Research On Piezoelectric Inertial Rotary Actuator Utilizing Asymmetrical Gripper With Variable Friction

Based on the sufficient analysis of the research status of the inertial piezoelectric actuators,in order to realize the different inertia force in different directions, the structure withasymmetry gripper is proposed from mechanism in this article. According to the analysis ofthe modern tribology theories, the piezoelectric actuator can rotate in the set direction bymean of changing the normal pressure on inertial piezoelectric actuator and frictioncoefficient to control the contact friction when the piezoelectric actuator rotate in contactsurface.The main research contents are as follows:1. The research status of the domestic inertial piezoelectric actuator are analyzed. Thefriction force between the inertial piezoelectric actuator and interface is changed when thepiezoelectric bimorphs with asymmetry gripper are actuated by the symmetric wave. Withdifferent friction force and different actuation force, the inertial piezoelectric actuator not onlyincrease rotation step but rotates steadily along the proposed direction.2. The amplitude of deflection and inertial force on the free tip of piezoelectric bimorphare analyzed. We analyze the influence of structural parameters on the amplitude of deflectionand inertial force of the piezoelectric bimorph by using Matlab. We determine the structuralsize of piezoelectric bimorph by synthetic analysis.3. A simplified finite element models is created based on the movement characteristic ofpiezoelectric bimorph with the structure of asymmetry gripper, and its first three naturalfrequencies and corresponding modal shape curve of the piezoelectric bimorph under thecondition of two different mechanical clamping lengths are analyzed using ANSYS. Acomparative analysis of the transient displacement and acceleration under different fixingconditions by mean of simulation and test, meanwhile the properties of inertial force ondifferent clamping lengths and driving frequency are studied using the methods of combiningsimulation and experiments. The results indicate that the piezoelectric bimorph with thestructure of asymmetry gripper have large inertial force with the clamping length of4mm anddriving frequency of10Hz.4. According to the moving principle of inertial actuator with the structure of asymmetrygripper, which has a fixed friction, design and manufacture a inertial piezoelectric actuator.The differential equation of piezoelectric bimorph with the structure of asymmetry gripper isestablished. Furthermore, putting up the simulation modal of the piezoelectric bimorph withthe structure of asymmetry gripper and the inertial actuator which not only has a fixed frictionbut has the structure of asymmetry gripper based on the differential equation by the softwareof Simulink. Simulation and experimental study on the inertial actuator which has the structure of asymmetry gripper and a fixed friction show that the inertial actuator can rotatesteadily, however, it has fallback action. And the rotating step’s change rules of the inertialactuator under different frequencies, different test voltage amplitude and different impactmasses are researched.5. Based on the principle of variable normal pressure and variable coefficient of friction,the moving mechanism of piezoelectric inertial rotary actuator utilizing asymmetrical gripperwith variable friction is expounded, and the driven-foot has plowing effect. Utilizing theSFT-2M typed disk and pin patterned friction wear tester, the friction coefficient ofdriven-foot between the two directions on the different materials’ surface are tested, wedetermined planar contact friction pairs which has a greater difference on both axes. Test therotating step of piezoelectric inertial rotary actuator utilizing asymmetrical gripper withvariable normal pressure among the different frequencies and different rotation angles, theoutcomes of the experiments show that the piezoelectric inertial rotary actuator utilizingasymmetrical gripper with variable normal pressure can rotate in the set direction steadilyunder the condition of a gripper difference of4mm, driving voltage of30V, driving frequency of5Hz and rotation angles of50°. When the driving frequency is19Hz, the inertial piezoelectricactuator has better linearity. Carry out the experimental test to adopting planar contact frictionpairs which has a greater difference on both axes, and the results indicate: the fallback actionof piezoelectric inertial rotary actuator decreased obviously as gripper difference of4mm,driving voltage of30V, frequency of5Hz, and rotation angles of50°. The rotated actuatordriven by piezoelectric inertial asymmetrical structure with variable friction has excellentcontrollability under the driving frequency of10Hz.