Researchers create hybrid terrestrial and aerial unicycle

Introducing the Roller-Quadrotor

The hybrid aerial and terrestrial vehicle developed by Wang, Zheng, and their team, is named Roller-Quadrotor, a rotary-wing aircraft that can fly and hover above the ground. The vehicle is based on a unicycle's structure; therefore, it can roll on the ground on numerous terrains and make it through narrow gaps. 

"This work overcomes the challenging problems of general rotorcraft, reduces energy consumption and allows movement through special terrains, such as narrow gaps," the researchers wrote in their paper. "It also solves the obstacle avoidance challenge faced by terrestrial robots by flying."

In their paper, Wang and Zheng present their vehicle’s design alongside a series of controllers and models that help it to fly, roll, and smoothly transition between these two operating modes. Zheng and Wang also outline the results of a series of experiments where their vehicle’s prototype was tested in an environment with motion capture sensors and cameras. 

"We design the models and controllers for the vehicle," Zheng, Wang and their colleagues wrote in their paper. "The experiment results show that it can switch between aerial and terrestrial locomotion, and be able to safely pass through a narrow gap half the size of its diameter. Besides, it is capable of rolling a distance approximately 3.8 times as much as flying or operating about 42.2 times as lengthy as flying."    

The future of the unicycle

In their subsequent study, the researchers plan to further enhance the vehicle's design, such as the accuracy of their model and introducing a better control algorithm. This could result in a better vehicle transition from flying to rolling mode while also improving its navigation capabilities. 

"We are also considering structural optimization and weight reduction, to further improve the energy consumption performance," the researchers concluded in their paper. "Furthermore, we will use planning algorithms to enhance vehicle mobility."

Study Abstract:

Roller-Quadrotor is a novel hybrid terrestrial and aerial quadrotor that combines the elevated maneuverability of the quadrotor with the lengthy endurance of the ground vehicle. This work presents the design, modeling, and experimental validation of Roller-Quadrotor. Flying is achieved through a quadrotor configuration, and four actuators providing thrust. Rolling is supported by unicycle-driven and rotor-assisted turn- ing structure. During terrestrial locomotion, the vehicle needs to overcome rolling and turning resistance, thus saving energy compared to flight mode. This work overcomes the challenging problems of general rotorcraft, reduces energy consumption and allows to through special terrain, such as narrow gaps. It also solves the obstacle avoidance challenge faced by terrestrial robots by flying. We design the models and controllers for the vehicle. The experiment results show that it can switch between aerial and terrestrial locomotion, and be able to safely pass through a narrow gap half the size of its diameter. Besides, it is capable of rolling a distance approximately 3.8 times as much as flying or operating about 42.2 times as lengthy as flying. These results demonstrate the feasibility and effectiveness of the structure and control in rolling through special terrain and energy saving.