An autonomous lawn mower comprising a mower body having at least one motor arranged to drive a cutting blade and to propel the mower body on an operating surface via a wheel arrangement, wherein the mower body includes a navigation system arranged to assist a controller to control the operation of the mower body within a predefined operating area; and wherein the mower body further includes a signal detecting module arranged to detect a signal representative of a navigational marker, wherein the autonomous lawn mower further includes a signal generating module arranged to generate the signal in the form of a signal loop (412, 422), wherein: the signal detecting module includes a sensor arranged to detect the magnitude of the signal loop (412, 422); and the signal generating module is configured to generate a first aforesaid signal loop within the predefined operating area whereby the position of the mower body relative to the predefined operation area is determined by the controller based on the magnitude of the first signal loop detected by the sensor, wherein the signal generating module is positioned on a detachable docking module for detachably receiving the mower body; and the detachable docking module is configured to generate a second aforesaid signal loop within a predefined docking area about the detachable docking module whereby the position of the mower body relative to the detachable docking module within the predefined docking area is determined by the controller based on the magnitude of the second signal loop detected by the sensor, wherein the first and second signal loops (412, 422) are time shifted pulses with the same frequency and the first and second signal loops (412, 422) are received by the sensor when the mower body is at a position inside the predefined operating area and the predefined docking area, wherein the controller is configured to identify the first and second signal loops (412, 422) individually based on the time shift between the pulses of the first and second signal loops (412, 422). wherein the mower body includes a navigation system arranged to assist a controller to control the operation of the mower body within a predefined operating area; and wherein the mower body further includes a signal detecting module arranged to detect a signal representative of a navigational marker, wherein the autonomous lawn mower further includes a signal generating module arranged to generate the signal in the form of a signal loop (412, 422), wherein: the signal detecting module includes a sensor arranged to detect the magnitude of the signal loop (412, 422); and the signal generating module is configured to generate a first aforesaid signal loop within the predefined operating area whereby the position of the mower body relative to the predefined operation area is determined by the controller based on the magnitude of the first signal loop detected by the sensor, wherein the signal generating module is positioned on a detachable docking module for detachably receiving the mower body; and the detachable docking module is configured to generate a second aforesaid signal loop within a predefined docking area about the detachable docking module whereby the position of the mower body relative to the detachable docking module within the predefined docking area is determined by the controller based on the magnitude of the second signal loop detected by the sensor, wherein the first and second signal loops (412, 422) are time shifted pulses with the same frequency and the first and second signal loops (412, 422) are received by the sensor when the mower body is at a position inside the predefined operating area and the predefined docking area, wherein the controller is configured to identify the first and second signal loops (412, 422) individually based on the time shift between the pulses of the first and second signal loops (412, 422). the signal detecting module includes a sensor arranged to detect the magnitude of the signal loop (412, 422); and the signal generating module is configured to generate a first aforesaid signal loop within the predefined operating area whereby the position of the mower body relative to the predefined operation area is determined by the controller based on the magnitude of the first signal loop detected by the sensor, wherein the signal generating module is positioned on a detachable docking module for detachably receiving the mower body; and the detachable docking module is configured to generate a second aforesaid signal loop within a predefined docking area about the detachable docking module whereby the position of the mower body relative to the detachable docking module within the predefined docking area is determined by the controller based on the magnitude of the second signal loop detected by the sensor, wherein the first and second signal loops (412, 422) are time shifted pulses with the same frequency and the first and second signal loops (412, 422) are received by the sensor when the mower body is at a position inside the predefined operating area and the predefined docking area, wherein the controller is configured to identify the first and second signal loops (412, 422) individually based on the time shift between the pulses of the first and second signal loops (412, 422).