347 Sensors and Materials, Vol. 35, No. 2 (2023) 347–363 MYU Tokyo S & M 3172 * Corresponding author: e-mail: white-knight@hanmail.net https://doi.org/10.18494/SAM4168 ISSN 0914-4935 © MYU K.K. https://myukk.org/ Design of Self-balancing Model-size Electrical Motorbike Robot Using Control Moment Gyroscope Rodi Hartono, 1 Seung Bin Kim, 1 Patrick Tshibang A Kalend, 1 Nam Kyun Baik, 2* and Kyoo Jae Shin 1 1 Department of Artifcial Intelligence Convergence, Busan University of Foreign Studies, 65, Geumsaem-ro 485 Beon-gil, Geumjeong-gu, Busan, 46234, Republic of Korea 2 Department of Smart Convergence Security, Busan University of Foreign Studies, 65, Geumsaem-ro 485 Beon-gil, Geumjeong-gu, Busan, 46234, Republic of Korea (Received October 18, 2022; accepted November 28, 2022; online published November 30, 2022) Keywords: electrical motorbike robot, control moment gyroscope, pole placement controller, linear- quadratic regulator controller In recent years, a significant amount of study has been conducted on how to control the equilibrium of an electrical motorbike robot (EMBot). This is essential because a stable EMBot must be controlled by a reliable system. In this study, we explored a number of approaches for stabilizing an EMBot by using a control moment gyroscope (CMG). The momentum from a flywheel’s rotation at a set speed is employed to counteract gravity and keep the EMBot balanced. To measure the roll angle of the EMBot, an inertial sensor is used. From generalized coordinate systems, a nonlinear mathematical model of the EMBot is derived using Lagrange’s equation. Pole placement (PP) and linear-quadratic regulator (LQR) controllers are utilized to test and observe the system’s stability. By determining the appropriate locations of the closed- loop poles in the PP controller and finding the optimal K-matrix value by selecting closed-loop characteristics in the LQR method, the performance of the system in maintaining stability can be identified. 1. Introduction Single-track vehicles, such as an electrical motorbike robot (EMBot), offer a number of benefits, one of which is that they are more convenient to use than multi-track vehicles. On the other hand, due to the nonlinear and unstable nature of the system, controlling an EMBot can be challenging. (1–3) One of the difficulties is in maintaining vertical stability or balance control when an EMBot is both in a static state and moving through the environment. (1–4) Therefore, a significant amount of research has been conducted in an attempt to discover a method that will stabilize an EMBot. The method chosen to control the vertical stability of an EMBot is highly dependent on the EMBot’s movement conditions. When an EMBot is not moving, the external torque affects the direction of the wheels and makes it more difficult for the EMBot to remain balanced. This is