Type-2 Fuzzy Sliding Mode Control Design for Self-Balancing Mobile Robot

Mobile robots have been a popular research topic in recent decades due to their many potential applications. One of the common types of mobile robots is the two-wheeled self-balancing robot, which operates based on the basic concept of an inverted pendulum. This concept represents an unstable system, so a proper controller is required to stabilize the system. This paper proposes a controller that combines a type2 fuzzy logic system and sliding mode control to stabilize and maintain the robot’s body balance in a straight upright position. Sliding mode control is a well-known robust controller with the ability to handle system disturbances. However, the presence of a switching law in sliding mode control can lead to the occurrence of chattering phenomena. Hence, a type-2 fuzzy logic system is applied to reduce the chattering effect by adjusting the switching gain of the sliding mode control. Additionally, the system’s stability is analyzed using the Lyapunov theorem. The simulation results demonstrate that the designed type-2 fuzzy sliding mode control not only reduces chattering but also decreases energy consumption by approximately 59.92% and reduces the undershoot of the pitching rate by about 33.5%, with only a 0.115-second longer settling time for pitching angle compared to conventional sliding mode control.