Microgripper is an important tool in high precision micromanipulation task, which directly affects the quality and efficiency of micromanipulation. This paper presents the design and control of a novel asymmetrical microgripper driven by a piezoelectric (PZT) actuator. The developed microgripper is designed as an asymmetrical structure with one movable jaw, so it has the advantages of no dense mode and fixed locating datum compared with the symmetrical microgripper with two movable jaws. The main body of microgripper is a compact flexure-based mechanical structure with a three-stage amplification mechanism. Based on the three-stage amplification structure, large-range, robust and parallel grasping operation can be realized. The characteristics analyses of the developed microgripper are carried out by finite element analysis (FEA). A position-force switching control strategy is utilized to regulate the position and grasping force of movable jaw. Discrete-time sliding model (DSM) controller is designed to control the position and grasping force. Experimental studies are conducted and the experiment results show that the microgripper exhibits good performance and high precision grasping operations can be realized through the developed control strategy.

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Design and control of a novel asymmetrical piezoelectric actuated microgripper for micromanipulation

This paper presents a novel piezoelectrically actuated dual-axis micromanipulator with an asymmetric compliant structure. The mechanical design of the micromanipulator is first presented. A novel guiding bridge-type mechanism was proposed and utilized in the left part of the micromanipulator to improve the dynamic performance of the micromanipulator. The analytical model has been established based on the pseudorigid-body model and matrix-based compliance modeling method. The kinematic and the precision of the micromanipulator have been analyzed, and the input and output couplings have been investigated. The prototype of the micromanipulator has been fabricated by wire electrodischarge machining. Then, open-loop experimental tests have been performed. The experimental results match well with the analytical calculation, and the amplification ratios are 11.12 and 4.64 for the left part and right part, respectively. Proportional-integral controller has been used to regulate the output displacement and grasping force, and a series of closed-loop experiments have been conducted to investigate the performance of the micromanipulator. The results show that the position resolution for both the right and left parts is 0.15 μm, and the force resolution is 4 mN.

Design of a Novel Dual-Axis Micromanipulator With an Asymmetric Compliant Structure

The piezoelectric-actuated compliant microgripper (PEACM) plays an essential role in the application fields such as biomedical engineering, microelectronics, and optical engineering. As compared with other categories of grippers, PEACM exhibits the advantages of high accuracy of displacement, large power to weight ratio, low energy consumption, and fast response speed. This paper reviews the recent advances on performance indices, classification, structural composition, optimization and modeling method, and control of PEACM. First, the gripper's performance indices and classifications are elaborated, which is beneficial to determine the design goal. Then, the compliant mechanisms adopted in the microgripper design are discussed, including the flexible hinge, displacement amplifier, and guiding mechanism. In addition, the optimization and modeling methods of the microgripper are presented. Popular types of position/force sensors and different displacement/force control strategies employed in the microgripper are surveyed. Moreover, the prospect on future development trend of the PEACM is discussed. The paper provides the reader with an overview of the recent advances on PEACM design and also a guideline on further development of the microgripper.

Recent design and development of piezoelectric-actuated compliant microgrippers: A review

Light-emitting diodes (LEDs) are considered an ideal substitute for low-efficiency traditional light sources with broad applications in all scientific disciplines. For the past recent years, several developments and innovations have been reported that strengthen the reliability and thermal efficiency of speeding up the LED packaging process. This paper reviews and summarizes various changes and improvements made to die attachment, wire bonding, phosphor coating, encapsulation processes, and thermal management. It also covers the reasons for choosing the materials at every stage of LED packaging. Moreover, the review reveals a broad scope for future research, particularly on thermal management by nanoparticles and improved light intensity by different synthesized phosphors.

Die attachment, wire bonding, and encapsulation process in LED packaging: A review

Design and development of a novel piezoelectrically actuated asymmetrical flexible microgripper

A microgripper capable of accurately releasing or clamping the microgold wire for ultrasonic bonding is a key component in integrated circuit and light-emitting diode wire bonders. A novel gripper with a piezoelectric (PZT) stack and flexible mechanism is presented. A dynamic model of the PZT gripper is established, and a method of suppression control for residual vibration is proposed. The vibration characteristics of the PZT gripper are calculated using finite-element modeling (FEM) to obtain the natural frequency, vibration mode, and displacement. An input-shaping algorithm is applied to restrain the residual vibration caused by the flexible structure. The performance of the control algorithm is discussed and compared to the performance of the square, trapezoidal, and synthetic control methods. Three typical input-shaping filters—zero vibration, zero vibration differential, and extreme insensitivity—are compared, and the effects of frequency and damping on vibration suppression are discussed. In the experiment, a high-speed camera is used to track the displacement of the gripper, and the relationship between displacement and driven voltage is proven. Impedance and frequency are measured by an impedance analyzer, and the results agree with the values from the FEM. The residual vibration with the different driver control methods is recorded by a noncontact laser Doppler vibrometer. With the input-shaping control method, the residual vibration of the PZT gripper is reduced to 10%, and the settling time is reduced by 0.7 ms compared to the original vibration, demonstrating that the method improves the performance of the PZT gripper.

Dynamics Modeling and Residual Vibration Control of a Piezoelectric Gripper During Wire Bonding

The invention discloses an automatic impedance matching ultrasonic circuit driver and an automatic dynamic matching method thereof. The automatic impedance matching ultrasonic circuit driver comprises a high-speed single chip module, a DDS signal generation module, a power amplifying module, an impedance dynamic matching module, a signal acquisition and control module and a protection circuit module which are in mutual connection. According to the invention, the design is skillful and reasonable, the dynamic matching module consists of a series of inductance components, the inductance of the dynamic matching module is controlled by a matching algorithm, the resonance of the system on the circuit structure is realized, the energy output of the circuit system is maximum, and reasonable matching between the ultrasonic driver and a transducer is realized. The high-speed single chip module can realize digital control of the whole ultrasonic driver, signal generation is the generation of a sine wave signal by adopting a DDS digital way, the power amplifying module can increase the voltage and current signals into the power required by the transducer, and the signal control module can realize the functions of automatic power tracking and the like.

Automatic impedance matching ultrasonic circuit driver and automatic dynamic matching method thereof

The utility model discloses an automatic impedance match's ultrasonic wave circuit driver and automatic dynamic matching method, it is including high -speed single -chip module, DDS signal generation module, power amplification module, impedance dynamic matching module, signal acquisition and the control module and the protection circuit module that link up each other, the utility model discloses a design benefit, reasonable, the dynamic matching module comprises a series of inductance device, and inductance through matching algorithm controls the dynamic matching module satisfies the resonance of system on circuit structure for the maximum output of circuit system energy reaches the reasonable match of ultrasonic drive ware and transducer. High -speed single -chip module can realize the digital control of whole ultrasonic drive ware, and signal generation is the formation of adopting the digital method of DDS realization sine wave signal, and the power amplifier enlargies the module can rise to the required power of transducer with the current signal with driving voltage, and signal control module can realize functions such as frequency automatic tracking.

Automatic impedance match's ultrasonic wave circuit driver

A piezoelectric vibration feeder is a necessary device for semiconductor manufacturing assembly. Its function is to automatically transport individual chip parts by precision vibration instead of by manual operation. In this paper, a mechanical structure for the piezoelectric feeder and electrical controller is designed and a prototype is developed. A vibration simulation model is established in ANSYS by the finite element method (FEM), and the frequency and vibration modal is attained. The mass-elastic model is established and the frequency is calculated by the numerical method. To drive and control the vibration feeder, a hardware driver consisting of an ARM microcontroller, a sinusoidal pulse width modulation driver module, an inverter circuit of insulated gate bipolar transistor modules, and an LC filter is designed. To achieve resonant vibration, a self-tuned proportional integral derivative (PID) controller for frequency tracking is investigated using MATLAB Simulink simulation. The dynamics and performance of vibration control are then verified through experimental testing using a laser Doppler vibrometer and an impedance analyzer. The mechanical frequencies of the piezoelectric feeder in the FEM, the numerical model, and the experimental measurement are found to agree well. The PID controller used for frequency tracking ensures the resonant vibration, which improves the efficiency and robustness of the piezoelectric feeder.

Dynamics Model and Vibration Control of Piezoelectric Feeder in Semiconductor Manufacturing Assembly

The invention discloses a double-frequency ultrasonic vibration machining transducer and working modes thereof. The double-frequency ultrasonic vibration machining transducer comprises a tool head, a sleeve clamp, an amplitude changing rod, a piezoelectric ceramic and a pre-tightening screw assembly. An elastic clamp head is arranged at the front end of the amplitude changing rod. The tool head is inserted into the elastic clamp head. The sleeve clamp is arranged on the elastic clamp head in a sleeving mode and enables the elastic clamp head to clamp the tool head. The piezoelectric ceramic is arranged on the tail end face of the amplitude changing rod through pre-tightening screw assembly. The structure design is ingenious; by reasonably setting the lengths of the amplitude changing rod and the piezoelectric ceramic and the structure shape of the amplitude changing rod, the tool head can work stably and efficiently under double frequencies; and by conducting corresponding parameter setting on driver program software, the low frequency working mode or the high frequency working mode can be selected according to different machining requirements, and accordingly materials are machined with the appropriate frequency, so that working reaches the ideal machining effect, the machining effect is effectively guaranteed, the product quality is improved, flexibility is high, the application range is wide, and the double-frequency ultrasonic vibration machining transducer is beneficial for being widely applied and popularized.

Li Zuohua

Papers

Dynamics Modeling and Residual Vibration Control of a Piezoelectric Gripper During Wire Bonding

Automatic impedance matching ultrasonic circuit driver and automatic dynamic matching method thereof

Automatic impedance match's ultrasonic wave circuit driver

Dynamics Model and Vibration Control of Piezoelectric Feeder in Semiconductor Manufacturing Assembly

Double-frequency ultrasonic vibration machining transducer and working modes thereof