Recently, the research team led by Professor Yan Xiaojun and Associate Professor Liu Zhiwei from the School of Energy and Power Engineering at Beihang University has achieved significant progress in the field of micro-power systems.

Following their breakthrough on May 8, when the Beihang robotic insect research was featured in a Nature sub-journal, the team’s advancements in robotic insects, titled "Forward and Backward Control of An Ultrafast Millimeter-Scale Microrobot via Vibration Mode Transition," have been recently published in Science Advances.

Professor Yan Xiaojun, Associate Professor Liu Zhiwei and Professor Qi Mingjing are the corresponding authors, while doctoral students Yu Xian and Zhan Wencheng are the first authors. Beihang University is the primary affiliation for the study.

Building upon the prototype of BHMbot (Beihang Microrobot), the team proposed a novel control method based on vibration mode transition for achieving "forward" and "backward" running in robotic insects. This innovation addresses the challenges of micro-robots navigating narrow, one-way enclosed channels that prevent turning around or rapid backward motion.

Micro-robotic insects have distinct advantages, including small size, high mobility, and excellent accessibility, making them ideal for applications in post-disaster rescue, structural inspections of large equipment, and information gathering. In these scenarios, micro-robots often need to maneuver within confined spaces. However, when entering a dead-end one-way passage too narrow for turning around, conventional designs face significant challenges. To address this, the team developed a 15-mm-long legged microrobot BHMbot-B (BeiHang Microrobot-Backward), which is capable of rapid forward and backward locomotion through vibration mode transition control.

Fig 1: Forward- and backward-moving mechanism of the BHMbot-B

By properly arranging the vibratory motions of the magnet, cantilever, and linkages, the pitching movement of the body and the vibration of the forelegs are in phase during the first-order vibration mode of the cantilever and in antiphase during the second-order mode, which induces the forward and backward movement of the microrobot. Owing to its outstanding load-bearing capacity, the BHMbot-B equipped with dual electromagnetic actuators, an onboard battery, and a control circuit, can execute complex running trajectories under wireless command.

Fig 2: Adaptability of the BHMbot-B on different surfaces and terrains

Fig 3: Untethered forward and backward running of the microrobot

Considering its future application, the capability of the BHMbot-B of carrying task loads such as a gyroscope and a microcamera is also verified. When equipped with a gyroscope, the BHMbot-B can transmit real-time positional data back to the host, which means that the host can send route planning information to the microrobot to facilitate autonomous navigation in the future. Furthermore, the microrobot, equipped with a microcamera, shows promise in collecting images in narrow spaces such as inside a large machinery. The next phase of the research will focus on realizing environmental sensing and autonomous navigation capabilities of the microrobot.

Fig 4: Motion stability and verification of carrying task equipment

Editor: Lu Meili