A robot arm is a type of mechanical arm, usually programmable, with similar functions to a human arm. The arm may be the sum total of the mechanism or may be part of more complex robot. The end effector, or robotic hand, can be designed to perform any desired task such as take out products, welding, gripping etc., depending on the application. For example, The producing of disposable products, robotic arm can work with conveyor belt to achieve a high automation. Robotic arm can stack the disposable products, like spoon, forks, food container etc., after take out it from injection molding machine. Then flow the stacked products to packing area. Compare to manual work, it does improve the efficiency. In some circumstance, close emulation of the human hand is desired, as in robots designed to conduct some large scale parts, like car parts, appliance industry etc., and also conduct some dangerous cases. Anyway, robot arms are needed everywhere.