1, the arm should have large bearing capacity, good rigidity and light weight.

The stiffness of the arm directly affects the stability, speed and positioning accuracy of the arm when grasping the workpiece. If the rigidity is poor, it will cause bending deformation of the arm in the vertical plane and lateral torsion deformation in the horizontal plane, the arm will vibrate, or the workpiece will be stuck and unable to work when moving. For this reason, the arm generally adopts a guide rod with good rigidity to increase the rigidity of the arm, and the rigidity of each support and connector should also have certain requirements to ensure that it can withstand the required driving force.

2. The moving speed of the arm should be appropriate and the inertia should be small.

The movement speed of manipulator is generally determined according to the production beat requirements of products, but it is not appropriate to blindly pursue high speed. When the arm reaches the normal movement speed from the static state, it is started, and when it drops from the constant speed to the stop, it is braked. The change process of speed is the speed characteristic curve. The arm is light and the start and stop are smooth.

3, arm movements should be flexible

The structure of the arm should be compact, so that the arm movement can be light and flexible. Adding rolling bearings or using ball guides to the boom can also make the arm move briskly and smoothly. In addition, for the cantilever manipulator, it is necessary to consider the arrangement of parts on the arm, that is, to calculate the moment of force of the arm's weight on the rotation, lifting and support center when moving parts. Unbalanced torque is very unfavorable to the movement of the arm. If the moment of force is too large, it will cause the vibration of the arm, and there will be a bow phenomenon when lifting, which will also affect the flexibility of the action. If it is serious, it will jam the arm and the column. Therefore, when designing the moment arm, the center of gravity of the moment arm should pass through the center of rotation or be as close as possible to the center of rotation to reduce the deflection moment. For a manipulator with two arms operating at the same time, the arrangement of the two arms should be as symmetrical as possible around the center to achieve balance.

4, the position accuracy is high

In order to obtain the high position accuracy of the manipulator, in addition to adopting advanced control methods, the following problems should be paid attention to in the structure:

(1) The stiffness, moment of force, inertia force and cushioning effect of the manipulator directly affect the position accuracy of the arm.

(2) Add setting device and travel detection mechanism.

(3) Reasonably select the coordinate form of the manipulator. Cartesian manipulator has high position accuracy, simple structure and motion, and small error. The error caused by rotary motion is the size error when magnifying. When the corner position is fixed, the longer the arm is extended, the greater the error. Because of its complex structure, the positioning of joint manipulator is determined by the mutual rotation angle of each joint, and its error is cumulative error, so its accuracy is poor and it is more difficult to ensure the position accuracy.