Xiao

Development and assessment of a novel hydraulic displacement amplifier for piezo-actuated large stroke precision positioning

In recent years, piezo-actuated micro/nano positioning stages emerge as a significant tool in the nanotechnology. However, the shortcomings of small positioning stroke and hysteresis of piezoelectric actuators have constrained their further development and applications. In this paper, a novel piezo-actuated hydraulic displacement amplifier (PHDA) based on Pascals law and area differential principle is first proposed aiming to solve the contradictions among positioning stroke, positioning resolution and mechanism dimension in piezo-actuated micro/nano positioning stages. After a series of optimal designs, the proposed PHDA mechanism is fabricated and experimentally tested. In this study, a piezoelectric (PZT) actuator P-840.20 with open-loop travel of 30 μm is employed, the experimental results indicate that the displacement amplification ratio can reach up to 34.6, thus the maximum output displacement can achieve up to around 1.02 mm. Both theoretical derivation and prototype test results testify the well performance of the proposed mechanism. This new amplifier can be widely extended to practical precision manipulation applications in case of large motion range required.

Development of an Electromagnetic Actuated Microdisplacement Module

This paper presents the mechanical design and control system design of an electromagnetic actuator-based microdisplacement module. The microdisplacement module composed of a symmetrical leaf-spring parallelogram mechanism and an electromagnetic actuator. The characteristics of the mechanism in terms of stiffness and natural frequencies are derived and verified. Both leakage flux and core inductance are taken into consideration during modeling the mathematic model of the electromagnetic actuator, and based on which, the system dynamic model is established. Due to the nonlinearity characteristics of the system, a dynamic sliding-mode controller is designed without linearizing the system dynamics. A prototype of the microdisplacement module is fabricated, and the parameters of the system are identified and calibrated. Finally, the designed dynamic sliding-mode controller is applied; step response and tracking performance are studied. Experimental results demonstrate that a submicrometer accuracy can be achieved by the module, which validate the effectiveness of the proposed mechanism and controller design as well. The research results show that the electromagnetic actuator-based module can be extended to wide applications in the field of micro/nanopositioning and manipulation.

Inverse Dynamics Analysis of a 6-PSS Parallel Manipulator

In this paper, a new six degrees of freedom (6-DOF) parallel manipulator with adjustable actuators is proposed. The kinematic model is firstly established and the kinematic analysis is performed afterward. Then the equations of motion are developed based on the concept of link Jacobian matrices. Finally, the principle of virtual work is applied to analyze the dynamics of this 6-PSS parallel manipulator. This methodology can be used on other types of parallel manipulators not only for 6-DOF but also with less than 6-DOF. To solve the inverse dynamics of the manipulator, a computational algorithm is developed and two trajectories of the moving platform are simulated.

Development and control of a compact 3-DOF micromanipulator for high-precise positioning

This paper presents a compact 3-DOF micromanipulator, which is a variant of the rigid 3-P(4S) parallel mechanism. Due to the special design, the proposed micromanipulator is compact in structure and large in workspace. Firstly, the design process of the micromanipulator is demonstrated in this paper. Then the mathematical model of the micromanipulator is derived, in which stiffness model of the compliant P(4S) chain and total stiffness of the compliant 3-P(4S)mechanism are calculated. Finally, a prototype of the micromanipulator is fabricated. Three electromagnetic actuators are utilized in this design. Control system based on dSPACE system is established and preliminary experiments are conducted. Both FEA simulation and experimental results reveal that the proposed micromanipulator has a good positioning performance, which is highly desirable in micro/nano manipulation and manufacturing. The main advantages of the micromanipulator are compact in structure, easy to control and non-contact in actuation.

Kinematics and workspace analysis for a novel 6-PSS parallel manipulator

In this paper, a novel 6-PSS parallel manipulator is designed and the three dimensional structure model is obtained with the Solidworks. The inverse kinematics analysis is performed based on the designed geometric parameters. And according to this analysis, we obtain the theoretical simulation results of virtual structures with different positions and orientations by using MATLAB software. These simulation structures verify the feasibility of this novel 6-PSS parallel manipulator. With a given orientation, a numerical search method is adopted in finding the reachable workspace with the judgment conditions of physical constraints, and the relationship between the reachable workspace and the size of the structure is studied in virtual simulation. Therefore, the range including the largest reachable workspace is achieved and a possible further application of this novel 6-PSS parallel manipulator is proposed, especially in some fields of different structure size requirements.

A novel flexure-based dual-arm robotic system for high-throughput biomanipulations on micro-fluidic chip

In recent years, robotic bio-manipulation emerges as a hot research topic in the micro/nano technology. In these applications, biological cell microinjection is a focus since it is a critical process for the further biological research such as genetic engineering and pharmacology research. This study aims to develop a novel robotic biomanipulation system combining with the micro-fluidic chip technology to improve the cell manipulation stability and throughput. Two novel flexure-based large-workspace micromanipulators with modified differential lever displacement amplifier (MDLDA) are presented in this paper. After a series of optimal designs and mechanism modeling, the mechanism performances are evaluated by the FEA method. Finally, the proposed micromanipulators are fabricated and visual-servo controlled to perform the practical zebrafish embryos injection task. In this work, two piezoelectric (PZT) actuators P-216.80 (open-loop travel is 120 μm) and one PZT actuator P-840.20 (open-loop travel is 30 μm) are utilized in the compliant mechanisms, the experiment results indicate that the displacement amplification ratios can reach up to 30.6 and 17.6, thus the maximum output displacements can achieve around 3.1273 mm and 0.528 mm, the rotation angle of the left micromanipulator can reach to around 26.5°. Both theoretical derivation and experimental implementation results well verify the advanced performance of the developed system.

Optimized PID tracking control for piezoelectric actuators based on the Bouc-Wen model

An optimized PID controller designed for piezoelectric actuator based on classical Bouc-Wen(BW) hysteresis model is proposed in this paper. Generally, hysteresis nonlinearity existing in the smart materials such as piezoelectric actuators can cause undesirable inaccuracy. In this paper, the classical BW hysteresis model is presented and parameters identification via the particle swarm optimization (PSO) approach for piezoelectric actuator is performed. For the purpose of obtaining a better tracking performance, the PSO method is adopted again to search for each parameter. The testing results validate that the optimized PID controller can enhance the PZTs tracking accuracy.

A novel kinematics analysis for a 5-DOF manipulator based on KUKA youBot

Inverse kinematics solutions can provide useful data for trajectory planning, motion control, etc. In this paper, a hybrid algebraic and analytical geometric solution with reservation method is proposed to solve the inverse kinematics, and the existence of all the possible solutions are specified. Therefore, without the selection and matching of multiple solutions for each joint, we can directly obtain the uniqueness of multiple solutions, according to the desired configuration in industrial application. Hence, for the method herein, it is not necessary to calculate all the possible solutions, therefore, compared with other methods, the computational efficiency is greatly enhanced. Finally, the proposed method is verified through simulation and experiment based on a KUKA youBot manipulator.

Design and analysis of a flexure-based modular precision positioning stage with two different materials

Generally, the motion range of the micro scale operation is within several hundreds of microns, and the conventional joints cannot satisfy the requirements due to manufacturing and assembling errors, hysteresis and backlash in the joints. The paper aims to discuss these issues.,The following issues should be considered: a micromanipulation stage should be designed using a small-dimensional scale driven by the small size of piezoelectric actuator and the components can be replaced due to fatigue failure caused by repeated cyclic loading. This paper proposes a modular design of a flexure-based 2-DOF precision stage made using aluminum (T6-7075) material and Acrylonitrile Butadiene Styrene plastic material. The piezoelectric actuator is adopted to drive the stage for the fast response and large output force. To compensate the stroke of piezoelectric actuator, a bridge-type amplifier is designed with optimized structure.,The simulation results validate the advantages of modular positioning stage fabricated by two different materials.,The stage can be used in micro scale precision’s applications. If it will be used in nanoscale precision, then some sensors in nanoscale of measurement should be used.,The designed stage can be used in biomedical engineering, such as cell injection testing, etc.,The designed stage will be used in micro/nanoengineering field, such as micro/nanomanufacturing or assembly, manipulation of cell, etc., which will push forward high technology to a higher level.,Two kinds of materials have been selected to make the positioning stage, which are seldomly found in literature on compliant mechanism field. A modular design concept is proposed for the positioning stage design.

New Yθ compliant micromanipulator with ultra-large workspace for biomanipulations

In recent years, biological micromanipulations emerge as a promising application in the micro/nano technology. Manual manipulation tends to have disadvantages of low success rate and low repeatability. In order to perform the robotic biomanipulations, a novel flexure-based Yθ large-workspace micromanipulator with differential lever displacement amplifier (DLDA) is proposed in this paper. After a series of optimal designs and mechanism modeling, the mechanism performance of the proposed micromanipulator is validated by using the Finite Element Analysis (FEA) method. Finally, the proposed micromanipulator is fabricated and close-loop experimentally tested to make a prototype characterization. In this study, two piezoelectric (PZT) actuators P-216.80 with close-loop travel 120 μm and close-loop resolution 2.4 nm are employed, the simulation and experimentally results indicate that the mechanism displacement amplification ratio can reach up to 31, thus the maximum output displacement can achieve around 3.3 mm, the rotation angle can reach up to around 26.5°. Both theoretical derivation and prototype test results well testify the proposed mechanism possesses satisfactory performance to perform the practical biomanipulations.