An unmanned vehicle is guided by selecting locations along a predetermined mute defining adjacent first, second and third linear portions. If an imaginary circle can be constructed that is mutually tangential to all three linear portions or to projections thereof, the vehicle is guided according to the circle intercept method until it reaches an imaginary point of contact (M) between the circle and the second linear portion or passes its traverse. If an imaginary circle cannot be constructed that is mutually tangential to all three linear portions or to projections thereof, an imaginary circle is constructed that is mutually tangential to the first and second linear portions; and the vehicle is guided along according to the leg intercept method until it reaches an imaginary point of contact (M) between the circle and the first linear portion or passes its traverse. The process is repeated iteratively in respect of successive locations