The design and implementation of an autonomous guidance system requires knowledge and an understanding of a wide range of technologies, from the physical dynamics of the vehicle (including mechanical and structural properties) to the accuracies and inaccuracies of the sensors used to guide the vehicle. At the simplest level a guidance system has: - A sensor to generate measurements. - A guidance law to convert the measurements into a requirement (usually a requirement on the acceleration of the vehicle). - A dynamical model/transfer function to convert the requirement into a desired control/command. - A control system to minimise the difference between the desired control and the actual control achieved.