What are degrees of freedom in robotic arms? (Easy guide)

How many degrees of freedom does each type of robot have?

Robotic arms vary greatly in complexity, number of joints, and ability. This means that they’re suited for different tasks. 

Let’s go into a little more detail about the most common types and their DOF:

• SCARA robots typically have three degrees of freedom. Their two rotational joints on a horizontal plane and one vertical joint allow precise movement within a defined workspace. They're excellent for assembly tasks (like screw driving, part fitting), pick-and-place operations, and dispensing applications.
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• Cartesian robots also often have three degrees of freedom. Their three linear joints (X, Y, and Z axes) enable them to move along straight lines, prioritizing precision within large workspaces. They're often very common in pick-and-place applications, transport, palletizing, and dispensing tasks where speed is less important than accuracy.
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• Six-axis articulated robots have the highest flexibility with six degrees of freedom.  Their six rotational joints mimic a human arm, allowing intricate movements, object manipulation at various angles, and adaptability to complex tasks. They're extremely versatile and used in applications like welding, painting, assembly, and palletizing.
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• Delta robots usually have three or four degrees of freedom. Though the exact configuration can vary, their unique design focuses on precise and extremely fast movement within a dome-shaped workspace. They're excellent for high-volume pick-and-place tasks, especially in the packaging and food processing industries.
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• Collaborative robots (Cobots) can have varying degrees of freedom, but the priority is on safe operation alongside humans. Their DOF might be slightly less focused on pure flexibility, as their sensors and safety features are equally important for their intended use. They're increasingly used in assembly tasks, machine tending, inspection, and other applications where human-robot collaboration is preferred — and beneficial.

Remember: There’s no one-size-fits-all answer when it comes to DOF and robot types. There are generalities. Not all SCARA robots have three degrees of freedom, for example. Always, always check with the manufacturer.

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How degrees of freedom in robotics affect robot arm capabilities

The more degrees of freedom a robotic arm has, the more skillful, versatile, and flexible (as in, suited for a wide variety of tasks) it can be. 

With great power comes great responsibility, and with additional joints comes additional flexibility and range of motion. Think of your own arm — with joints at the shoulder, elbow, and wrist, you have a high level of manipulability.

It will be easier to understand if we break down levels of freedom a bit further: 

• 1 DOF (One Degree of Freedom): This is the most basic form of movement in a robot joint. It allows the robot to move in only one direction along a linear path, like extending an arm or opening and closing a gripper — think of a light switch that can only be flipped up or down.
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• 2 DOF (Two Degrees of Freedom): Here, the joint can move in two independent ways. Imagine a robotic arm moving along a flat plane. It can typically extend and retract (linear movement) along one axis, and also rotate left and right (rotational movement) around another axis. This combination allows for tasks like picking up objects on a flat surface.
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• 3 DOF (Three Degrees of Freedom): Adding another DOF grants the robot movement in three independent directions. This is commonly achieved with a three-axis robotic arm. It can move forward/back, left/right, and up/down along linear paths, creating a wider range of motion. This allows for picking and placing objects at different heights or stacking items.
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• 4 DOF (Four Degrees of Freedom): Less common than the previous examples, 4 DOF robots can usually move in the same three linear directions (forward/back, left/right, up/down) as a 3 DOF robot, but with the addition of one rotational freedom. This might be achieved by adding a wrist joint that allows the robot to twist its gripper, further enhancing its manipulation capabilities.
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• 5 DOF (Five Degrees of Freedom): Building upon 4 DOF, a 5 DOF robot might have the same linear movements but with a more complex wrist joint. This could allow for not only twisting but also tilting the gripper, granting even greater control over object orientation.
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• 6 DOF (Six Degrees of Freedom): This is considered full articulation for most industrial robots. They can achieve all three linear movements (forward/back, left/right, up/down) and all three rotational movements (twisting, tilting, and rotating the arm itself). This allows for incredibly precise and complex manipulation, mimicking the flexibility of a human arm.
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• 7+ DOF (Seven Degrees of Freedom and More): In specialized applications, robots might have even more DOF. These additional joints might offer specific functionalities tailored to unique tasks. For example, a snake robot designed for navigating tight spaces might have many DOF to achieve a serpentine movement.
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In short: The number of degrees of freedom directly impacts how well a robotic arm can imitate human movement and dexterity. 

More degrees of freedom means the arm has a greater range of motion and flexibility, enabling it to reach around obstacles and manipulate objects with higher precision. Conversely, fewer degrees of freedom reduce flexibility and overall dexterity.

Also worth mentioning: In the future, it’s likely that we’ll see even more “inhuman” robots that don’t necessarily mimic the capabilities of human arms. As engineers get more creative, new iterations may have even more DOF than we can currently imagine.

Summing up

We’ve gone deep into degrees of freedom in robotics, so now you have a clear understanding of what each DOF can bring to the table! While it may seem complex at first, the more you learn, the more intuitive it becomes. 

The most important part is clearly visualizing how each joint moves and counting up the degrees of rotational and linear freedom. 

With some hands-on experience programming, deploying, and observing various robot arms, you’ll start getting in as you get more… hands-on experience (that’s really the last time). 

For now, just remember that more degrees of freedom allow more complex movements, but also require more sophisticated controls.

Then, it’s just a matter of researching how many degrees of freedom you need for your application. Carefully weighing your budget, application, facilities (as in, whether you’ll need to renovate), and available models is the recipe for success!

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Next steps

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