抄録
Development of a sphere-shaped mobile robot as a mobile base for home agent robots is described. Previously, a driving mechanism has been introduced employing a tricycle omni-directional internal drive unit and a prototype robot has been fabricated. Then, a set of equations of velocity references for the wheels have been derived which enable the internal unit to move smoothly along the inner surface of the sphere. Besides, a dynamics model to express rotational movements of the proposed robot has been derived. In this presentation, first, a control scheme is derived on the basis of these results in order to suppress swinging movements of the internal drive unit, employing a posture angle of the unit measured by an on-board IMU sensor. The validity of the scheme is confirmed through both simulations and experiments, which, in turn, confirms the validity of the dynamics model. Second, velocity control of the outer sphere employing a simple gain feedback compensation is examined. However, the model equations and simulation results show that the effect of the swing suppression control is eliminated by the simple gain compensation, which may lead to a poor control performance. Thus, an improved control scheme is expected as a future study plan.
