Jihao Liu

Linearity of the Force Leverage Mechanism Based on Flexure Hinges.

This paper proposes development of a force leverage mechanism based on the flexure hinges. The primary function of this leverage mechanism is to transform an objective unbalance force/moment to a force sensor in the static unbalance measure system. The measure precision is dependent on the linearity of the force transmission of the force leverage mechanism. The kinematics of the force leverage mechanism is modeled based on the elastic model. The finite element method is used to verify the analytical solutions. Moreover, the effect of the initial external load on the linearity is investigated. Further, the virtual experiment is carried on to verify the linearity and sensitivity. The static unbalance measure system employing the proposed leverage mechanism has the advanced sensitivity of less than 0.03 gcm and performs excellent linearity.

Dynamic Drive Performances of the Bionic Suction Cup Actuator Based on Shape Memory Alloy

This paper proposes a design of SMA-based bionic suction cup actuator, the core of which is that the bias spring cooperates with the SMA spring to produce a displacement at the varying temperature caused by the drive current. To characterize the dynamic drive performance of the actuator, the thermodynamic model is established by the constitutive model of SMA material of Tanaka series. The simulation model for the bias SMA spring actuator in MATLAB/SIMULINK is built. Moreover, the effects of different load and different driving environment on the displacement of SMA actuator as well as the corresponding reaction time are investigated. The steady displacement response enlarge with the drive current increasing, while the load readjusts the initial deformation of the actuator and also enlarges the final steady shearing displacement. Further, based on the actuator driving performance, the adsorption characteristics of the bionic suction cup are studied and verified experimentally.

Piezoelectric Micro-Pump Suction Cup Design and Research on the Optimal Static Driving Characteristics

This paper first introduces the design and principles of a negative pressure suction cup with integrated piezoelectric valveless micro-pump. Laser engraving technique is used to build the multilayer prototype. In order to improve the adsorption performance of the suction cup, the static driving characteristics of the piezoelectric actuator have been optimized: based on a series of assumptions according to piezoelectric composite oscillators, a theoretical mechanics model of circular single-chip piezoelectric actuator has been constructed to explore the lateral deformation of the piezoelectric actuator in the effect of simple electric load. By the method of finite element simulation, the model is verified. Further, through optimizing its geometry design, the piezoelectric actuator has been enabled of the best static deformation characteristics.

Force transmission of flexure-based leverage mechanism for static unbalance measuring system under self-gravity effect

This article proposes a flexure-based leverage mechanism that improves the performance of the static unbalance measurement system in terms of sensitivity and precision. The primary function of the flexure-based leverage mechanism is to transform the objective unbalance force/moment from the double-frame platform to an electromagnetic force balance sensor. A model of the flexure-based leverage mechanism was established to investigate the displacement/force amplification based on the elastic model. The finite element method was used to verify the analytical solutions. Considering the gravity effects, the self-weight of the rigid bodies in this leverage mechanism has an effect on the reading in the sensors. However, the linearity characteristics are not sensitive to the self-weight of the proposed leverage mechanism and the stiffness of the flexure hinges. Virtual experiments conducted to verify the linearity and sensitivity of the system indicated that depending on the leverage function of the flexure-based leverage mechanism, the systematic sensitivity is less than 0.02 g/(g cm), the resolution is 0.0013 g cm, and the maximum linearity error is 2.7%.

Analytical Model for Flexure---Based Proportion Parallel Mechanisms with Deficient---Determinate Input

This paper presents the design and the specific analysis of a novel spatial symmetrical compliant mechanism with closed - loop subchains which is capable of driving the piezoelectric valve-less micropump in high frequence. This design of the topological configuration evolving from the bridge-type magnification mechanism amplifies the longitudinal deformation of the piezoceram actuators in parallel to the transverse displacement generation in dozens of times. In order to further estimate the performance of displacement amplification, the elastic beam theory, screw theory and the Pseudo Rigid Body Model PRBM are adopted to determine the ideal displacement amplification ratio. The FEM simulation is carried out to cross validate the design of the flexure-based mechanisms.

A Novel 5-DOF welding robot based on SCARA

This paper raises and analyses a novel 5-DOF welding robot which is based on SCARA. The robot is not only compatible but multifunctional because of the introduction of functional end that consists of two degrees of freedom, which are mutually perpendicular. After building the model, the kinematics analysis is carried out, through which the general formula of the forward as well as inverse kinematics is reached with D-H method. And only in that way, the human can get the method which is used for the position and velocity of the 5-DOF robot. In order to ensure the reliability of the robot in practical application, the modality of it is analyzed with ANSYS.

A novel miniature spatial hybrid compliant-paralleled mechanism for film micropump

Miniature actuators and methodologies play an important role in the performance of the film micro-pumps that could deliver high precision amount of the fluid. A common type of thin film micro-pump equips with film membrane in the asymmetry structure generating a polarization axial, which raises an inconvenient topic that has attracted increasing interest. This paper formulates and analyzes a novel spatial hybrid compliant mechanism with three chains in parallel with multiple-axis flexure hinges. In this design of miniature compliant-paralleled mechanism, a novel displacement magnification, has unique abilities of transmitting radial in-plane input displacements in parallel into centrally axial output deflection in out-plane and performs excellent in amplify ratio. In order to determine output generating deflection and stress intensity issue, Pseudo Rigid Body Model (PRBM) methodology and elastic mechanics are employed. In addition, in the parallel kinematic mechanism couples inputting parts which effectively decreases error ratio resulting from asynchrony of input amplitudes in parallel. To verify the performance of the miniature actuator, ANSYS is employed to simulate by the means of finite element analysis.

An Optimal Feedback Approach for the Stabilization of Linear Systems Subject to Input Saturation and Magnitude-Bounded Disturbances

Disturbance may severely degrade the control accuracy of an input-saturated system and even induce instability. This paper intends to present an approach to realize optimal disturbance attenuation for an input-saturated system subject to magnitude-bounded disturbance. Based on circle criterion and the techniques of linear matrix inequalities and convex optimization, stability properties of a system under a known feedback controller are analyzed and an linear approach of synthesizing optimal feedback controller is proposed. Illustrative examples are given and state trajectories of the system before and after stabilization are compared to examine the effectiveness of the proposed approach. The simulation results show that the synthesized controller is effective in stabilizing the system and realizing optimal disturbance attenuation.