Universal Robots Robotic Arm – Design Requirements for Robotic Arms

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

The rigidity of the arm directly affects the smoothness of the movement, the speed of movement and the positioning accuracy when the arm grabs the workpiece. If the rigidity is poor, it will cause the bending deformation of the arm in the vertical plane and the lateral change of the horizontal plane, and the arm will vibrate, or the workpiece will be stuck and unable to work during action. For this reason, the arm generally chooses a guide rod with good rigidity to increase the stiffness of the arm, and the rigidity of each support and connector also has certain requirements to ensure that it can withstand the required driving force.

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

The movement speed of the manipulator is generally determined according to the production cycle requirements of the product, but it is not appropriate to blindly pursue high speed. The arm from the abort state to the normal movement speed is the start, from the normal speed to the stop of the immobility is the braking, and the speed change process is the speed characteristic curve.

The weight of the arm is light, and the smoothness of starting and stopping is good.

3. Arm movements should be flexible

The structure of the arm should be compact and compact, so that the arm movement is light and flexible. Installing rolling bearings on the arm or using ball guides can also make the arm movement light and smooth. In addition, for the cantilever manipulator, it is necessary to consider the placement of parts on the arm, that is, to calculate the weight of the arm when moving the parts to the reversing, lifting, and supporting center of the gravity moment. The gravitational moment is very unfavorable to the arm movement, the gravitational moment is too large, it will cause the vibration of the arm, and a kind of countersunk phenomenon will occur when lifting, and it will also affect the flexibility of the movement, and the arm and the column will be stuck when it is severe. Therefore, when planning the arm, try to make the center of gravity of the arm pass through the center of reversal, or as close as possible to the center of reversal, so as to reduce the deviation. Torque. For manipulators that operate with two arms together, the placement of the two arms should be as symmetrical as possible in the center to achieve balance.

4. High azimuth accuracy

In order to achieve high azimuth accuracy, in addition to the selection of advanced control methods, the manipulator also pays attention to several problems in the structure:

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

(2) Add positioning equipment and stroke testing mechanism.

(3) Reasonable selection of the coordinate form of the manipulator. The azimuth accuracy of Cartesian coordinate manipulator is high, and its structure and movement are relatively simple, and the error is small. The error of the reversal motion is the scale error when magnifying, when the corner orientation is certain, the longer the arm is extended, the greater the error; Articulated manipulator because of its complex structure, the positioning of the hand end is determined by the angle of each part joint to each other, and its error is a stacking error, so the accuracy is poor, and its azimuth accuracy is also more difficult to ensure.

5. Strong versatility and can get used to a variety of operations; It has good manufacturability and is easy to repair and adjust

The above requirements are sometimes often opposed to each other, with good rigidity, large load, thick structure, many guide rods, and added arm weight; With the addition of moment of inertia, the impact will be large, and the azimuth accuracy will be low. Therefore, when planning the arm, it is necessary to grasp the weight according to the manipulator. Various factors such as degree, operating range, movement speed, overall layout and working conditions of the manipulator are comprehensively considered to achieve accurate, reliable, flexible, compact structure, large stiffness and small weight, and then ensure the accuracy of the certain orientation and the habit of rapid action. In addition, thermal radiation should be taken into account in the case of thermal processing robots, with long arms to keep away from heat sources and equipped with cooling equipment. Dust-proof equipment is also required for the manipulator for dust work.

Universal Robots Robotic Arm – Design Requirements for Robotic Arms

Universal Robots Robotic Arm – Design Requirements for Robotic Arms

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