industrial robot manipulator is the earliest, is the earliest of the modern robot, it can replace human labor to realize the mechanization and automation of production, can operate in order to protect the personal safety in harmful environment, so it is widely used in machinery manufacturing, metallurgy, electronics, light industry and atomic energy and other departments.

The manipulator is mainly composed of three parts, the actuating mechanism, the driving mechanism and the control system. This paper mainly introduces the three main elements of the drive and control system of the manipulator design: stepper motor, stepper motor driver, controller.
The robot can be divided into hydraulic, pneumatic, electric and mechanical manipulators according to the driving modes. Three degrees of freedom manipulator in this paper belongs to mixed type manipulator, which combines the advantages of electric and pneumatic manipulator, which saves the travel switch and PLC I / O ports, and reached the purpose of simple operation and accurate positioning.

The manipulator is an electromechanical integration automatic device which simulates the human arm movement, and replaces the hand in order to capture, carry the workpiece or manage the tool according to the setting program, the trajectory and the requirement. Three degree of freedom manipulator, also known as 3D robot, can achieve three degrees of freedom direction (horizontal, vertical and rotating) grab or put things, with a wide range of operations, flexibility, and widely used features.

Programmable logic controller (PLC) is a kind of electronic control device designed for industrial applications. It is widely used in industrial control system because of its high reliability, strong function, simple programming and friendly man-machine interface.
The stepping motor is an open loop actuating element that transforms an electric pulse signal into angular displacement or linear displacement. In the case of non overloading, the speed and stop position of the motor only depend on the frequency of the pulse signal and the number of pulses. The existence of this linear relationship, with stepper motor only periodic error and no cumulative error characteristics, the speed and position control of the field of the application of a very broad.

1 system structure and motion of manipulator
The manipulator is cylindrical coordinate type. The mechanical arm of the left and right movement (horizontal direction) by the telescopic stepping motor control, up and down movement (vertical direction) by lifting stepper motor control, anti clockwise and clockwise rotation is controlled by reversible DC motor chassis. The clamping device of manipulator adopts joint structure, its clamping and releasing is driven by air pressure and controlled by electromagnetic valve.

The manipulator can move the workpiece from the A to the B at the action of the setting program.
2 manipulator control system design

 The manipulator system is equipped with manual operation and automatic operation. Automatic mode is divided into automatic back to the origin, single step, single cycle, continuous four modes of work.