Articulated Robots Have Degrees Of Freedom

Articulated robots have rotary joints. A rotary joint is a connection between two objects. The connection allows both objects, even though each is connected to another object, the ability to rotate or have movement up to 360 degrees. The two rigid objects that are attached by the joint are sometimes called a kinematic pair while the joint is referred to as a mechanical constraint. Most of the time these two objects that are connected together are cylindrical. The connection gives both objects increased capabilities to perform work functions. Articulated robots usually have several of these connections which gives them a great deal of flexibility in performing work duties. Each joint that a robotic has represents an increase in freedom to perform tasks. There is no limit to the number of rotary joints that articulated robots can have and a robotic may have other types of joints to increase its capability even more.. After a certain number of joints, however, there would be diminishing capability of the robotic to do any productive work. All the movements of each of the objects that are connected together to create articulated robots must be programmed to move in order to do the tasks that they are assigned to do. The more joints that a robotic has, the more complex become the robotic functions. These are called degrees of freedom. An increase in the complexity of the robotic would increase the set of instructions that tell the robot when, where, and how to move. Usually articulated robots are assigned a limited number of tasks to perform.

Most of the time articulated robots are assigned to one work station in a group of work stations that perform individual steps in manufacturing or assembly operations. To create the work assignment for an articulated robotic work station one must take into account the:

Payload in doing the task
– How much weight is required to be lifted to complete this task?
Cycle time required to perform the task
– How much time is required to complete the task?
Required motion to complete a task
– What movements are require to complete the task?
Position in which the task is performed
– What position or positions are required to complete the task?
Operating environment where the task is performed
– How does the environment effect the completion of the task?
– How does the task effect the environment where it is accomplished?

Not unlike the industrial engineering functions in factories of years gone by, the program designed to run a robotic work station must take into account how it interacts with the other work stations on “the line”. One of the big differences between the work increments defined by industrial engineers years ago and the program steps defined by robotic programmers today is the inaccuracy of humans as opposed to the speed and accuracy of robotics. Articulated robots are capable of very precise and unending, repetitive tasks that simply cannot be done as accurately and as swiftly by humans. In many cases the robotic replacement for a human in a production line can perform many more steps in the manufacturing process than the human could ever hope to accomplish at the same work station.

The joints of articulated robots are programmed to work in unison with other parts of the robotic or can work independently. This characteristic gives the robotic a high degree of functionality. There are great variations in the kinematics of articulated robots. This arrangement of the rigid member and the joints in the robot determines what the type and range of motions of the robotic. Simple tasks that are to be performed require only a limited amount of rigid parts and joints, while multiple rigid parts and multiple joint can do more challenging tasks or even several tasks.

The utility of articulated robotics has grown so much in the last few years that they can now do the most minute work on the smallest objects, while their counterparts work with very large objects.

Characteristics of articulating robotics have moved toward meeting the needs of demanding manufacturing operations. Directly coupled drives are much more reliable than robotics built with belts, pulleys or chains. There are various mounting options, depending on robotic size, upright, inverted, or wall, whatever meets the needs of the application. Cables are enclosed in the body of the housing to eliminate entanglement. Encoders have absolute positioning so that homing or calibration is eliminated at power-up. Other units have both pneumatic and electrical connections. With articulated robotics installed on a rail more than one unit can share the same central processing unit. These units are most versatile for medium payloads and work well for welding, wash down and clean room applications.

Small articulated robotics, if installed on the floor, require less floor space for operation. These type units can be configured in multiple ways to accommodate a wide variety of reach, payload, and application requirements. Some units are controlled by multitasking controllers with individual axis monitoring. A single electric gripper or two pneumatic grippers can handle components. The gripper force is continuously adjustable, so that fragile items are handled safely and securely. Larger counterparts of these robots have extra long reach area with very small footprints, but with higher payloads. These are useful in spot welding, material handling, sealing, die and investment casting, material movement, machine tending, assembling of small parts, calibration, and testing, grinding, polishing, and bonding.