PVAJT Streaming Motion

Table of Contents

• 🔹 What is PVAJT Motion
• 📜 Sample Code

Stream arrays for precise control over Positions, Velocities, Acceleration, Jerk, and Time deltas directly to the frame buffer. Achieve absolute control over the motion path.

🔹 What is PVAJT Motion

PVAJT motion is a lot more complicated to use because it requires an array of Positions, Velocities, Acceleration, Jerk, and Time deltas. The controller is not responsible for any calculations because it streams the arrays straight to the frame buffer. This makes it very flexible and gives users absolute control over the motion path. The controller does not do any interpolation or calculations because everything it needs is calculated beforehand in the PVAJT arrays. PVAJT motion must all be provided in advance and cannot be appended to.

The effect of velocity, acceleration, and jerk depends on the time between points. Larger time deltas increase the influence of the higher-order terms, while at the opposite extreme (using 1-sample time deltas) the motion is equivalent to PT.

Move PVAJT

Output Example

PVAJT is useful if you must control the acceleration and jerk percent profile throughout motion. The example to the right shows a 50% jerk SCurve trapezoidal move. This move requires 7 elements in each array. One segment for each rising/constant/falling segment of the acceleration profile. The math for PVAJT can be very cumbersome. We recommend you explore all other motion types before trying to implement this method. Note: The Position, Velocity, Acceleration, and Jerk arrays are all direction sensitive meaning you must put a (-) sign on negative numbers.

📜 Sample Code

• C#

  /*  Demonstrates PVAJT (Position-Velocity-Acceleration-Jerk-Time) streaming motion.
      PVAJT motion requires position, velocity, acceleration, jerk, and time arrays.
      The controller uses all specified motion parameters for each segment.
  */
   
  using RSI.RapidCode; // RSI.RapidCode.dotNET;
   
  Console.WriteLine("📜 Axis Streaming Motion: PVAJT");
   
  // get rmp objects
  MotionController controller = MotionController.Get();
   
  try
  {
      Helpers.CheckErrors(controller);
   
      // get axis
      Axis axis = controller.AxisGet(Constants.AXIS_0_INDEX);
      Helpers.CheckErrors(axis);
   
      // configure phantom axis
      Helpers.PhantomAxisReset(axis);
   
      int points = 3;                             // total number of streamed points
      int emptyCount = 2;                         // e-stop generated if there are this number or fewer frames loaded
   
      double[] positions = [1.0, 0.5, 0.75];      // positions to reach
      double[] velocities = [10.0, 20.0, 40.0];   // velocities for each position
      double[] accelerations = [4, 4, 4];         // accelerations for each move
      double[] jerks = [50, 50, 50];              // jerks for each move
      double[] times = [0.4, 0.2, 0.1];           // time deltas for each position
   
      axis.AmpEnableSet(true);
   
      axis.MovePVAJT(positions,                   // positions to reach
                     velocities,                  // velocities for each position
                     accelerations,               // accelerations for each move
                     jerks,                       // jerks for each move
                     times,                       // time deltas
                     points,                      // total number of points
                     emptyCount,                  // minimum frames before e-stop
                     false,                       // whether points are kept
                     true);                       // if this is the last MovePVAJT call (true = final point, false = more points expected)
   
      // wait for motion to complete
      axis.MotionDoneWait();
   
      Console.WriteLine($"Final position: {axis.CommandPositionGet()}");
      
      // cleanup
      Helpers.AbortMotionObject(axis);
  }
  // handle errors as needed
  finally
  {
      controller.Delete();  // dispose
  }