The seventh axis of the robot (robot ground rail) is driven by the servo motor to drive the robot along the track to do linear movement, so that the robot can quickly and accurately reach the designated position for work (welding sheet metal workpiece or processing), expand the working radius of the robot, expand the scope of application of the robot, and multiple devices can be integrated into the linear system to improve the efficiency of the robot. The track is divided into line rail and hard rail, and the walking transmission mode has the form of pinion rack and CAM roller. The positioning accuracy of the CAM roller structure is higher than that of the pinion rack structure, and the repeated positioning accuracy of the CAM roller structure can reach 0.02mm.