Transport （a non-dimensional number defined as the energy used per unit weight per unit distance moved） is 3.34. Our results indicate that simple robotic designs that copy the basic features of natural organisms provide a promising alternative over conventional wheeled robots.

Optimization design of extensor for improving locomotion efficiency of inchworm-like capsule robot

An inchworm-like capsule robot(ILCR) is a promising device for a minimally invasive diagnosis and treatment of colon diseases. It consists of two expanders and one extensor, the former provides a traction force by expanding the colon and the latter can elongate and retract to enable active locomotion. However, the locomotion efficiency of the ILCR can be seriously lowered by the complex colon environment featuring slippery, viscoelastic, and suspend properties, which has been a main obstacle to its clinical application. This paper aims at improving the locomotion efficiency of the ILCR by optimizing its extensor design. To do this, the locomotion resistance of the ILCR in the colon is analyzed, and complying with a requirement that the traction force must be larger than the locomotion resistance to avoid slipping, a restriction on the extensor design is obtained. Then under the restriction and with reference to the Hyperelastic model which correlates stress and strain of colon tissue, a model for analyzing the influence of the design parameters of the extensor on the locomotion efficiency of the ILCR is built. With this model, the extensor has been optimized and the optimized results have been used to guide the development of a novel extensor, which employs two pairs of lead-screws and nuts and is actuated by one motor. Ex-vivo experiment has shown that the novel extensor can improve the locomotion efficiency of an ILCR prototype by 57%, without changing its total length.

尺蠖型超磁致伸缩旋转驱动器驱动信号设计与试验

为了解决传统的“信号发生器+功率放大器”产生的信号无法满足尺蠖型旋转驱动器多路、正方波波形需求的问题,设计了一种通过Cmos控制脉冲模块“通-断”时机的信号控制器,从而得到特定时序的3路正方波信号。通过这种方案得到的3路驱动信号为正方波电流信号,从而避免了超磁致伸缩材料的“倍频”现象的发生。通过设置信号周期、占空比和延迟等参数,能够输出设定时序的三路正方波驱动信号。根据电压定律,将正方波简化成阶跃波形,建立了驱动信号的电流模型,并进行了参数辨识。在工作频率范围内,电流解析式能准确地表示电流信号。搭建试验平台进行了试验测试,试验结果表明,在工作频率范围内,信号控制器输出的正方波波形优于“信号发生器+功率放大器”产生的方波信号,设定的3路信号能够驱动尺蠖型旋转驱动器产生步进旋转运动。通过优化驱动信号时序,将旋转驱动器最大工作频率由160 Hz提至210 Hz。

基于自锁结构的尺蠖式压电直线驱动器设计

设计了一种具有大行程、大输出力的尺蠖式压电直线驱动器。驱动器包括左、右2组结构相同的箝位机构、主驱动压电陶瓷以及输出方轴。该驱动器结构相对简单紧凑,并可断电自锁。箝位机构采用自锁结构,具有足够大的箝位力,因此驱动器可以有效实现较大的输出力。最后采用有限元法对箝位机构的位移、应力、振动模态以及固有频率进行了仿真分析,对其进行结构优化。

面向翼面展开的压电直线位移累积作动器轻量化设计

现代小型制导飞行器中常用的电磁式伺服舵机存在寄生磁场影响导航制导精度,同时其减速机构将增加舵机系统体积与质量的问题,而且电磁舵机的工作温度范围较小。近期发展的一种新型压电直线位移累积高功率密度作动器能够有效解决这些问题。建立了该作动器的虚拟样机模型,通过与实验数据进行对比,验证了虚拟样机模型的可靠性。为使作动器在满足翼面展开需求下质量最轻,采用Isight与Adams联合仿真,对压电作动器的压电堆外径、长度、激振频率等参数进行了优化,最终达到了50.8 W/kg输出功率,实现了与现有伺服电机相当的功率密度。

尺蠖式压电线性作动器设计及实验研究

针对空间环境下小型抓取操作机构对新型作动器的使用需求,考虑压电作动器具有耐温范围宽、无电磁干扰及断电自锁等特点,仿照昆虫尺蠖的行走方式设计一种新型压电线性作动器。首先,利用柔性铰链式位移放大机构放大压电陶瓷(Pb-Zr-Ti,简称PZT)叠堆的输出位移,以增大线性作动器的移动步长及对导轨的夹紧变形量,将多个压电陶瓷叠堆器件分为3组,分别作为尺蠖式压电线性作动器的2个夹持单元和1个推进单元的激励源,以获得较大的驱动力并进一步增大作动器的移动步长;其次,借助有限元仿真分析软件,研究压电陶瓷叠堆力电耦合行为的预测方法,并实验验证该方法的可行性;然后,简化柔性铰链式位移放大机构,提出放大倍数的数值分析方法,对位移放大机构在压电陶瓷叠堆作动方向上的刚度进行仿真分析,并验证放大倍数的数值分析方法的准确性;最后,基于设计的线性作动器开展实验研究。结果表明:位移放大机构对压电陶瓷叠堆输出位移的放大倍数为7.3,处于理论值与仿真值之间;在激励电压频率为5 Hz时,作动器的最大空载移动速度为413μm/s;作动器的最大推动力为16 N,对应的驱动速度为19μm/s。以上研究结果能为小型抓取操作机构的智能驱动提供技术支持。

基于压电驱动的精密步进旋转电机

为了保证微小型电机的速度和承载能力,同时获得较高的运转分辨率,提出一种以压电叠堆为驱动元件基于尺蠖运动原理的新型精密旋转电机方案。电机结构中转子无绕线结构,定子采用柔性铰链双侧对钳方式交替对转子起到钳位作用。对电机工作原理进行了分析研究,采用MSC Patran/Nastran有限元软件对机械结构进行了仿真分析,并对所开发的电机样机进行了实验测试。测试结果与理论分析结果基本相符,所开发样机的旋转速度可达3308．6μrad/s、输出扭矩为0．294N·m、单步最小转角(旋转分辨率)为 0．206μrad。电机性能稳定可靠,可望在光学工程、精密工程等相关领域得到应用。

大行程纳米级步距压电电动机

介绍了一种基于尺蠖运动原理的大行程纳米级步距压电电动机。在结构设计方面,变传统单驱动器结构为双驱动器结构,采用新颖的推-拉接力运动原理,配以适当的四路驱动信号,实现了压电电动机的连续匀速运动。通过试验对电动机的性能进行了测试,结果表明:电动机的运动位移是线性的,运动速度在驱动电压为300 V时可达12μm/s,最小步距小于6nm,行程大于10mm。

磁控形状记忆合金蠕动型直线电机研究

磁控形状记忆合金(MSM)是一种新型具有形状记忆功能的合金材料,不仅变形率大,易于控制,动态响应速度高,而且功率密度大和机电能量转换效率高,特别适合于制造高精度的运动与位置控制执行器。该文首先介绍MSM材料在磁场作用下的变形机理与磁控特性,然后分析利用仿生学蠕动原理将MSM小步距的位移累加形成直线电机所需要的大行程的工作原理,而后论述蠕动型MSM直线电机的设计与控制方法,最后给出样机的试验结果。

杠杆式尺蠖压电直线驱动器

设计了一种基于尺蠖运动原理的压电直线驱动器,用于解决光学领域中的精密定位问题。该驱动器采用了对称杠杆式位移放大机构,在保证钳紧力的同时,可以获得较大的驱动位移。阐述了尺蠖式压电驱动器的工作原理,对杠杆式柔性放大机构的位移损失、压电陶瓷与柔性机构的耦合特性及箝位机构与中间驱动机构的刚度进行了分析。利用有限元软件Ansys对钳位机构和驱动机构的变形、应力、输出位移和固有频率等参数进行了仿真分析。最后,搭建了实验平台,测试了驱动器的各项性能。测试结果显示,该驱动器的行程为±25mm,钳紧力为17N,承载力为11N,最大和最小步距分别为55μm和60nm。当驱动电压为150V时,驱动器的最高驱动速度为1.259mm/s。得到的性能指标满足光学领域精密定位需要。

尺蠖型压电直线驱动器的动态特性

分析了尺蠖型压电直线驱动器的结构原理,建立了驱动器系统动力学模型。对驱动器定子进行了模态分析,并对分析结果进行了评价。对设计开发的驱动器样机输出特性进行了试验测试,实验测得驱动器单步输出位移稳定可靠,100 V驱动电压下,单步输出位移为9.8μm。对驱动器直线动子的速度、加速度特性进行了测试,依据速度、加速度信号进一步分析了驱动器的动态响应特性。实验结果表明,所开发的驱动器具有动态特性好、运动稳定等优点。

大行程纳米级压电微动工作台的设计与试验研究

介绍了一种基于尺蠖运动原理的大行程纳米级级平台式步距压电微动台。在结构设计方面,夹紧器和驱动器都采用压电陶瓷对称结构,配合夹紧器的夹紧、放松,驱动器伸长或缩短,实现推-拉接力运动,保证微动台运动的平稳性和连续性;采用平台式结构,增强了其实用性。驱动控制方面,配以适当的四路驱动信号,实现了压电微动台的单步、多步连续匀速运动。通过试验对微动台的性能进行了测试,结果表明:微动台的运动位移是线性的,运动速度在驱动电压为200V可达13.9μm/s,最小步距小于10nm,行程大于20mm。

大负载精密驱动超磁致伸缩直线电机动力学建模与仿真

基于一种新型的精密大负载超磁致伸缩直线电机进行了整机动力学建模和仿真,尝试分析巨磁致伸缩直线电机的频率特性和负载特性,提供了一种对于尺蠖运动超磁致伸缩直线电机进行整机建模和性能分析的有效方法.在建模过程中,采用Jiles-Atherton磁滞模型以补偿磁滞回对直线电机输出的影响,并提出了直线电机驱动大负载时的滚动摩擦修正.通过建模与仿真,验证了直线电机结构设计方案的可行性.仿真和实验对比结果表明,该动力学模型实现了超磁致伸缩直线电机的变激励、变负载运动的准确模拟.

蛇形机器人一种基于serpenoid曲线的蠕动步态

提出了一种基于serpenoid曲线的蛇形机器人的蠕动步态模型。建立了运动波形上各相邻连杆间角度的运动方程,并给出该步态的两个效率判据,最后通过仿真和实验讨论了三个参数(连杆之间相对角度摆动幅度α、相位差β以及参与组成半个正弦波形的连杆数n)对步态效率的影响。

被动箝位蠕动直线压电驱动器数学模型及仿真

基于蠕动式直线驱动器的工作原理,引入三角放大结构,设计一款单向直线被动箝位压电驱动器。该驱动器由驱动和保持箝位体、驱动体和导轨等组成,其箝位体采用三角放大结构,有效提高箝位体压电叠堆的输出位移,箝位体在通电状态下可解除对导轨的箝位,在断电状态下可自锁导轨。利用机械振动能量法,建立驱动器主要结构的数学模型,研究驱动体和箝位体结构参数对等效刚度和响应频率的影响,借助于有限元仿真分析和试验,验证数学模型所设计的结构参数的有效性,测试驱动器负载特性以及不同载荷下的动态响应频率。