Transition Between Moves

A transition mode must be specified when a new move is appended to a move that is already in progress.

Different transition parameters may be required, depending on the transition mode.
This characterizes the contour of the transition segment.

The supported transition modes are:

No Transition (TM_NONE)
Corner Distance (TM_CORNER_DISTANCE)
S-Curve Corner (TM_SCURVE_CORNER)

Transition Mode Parameters

Parameters	Number of Transition Parameter Array Elements	Transition Parameter Index	Transition Parameter Name	Transition Parameter Description	Units
TM_NONE	0	N/A	N/A	No transition.	N/A
TM_CORNER_DISTANCE	2	0	Corner Distance	Distance to the corner of the deviation and the return point from the original contour.	User units
TM_CORNER_DISTANCE	2	1	Velocity	The velocity value of the transition segment.	User unit/sec
TM_SCURVE_CORNER	1	0	Corner Distance	Distance to the corner of the deviation and the return point from the original contour.	User units

No Transition (TM_NONE)

Insert no transition contour segment.


Motion Path		Motion Velocity Profile

The motion blocks are not modified and no transition curve is inserted using this mode.
- This is the only possible transition mode for the Buffer Modes.
No transition parameters are used for this transition mode.

Corner Distance (TM_CORNER_DISTANCE)

Transition with given corner distance.


Motion Path		Motion Velocity Profile

The corner distance transition mode is specified using TM_CORNER_DISTANCE as the transition mode for a motion block.

Transition Parameter Index

Transition Parameter Index	Name	Description
0	Corner Distance	Distance to the corner of the deviation and the return point from the original contour.
1	Velocity	The velocity value of the transition segment.

Corner Distance transitions are handled differently, depending upon whether the connecting moves are lines or arcs, and all of the possible combinations, (line-line, arc-arc, line-arc, arc-line).
- Arc-to-Arc transitions shorten the arc with the larger radius by the corner distance.
  - See Arc-to-Arc Transitions.
- Line-to-Arc and Arc-to-Line transitions shorten the linear move.
  - See Line-to-Arc and Arc-to-Line Transitions.
- Line-to-Line transitions shorten the next move by the corner distance.
  - See Line-to-Line Transitions.

S-Curve Corner (TM_SCURVE_CORNER)

Transition with given corner distance, using Jerk for each axis profile.


Motion Path		Motion Velocity Profile

The S-Curve Corner transition mode is specified using TM_SCURVE_CORNER as the transition mode for a motion block.

Transition Parameter Index

Transition Parameter Index	Name	Description
0	Corner Distance	Distance to the corner of the deviation and the return point from the original contour.

All S-Curve Corner transitions start and end the transition with zero acceleration.
- If an S-Curve Corner transition is used with buffer mode BM_ABORTING and during acceleration or deceleration phases of the first move, then the axes experience an acceleration discontinuity at beginning of the transition.
Only Line-to-Line transitions are supported with S-Curve Corner.
- Line-arc, arc-arc, arc-line are not supported.
Line-to-Line transitions shorten the next move by the corner distance.
- See S-Curve Corner Line-to-Line Transitions.
Changes to the velocity override during the transition do not take effect until after the transition has completed.
S-Curve Corner transitions only depend on the corner distance, the incoming and outgoing move velocities, and the incoming and outgoing move directions.
- The transition may exceed the maximum specified values for velocity, acceleration, deceleration, and jerk of the incoming and outgoing moves.
  - Jerk and peak acceleration increase with a larger angle between the incoming and outgoing move directions.
  - Jerk and peak acceleration decrease with a larger corner distance.
To approximate the path peak acceleration and jerk during the transition, we can use these equations:
- V_avg = The average of the slew speeds of the incoming and outgoing moves.
- θ = The angle between incoming and outgoing moves.
- CD = Corner distance.
- If actual accel = k_a typical accel and actual jerk = k_j typical jerk, then:
  - k_a has an average value of 1 with a standard deviation of 0.5.
    Values of k_a have been observed as large as 3.
  - k_j has an average value of 1 with a standard deviation of 1.1.
    Values of k_j have been observed as large as 12.

The formulas are approximate guidelines.
Your application may experience different behavior.