Application Cases

Experiment Name: Study on Hysteresis Effects in the Output Force of Piezoelectric Actuators

Research Direction:Piezoelectric ceramic actuators can provide micron-level travel with the advantages of high-speed response, small size, and high working bandwidth. Therefore, they are widely used in components of high-precision systems. Due to the influence of hysteresis in piezoelectric ceramic actuators, and the fact that hysteresis becomes more pronounced with increasing input voltage frequency, hysteresis can severely affect control accuracy when the operating frequency varies over a wide range.

Hysteresis nonlinearity in piezoelectric ceramic actuators, due to the polarization process, is an inherent characteristic of the material itself. This nonlinearity can lead to a decrease in control system stability, making it difficult to determine appropriate control parameters. In severe cases, it can cause instability in the control system. Research on hysteresis characteristics modeling and control methods for piezoelectric ceramics generally requires the establishment of an accurate hysteresis model. Due to the complexity and diversity of hysteresis phenomena, modeling and controlling hysteresis is an extremely challenging task, and there is currently no unified hysteresis model in the international academic community. Researchers generally approach hysteresis modeling from two aspects: one is based on physical principles, deriving the relationship between input voltage and output displacement of piezoelectric materials through physical quantities such as stress, strain, magnetic induction strength, and electric field strength, such as the Jiles-Atherton model. Establishing a hysteresis model based on physical principles is difficult, and different piezoelectric materials exhibit different hysteresis phenomena. Models derived from physical principles are only applicable to one type of hysteresis material and lack generality. The second method is to establish a hysteresis model based on the hysteresis phenomenon itself. Phenomenon-based models do not care about the physical principles behind the hysteresis phenomenon but focus on mathematical modeling of the hysteresis phenomenon, making them more widely applicable.

Experiment Purpose:To analyze the output force characteristics of piezoelectric actuators.

Testing Equipment:Piezoelectric actuator, ATA-308 power amplifier, charge amplifier, data acquisition card, upper computer.

Experimental Process:The experimental process is shown in Figure 1-1. First, the upper computer controls the data acquisition card to generate the excitation signal, which is then amplified by the ATA-308 power amplifier and applied to the piezoelectric ceramic. The piezoelectric force sensor collects the charge signal generated by the output force of the piezoelectric actuator. The charge signal is converted into a voltage signal through the integrating and conditioning circuits in the charge amplifier. The input voltage signal and the output force signal are synchronously collected for analysis of the output force characteristics of the piezoelectric actuator.

Figure 1-1 Experimental Principle Block Diagram

Experimental Results:The nonlinear characteristics of piezoelectric actuators are composed of hysteresis, creep, and vibration phenomena, with hysteresis being the dominant factor. Hysteresis in piezoelectric actuators is not only observed in the relationship between input voltage and output displacement but also in the relationship between input voltage and output force. The magnitude of the output force is not only related to the current value of the input voltage but also to the previous extreme values of the input voltage. This behavior is equivalent to the piezoelectric actuator recording the historical extreme values, hence the term "memory characteristic" of hysteresis.

In the experimental platform, the input voltage and output force signals of the piezoelectric ceramic actuator are synchronously collected, as shown in Figure 1-2a). The relationship between input voltage and output force is shown in Figure 1-2b). When the input voltage is a decaying sine wave, the voltage-output force curve shows multiple hysteresis loops of different sizes. The voltage-output force curve in this experiment indicates that the value of the output force is related to whether the voltage is in the rising or falling phase, as well as to the previous extreme values of the input voltage. This experiment verifies that the piezoelectric actuator exhibits the same hysteresis phenomenon in the voltage-output force relationship as in the voltage-displacement relationship. It is a multi-valued mapping relationship, and hysteresis has memory characteristics. In addition to memory characteristics, hysteresis also exhibits wiping-out and congruency properties.

Figure 1-2 Memory Characteristics of Hysteresis

Power Amplifier Recommendation: ATA-308C Power Amplifier

Figure: Performance Parameters of the ATA-308C Power Amplifier

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