Which robot type rotates around joints and is associated with polar coordinates?

• A. polar
• B. SCARA
• C. cartesian
• D. articulated

Answer: (A)

Radial position combined with an angle is the natural way to describe where the end effector sits when the arm rotates around a fixed base. A polar-type robot is built with joints that revolve around that base and with an arm length that can extend or retract, so the position of the hand or gripper is described by the distance from the base (r) and the angle around the base (θ). That directly uses polar coordinates, making this robot type the best fit for the description.

In contrast, others are explained more naturally in different coordinate systems or with linear motions. A SCARA robot operates mainly in a horizontal plane with rotary joints plus a vertical rise, but its core kinematics are not described primarily in polar terms. A Cartesian robot moves along straight x, y, and z axes. An articulated robot uses multiple rotary joints with more general spatial motion, not inherently expressed in polar coordinates.