Application Cases

Experiment Name: Performance Testing and Closed-Loop Control Experiment of Two-Degree-of-Freedom Ultrasonic Motor

Research Direction: Piezoelectric Drive Technology, Design of Two-Degree-of-Freedom Ultrasonic Motor, Electromechanical Coupling Modeling, Performance Testing, and Closed-Loop Control Research

Experiment Objective: This experiment aims to verify the design rationality of a two-degree-of-freedom ultrasonic motor based on longitudinal vibration and bending-bending composite vibration, achieving dual functionality: moving along a robotic arm (linear motion) and driving the robotic arm joint rotation (rotational motion). The impedance characteristics, vibration characteristics, and mechanical output characteristics of the ultrasonic motor are tested to provide experimental validation for the electromechanical coupling mathematical model. A closed-loop control system is constructed to achieve precise tracking of speed step signals for the ultrasonic motor through PID control, laying the technical foundation for precision positioning in piezoelectric drive platforms. The feasibility of using the ultrasonic motor to drive a robotic arm is verified, providing theoretical and technical support for the development of industrial robots towards high speed, high precision, and lightweight design.

Testing Equipment: Ultrasonic motor, signal generator, ATA-4051 high-voltage power amplifier, impedance analyzer, torque wrench, photoelectric encoder, SIKO magnetic scale sensor, PC, etc.

Figure 1: Schematic Diagram of Ultrasonic Motor Drive Control

Figure 2: Physical Setup of Ultrasonic Motor Drive Control

Experimental Procedure: First, the two-degree-of-freedom ultrasonic motor prototype was fabricated, assembled, and preloaded. A basic performance testing system and a Quanser closed-loop control system were constructed. Subsequently, the impedance characteristics of the motor were tested. Under bending-bending composite vibration mode and longitudinal vibration mode, the frequency, voltage amplitude, and load were varied to measure the output speed. Finally, a PID control model was established based on MATLAB/Simulink. A step speed signal was applied, and closed-loop control was achieved using feedback from the magnetic scale sensor, with data recorded.

Experimental Results:
Impedance testing showed that both the bending-bending composite vibration mode and the longitudinal vibration mode exhibited stable resonance frequencies, with slight deviations from simulation values. In terms of mechanical output, the maximum no-load speed of the bending-bending composite vibration mode was 297.05 mm/s, while the longitudinal vibration mode (with a 60° angle) achieved a maximum no-load speed of 394.96 mm/s. Both modes provided stable output under a 30 N load. In closed-loop control, the longitudinal vibration mode exhibited a response time ≤ 0.3 s and a steady-state error < 5%, while the bending-bending composite vibration mode achieved a response time ≤ 0.2 s and a steady-state error < 3%. These results verified the feasibility of the motor's two-degree-of-freedom motion and its capability to drive a robotic arm.

Product Recommendation: ATA-4051C High-Voltage Power Amplifier

Figure: ATA-4051C High-Voltage Power Amplifier Specifications and Parameters

This document is compiled and released by Aigtek Antai Electronics. For more case studies and product details, please stay tuned. Xi’an Aigtek Antai Electronics has become a large-scale instrument and equipment supplier with a wide range of products in the industry. Demo units are available for free trial.