Question

In which of the following 3 – Degree of freedom robot arm configuration gives a partial spherical shell space as work volume to the manipulator?

• A. Cylindrical coordinate system
• B. Cartesian coordinate system
• C. Polar coordinate system
• D. Selective Compliance Assembly Robot Arm

Hint:

Think of the Earth. We use Polar coordinates (latitude, longitude, and radius) to describe our Sphere. Similarly, a Polar robot creates a Spherical work volume.

Answer 1

The Correct Option is C

1. Polar Coordinate Robot (Spherical Robot): A robot in a

Polar coordinate system (often called a Spherical configuration) typically has two rotational (revolute) joints and one linear (prismatic) joint (2R + 1P).

• Base Rotation: The arm can rotate around a vertical axis.

• Elevation: The arm can pivot up and down.

• Extension: The arm can extend or retract in a straight line.
Because the arm pivots from a central point, the resulting reach defines a

partial spherical shell or a "spherical work volume."

2. Comparing Other Configurations:

• Cartesian (PPP): All three joints are linear. The work volume is a simple

rectangular box or cube.

• Cylindrical (RPP): One rotation and two linear movements. The work volume is a

cylinder.

• SCARA (RRP): Uses two rotational joints in a horizontal plane and one vertical linear joint. Its work volume is generally a

complex cylindrical shape.