Research on Stick-Slip Principle and Experiment Basing on Two-Masses Friction Oscillator
|School||Harbin Institute of Technology|
|Course||Mechanical and Electronic Engineering|
|Keywords||two-masses friction oscillator nonlinear vibration PSD frequency response system stability|
Large-ranged micro-manipulator is still at the stage of experiment, while the successful prototypes are rarely demonstrated. The low driving force, low precision, and low stability are the most major obstacles for the real application. Namely, all those defections result from the lack of studying on the driving principles. The key approach of solving the problem is to establish a more reasonable model to analyze the factors which affect the movement. Furthermore, it becomes easier and more reliable to obtain the stability control strategy.In fact, the friction is the main factor of Stick-Slip driving principle. In this paper, starting from nonlinear vibration, the author analyzes the Stick-Slip principle based on the dynamical friction model. The research includes the phase-space of the two- masses friction model and the state transition area is then proposed; includes the system response of the model and develops the best driving frequency of the Stick-Slip principle; also includes the friction compensation method and proposes the approach of using positive compensation and energy compensation to promote the performance of the Stick-Slip driving principle and is validated by the experiment.Firstly, based on the two-masses simplified engineering model of the Stick-Slip principle, the simulation of the Stick-Slip principle vibration characteristic is completed. The composite theory of the forced vibration and the self-excitation oscillation is presented. Based on the three-D.O.F spherical micromanipulator, the procedure of the Stick-Slip driving is divided into four stages and the composite theory is verified.Then, the phase-space equations is presented in accordance with the two-masses friction oscillator dynamic equations, taking the relative velocity as the factors, to obtain the criterion of how to distinguish the stick phase and slip phase, which makes convenience for the optimization of the design, and the stability control strategy. Afterwards, the frequency response is studied as follows. The common solution is given based on the harmonic balance method, numerical method and the optimization theory; the two-masses friction oscillator model is analyzed by means of MATLAB. Combined with vibration analysis, Stick-Slip area dividing, and the frequency response, the movement stability condition is discussed. By way of the stability discussion under the Coulomb friction model, the normal force compensation method and the additive vibration control method is presented. Therefore it is by stabilizing the friction drive system that it actualizes the controllability and stability, which is simple to be realized on the micro manipulator.In the end, the electromagnet-based compensation apparatus is designed and completed. Considering the three piezoelectric ceramic tube-driven plate as the research target, and driven by the sawtooth wave output of the multi-channel parallel piezoelectric ceramic power, the plate motion characteristics are measured by the three ways of PSD, capacitance micrometer and accelerometer. From the graphing curves of the output and the comparison with the sawtooth input, ultimately, the validity of the theoretical analysis is proved.