An autonomous machine comprising: a tractor unit; a trailer unit; one or more accelerometers (3A, 3B) configured to measure acceleration of at least one of the tractor unit and the trailer unit along three perpendicular axes; a velocity sensor configured to measure a velocity of the autonomous machine; a controller configured to: - receive acceleration data from the one or more accelerometers (3A, 3B); - receive velocity data from the velocity sensor; - determine whether the acceleration of at least one of the tractor unit and the trailer unit exceeds a predetermined maximum acceleration threshold; - in the event that the acceleration of at least one of the tractor unit and the trailer unit does exceed the predetermined maximum acceleration threshold, to reduce the velocity of the autonomous machine until the acceleration of at least one of the tractor unit and the trailer unit has decreased below the predetermined maximum acceleration threshold; and - increase the velocity of the autonomous machine towards and up to a predetermined maximum velocity threshold for the autonomous machine; characterized in that the velocity of the autonomous machines is only increased towards and up to a predetermined maximum velocity threshold for the autonomous machine after a time delay. a tractor unit; a trailer unit; one or more accelerometers (3A, 3B) configured to measure acceleration of at least one of the tractor unit and the trailer unit along three perpendicular axes; a velocity sensor configured to measure a velocity of the autonomous machine; a controller configured to: - receive acceleration data from the one or more accelerometers (3A, 3B); - receive velocity data from the velocity sensor; - determine whether the acceleration of at least one of the tractor unit and the trailer unit exceeds a predetermined maximum acceleration threshold; - in the event that the acceleration of at least one of the tractor unit and the trailer unit does exceed the predetermined maximum acceleration threshold, to reduce the velocity of the autonomous machine until the acceleration of at least one of the tractor unit and the trailer unit has decreased below the predetermined maximum acceleration threshold; and - increase the velocity of the autonomous machine towards and up to a predetermined maximum velocity threshold for the autonomous machine; - receive acceleration data from the one or more accelerometers (3A, 3B); - receive velocity data from the velocity sensor; - determine whether the acceleration of at least one of the tractor unit and the trailer unit exceeds a predetermined maximum acceleration threshold; - in the event that the acceleration of at least one of the tractor unit and the trailer unit does exceed the predetermined maximum acceleration threshold, to reduce the velocity of the autonomous machine until the acceleration of at least one of the tractor unit and the trailer unit has decreased below the predetermined maximum acceleration threshold; and - increase the velocity of the autonomous machine towards and up to a predetermined maximum velocity threshold for the autonomous machine; characterized in that the velocity of the autonomous machines is only increased towards and up to a predetermined maximum velocity threshold for the autonomous machine after a time delay.