 In order to actively control the position and body orientation of a ballbot by a sensor-computer-actuator framework, beside a suitable microprocessor or some sort of other computing unit to run the necessary control loops, a ballbot fundamentally requires a series of sensors which allow to measure the orientation of the ball and the ballbot body as a function of time.To keep track of the motions of the ball, rotary encoders (CMU Ballbot, BallIP, Rezero, Kugle) are usually used.Measuring the body orientation is more complicated and is often done by the use of gyroscopes (NXT Ballbots) or, more generally, an Inertial Measurement Unit (CMU Ballbot, BallIP, Rezero, Kugle) which includes an accelerometer, gyroscope and possibly magnetometer whose measurements are fused into the body orientation through AHRS algorithms.