# Singularities with a six-axis articulated robot kinematic

A distinction is made between three types of singularity:

1. Wrist singularity
2. Elbow singularity
3. Shoulder singularity

## Wrist singularity

This occurs when angle A5 (axis B3) is equal to zero.

## Elbow singularity

An elbow singularity occurs when the wrist lo located on a straight line running through the axes B1 and B2. When HD12 = 0, this corresponds to an angle A3 (axis B2) equal to zero.

Elbow singularity

## Shoulder singularity

A shoulder singularity occurs when HD32 = 0 if the wrist is located on the extended C1 axis.

When HD32 ≠ 0, the shoulder singularity occurs if the wrist is located on the cylindrical sleeve of radius HD32 about the C1 axis.