What is the general configuration of a jointed-arm robot denoted by TRR?

• A. It mimics the configuration of a human arm.
• B. It is a planar robot with all joints in a single plane.
• C. It uses only linear actuators with no rotation.
• D. It uses spherical joints to achieve full three-dimensional rotation.

Answer: (A)

In robotics, a jointed-arm robot with the TRR designation is understood as a serial arm with three rotary joints arranged in a way that mimics a human arm—shoulder, elbow, and wrist—providing three independent rotational axes to reach and orient the end effector in 3D space. This anthropomorphic arrangement is what makes it feel like a human arm in terms of motion and control. It isn’t limited to motion in a single plane, which would describe a planar or 2D robot, and it isn’t built from only linear actuators or from spherical joints, which would change the type of motion and constraints.