Modeling of self-tilt-up motion for a two-wheeled inverted pendulum

Purpose - The purpose of this paper is to present a two-wheeled inverted pendulum with self-tilt-up motion ability. With this ability, the two-wheeled inverted pendulum can erect without assistance, and then the vehicle can be autonomously deployed. The paper proposes an approach to achieve this self-tilt-up motion, which involves precessional motion. Design/methodology/approach - A flywheel is mounted inside the vehicle to perform high-speed spinning. The flywheel and body of the vehicle are forced to move around a fixed point and precessional motion occurs. As a result of the precessional motion, a moment is synchronously generated to tilt the body up to the upright position. Since no external force is applied on this two-wheeled inverted pendulum, it is called self-tilt-up motion. A 3D model and a prototype are built to validate this approach. Findings - The simulation and experimental results show that the self-tilting-up motion is successful. Research limitations/implications - This paper presents a self-tilt-up motion for a two-wheeled inverted pendulum. With the analysis of the dynamics, simulation demonstrations and prototype development, the results show that the vehicle could perform self-tilt-up motion without any assistance. The principle of this self-tilt-up motion involves processional motion of rigid body. We also pointed out the factors that play important roles in influencing the performance of self-tilt-up motion and then define the switching time for the motion to switch to dynamic balance movement. Originality/value - Traditional multi-wheel robots cannot work when they overturn. However, the two-wheeled inverted pendulums with self-tilt-up ability do not have this shortcoming. They can stand up to keep working even if they fall down. A two-wheeled inverted pendulum with self-tilt-up ability can be applied to many places. Equipped with solar battery, it can be used as an independent explorer. This type of vehicle can be deployed in swarms for planetary detection. For example, many small two-wheeled inverted pendulums assist a lunar rover for exploration, samples gathering, etc.