Research On Friction-assisted Impact Inertial Piezoelectric Actuators

Precision driven technology is a key common technology of high-end equipment and precision instruments in the fields of scientific research,industry,and medical.It is the basic support for the development of Chinese high-end manufacturing industry.The development of the above-mentioned fields also puts forward higher requirements for driving devices.Piezoelectric actuators utilize the inverse piezoelectric effect of piezoelectric intelligent materials to achieve driving,and have the characteristics of fast response,wide frequency bandwidth,high precision,non-magnetic,good environmental adaptability,and self-locking at power-off,which has received widespread attention.Among them,impact inertial piezoelectric actuators are characterized by their simple structure,convenient control,large stroke,and high resolution,making them promising candidates for various applications.Existing research has made positive progress in areas such as structural innovation and improvement of output performance.However,the core issue of output performance relying on inertial mass remains unresolved,leading to typical challenges such as low thrust-weight ratio,poor performance consistency in different motion direction,and miniaturization.To address these issues,this dissertation conducts a comprehensive study on the influence of auxiliary friction and inertial mass on output performance through dynamic simulations and experiments.Then,this dissertation conducts research on the development and output performance testing of impact inertial piezoelectric actuators based on friction-assisted.The main research contents of this dissertation are as follows:(1)A study was conducted to investigate the influence of auxiliary friction and inertial mass on output performance.The driving force and single step displacement comparison between the traditional and friction-assited actuators.Dynamics simulations and experimental studies were carried out using a designed piezoelectric actuator with adjustable friction.The results showed that auxiliary friction can reduce the dependence of output performance on the inertial mass.Under different conditions of main friction and driving voltage,the single step displacement exhibited three distinct trends with increasing auxiliary friction: gradually increasing,first increasing then decreasing,and gradually decreasing.Compared to the inertial mass driving,there exists a specific proportion of auxiliary friction within a wide range of mian friction,which enables the actuator to increase its single step displacement at high driving voltages and decrease it at low driving voltages.This suggests that auxiliary friction has the ability to synchronize the enhancement of both speed and resolution.(2)A study was conducted to investigate the influence of various conditions such as auxiliary friction,preload deformation,driving signal,and external load on the output force and thrust-weight ratio.An ultra-high thrust-weight ratio was achieved by utilizing auxiliary friction.Firstly,the principle of how auxiliary friction enhances the thrust-to-weight ratio of the actuator was explained.Then,an impact inertia piezoelectric actuator with high thrust-weight ratio was proposed.The structural design of the actuator was carried out through static analysis,and the motion process and force conditions of the actuator were analyzed in detail.Furthermore,an experimental system was set up,and a series of experiments were conducted.The experimental results showed that auxiliary friction had a significant effect on enhancing the output force.The developed actuator achieved a thrust-weight ratio of54.42,which is much higher than that of impact inertia piezoelectric actuators reported in existing literature.(3)A study was conducted to investigate the dependence of output performance on the motion angle.By utilizing auxiliary friction,high stepping consistency was achieved for the actuator across different motion angles.Firstly,the principle of how auxiliary friction improves the dependence of output performance on motion angle was explained.Then,a small impact inertia piezoelectric actuator with a rhombic displacement amplification mechanism was designed.The structural parameters of the actuator were optimized using the response surface optimization method.The motion principle of the actuator and the force conditions during motion were elaborated.Furthermore,based on the developed actuator prototype,an experimental system was set up to explore the output performance of the actuator at different motion angles,including speed,resolution,and output force.The relationship between the motion angle and output performance was clarified.Experimental results showed that the output performance of the actuator was relatively insensitive to the direction of motion,resulting in high consistency between upward and downward motions.The consistency coefficient reached 0.32.(4)Based on friction-assisted,a study was conducted to simultaneously enhance multiple output performances of miniaturized impact inertial piezoelectric actuators.Firstly,an actuator with spatial deployable structure was designed based on structural parameter variations.Dynamic simulations and experimental comparisons were conducted to study the output performance of the actuator with and without auxiliary friction.The results showed that compared to the case without auxiliary friction,the auxiliary friction increased the maximum speed of the actuator by 99%,resolution by 31%,and output force by 67.2%.Furthermore,to address the challenge of design and fabrication for miniaturized actuators,a method was proposed to utilize different numbers of flexible driving feet at both ends of these units to achieve auxiliary friction.A smaller and lighter actuator with spatial interdigital structure was developed and its output performance was tested under various experimental conditions.When compared to existing literature,these actuators exhibit not only smaller sizes and lighter masses but also excellent comprehensive output performances,demonstrating the beneficial effect of auxiliary friction in enhancing multiple output performances of miniaturized impact inertia piezoelectric actuators.In summary,this study has explored the influence of auxiliary friction and inertial mass on output performance such as single step displacement and output force.Based on frictionassisted,impact inertia piezoelectric actuators with high thrust-weight ratio,vertical motion capability,and excellent comprehensive output performance were developed.The related theoretical and experimental studies provide theoretical and technical support for further breakthroughs in the output performance of such actuators,contributing to the development of high-performance piezoelectric actuators and their applications in relevant fields.