Which statement about degrees of freedom is true?

• A. The number of joints equals the DOFs
• B. The number of DOFs equals the number of sensors
• C. The DOFs describe the number of independent movements the system can perform
• D. The DOFs describe the energy capacity of the system

Answer: (C)

Degrees of freedom tell you how many independent motions a system can perform. In robotics and mechanics, this is the number of independent coordinates needed to describe the system’s configuration. For a free rigid body in space, there are six DOFs: three translational and three rotational movements. When joints connect parts, they constrain motion, so the total DOF is determined by the allowed motions of the joints, not just by how many joints there are. Therefore, the statement that DOFs describe the number of independent movements the system can perform is the accurate one. The other ideas mix up what DOFs measure: joints don't always equal DOFs due to constraints; sensors relate to sensing capability, not the count of independent motions; and energy capacity is about energy storage or power, not motion independence.