Overview

The PVT function commands an axis using a sequence of Position-Velocity-Time points. The axis will pass through the specified position at the specified velocity at the specified time. (PVT stands for Position-Velocity-Time.)

PVT functions have the following characteristics:

  1. Along the entire path, the position and velocity of the commanded axis is continuous.

  2. Between two points, the acceleration of the commanded axis changes linearly (the jerk is constant).

  3. With the StartPVT (Interpolation) function, up to maxPvtInterpolateAxes axes may be interpolated. The specified axes will start motion in the same communication cycle.

  4. The PT, VT, and AT functions allow only the position and time, velocity and time, or acceleration and time to be specified for each point.

Before a PVT command can be executed, buffer memory for storing point data must be allocated to the commanded axis. When executing the StartPVT (Interpolation) function, buffer memory must be allocated to all commanded axes.

Buffer memory is allocated with the CreatePVTBuffer function. If a PVT motion is started with the StartPVT, StartPVT (Interpolation), StartPT, StartVT, or StartAT function before allocating buffer memory, a default size buffer memory (of size maxPvtAppendPoints) is allocated. However, allocating buffer memory this way is not recommended because there is always a possibility that any memory allocation will fail. For additional information, see Function Calls Related to Memory Allocation.

To execute a PVT command containing more than maxPvtAppendPoints points, additional point data must be specified using the optional arguments of the PVT function.