Introduction to Robotics
Guess first
Where does a robot arm suddenly get stuck?
Most students get this wrong about robot arms
Quick check · tap an answer to continue
Lesson notes
Key points
- When an arm stretches fully straight, two joint axes line up and the arm loses a direction it can move in.
- Near that pose, tiny tool motions demand huge joint speeds, because the Jacobian's determinant approaches zero.
Definitions
- Singularity
- A configuration where the arm loses a degree of freedom and the Jacobian loses rank.
Takeaway: Singularities happen when the Jacobian loses rank, often at full stretch.
Quick check: A two-link arm moves its tip. In which pose does it lose the ability to move in some direction?
- At maximum payload
- Fully stretched out straight
- Moving at top speed
Fully stretched or folded arms hit singularities where det J equals zero.
SingularityJacobian
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