Arc
You can use Arc functions to load parameters for circularly interpolated moves. It includes 2D circular arcs, 3D helical arcs, and full 3D spherical arcs functions.
Circular interpolation is an advanced feature of NI-Motion and is primarily used in continuous path applications such as machining, pattern cutting, liquid dispensing, robotics, and so on. For maximum smoothness and accuracy, the NI-Motion DSP implements arcs through a cubic spline algorithm.
Arc functions are always sent to a vector space. Velocity and acceleration parameters loaded by executing those functions on the vector space are used as the vector velocity and vector acceleration for all subsequent arc moves. All arc parameters are double-buffered and take effect upon the next Start Motion or Blend Motion functions execution.
 |
Note Arc radius determines the practical range for vector acceleration and velocity. Unrealizable vector values generate an error and the start or blend does not execute. |
You can blend arc moves into linearly interpolated moves and vice versa. You also can load all axes in the vector space in the same blend factor with the Load Blend Factor function.
Arc moves are defined relative to their starting position and as such, are inherently operated in relative position mode. This approach guarantees that the axes are already on the circle in the x'y' plane, and avoids any impossible situations where the end point of the last move and the beginning of the arc move are not coincident. The mode selected with the Set Operation Mode function has no effect on the arc move. It can, however, affect the linearly interpolated vector move you might be blending into or from.