This work presents a novel geometric framework for self-balancing as well as planar motion control of wheeled vehicles with two fewer control inputs than the configuration variables. For self-balancing control, we shape the kinetic energy in such a way that the upright direction of the robotâs body becomes a nonlinearly stable equilibrium for the corresponding controlled Lagrangian which is inherently a saddle point. Then for planar motion control of the robot, we set its position and attitude as an element of the special Euclidean group SE(2) and apply a logarithmic feedback control taking advantage of the Lie group exponential coordinates. For simulation and evaluating the controllers, the unified dynamic model of the self-balancing mobile robot (SMR) is developed using the constrained Euler-Lagrange equations.