A system using one or more robots to assist a human in order fulfillment, comprising: a server configured to receive an order comprising an order item; inventory storage operably connected to the server, the inventory storage comprising inventory items; a mobile order robot operably connected to the server, the order robot configured to assist the human to pick an order item from the inventory items, wherein assisting comprises leading or following the human and one or more of the server, the inventory storage, and the order robot being suitable for operable connection to a human-operated device, the human-operated device being configured to assist the human to pick the order item, wherein the order robot comprises a control program, an actuator for moving the order robot and an information capture device configured to make an information capture and where said information capture includes a selection of the order robot by the human wherein the information capture device comprises one or more of a depth camera, a Red Green Blue camera, another photographic camera, a videocamera, a laser, a wireless receiver, a fiducial and a scanner; the information capture device being further arranged to perform an information capture that detects a human location and/or tracks motion of the human, and the control program being arranged, once the human has been detected, to send commands to the actuator of the order robot to adjust the robot position relative to the human using information obtained by the information capture device in the information capture, so that the order robot moves in the correct direction so as to maintain a substantially constant distance from the human and/or a substantially constant orientation to the human, in order to lead or follow the human, wherein the constant distance and/or constant orientation are predetermined by a user. a server configured to receive an order comprising an order item; inventory storage operably connected to the server, the inventory storage comprising inventory items; a mobile order robot operably connected to the server, the order robot configured to assist the human to pick an order item from the inventory items, wherein assisting comprises leading or following the human and one or more of the server, the inventory storage, and the order robot being suitable for operable connection to a human-operated device, the human-operated device being configured to assist the human to pick the order item, wherein the order robot comprises a control program, an actuator for moving the order robot and an information capture device configured to make an information capture and where said information capture includes a selection of the order robot by the human wherein the information capture device comprises one or more of a depth camera, a Red Green Blue camera, another photographic camera, a videocamera, a laser, a wireless receiver, a fiducial and a scanner; the information capture device being further arranged to perform an information capture that detects a human location and/or tracks motion of the human, and the control program being arranged, once the human has been detected, to send commands to the actuator of the order robot to adjust the robot position relative to the human using information obtained by the information capture device in the information capture, so that the order robot moves in the correct direction so as to maintain a substantially constant distance from the human and/or a substantially constant orientation to the human, in order to lead or follow the human, wherein the constant distance and/or constant orientation are predetermined by a user.