Application Cases

Introduction

Miniature piezoelectric robots are well-suited for space-constrained scenarios thanks to their compact structure, light weight, agile mobility and low power consumption. Representative application fields include micro-manipulation, confined-space search-and-rescue missions, equipment fault detection, optical fiber alignment, micro-electronic packaging, cell-level micro-operation, and metasurface optical component fabrication. Practical tasks in these domains commonly demand miniaturized positioning equipment that can deliver nanoscale resolution, cross-range stepping motion, and considerable payload capacity for mounting auxiliary functional components.

Series of prototype experiments in this paper offer solid performance verification for the above-mentioned application requirements. Comprehensive tests characterize the robot’s resolution, speed, payload capability, motion repeatability and surface adaptability. The robot achieves nanometer-level linear resolution and microradian-level rotational resolution, along with an extraordinary payload-to-weight ratio far exceeding existing counterparts. Moreover, practical fiber-alignment tests covering pure linear, pure rotational and coupled motion modes have been completed. These experimental results demonstrate that the balanced overall performances of MBPR can satisfy the rigorous positioning and load-bearing demands of real-world micro-operation tasks, bridging laboratory prototype research and practical engineering deployment for miniature piezoelectric robotic platforms.

Research Direction

Piezoelectric Driving Technology

Experimental objective

Output characteristics under different driving voltages, motion resolution, output characteristics under different driving frequencies, load capacity, return error and motion repeatability, fiber alignment application

Testing equipment

Computer, Signal Generator (DG1062z, Beijing RIGOL Technologies Co., Ltd.), Power Amplifier (ATA-2082, Xi'an Aigtek Electronic Technology Co., Ltd.), Capacitive Displacement Sensor (DT6500, Micro-Epsilon (Beijing) Co., Ltd.; including controller and capacitive probe)

Experimental process

To evaluate the output characteristics of the prototype, a corresponding experimental system was established. The system mainly consists of a computer, a signal generator (DG1062z, Beijing RIGOL Technologies Co., Ltd.), a power amplifier (ATA-2082, Xi'an Aigtek Electronic Technology Co., Ltd.), the prototype, and a capacitive displacement sensor (including controller and capacitive probe) (DT6500, Micro-Epsilon (Beijing) Co., Ltd.). The working principle is as follows: the signal generator generates an initial sawtooth wave voltage signal, which is amplified by the power amplifier to a preset amplitude and then applied to the piezoelectric element of the prototype. Meanwhile, the capacitive probe collects the change in distance between it and the MBPR, and the data is transmitted to the computer via the controller for storage. The experiments were conducted on an optical platform. Except for the section on output characteristics under different bearing surfaces, all experiments were completed on a smooth marble support surface. The surface was cleaned with anhydrous ethanol to avoid contaminants affecting the friction characteristics. To reduce the influence of vibration and temperature on the test results, all experiments were conducted on an optical platform at room temperature.

Figure1  Experimental system. The system primarily comprised a computer, a signal generator, a power amplifier, a MBPR prototype, and a capacitance micrometer (including controller and capacitive probe).

Figure2  (a) Experimental principle. The drive signal is generated by the signal generator, amplified by the power amplifier, and then applied to the piezoelectric ceramics. The output displacement is measured using the capacitance micrometer. (b) Dimensions of MBPR prototype. (c) Mass of MBPR prototype. 

Experimental results

This paper proposes a miniature bipedal 2-DOF piezoelectric robot. Utilizing the cooperative inertia principle of its two driving feet, the robot achieves cross-scale linear and rotational motion. Through an innovative configuration design, the robot achieves a high payload-to-weight ratio while maintaining miniaturization, and achieves balanced performance in key indicators such as speed and motion resolution. A prototype with dimensions of 42×32×11.05 mm³ and a mass of 47.4 g was fabricated, and its output performance was tested. The experimental results show that the prototype achieves highly stable linear and rotational two-degree-of-freedom motion output. By changing the symmetry of the driving signal, bidirectional motion with small deviation can be achieved, and high bidirectional motion stability is exhibited over a long stroke range. The motion resolutions of the LX and RZ degrees of freedom are 6 nm and 74 nrad, respectively; the maximum speeds are 3.26 mm/s and 105.34 mrad/s, respectively; the maximum payloads are 11 kg and 10 kg, respectively, with corresponding payload-to-weight ratios of 232 and 211. The prototype exhibits stable stepping characteristics on various support surfaces such as marble, aluminum, and paper. In addition, the robot has successfully achieved fiber alignment in various scenarios.

This work provides a new paradigm for improving the payload-to-weight ratio of robots, significantly expanding their application range. Future research will focus on further miniaturization and lightweight design, improvement of stepping displacement, and expansion of application scenarios.

Figure3 Output performance of MBPR under various excitation voltages. (a) Stepping characteristics of LX DOF under a voltage range from 50 to 600 Vp-p. (b) Stepping characteristics of RZ DOF under a voltage range from 50 to 600 Vp-p. (c) Linear speed under a voltage range from 50 to 600 Vp-p. (d) Angular speed under a voltage range from 50 to 600 Vp-p. All the above experiments are performed at 1 Hz.

Figure4  Output performance under different payloads of MBPR. (a) Stepping characteristics of LX DOF under a payload range from 0 to 8 kg at 600 Vp-p. (b) Stepping characteristics of RZ DOF under a payload range from 0 to 8 kg at 600 Vp-p. (c) Relationship between linear speed and payload at 100, 350, 600 Vp-p and 1 Hz, respectively. (d) Relationship between angular speed and payload at 100, 350, 600 Vp-p, respectively. All the above experiments are performed at 1 Hz.

The effectiveness of the amplifier in this experiment

amplifying the low-voltage waveform output by the signal generator without distortion to the higher voltage required to drive the piezoelectric element

Application fields

micro-manipulation, optical fiber alignment, microelectronic packaging, cell micromanipulation, metasurface optical component fabrication,miniature piezoelectric robot