A plurality of autonomous mobile robots, comprising: a first mobile robot including a first module for transmitting and receiving an Ultra-Wideband signal; and a second mobile robot including a control unit and a plurality of second modules for transmitting and receiving the UWB signal, wherein the second mobile robot comprises a first UWB anchor (710b-1) and a second UWB anchor (710b-2) included in the plurality of second modules and located at different positions; characterized in that: the first mobile robot includes a transmitting optical sensor for outputting laser light, and the second mobile robot includes a receiving optical sensor for receiving the laser light; wherein the control unit of the second mobile robot is configured to determine a relative position of the first mobile robot based on the UWB signal received through the plurality of second modules and a determination of whether or not the laser light has been received by the receiving optical sensor; wherein the control unit of the second mobile robot is configured: - to determine a first distance between the first UWB anchor (710b-1) and the first module and a second distance between the second UWB anchor (710b-2) and the first module, in response to the UWB signal output from the first module being received through the first and second UWB anchors (710b-1, 710b-2); - to determine two intersections between a first circle and a second circle, wherein the first UWB anchor (710b-1) is a center of the first circle and the first distance is a radius of the first circle, and wherein the second UWB anchor (710b-2) is a center of the second circle and the second distance is a radius of the second circle; and - to determine one of two positions determined by the first module and the plurality of second modules as the relative position of the first mobile robot, based on whether the laser light is received through the receiving optical sensor. a first mobile robot including a first module for transmitting and receiving an Ultra-Wideband signal; and a second mobile robot including a control unit and a plurality of second modules for transmitting and receiving the UWB signal, wherein the second mobile robot comprises a first UWB anchor (710b-1) and a second UWB anchor (710b-2) included in the plurality of second modules and located at different positions; the first mobile robot includes a transmitting optical sensor for outputting laser light, and the second mobile robot includes a receiving optical sensor for receiving the laser light; wherein the control unit of the second mobile robot is configured to determine a relative position of the first mobile robot based on the UWB signal received through the plurality of second modules and a determination of whether or not the laser light has been received by the receiving optical sensor; wherein the control unit of the second mobile robot is configured: - to determine a first distance between the first UWB anchor (710b-1) and the first module and a second distance between the second UWB anchor (710b-2) and the first module, in response to the UWB signal output from the first module being received through the first and second UWB anchors (710b-1, 710b-2); - to determine two intersections between a first circle and a second circle, wherein the first UWB anchor (710b-1) is a center of the first circle and the first distance is a radius of the first circle, and wherein the second UWB anchor (710b-2) is a center of the second circle and the second distance is a radius of the second circle; and - to determine one of two positions determined by the first module and the plurality of second modules as the relative position of the first mobile robot, based on whether the laser light is received through the receiving optical sensor. - to determine a first distance between the first UWB anchor (710b-1) and the first module and a second distance between the second UWB anchor (710b-2) and the first module, in response to the UWB signal output from the first module being received through the first and second UWB anchors (710b-1, 710b-2); - to determine two intersections between a first circle and a second circle, wherein the first UWB anchor (710b-1) is a center of the first circle and the first distance is a radius of the first circle, and wherein the second UWB anchor (710b-2) is a center of the second circle and the second distance is a radius of the second circle; and - to determine one of two positions determined by the first module and the plurality of second modules as the relative position of the first mobile robot, based on whether the laser light is received through the receiving optical sensor.