Scott-Russell Mechanism Research Articles

Development and Testing of a Dual-Driven Piezoelectric Microgripper with High Amplification Ratio for Cell Micromanipulation

Cell micromanipulation is an important technique in the field of biomedical engineering. Microgrippers play a crucial role in connecting macroscopic and microscopic objects in micromanipulation systems. However, since the operated biological cells are deformable, vulnerable, and typically distributed in sizes ranging from micrometers to millimeters, it poses a huge challenge to microgripper performance. To solve this problem, this paper develops a dual-driven piezoelectric microgripper with a high displacement amplification ratio, large stroke, and parallel gripping. By adopting modular configuration, three kinds of flexure-based mechanisms, including the lever mechanism, Scott–Russell mechanism, and parallelogram mechanism are connected in series to realize three-stage amplification, which effectively makes up for the shortage of small output displacement of the piezoelectric actuator. At the same time, the use of the parallelogram mechanism also isolates the parasitic rotation movement, and realizes the parallel movement of the gripping jaws. In addition, the kinematics, statics, and dynamics models of the microgripper are established by using the pseudo-rigid body and Lagrange methods, and the key geometric parameters are also optimized. Finite element simulation and experimental tests verify the effectiveness of the developed microgripper. The results show that the developed microgripper allows an amplification ratio of 46.4, a clamping stroke of 2180 μm, and a natural frequency of 203.1 Hz. Based on the developed microgripper, the nondestructive micromanipulation of zebrafish embryos is successfully realized.

A novel gas spring based negative stiffness mechanism for seismic protection of structures

The integration of negative stiffness (NS) elements in the concept of seismic base isolation constitutes an innovative and highly effective approach for ensuring the safety of structures against the damaging effects of earthquakes. With these isolators, the system’s natural frequency is significantly decreased and thus the transmissibility of seismic forces for all the frequencies above the natural one is reduced. The KDamper is such a representative device that has been implemented in many types of structures improving their dynamic performance due to its superior damping and isolation properties. This study investigates the performance of a variant of the KDamper, referred to as SBA (Seismic Base Absorber), which is equipped with a novel NS element. The SBA combines an extended version of the KDamper with a parallel-connected inerter used to further decrease the structure’s natural frequency without reducing its static stiffness. The NS element of this device is selected to be realized with a modified Scott-Russell mechanism with an extension link that is connected through a revolute joint with a vertical pre-compressed gas spring. This configuration enables the NS element to keep the pre-tension of the spring internally without transmitting it to the superstructure. Additionally, the gas springs provide high and undiminished values of NS in the entirety of motion and are capable of supporting heavy oscillating structural masses without running into issues like buckling or yielding, unlike the conventional compression springs. The performance of the SBA equipped with this NS element is evaluated through numerical simulations both in frequency and time domains, considering a single degree of freedom (SDOF) system and having as excitation input 30 artificial and 20 real accelerograms. To draw the necessary conclusions these simulations are also conducted for a conventional and a highly damped base isolation system as well as a linear SBA system. In addition, a comparative analysis is performed between the proposed NS element and an equivalent element that incorporates linear springs. The results highlight the effectiveness of the SBA in reducing the maximum dynamic responses and the superiority of gas springs over the linear ones in terms of stability and feasibility of the system.

Design and Simulation of a Single Piezoelectric-Driven Rotary Actuator with Double-Layer Flexible Mechanism

A novel pure rotary actuator with a double-layer flexible mechanism (RA-DFM), which is driven by a single piezoelectric ceramic in the lower mechanism and generates rotational motion in the upper mechanism, is proposed in this paper. The output of piezoelectric ceramic is successively amplified using an enhanced double Scott–Russell mechanism and two lever-type mechanisms to obtain a large rotation range. The static, kinematic and dynamic properties of the RA-DFM are numerically analyzed, and the actual output of the piezoelectric is analyzed considering the input stiffness. The geometric parameters of the RA-DFM are optimized based on the constructed numerical models. Finite element analysis has been implemented to validate the correctness of the theoretical models and further evaluate the output property. The simulation results show the maximal rotation angle of the RA-DFM is 15.14 mrad with 0.44% center drift.

Development of a novel piezoelectric-driven non-resonant elliptical vibrator with adjustable characteristics.

Aiming at the fabrication of a micro-textured surface, a novel piezoelectric-driven non-resonant elliptical vibrator is proposed in this paper; the output characteristics could be adjusted by the length change of the tool holder. The flexible mechanism is the primary structure of the vibrator, which includes a lever type mechanism, an enhanced Scott-Russell mechanism, and a T-shaped mechanism. The former two mechanisms are used to enlarge the output of the piezoelectric actuator, and the T-shaped mechanism is applied to transfer the parallel movements to the elliptical trajectory. The theoretical models including the elliptical trajectory, output stiffness, and resonant frequencies are established to investigate the impacts of the tool holder and controlling signals on the output characteristics of the vibrator, which are further validated using the finite element analysis method. A prototype is developed by integrating the non-resonant elliptical vibrator assembly and controlling system. Some experiments are carried out to verify the basic performance and the adjustable properties of the vibrator.

Jump Assist Device Cooperating with Human Using Scott-Russell Mechanism

Jump Assist Device Cooperating with Human Using Scott-Russell Mechanism

Design, modeling, and testing of a one degree of freedom manipulator with three-stage amplification mechanism.

The one degree of freedom (1-DOF) manipulator with nano-resolution is a significant component in the micro-/nano-manipulation. In order to simultaneously achieve a large stroke and high precision, a piezo-driven 1-DOF flexure-based manipulator consisting of an enhanced double Scott-Russell mechanism (EDSRM), a lever type mechanism, and a Z-shaped mechanism is proposed in this paper. Analytical models are developed to examine the kinetostatic and dynamic properties of the manipulator. A finite element analysis is further performed to evaluate the characteristics of the EDSRM and the complete manipulator. The prototype is fabricated on monolithic AL7075, and various experimental tests have been carried out to investigate the correctness of the modeling. The experimental results show that the proposed manipulator has a satisfactory amplification ratio, static stability, and dynamic performance.

A non-redundant piezoelectric center-rotation platform with a single-layer structure and a large working range

This paper reports the design, modeling, and testing of a new single-layer center-rotation platform driven by a single piezoelectric actuator. The platform avoids actuator redundancy and exhibits a large rotation angle, high-precision resolution, and high resonant frequency. The pure center- rotation motion is realized by combining the improved Scott-Russell (SR) mechanism and lever- guided structure. The auxiliary stiffness mechanism at the input end of the SR mechanism also improves the stability of the rotation platform. An analytical model is established based on the finite element method, and the key parameters affecting the structural performance are investigated. A prototype is finally manufactured, and several experiments are conducted to test the proposed platform. The experimental results show that the rotation angle is 16.8 mrad, the resonant frequency is 527.3 Hz, and the resolution is 0.29 μrad. Thus, the platform is capable of precision center rotation.

A novel compliant XY micro-positioning stage using bridge-type displacement amplifier embedded with Scott-Russell mechanism

This paper presents a new bridge-type compliant displacement amplifier embedded with Scott-Russell mechanism. Based on this design, a novel compliant XY micro-positioning stage is also designed, analyzed and tested to illustrate the advantages of the proposed amplifier. The main feature of the new amplifier is to employ Scott-Russell mechanism to replace one arm of the compound bridge-type mechanism, aiming to improve its lateral stiffness and the natural frequency in the working direction. The compliant XY micro-positioning stage is driven by two novel bridge-type amplifiers with orthogonal distribution. Double parallelogram guide mechanisms are added at the output ends of the bridge-type mechanisms to further lower the parasitic movements of the XY stage. Then, an analytical model based on the stiffness matrix transfer method is established for the static and dynamic characteristics of stage, which are also verified by performing finite element analysis. Finally, an experimental prototype is manufactured and its static and dynamic performances are tested. The test results demonstrate that the stage can realize a workspace of 181.0 μm × 179.5 μm with motion resolution of 20 nm and a maximum coupling error of 1.07%. The natural frequencies of XY stage along the working direction are 178 Hz and 248 Hz respectively when the PZTs are not installed or installed. Additionally, the trajectory tracking performance of the stage is also preliminarily evaluated. All of the results obtained from the analytical model, finite element analysis and experimental tests verify the effectiveness of the novel bridge-type displacement amplifier and the compliant XY micro-positioning stage.

Fractional order zero phase error tracking control of a novel decoupled 2-DOF compliant micro-positioning stage

This study focuses on a piezo-actuated two-degrees-of-freedom (2-DOF) decoupled compliant micro-positioning stage driven by a novel compound bridge-type amplification mechanism embedded with Scott-Russell mechanism. According to the system identification, the transfer functions of two working directions are obtained. Both of the measured dynamic cross couplings between them are also lower than −40 dB, demonstrating that the single-input-single-output control strategy can be adopted reasonably. Based on the identified frequency response, a fractional order proportional-integral (FOPI) controller is designed for the 2-DOF compliant micro-positioning stage. Compared with the integer order proportional-integral (IOPI) controller using same parameters, the amplitude error of the FOPI controller is 2% lower than that of IOPI controller. Additionally, a fractional order zero phase error controller (FOZPETC) is designed by obtaining the inverse of the fractional order closed-loop system in a large frequency range. And the gain of the corrected control system is 1 in a wide frequency band to eliminate the phase error in the close-loop control system. Finally, using the compound control strategy of FOZPETC+FOPI, a series of trajectory tracking tests are carried out on the proposed novel 2-DOF compliant micro-positioning stage. All the experimental results prove that the designed controller can achieve good positioning and tracking performance of the micro-positioning stage, and confirm the effectiveness of the compound control strategy of FOZPETC+FOPI.

Design and test of a compact compliant gripper using the Scott–Russell mechanism

This paper presents the design, modeling, fabrication, and test of a monolithic compliant gripper for micro-manipulation applications. A compact compliant mechanism that enables in-principle straight-line parallel jaw motion is obtained, by combining the Scott–Russell mechanism and the parallelogram mechanism. The right-circular corner-filleted (RCCF) flexure hinge is adopted to achieve a large displacement of lumped-compliance joints. A pseudo-rigid-body model (PRBM) method with the help of the virtual work principle is performed to obtain parametric analytical models including the amplification coefficient and kinetostatics. Finite element analysis (FEA) is conducted to validate the analytical model and capture adverse parasitic motions of jaws. A monolithic prototype was fabricated, the test results of which show satisfactory performances.

DESIGN OF AN ACTIVE SEAT SUSPENSION FOR A PASSENGER VEHICLE

AbstractThe design of an active seat suspension for a mid-class passenger vehicle based on the given set of requirements is considered a combination of four subsystems; the carrier, the actuator, the spring, and the damper. The design of the former two is considered through the 10 and 16 concepts for each, respectively. Two overall designs are proposed for further development. One based on a dual Scott-Russell mechanism and one based on Sarrus mechanism. The first one is evaluated to have high stiffness, the second to be more cost-effective. The detailed design of the first concept is presented.

Development of a gecko-like robotic gripper using Scott–Russell mechanisms

SummaryThis paper describes the development of a gecko-inspired robotic gripper for grasping flat objects using Scott–Russell mechanisms. Compared to previously reported grippers that utilize gecko-like adhesives, the one presented here produces higher normal adhesion and has robustness and controllability advantages. To verify the applicability of proposed gripper, a mechanical model and experimental results on a variety of substrates are presented. The experimental results demonstrated a 19.6% and 50% increase in normal adhesion using a preload of <15 and <30 N, respectively, compared to previously reported results under similar testing parameters and conditions.

Design and analysis of a displacement amplifier with high load capacity by combining bridge-type and Scott-Russell mechanisms.

To improve the load capacity of flexure-based amplification mechanisms, a flexure-based displacement amplification mechanism is developed in this study by combining the bridge-type and the Scott-Russell mechanisms. The four arms of the traditional bridge mechanism are replaced by four Scott-Russell mechanisms that provide the advantages of good symmetry, compact structure, and higher load capacity. An analytical model is formulated using a stiffness matrix to analyze the natural frequency, input and output stiffnesses, displacement amplification ratio, and load capacity of the proposed mechanism. The design model was subjected to both experimental methods and finite element analysis for verification, and the two sets of results were in good agreement. This proves the effectiveness and applicability of the analytical model and the proposed amplification mechanism. The output stiffnesses of the modified bridge-type amplifier and the traditional bridge-type amplifier are 0.158 N/μm and 0.041 N/μm, respectively, indicating excellent load performance of the modified bridge-type amplifier.

Design, analysis and testing of a novel decoupled 2-DOF flexure-based micropositioning stage

This paper presents the design, analysis and testing of a novel decoupled 2-DOF flexure-based micropositioning stage driven by piezoelectric-actuators (PZTs). In order to enlarge the travel range, a Scott-Russell mechanism and leverage mechanism are arranged in series, constituting a two-grade displacement amplifier to conquer the small displacement of the PZT. The design micropositioning stage is composed of symmetrically distributed flexure modules and each flexure module comprises compound parallelogram flexure beams serving as input decoupling, which allows the output decoupling by employing the tridimensional double compound parallelogram flexure mechanism. Based on the analytical model of both the amplifier and the XY stage established in static and dynamic analysis, the dimensions and performance of the stage has been conducted, which are verified by finite element analysis with ANSYS Workbench and prototype experiment with the fabricated prototype of the designed stage. It can be seen that the workspace of the developed stage is m with the maximum output coupling errors of 0.693% and 0.637% in the y and x directions. The experimental results demonstrate that the proposed micropositioning stage possesses good performance in trajectory tracking and can achieve a wide range of precise positioning.

Design of a novel 5-DOF flexure-based compound alignment stage for Roll-to-Roll Printed Electronics.

Alignment stage is a pivotal component for Roll-to-Roll Printed Electronic (R2RPE), especially for Roll-to-Roll inkjet printing. This paper presents the design, modeling, and testing of a new flexure-based compound alignment stage for R2RPE. In this design, the alignment stage has 5-DOF (Degree of Freedom) motions for compensating the alignment errors and only the rotation motion about the y-axis is redundant. The stage is constructed in series by four key parts and adopts a compounded flexure structure to achieve a great performance. Each part is driven by a piezoelectric actuator or voice coil motor actuator to obtain one or two DOF motion. In order to enlarge the travel range of the alignment stage, a Scott-Russell mechanism and a lever mechanism are arranged in series for forming a two-grade displacement amplifier to overcome the small displacement of the actuator. Based on the pseudo-rigid-body simplification method, alignment models are developed. Kinematic and static analyses are conducted to evaluate the performance of the stage in terms of travel range and input stiffness. Finite element simulation is carried out to examine the mechanical performance and the theoretical models. A prototype is fabricated and experiments are conducted. Results show that the proposed alignment stage possesses an error compensation workspace of 148.11μm×149.73μm×813.61μm×1.558mrad×3.501mrad with output coupling errors of 0.693% and 0.637% between the x- and y-axis, which meets the requirements of Roll-to-Roll inkjet printing.

Design and Development of Compliant Mechanisms Using Parameterization Technique

Design and development of compliant mechanism based systems with precision motion are the need of the hour in micro-precision industry. Compliant mechanisms coupled with the proper flexure hinge can provide excellent accuracy contrary to conventional rigid body mechanism. Various design methods are proposed to design a compliant mechanism such as structural optimization technique, Pseudo Rigid Body Model, Inverse Methods and Intuitive methods. Developing a manufacturable monolithic compliant mechanism is highly challenging. In this paper we have attempted a novel approach to design a compliant mechanism with circular based contemporary flexure hinge. The initial design of flexure hinge is designed intuitively and selection of appropriate geometrical parameters of the flexure hinges is another critical task in the design process. The developed hinges are parameterised using the general screening algorithm in ANSYS Workbench to obtain precise dimensions. The initial design of flexure hinge is designed as a curved beam which have fixed centre of rotation during execution. The method is implemented to design a four bar compliant mechanism and compared with the mathematical results. Scott-Russell straight line mechanism is also developed using this approach and verified its effectiveness. Dimensions of the developed hinges are also provided in the paper to enable future researchers to implement and improve the design.

A novel piezoelectrically actuated 2-DoF compliant micro/nano-positioning stage with multi-level amplification.

This article presents a novel two-degrees-of-freedom (2-DoF) piezo-actuated parallel-kinematic micro/nano-positioning stage with multi-level amplification. The mirror symmetric stage consists of four leverage mechanisms, two Scott-Russell mechanisms, and a Z-shaped flexure hinge (ZFH) mechanism. Taking advantage of the ZFH mechanism, 2-DoF motions with final-level flexural amplification and decoupled motion guidance are achieved. Analytical models of the stage are developed and validated through finite element analysis to characterize its working performance. Practical testing of a prototype stage is conducted to demonstrate the design process and to quantify its response characteristics. Due to the utilized multi-level amplification, a practical amplification ratio of 13.0 is realized by the prototype. The decoupled output motion guidance feature of the stage makes it amenable for implementation in raster scanning type of measurements.

New Structural Design of a Compliant Gripper Based on the Scott-Russell Mechanism

This paper presents the structural design and analysis of a novel compliant gripper based on the Scott-Russell (SR) mechanism. The SR mechanism in combination with a parallelogram mechanism enables the achievement of a pure translation of the gripper tips, which is attractive for practical micromanipulation and microassembly applications. Unlike traditional pure-translation grippers, the reported SR-based gripper exhibits a simple structure as well as compact dimension because the in-plane space is fully used. The kinematics, statics and dynamics models of the gripper mechanism are established, and finite element analysis (FEA) simulations are carried out to verify the structure design. A prototype has been developed for experimental testing. The results not only demonstrate the feasibility of the proposed SR-based gripper design but also reveal a promising performance of the gripper when driven by piezoelectric stack actuators. Moreover, several variations of the gripper structure are presented as well.

Design and Kinematics Modeling of a Novel 3-DOF Monolithic Manipulator Featuring Improved Scott-Russell Mechanisms

This paper proposes the design of a novel 3-DOF monolithic manipulator. This manipulator is capable of performing planar manipulations with three kinematically coupled DOFs, i.e., the translations in the X and Y axes and the rotation about the Z axis. An improved Scott-Russell (ISR) mechanism is utilized to magnify the displacement of the piezoelectric actuator (PEA). Unlike the SR mechanism, a set of leaf parallelograms is incorporated into the drive point of the ISR mechanism as a prismatic joint. As a result, the linearity of motion and stability are improved. With circular flexure hinges being treated as revolute joints, the forward kinematics and inverse kinematics of the 3-DOF manipulator are analytically derived. Computational analyses are performed to validate the established kinematics models. Due to the unwanted compliance of the flexure hinges, the actual displacement amplification ratio of the ISR mechanism is smaller than its theoretical value. This is the main cause of the discrepancies between the analytical and computational results. The reachable workspace and the static/dynamic characteristics of the 3-DOF manipulator are also analyzed.

A novel flexure-based microgripper with double amplification mechanisms for micro/nano manipulation

This paper describes the design, modeling, and testing of a novel flexure-based microgripper for a large jaw displacement with high resolution. Such a microgripper is indispensable in micro∕nano manipulation. In achieving a large jaw displacement, double amplification mechanisms, namely, Scott-Russell mechanism and leverage mechanism arranged in series, are utilized to overcome the limited output of microgrippers driven by piezoelectric actuators. The mechanical performance of the microgripper is analyzed using the pseudo rigid body model approach. Finite element analysis is conducted to evaluate the performance and validate the established models for further optimum design of the microgripper. The prototype of the developed microgripper is fabricated, with which experimental tests are carried out. The experimental results show that the developed microgripper is capable of handling various sized micro-objects with a maximum jaw displacement of 134 μm and a high amplification ratio of 15.5.