Study On Decoupling Approach Of Time-Sharing Of Piezoelectric Self-Sensing Actuator

In the areas of measurement and control technology of mechanical and electrical systems, generally actuators and sensors are both needed when implementing measurement and control. The self-sensing actuator (SSA) is functional integration of sensor and actuator, that is to say, it can be simultaneously used as both a sensor and an actuator, so it have the advantages of achieving true collocated control and decreasing structural weight and volume. Piezoelectric SSA is one of the most attracted components in the research field of SSA which emphasizes particularly on its decoupling approaches. At present, the decoupling approaches mainly include bridge circuit method and space-sharing method. With the object of the cantilever beam glued piezoelectric element, the time-sharing approach is proposed and studied on theory and application in this paper.According to the theory of bilateral piezoelectric transducer of current-source type, three equivalent circuits of piezoelectric ceramic element are derived in which the controlled charge equivalent circuit is the main model to analyze time-sharing approach. Based on transfer matrix of bilateral network, the principle of time-sharing approach is elaborated and the sensor and actuator equations are deduced, then the implementation project of time-sharing approach is proposed and its key technologies, such as the choice of switching device, the design of switch circuit and switch sequential pulse, are discussed.By means of contrast experiments, the sensing and actuating effects of piezoelectric SSA in time-sharing approach are validated in terms of qualitative and quantitative analysis. Experimental results show that time-sharing piezoelectric SSA can be used as independent sensor and actuator, which is at a cost of reducing part of actuating capability. The results also indicate that sensing and actuating effects are correlated with the distribution of sensing and actuating time-slots, therefore, four rules of distributing time-slot are summarized in this paper.In order to prove the practical feasibility of time-sharing approach, the time-sharing piezoelectric SSA is applied to the beam's active vibration control. Based on virtual instrument flat of LabVIEW software, positive position feedback control and independent modal space control are adopted to control beam's persistent disturbance and instantaneous disturbance respectively. The experimental results clearly indicate that both control methods can suppress the beam's vibration effectively, which reveals time-sharing approach can achieve the self-sensing and self-actuating function of piezoelectric element. In the experiment of independent modal space control, the results show that the decay time of controlled cantilever beam reduces to 20% of the uncontrolled condition, which is basically consistent with theoretical simulation.