Spot welding robot is the auto production line, improve production efficiency and raise the quality of welding car, 1 the labor intensity of a robot. It is characterized by two 2 of robots for spot welding of st eel plate, bearing a great need for the welding tongs, general in dozens of 3 or more, then its speed in 1.5-2 meters per second of such high-speed movement. So it is generally five to six degrees of freedom, 4 30 to 120 kilograms, the great space, probably expected that the work of a 5 space, a high velocity, the concept of freedom. That is to say, movement is relatively 6 of the number of components, the equivalent of our body, 7 is a rotary degree of freedom. We have to be able to hold his arm, Arm can be bent, then this three degrees of freedom, 8 there is a wrist posture 9 to the use of the three autonomy, the general robot has six degrees of freedom. We will be able to space the three 10 , three postures, the robot fully achieved, and of course we have less than six degrees of freedom. Have more than six degrees of freedom robot, in different occasions the need to configure.