Arc Moves

An arc move causes a coordinate space of axes to move on a circular, spherical, or helical path. You can move two-dimensional vector spaces in a circle only on a 2D plane. You can move a 3D vector space on a spherical or helical path.

Each arc generated by the motion controller passes through a cubic spline algorithm that ensures the smoothest arc. This also ensures negligible chordal error, which is error caused when two points on the surface of the arc join with each other using a straight line. A cubic spline algorithm generates multiple points between every two points of the arc, ensuring smooth motion, minimum jerk, and maximum accuracy at all times. The data path is shown in the following figure.

Note  Arc moves must meet the requirements of the equations in NI 73xx Arc Move Limitations or an NIMC_invalidVelocityError is generated.