Theoretical And Experimental Research On Two-degree Stepping Precision Piezoelectric Actuator

Among modern driving techniques, precision driving techniques focusing onpiezoelectric elements play more important role. The technique applying widelyhas covered precision optics, micro-electronics, aviation, manufacture,micro-assemble machine, micro-robot, biomedicine and genetics engineering etc.For PZT implements has many benefits such as small volume, large output power,high frequency response and high resolution, no magnetic force disturb and so on.As the result, multi-degree precision driving has capability to achieve long distancehigh-resolution and great driving power. So, under sustaining of national High-techdeveloping project (863 project), to get novel stepping two-degree presion PZTactuator, researches involving basic theory, structure design, experiments test werewell done.First, analyzing quality of PZT material and equation in the ariticle. Comparedwith other PZT stack implements, PZT stack have more powerful force, fasterreaction speed and higher distortion resolution, so PZT stack was indicated asdriving implements. Specialities including capacitance, response, slow-moving,mechanics and temperature Which were related to PZT stack and driving capabilitywere analyzed.During basal research on structure of single-degree stepping actuator, it hasbeen explored from many aspects like option for actuator manufacture material,structure of flexible hinge and its pair of all size parameters, design of PZT stackpretightening force, structure of position modulation, mode of actuator clamping anddriving. According to character of PZT stepping actuator clamping, a novel doubleoutside clamping, which realize precision modulation between clamping sides andactive cell and assure clamping structure has large clamping force, reliableclamping motion and tiny clamping error.Based on theoretical research, schemes for two sets of two-degree PZTactuator, combinatorial and the whole body, have been developed and be maderesearch.1.Research on Precision Combinatorial style two-degree PZT actuatorTwo sets of single free-degree stepping linear PZT, separation style doublesides clamping outside driving inside, and whole body double sides clampingoutside driving outside, were presented in the article. The former had advantageslike simple structure, easy machining, available to guarantee precision formanufacture and assembling. The latter improved the former for rigid and drivingforce was increased great, meantime, assembling and modulating were easier,stability increased than before. Dynamics mode for two kinds of actuator keystructure, movement transfer function and finite element analysis providedguarantee for machining precision, made relevant technics routine, at the same time,speciality of actuator was detailedly studied and tested.Two free-degree linear precision PZT actuator was constructed bycombination. Correlation and influence between two free-degree movement wereanalyzed and speciality was test. The main standards were following: resolutionalong x-axis for two-degree actuator is 0.028 μ m, maximum velocity reach446 μ m /s,dynamic driving reach 1.2Kgf(about 11.8N),whole working distancereach 20mm, resolution along y-axis for two-degree actuator is 0.048 μ m,maximum velocity reach 412 μ m /s,dynamic driving reach 2.85Kgf(about27.9N),whole working distance reach 20mm.These results presented that two single free-degree precision PZT actuatorcombining suitably can achieve linear movement with higher resolution, largertravel range and driving force.2.whole style two free-degree precision stepping actuatorDynamics mode and finite element analysis were made research on flexiblehinge between rotation and linear movement for two free-degree actuator.Correlation and influence between circumvolving movement and linear movementfor two-degree actuator has been analyzed, method for test was raised. Bycalculating, reference counterbalance was got. Undergoing a number of tests ontwo-degree actuator, main capability parameter was following: circumvolving steplength resolution of circumvolve actuator is 0.3 μ rad, resolution of linear actuatoris 0.019 μ m, circumvolving velocity reach 0.01 rad ? s?1,linear velocity reach482 μ m ? s?1(about 28.9 mm ? min?1),dynamic circumvolving torque reach0.38 N ? m,dynamic linear power reach 4Kgf(about 39.2N), circumvolving distanceis 360°,linear distance is 20mm.It is proved by test that whole style two free-degree linear and rotationprecision PZT actuator achieve linear and rotation movement under high resolution,large travel range, great driving force, high speed and satisfy different need forrotation precision actuator while assuring structure miniaturization. Its capability isbetter than combinatorial style two free-degree precision PZT actuator.Finally, driving controlling on stepping precision PZT actuator was studiedin the article. Based on instruments of lab, GPIB consist of closed-loop controlsystem by using LabVIEEW, according to movement character of stepping PZT,controlling method and flow was established. Pre-check controlling flow wasdesigned to eliminate or decrease interference. When over modulation waspermitted, linear actuator orientation reach 0.05 μ m, circumgyrate orientationreach 0.5 μ rad, When over modulation was not permitted, linear actuatororientation reach 0.08 μ m, circumgyrating orientation reach 1 μ rad.Creative work in article involved several parts:1. PZT stack as Drivingelements was put forward, precision pretightening modulation structure by usingcuniform slip block worked in the way of clamping outside in double sides, whichensure precision modulation between clamping sides and runners and stability ofrunner and clamping,2. Driving outside by elasticity of flexible hinge was not onlybalance positive and negative driving force, also raised resolution,3.The newmethod that linear and rotation movement realized in single structure was putforward for the first time, the structure was more light and better output, 4.Virtualclose-loop control raising actual orientation precision of two free-degree actuatorwas put forward.It is common to construct by combination in domestic and foreign twofree-degree precision PZT actuators, but hardly any find publishing research paperson constructing two free-degree precision PZT actuator based on whole flexiblestructure. Relevant research work of two free-degree precision PZT actuator wascompleted under support by national 863 project and nature science foundationproviding a base for further research.