Glossary · Motion control and drives
Linear interpolation
Also known as: Straight-line interpolation
German: Linearinterpolation
In motion control and CNC, linear interpolation is the coordinated movement of two or more axes so that the tool or load travels on a straight line from the start point to the target point at the programmed speed.
- Motion control
In one sentence
Linear interpolation moves several axes together so the tool travels in a straight line from start to target at the programmed speed.
Example
A CNC program uses linear interpolation (G01 in ISO 6983 G-code) to mill a straight chamfer.
How it applies
- Engineering: For Cartesian machines, linear interpolation is a proportional distribution of the move over the axes. For robots, a straight Cartesian line requires continuous Inverse kinematics.
- Commissioning: Straightness at speed reveals mismatched axis tuning.
- Operation: Linear moves of robots can fail near singularities, while joint moves reach the same target on a different path.
- Documentation: Explain the difference between linear and joint moves in robot programming manuals, including the path each takes; people teaching robots near fixtures need to know the path is different.
Linear interpolation vs. rapid traverse
In CNC, rapid traverse (G00) moves axes at maximum speed, often not on a straight line. Linear interpolation (G01) moves on a straight line at the programmed feed.