MotionInterpolationMode Parameter

Use the MotionInterpolationMode parameter to change the cubic-spline polynomial algorithm that the controller uses to interpolate some motion functions to the position update rates of the axes. The controller interpolates the specified motion functions only for the conditions that follow:

• If the value of the MotionUpdateRate Parameter is less than the position update rate of an axis, the controller interpolates the motion that was generated by the MoveLinear(), MoveCw(), MoveCcw(), or MoveRapid() function.
• If the value of the $time argument that you specify to the MovePt() or MovePvt() function is greater than 1.0 divided by the position update rate of an axis, the controller interpolates the motion that was generated by the MovePt() or MovePvt() function.

For more information, refer to the table that follows.

Table: Position Update Rates

Drive Type		Position Update Rate
Servo Axis	FLEX, iXA4, and XA4	10 kHz
	All others	20 kHz
Galvo Axis		100 kHz

2-position / 2-velocity is the default setting of the MotionInterpolationMode parameter. The controller uses all available positions and velocities to generate a cubic spline interpolation. For this setting, the controller uses true velocities, which are the velocities that you specify. Aerotech recommends that you use this setting when you use the MoveLinear(), MoveCw(), MoveCcw(), MoveRapid(), and MovePvt() functions.

When you set this parameter to 3-position / 1-velocity, the controller uses three positions and a previously estimated velocity to generate a cubic-spline interpolation. For this setting, the controller uses an estimated velocity and ignores the velocity that you specify. Aerotech recommends that you use this setting when true velocities are not available.