Intelligent Robust Disturbance Rejection Control of a Ballbot Drive Micromobility Vehicle

We propose a hybrid adaptive control method with robust disturbance rejection for a novel personal micromobility vehicle that uses ballbot drive mechanics with a single spherical wheel. Intelligent control of such a micromobility vehicle is significantly sensitive to discrete events of short duration and high-intensity road disturbances and shocks. Sudden bumps, potholes, pavement or kicks typically cause these events. Our approach combines adaptive disturbance observer (DOB) with two other techniques to achieve better and more robust nonlinear control of a ballbot drive vehicle (BDV) against small to large external disturbances. The proposed hybrid DOB-Based combined control system (DOB-CCS) stabilizes the body position via a DOB-based partial feedback linearization (PFL) strategy while enabling ball movement on the floor by introducing a DOB-based sliding mode control (SMC). The control scheme consists of linearly combined components responsible for maintaining an upright posture about unstable equilibrium points and tracking the motion under disturbances. Simulations, real-platform experiments and respective comparative studies show the efficacy of the proposed method for a BDV to reject external disturbances. The practical performance of the proposed DOB-CCS strategy is experimentally validated and compared with a CCS method. The experimental results indicate less than 0.7 and 1.5 degrees of ballbot's orientation error and robust rejection of disturbances under kicks during balancing and transferring modes, respectively.