1) The structure and control scheme of the Cartesian coordinate type robot is similar to that of the machine tool. Its three motions (x, y and z) reaching the spatial position are composed of linear motion. The advantages of this type of robot are that the kinematic model is simple, the displacement resolution of each axis is constant at any point in the operating volume, and the control accuracy is easy to be improved; The disadvantage is that the mechanism is huge, the working space is small, and the operation flexibility is poor. This form is often used by simple and special welding robots.
2) The cylindrical coordinate robot is equipped with a column on the base horizontal turntable, and the horizontal arm can move up and down along the column and retract in the horizontal direction. The advantage of this structural scheme is that the end operator can obtain high speed, but the disadvantage is that the farther the end operator extends away from the axis of the column, the lower the linear displacement resolution accuracy.
3) Compared with cylindrical coordinate structure, spherical coordinate structure is more flexible. However, when the code disk with the same resolution is used to detect the angular displacement, the linear displacement resolution of the telescopic joint is constant, but the linear displacement resolution of the rotating joint reflected on the end operator is a variable, which increases the complexity of the control system.
4) The structure of all joint robot is similar to human waist and hand. Its position and posture are realized by rotary motion. Its advantages are compact mechanism, good flexibility, small floor area, large workspace and high linear speed of end manipulator; Its disadvantage is that the kinematic model is complex, high-precision control is difficult, and the spatial linear displacement resolution depends on the pose of the robot arm.