Degrees of freedom is the number of independent movements a robot can make. A robot arm that slides up and down has one degree of freedom. Add a rotating base and it has two. Add a wrist that tilts and rotates and the count climbs. Each degree of freedom corresponds to a joint or a movable axis.

In space, a rigid body has six degrees of freedom: three translations and three rotations. A robot that can control all six can position and orient an object anywhere within its reach. Fewer than six and some positions or orientations are impossible. More than six and the robot is redundant, which can be useful for reaching around obstacles.

Degrees of freedom in common robots

• SCARA robot: four degrees of freedom, fast assembly.
• Six-axis industrial arm: six degrees, full pose control.
• Humanoid arm: seven degrees, redundant like a human.
• Delta robot: three degrees, high-speed pick and place.
• Mobile robot: three degrees on the floor, more with a manipulator.

More degrees of freedom means more flexibility but also more complexity. Each joint adds weight, cost, and control challenges. Inverse kinematics, figuring out what joint angles produce a desired position, becomes harder as the count rises. Redundant robots can choose among many solutions. That flexibility lets them avoid singularities, configurations where the math breaks down and the robot loses control. Degrees of freedom is a simple count with deep consequences for what a robot can and cannot do.