How does a SCARA robot differ from a jointed-arm robot?

• A. It uses vertical axes for shoulder and elbow joints to enable horizontal compliance during insertion tasks.
• B. It uses only rotational joints with no linear motion.
• C. It is limited to planar motion with two axes.
• D. It cannot perform insertion tasks.

Answer: (C)

SCARA robots are built to move mainly in a single plane. They use a pair of rotary joints that sweep the arm in the horizontal plane, giving precise X and Y positioning with fast, stiff motion. Because the motion stays in that plane, SCARA is especially well-suited for insertion tasks and other planar assembly work. A jointed-arm robot, by contrast, stacks multiple rotary joints along the arm, which allows movement and orientation in three-dimensional space—reaching up and down, twisting, and maneuvering around obstacles. That extra freedom comes with more complexity and typically different speeds for 3D tasks. So the defining distinction is that SCARA is limited to planar motion with two axes, whereas a jointed-arm robot can operate in 3D with multiple axes.