Application Cases

Experiment Name: Construction of an MFC-Actuated Flexible Arm Component System

Test Purpose:
An experimental system for the MFC-actuated flexible arm component was constructed to test the bipolar asymmetric hysteresis characteristics between the end deformation displacement of the flexible arm component and the driving voltage of the MFC actuator. Based on the classical Prandtl-Ishlinskii (PI) model, an improved PI hysteresis model was developed by superimposing a series of bilateral dead-zone operators with different weights and thresholds. This enhancement improves the model's ability to approximate asymmetric hysteresis behavior. To describe the system's dynamic characteristics, a discrete transfer function model was employed to represent the linear dynamics, which was then cascaded with the quasi-static improved PI hysteresis model to form a combined model, referred to as the piezoelectric flexible arm system. Finally, the characteristic parameters of the improved PI hysteresis forward and inverse models, as well as the discrete transfer function model, were identified using the least squares method. Experimental validation of the proposed combined model confirmed its effectiveness.

Test Equipment:
High-voltage amplifier, DC power supply, sensor controller, laser displacement sensor, actuator, etc.

Experimental Process:

Figure 1: Schematic Diagram of the MFC Structure

The composition of the MFC structure is illustrated in Figure 1. The incorporation of epoxy resin in the MFC structure enhances the overall flexibility, reliability, and deformation capability of the composite. The interdigitated electrode arrangement significantly improves the strain actuation efficiency of the piezoelectric material. Compared to traditional piezoelectric ceramic patches, MFCs exhibit substantially enhanced deformation and driving capabilities. Therefore, MFC actuators are ideal components for active deformation, drive control, and vibration suppression in flexible structures.

To evaluate the actuation performance of the MFC actuator, an experimental system for the MFC piezoelectric flexible arm component was constructed. Two MFC actuators were symmetrically bonded to the left and right surfaces at the root of the aluminum-based flexible arm component using epoxy adhesive. During testing, the PC transmitted the driving voltage signal for the MFC actuator to a multi-slot embedded USB Compact-DAQ chassis via the USB bus. The signal was then converted into an analog voltage signal by a D/A module. This voltage signal was amplified by a high-voltage amplifier and applied to the MFC piezoelectric flexible arm. The MFC actuator achieved precise deformation displacement of the flexible arm through the inverse piezoelectric effect of the piezoelectric material. A laser displacement sensor, horizontally installed at the end of the flexible arm component, detected the deformation displacement in real time. The displacement signal was conditioned by the controller into an analog voltage signal, transmitted to the D/A module embedded in the chassis, and finally sent back to the PC via the chassis and USB bus. The entire testing system was implemented on the LabVIEW platform.

Experimental Results:

Figure 2: Hysteresis Characteristic Curve of the MFC Actuator

The operating voltage range of the MFC actuator is -500 V to +1500 V. During testing, sinusoidal driving voltage signals with peak-to-peak values of 400 V, 600 V, and 800 V at a frequency of 0.1 Hz were applied to the MFC actuator. The relationship between the end deformation displacement of the flexible arm component and the driving voltage is shown in Figure 2(a). Under the same input voltage but at different frequencies, the hysteresis of the piezoelectric flexible arm exhibited rate-dependent characteristics, as illustrated in Figure 2(b).

The experimental results indicate significant hysteresis between the driving voltage of the MFC actuator and the deformation displacement of the flexible arm component. The initial loading curves of the hysteresis loops under different excitation voltages generally overlapped. As the excitation voltage amplitude increased, the hysteresis became more pronounced. Under a sinusoidal excitation of 800 V peak-to-peak voltage, the maximum hysteresis error in the displacement of the flexible component reached 50.6%. Notably, under the bipolar driving voltage of the MFC actuator, the positive and negative deformation displacements of the flexible arm component exhibited, with the offset increasing as the driving voltage amplitude increased. Under a ±400 V unbiased driving voltage, the offset error between the positive and negative displacements of the flexible beam component reached 24.4%.

Recommended High-Voltage Amplifier: ATA-7015

Figure: ATA-7015 High-Voltage Amplifier Specifications

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