Introduction to Robotics
Guess first
How many DOF does your arm really have?
Most engineering students get this robot question wrong
Quick check · tap an answer to continue
Lesson notes
Key points
- A rigid body moving freely in 3D space has six degrees of freedom: three positions and three orientations.
- Your arm from shoulder to wrist has seven joint DOF, one more than needed, which makes it a redundant manipulator.
Takeaway: Six DOF fully positions and orients an object; seven is redundant.
Quick check: How many degrees of freedom does a human arm have, shoulder to wrist?
- 3
- 6
- 7
Six DOF fully places a body in 3D; more than six means redundant.
Six DOFRedundancy
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