Our laboratory has carried out research on various types of robots. The principle of our research is to simplify the design of the robot while meeting the requirements for use. We have introduced research methods for deployable structures and bionics in the design of robots.

Deployable structures have the inherent capability of changing their size and morphology significantly with minimal mobility. Threefold-symmetric Bricard linkage is a 6R overconstrained linkage with good folding characteristics. Combining threefold-symmetric Bricard linkage with robotics, a novel deployable robot is developed. It can adjust its morphology to adapt to multiple tasks or uncertain environment.

A transformable robot based on threefold-symmetric Bricard linkage

Through the observation of the movements of hexapod insects such as mantis and ants, we found that they have a movable multi-segmented body. When encountering an obstacle, they will lift the front segment of the body to increase its ability to climb obstacles. Inspired by this motion pattern, we designed a hexapod crawling robot named “HIbot” with two movable body segments. When HIbot encounters an obstacle during locomotion, it will lift the front segment passively due to the friction between the legged-wheels and the obstacle. This robot can crawl in various outdoor environments such as gravel, grassland, etc. With the help of the legged-wheels and the movable body segments, it can cross obstacles that are as high as 2.8 times of the radius of the legged-wheel. Such characteristics give the robot a great potential in applications.

A Highly Mobile Crawling Robot Inspired by Hexapod Insects

These two types of robots are suitable for security and disaster investigation missions due to their deformability and high climbing ability. Future work will further take inspirations from the deployable structures and the body-environment interplayed behaviors of animals, and investigate cooperation strategies between mechanical and computational intelligence in a robotic system.

In addition, the soft robots actuated by the environment can respond to light, heat, chemical substances, magnetic fields, humidity and other stimuli to achieve specific locomotion and functions, which become a research trend in the area of robotics. The greatest challenge in their design is the integration of the actuator, energy sources and body of robots while achieving fast locomotion and well-defined programmable trajectories under constant conditions without the need for an externally modulated stimulus.
To tackle this problem, through interdisciplinary collaboration, we developed such a soft robot called the Hydrollbot by using a humidity-sensitive agarose film that achieved continuous fast self-rolling locomotion in a constant-humidity environment. The Hydrollbot overcame the isotropic and random bending of the film and had velocity of 0.714 BL/s in a straight line, which increased the speed of soft robots that moved in a constant-humidity environment by two magnitudes and was much faster than current reported soft robots actuated by a variable-humidity environment. Meanwhile, the Hydrollbot was capable of carrying a payload up to 100% of its own weight, and the trajectory of the Hydrollbot could be programmed. This work provides a new idea of interdisciplinary research in the structural design of soft robots actuated by the environment, and is expected to advance the applications of humidity-driven soft robots in medical treatment, sensing, actuation, and so on.

A Humidity-powered Soft Robot with Fast Rolling Locomotion