Design And Experiment Of A Microminiature Resonant Multi-foot Piezoelectric Robot

Microminiature robots are a popular direction for robot technology research and development in recent years.Based on their small size,light weight,flexible motion and other characteristics,they can be used in many fields such as bioengineering,military reconnaissance,energy detection,and micromanipulation.The piezoelectric driving technology has many advantages such as high resolution,fast response speed,simple structure and self-locking when power off,which provides a new direction for the breakthrough of new driving technology for microminiature robots.At present,the microminiature piezoelectric robot can be divided into the resonant type and the non-resonant type according to its working mode.The former is good to achieve higher motion speed and microminiature design,while the latter is good to achieve higher motion resolution.In this thesis,inspired by the segmentation of arthropod,a microminiature resonant multi-foot piezoelectric robot is designed,and the continuous sine excitation mode and pulse sine excitation mode are used,the robot can achieve both high speed and high motion resolution.The piezoelectric-leg configuration based on the integrated design of foot and leg is proposed referring to the segmentation and movement mechanism of arthropod,and its working principle is determined,which uses the second-order hybrid bending modes of the piezoelectric-leg to achieve its driving capability.The working principle of the piezoelectric-leg is analyzed,the polarization direction,arrangement of the piezoelectric ceramics and the required excitation scheme are determined.The connection structures are designed based on the determined piezoelectric-leg configuration,and the topological configurations of the microminiature resonant multi-foot piezoelectric robot are planned based on the linear arrangement and the circumferential arrangement,respectively.The motion modes that can be realized by each robot topological configuration are analyzed,and the motion gait and the required excitation scheme corresponding to each motion mode are planned.By comparing the characteristics of multiple robot topological configurations such as the motion mode,the first topological configuration of the robot(the linear piezoelectric robot I)was selected as the specific research object.The dynamic model of the piezoelectric-leg is established based on the Timoshenko beam theory,the relationships between the displacement of its driving tip and the main structural parameters,material parameters and the applied exciting voltage are obtained,the main structural and material parameters of the piezoelectric-leg are determined based on the dynamic model.The simulation analysis of the piezoelectric-leg is performed by using the finite element method to determine the geometric parameters of the thin-walled beam,and verify the accuracy of the established dynamic model.The final structure and material parameters of the linear piezoelectric robot I are determined with the finite element method.The piezoelectric-legs and the linear piezoelectric robot I prototypes are processed and assembled.The vibration mode characteristics of the piezoelectric-legs and the displacement characteristics of the driving tips are tested,and the test results are in good agreement with the design goal that the second-order bending frequency of the piezoelectric-leg is 25 k Hz.For the characteristics of the linear piezoelectric robot I with a wide range of motion speed,two measurement schemes corresponding to the high-speed and low-speed motions of the robot are designed.A series of experimental studies on the linear motion of the robot are carried out,the experimental results show that: the maximum speed achieved by the linear piezoelectric robot I is 516.3mm/s,and the minimum speed is 4.4?m/s,the speed range spans 5 orders of magnitude;the minimum resolution and maximum load are 0.44?m and 200g(approximately 4.7times its own weight),respectively;the robot has successfully completed climbing movement in a pipeline with a maximum inclination angle of 9.8°;and the robot successfully crossed various obstacles such as gullies,potholes and bulge.In addition,the steering motion and the rotational motion of the robot are tested,and the results show that the robot achieved a minimum turning radius of 182.1mm at 25Vp-p and a maximum rotational speed of 315°/s at 100Vp-p.The experimental results fully show that the microminiature resonant multi-foot piezoelectric robot developed in this thesis has obvious advantages such as wide speed range,high resolution,and strong obstacle-crossing capability.