With the speed at which technology advances, there is little room for suboptimal performance and out-of-date tech. Precise positioning is a field where advancement is needed, as many conventional applications feature tools that are much larger than the objects being worked upon, making high precision a difficult task. Additionally, those that are highly precise have a limited range of motion. Researchers did not want to compromise, and instead set out to create a highly precise machine with a wide range of motion, and were able to do so by developing a palm-sized, precise positioning robot making use of piezoelectric actuators.
Results were published in Advanced Intelligent Systems in January 2026.
Conventional precision stages are limited in their range of motion, and mobile robots are limited in their positioning accuracy. Researchers from YOKOHAMA National University devised a way to combine the working elements of both previous conventional technologies to make a mobile robot that is the best of both worlds by using piezoelectric actuators to fully bring their concept to life in what is called a Holonomic Beetle (HB).
"This work introduces a new paradigm in robotic motion control that helps bridge the performance gap between mobile robots and ultraprecise positioning technology by adapting a simple control method to a piezo-actuated mobile robot with high-resolution measurement," said Ohmi Fuchiwaki, Associate Professor at YOKOHAMA National University and researcher of the study.
Piezoelectric actuators are high-precision devices that convert electrical energy into mechanical displacements operating on the piezoelectric effect. This effect occurs when an electric field meets a piezoelectric material, causing the internal structure of that material to respond through either expansion or contraction. This structural change improves the life of the material, provides quick response times and high precision and resolution.
"On multiple sizes of XYΘ planes, we conducted precise path-following experiments with a small, high-resolution mobile robot. It walked along all paths with under 0.5 - 4.75 µm of path errors. This result shows that our mobile robot using PID control is a suitable application for both precise positioning and wide transportation of sub-micrometer to centimeter-sized objects," said Fuchiwaki.
The results showed HB working well with suppressed path errors for both simple and complex routes across all scales used. The root mean square error value, or RMSE, is less than one micrometer. Lower values using RMSE indicate a lower magnitude of error between the predicted and actual values, and with continued improvement of the robot, researchers believe the RMSE value can be improved upon in the future.
The future of HB is bright and full of further improvements. Researchers would like to improve the motor speed, increase the mechanical rigidity, attach a vibration reduction mechanism, and introduce model-based control to further suppress random movements and vibration-induced errors. Additionally, making HB more accessible by making it usable in different workspaces and more practical operating conditions is key to establishing the ultimate goal of the researchers: a mobile alternative to conventional precision technology that is hyper accurate and can be a low-cost, scalable tool for use in many different fields.
Eiji Kusui, Chihiro Sekine, Taiki Goto, Ryosuke Kinoshita, Yuko Nishimura, Shogen Sekiguchi, Satoshi Ando, Yuto Oishi, Yusuke Matsui and Ohmi Fuchiwaki from the Department of Mechanical Engineering at YOKOHAMA National University contributed to this research.
The Nakanishi Scholarship Foundation, NSK Foundation for Advancement of Mechatronics, Takahashi Industrial and Economic Research Foundation, Tsugawa Foundation and Mitsubishi Foundation Research Grants in the Natural Sciences made this research possible.
