Articulating Arm Robots, 4 and 6 Axis

Articulating Arm Robot
Fanuc Robot Motoman Robot ABB Kuka
Fanuc Motoman ABB Kuka Robot

Or Vertical Articulating Arm, This robot has three main rotary axes, and additionally may have a two or three-axis wrist. The most important characteristic that is offered by this robot configuration is the excellent maneuverability. The six-axis articulation allows orientation of the wrist in practically any position. Fanuc Robot Motoman ABB Kuka

The repeatability is good (0.1-0.5mm); however, large sizes of the robot may not be adequate for precision assembly. The working envelope is large, relative to the size. The maximum payloads are between 5-400kg, depending on the robot size. Tool tip speed is quite fast (1000-2000mm/s).

This robot is perhaps the most widely used and flexible type of robot. It is capable of a wide range of motion and reach. While it may not be quite as fast as the Scara type of robot, it can generally do the same type of tasks. Given the task of palletizing, the Articulating Arm robot is capable of palletizing many pallet positions simultaneously, while the Scara is more limited due to its smaller reach. A 6 axis Articulating Arm robot can be used for welding, painting, material handling, palletizing and many other types of operations. A 4 axis Articulating Arm robot has lesser capabilities as far as pickup and placement of materials, but will typically be faster. 6 axis robots of this type are widely used in the Automotive industry, while 4 axis robots are typically used for palletizing operations, where speed is more critical than flexibility. Shown is a Kawasaki Articulating Arm robot.

4-Axis

As mentioned above, the 4 axis Articulating Arm robot is mostly used in palletizing and material handling operations. An "axis" refers to a range of motion. So, as can be seen in the drawing, the A-1 "joint" is the primary motion center for this robot, as it turns the whole robot around. Shown is a drawing of a Kuka robot, however, all robot manufacturers have different nomenclature for the various joints. In the case of Kuka, they call the primary joint A-1, Fanuc calls it J1, but no matter what it is called the speed of this joint is usually the dominant factor in overall robot speed.

As you can see, the A-2 and A-3 joint work in unison to extend the robot outward toward its target. If you look closely at the picture, you will notice a bar along the top of the robot. This bar keeps the A-6 joint perpendicular to the floor. The A-6 joint is where the end effector (or gripper) is mounted. It rotates so that proper placement of the payload can be achieved. Fanuc Motoman ABB Kuka

6-Axis

As with the 4 axis unit above, the A-1 joint is the prime mover.

The A-2 and A-3 joints extend the robot and the A-6 joint rotates the end effector. Unlike the 4-axis unit, the 6-axis type of robot has an A-4 and A-5 joints. Although it may seem from the drawing that the A-4 joint works with the A-6 joint for rotational movement, such is not the case, as the A-4 joint has the ability to rotate the A-5 joint as well. Using the A-4 and A-5 joints, it is possible to pickup a part that is not necessarilly parallel to the floor, i.e., ALL range of motion is possible. That's why this type of robot is so popular with welding, painting and extrusion type applications. The 6 axis robot is generally more precise in its accuracy to position its end effector than 4 axis models. It is also usually more expensive than the 4 axis models.