| In recent years,with the development of science and technology,micro/nano level positioning drive technology has increasing demands for positioning drive system’s stroke and accuracy in many high-tech fields such as micro/nano operation,precision optics,ultra-precision fabrication,biomedicine,aerospace,etc.Up to now,traditional positioning drive devices have been unable to meet the urgent requirements for high-precision positioning drive technology in the above-mentioned areas.In response to these demands,new piezoelectric actuators with precise positioning and driving functions have emerged,and among them,the actuators driven by the inchworm mechanism and by the inertial-impact principle that based on the excellent dynamic characteristics of piezoelectric elements have been particularly prominent in the field of precision positioning drives.Compared with the traditional drive devices,these new piezoelectric actuators are often widely used in the above mentioned fields because they have a more compact structure,higher precision,faster response,greater driving force,and a larger movement stroke.However,the traditional piezoelectric ceramic actuators are mainly with single-degree-of-freedom mechanical structure and their output forms are relatively simple,and their output displacements are small,which severely limits their application in more piezoelectric drive technology.What’s more,for some conventional piezoelectric bimorph type actuators,it is often impossible to efficiently meet the requirements of vertical micro/nano level high output accuracy and high load carrying capacity due to the inability to overcome the gravity.Therefore,it is very important to design a piezoelectric actuator with a compact structure,large output force,and high repetitive positioning accuracy,which can simultaneously have linear motion and rotational motion output.Regarding that the existing inertial impact type and inchworm type drivers are mainly due to the problems of small bearing capacity and single output freedom,respectively,this paper proposes a hybrid drive scheme combining the principle of inertial impact and the principle of inchworm driven.The driving principle of each moving unit and the dynamic model of the corresponding mechanical structure are systematically analyzed,and the deformation,the stress distribution of various orders and mode shapes under its working condition is simulated,and then the prototype of the actuator is manufactured based on this theory.In addition,a test system was built to test the output characteristics of the developed actuator.The resolution of the linear motion unit was 2.15 μm,the maximum step displacement was 8.61 μm,and the maximum load was 93 g,while the minimum step angle is 46.62 μrad,the maximum step angle is 761.25 μrad,and the maximum step rotating speed is up to 6031.65 μrad/s.The experimental results show that the hybrid-driven multi-DOF piezoelectric actuator developed in this paper can meet the requirements of micro-/nanometer-level high-precision rotation/linear output and high load carrying capacity in the gravity direction,and solves the problems for current piezoelectric bimorph type inertial impact actuator such as the insufficient driving force,large size,single output degreeof-freedom,small carrying capacity,cannot be driven precisely in the direction of gravity but can only be macroscopically moved,and when replacing the driving mechanism for precise movement cause macro/micro switching such as absolute displacement deviation.The research work of this paper can play a role in promoting the application of piezoelectric precision drive technology.Furthermore,it has a broad application prospect in many high-tech fields such as micro/nano processing,micro/nano operation,precision optics,aerospace and so on. |
