Inchworm Principle Research Articles

Designing Ordered Structure with Piezoceramic Actuation Units (OSPAU) for Generating Continual Nanostep Motion.

Continual precision actuations with nanoscale resolution over large ranges have extensive requirements in advanced intelligent manufacturing and precise surgical robots. To produce continual nanostep motion, conventionally, multiple pairs of piezo‐actuators are employed to operate in inchworm principle under complex three‐ or four‐phase timing signal drive. Inspired by the idea of ordered structures with functional units, a much simpler nanostep piezoelectric actuator consisting of (2 × 2) arrayed, cofired multilayer piezoceramic actuation units is developed, which operates in an artificially generated quasi shear mode (AGQSM) that is missing in natural piezoelectric ceramics. Under only one‐phase square‐wave voltage drive, the actuator can produce a stable, continual nanostep motion in two ways at nonresonant frequencies, and the obtained minimum step displacement is as low as 7 nm in open control, indicating its potential application as a precise finger or knife actuator in surgical robots. This work is of great guiding significance for future actuator designs using the methodology of ordered structure with piezoceramic actuation units and AGQSM.

Piezoelectric inchworm rotary actuator with high driving torque and self-locking ability

One major obstacle to the development of a piezoelectrically-driven actuator with a large motion range is the requirement to provide a high load capacity and a reliable self-locking capability simultaneously for most applications. In this work, a piezo-driven rotary actuator with a simple and compact structure is designed based on the inchworm principle to realize long-range rotary motion. High driving torque with a self-locking capability at rest is achieved by integral design of the overall structure, in which the distributions and stiffness values of the flexure hinges are carefully designed. A prototype was fabricated and the working performance of the device was tested. The test results demonstrate that the driving torque of the prototype is more than 245 Nmm, with self-locking torque of more than 882 Nmm. In addition, the maximum rotary speed is 26.74 mrad/s at a driving frequency of 180 Hz, and a minimum step rotary angle of 4.79 μrad is obtained at a step driving voltage of 10 V.

Design and Research on a Biped Clamp and Pull Piezoelectric Linear Motor Based on Inchworm Principle

The piezoelectric linear motor based on piezoelectric ceramic stack has a potential in high-tech field’s application such as optical waveguide packaging. Mechanical properties of piezoelectric linear motors in the existing researches still need to be improved. So have designed double foot clamping type piezoelectric linear motor based on the principle of inchworm, and analyzed the working principle. The performance analysis of the driving mechanism shows that the relationship between the amplitude of driving mechanism and voltage values is positively proportional, and the influence of frequency on its amplitude is not big. The performance of the clamping mechanism was studied through experiments. First, verified the feasibility of the principle, tested the amplitude and found that the amplitude increases with the increase of the voltage, but due to the influence of clamping mechanism modal, amplitude tends to be zero as frequency increase to a certain extent. Second, amplitudes of the driving foot in two clamping mechanism were compared to ensure the consistency of amplitude of each driving foot, and the magnification of driving mechanism displacement was obtained by clamping mechanism in the practical work. Analyzed the rail vibration caused by driving foot and the prototype speed characteristics and load characteristic, and obtained speed characteristic curve are, in which, the speed of the motor increases with increasing voltage, but will not be able to continue to increase when the voltage reached to 60V, and the related curve between frequency and speed is similar to the frequency characteristic curve of the clamping mechanism, which is mainly due to the impact from the clamping mechanism modal. Obtained the maximum output of the motor power is 1.8 N through the load characteristic experiment.

OS1003 独立三自由度を有する尺取虫型自走機構の振動特性の検証

Recently multi-axial precise positioning technologies have played an important role for a development of portable devices. For example, we need the technologies for assembling tiny chip parts into cell phone, laptop PC, and MEMS device. We also need them for testing integrated circuits and nanometer-sized-materials and bio-cell processing. Multi-axial linear stages inside conventional surface mounting technology (SMT) instruments are over 100kg. They are much larger and heavier than tiny chip parts of 1mg. Those instruments generate big vibrations to other precise instruments around them because of their high-inertia. In those 10 years, we have developed holonomic and omnidirectional mobile mechanism which moves inchworm principle actuated by several piezoelectric actuators and a pair of electromagnets. In this paper, we evaluate vibration property of the mechanism and discuss theoretical framework of an elimination of influence from outer vibration.

Development of a compact 2-DOF precision piezoelectric positioning platform based on inchworm principle

A piezoelectric positioning platform by means of inchworm motion principle is developed, and it can achieve both linear and rotary motions. The designed positioning platform can provide large range motion with high resolution in a compact size. Eight piezoelectric stacks and several flexible hinges are used in the stator and the slider. The working principle of the proposed positioning platform is analyzed. Experiments of the prototype are carried out and the results show that the developed positioning platform has stable working characteristics under the certain working conditions. For the rotary motion of the positioning platform, the minimum stepping angle is 0.23μrad, the maximum rotary velocity is 3521.70μrad/s and the output torque is 0.294Nm. When the platform works in the linear model, the minimum stepping displacement is 0.15μm, the maximum velocity is 105.31μm/s and the largest output load is 4.9N. The designed positioning platform can be used in the fields of nanotechnology, precision machining, MEMS, bioscience and so on.

Design and experiment performances of an inchworm type rotary actuator

A piezo-driven rotary actuator by means of inchworm principle is proposed in this paper. Six piezo-stacks and flexure hinges are used to realize large rotation ranges with high accuracy both in the forward and backward motions. Four right-angle flexure hinges and two right-circular flexure hinges are applied in the stator. The motion principle and theoretical analysis of the designed actuator are discussed. In order to investigate the working characteristics, a prototype actuator was manufactured and a series of experiment tests were carried out. The test results indicate that the maximum rotation velocity is 71,300 μrad/s; the maximum output torque is 19.6 N mm. The experiment results confirm that the designed actuator can obtain large rotation motion ranges with relatively high output torques and different rotation speeds on the condition of different driving voltages and frequencies.

Design of a Long Distance Unidirectional Piezoelectric Motor Based on Non-Resonant Inchworm Principle

The advantages of linear piezoelectric motor which has low velocity, large output force, non-electromagnetic disturbance and high response speed are concerned wildly in astronautic industry and manufactural industry. A unidirectional and linear piezoelectric motor has been designed based on these advantages. The stiffness and resonant frequencies of the clamping structure and driving structure are calculated by mathematic model. The characteristics of long distance, slow velocity and large output force are realized. This motor can be used in the equipment which needs long distance, small inertia, large driving force and disposable movement. The stiffness and resonant frequencies of clamping structure and driving structure, no-load characteristic and motion characteristics under different loads are tested in the experiment. The results of the stiffness satisfy the theoretical design. The no-load resonant frequencies are high and the maximum resonant frequency dwindles with increasing load.

Design and experimental research of a novel inchworm type piezo-driven rotary actuator with the changeable clamping radius

In this paper, a novel piezo-driven rotary actuator with the changeable clamping radius is developed based on the inchworm principle. This actuator mainly utilizes three piezoelectric actuators, a flexible gripper, a clamping block, and a rotor to achieve large stroke rotation with high resolution. The design process of the flexible gripper consisting of the driving unit and the clamping unit is described. Lever-type mechanisms were used to amplify the micro clamping displacements. The amplifying factor and parasitic displacement of the lever-type mechanism in the clamping unit was analyzed theoretically and experimentally. In order to investigate the rotation characteristics of the actuator, a series of experiments was carried out. Experimental results indicate that the actuator can rotate at a speed of 77,488 μrad/s with a driving frequency of 167 Hz. The rotation resolution and maximum load torque of the actuator are 0.25 μrad and 37 N mm, respectively. The gripper is movable along the z direction based on an elevating platform, and the clamping radius can change from 10.6 mm to 25 mm. Experimental results confirm that the actuator can achieve different rotation speeds by changing the clamping radius.

In-pipe Minimachine and Principles of its Motion and Control

The paper deals with the minimachine designed to move within the pipes with inner diameter less than 25 mm. The minimachine consists of two modules connected by a link of variable length enabling to change their mutual distance. Motion is based on inchworm principle known from biology. In motion sequence one of the modules is anchored to the inner surface of the pipe, while the second is released and moved forward by change of the link length. The principle of the link length change consists in transformation of the actuator rotary movement to the linear motion. Problem of anchoring the modules by flexible metal bristles is analyzed in the paper.

A 3-DOFs mobile robot driven by a piezoelectric actuator

In this paper, a novel miniature-step mobile robot with three degrees of freedom (DOFs) isdeveloped based on the inchworm principle. This device, driven by a piezo stack actuator,utilizes a rhombic flexure hinge mechanism and four electromagnetic legs to achieve largestroke translation and rotation with high resolution on a platform. The design process ofthe rhombic flexible frame and the electromagnetic legs is described. The electric circuitsfor generating appropriate voltage signals are designed to control the legs to clamp to andrelease from the platform. In order to investigate the motion characteristics of the device, aseries of experiments was carried out. The experimental results confirm that thedevice is capable of performing a 3-DOFs motion with a high resolution on aplatform. Furthermore, the platform loading capacity allows some additional deviceslike a gripper or any other device for a particular application to be mountedon board. This enables the device’s potential in a wide variety of applications.

A CONTROL METHODOLOGY FOR AN INCHWORM PIEZOMOTOR

This paper describes a control methodology developed for an inchworm-type precision piezomotor. The report presents a motor designed based on the classical inchworm principle and a dynamical model of the motor. A hybrid control method that consists of a traditional PID controller and a rule-based scheme is developed and the controller is shown to offer good performance when tracking sinusoidal and arbitrary signals.

Compact and precise positioner based on the Inchworm principle

In this paper, we present a piezoelectric linear micropositioner.Its principle and configuration provide an elegant solution to confinedpositioning problems requiring compact systems. The developed device shows ahigh accuracy together with large travel ranges, due to a stepwise operationprinciple. A simple, low-cost realization process combined with an assemblystep has been used to implement the device.The positioner operation principle is based on the well known Inchwormprinciple: the accurate synchronization of piezoelectric actuation and theuse of electrostatic forces as clamping systems produces a step-by-stepdriving of a slider along the direction of the piezotransducer expansion. Theapplied principle makes possible a flexible and reliable control of the sliderpositioning speed, either through the `step-by-step' sequence frequency orthrough the step length.A positioner was designed and realized to demonstrate the device workingprinciple. Bidirectional, millimeter-range slider motion was performed andslider speeds ranging from a few µm s-1 to a few hundreds ofµm s-1 were measured. Three hundred nm steps were estimated at 10 Vdriving voltage.The process used also allows the realization of similar X-Y positionerdesigns combining several degrees of freedom.

Magnetostrictive linear motor development

We are currently designing a high force linear motor that utilizes the inchworm principle coupled with multi-phase actuation. The efficient design of a 17 kN force linear motor that utilizes the magnetostrictive material Terfenol-D requires a transient electromechanical model to determine the operating parameters. The model is described and results indicated. It is found that control of the frequency and current inputs are all that is necessary to control the speed and power handling ability of the motor. Resonant operation is discussed along with increased efficiency power actuation schemes.