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Edge to Trajectory

In one sentence: Automatically generate a series of trajectory waypoints by discretising selected geometry edges at a specified point density.

Overview

Workbench: Robot
Menu: Robot → Edge to Trajectory
Shortcut: none

Deprecated workbench

The Robot workbench is deprecated as of FreeCAD 1.0.

Discretises each selected edge into evenly-spaced waypoints and populates the selected trajectory with them. Creates a Robot::Edge2TracObject that links the edge geometry to the trajectory — if the edges change, the waypoints update automatically.

Intuition

Instead of manually recording each waypoint along a weld seam or machining path, you select the edges of the geometry and let FreeCAD compute the evenly- spaced path points automatically. The denser the points, the more accurately the robot will follow the edge's curvature.

When to use it

  • Generating welding, painting, or machining paths from existing CAD geometry.
  • Creating inspection paths along part edges.
  • Any task where the robot must follow a geometric feature rather than visit discrete manually chosen points.

When NOT to use it

  • Complex 3-D curves requiring orientation control — Edge to Trajectory computes positions but uses default orientation. Use Dress-Up Trajectory to override orientations at specific waypoints.

Step-by-step

  1. Select the edges to follow (Ctrl+click for multiple edges).
  2. Also select a Robot::RobotObject and a Robot::TrajectoryObject.
  3. Choose Robot → Edge to Trajectory.
  4. In the task panel, set:
  5. Point distance — spacing between waypoints in mm.
  6. Minimum point distance — minimum distance to avoid clustering.
  7. Velocity — default velocity for generated waypoints.
  8. Click OK.

Parameters

Parameter Description
Point distance Target spacing between consecutive waypoints along each edge (mm)
Min point distance Skip points closer than this value to avoid dense clusters at junctions
Velocity Default velocity for all generated waypoints
Base frame Reference coordinate frame for the trajectory
Tool frame Tool frame used for all generated waypoints

Common mistakes and pitfalls

Too many waypoints — point distance too small

Cause: Very small Point distance on long edges generates thousands of waypoints, slowing down simulation and KRL export.
Fix: Set Point distance to 1–5% of the total path length as a starting point.

Waypoints don't follow the edge smoothly

Cause: Point distance is too large relative to the edge's curvature — the robot will cut corners.
Fix: Reduce Point distance, especially in high-curvature regions.

Python API

import FreeCAD as App

doc = App.ActiveDocument
e2t = doc.addObject("Robot::Edge2TracObject", "EdgeTraj")
e2t.RobotObject = doc.getObject("Robot")
e2t.TrajectoryObject = doc.getObject("Trajectory")
e2t.PointDistance = 1.0   # mm
doc.recompute()

See also