 In their present state, the arms cannot be used for any significant manipulation, but are used to study their effects on the dynamics of ballbot.The mathematical MIMO-model which is needed in order to simulate a ballbot and to design a sufficient controller which stabilizes the system, is very similar to an inverted pendulum on a cart.The LEGO NXT Ballbot, Adelaide Ballbot, Rezero and Kugle include actuator models in their robot models, whereas CMU Ballbot neglects the actuator models and models the Ballbot as a body on top of a ball.