Init Scaling — Resolving Dual-Solution Conflicts in End Mount Target Tracking¶
Target Tracking Resolved Bolt family BOTH
Summary¶
Target Tracking kinematics can produce two mathematically valid solutions for the same camera position — the rig can reach the target with the arm in two different physical configurations. When Flair cannot decide which solution to use, the camera may flip suddenly between configurations mid-move, or the move may refuse to build. The Init Scaling setting in Miscellaneous Setups tells Flair which solution to prefer at initialisation. This is particularly important in End Mount configurations, where dual-solution conflicts are more frequent than in Top Mount.
Symptoms¶
- In End Mount: camera unexpectedly flips to a different arm configuration during a move
- Target Tracking move builds correctly in Top Mount but produces flips or errors in End Mount
- The rig appears to "choose the wrong side" when approaching certain positions — arm inverts when it should not
- Two waypoints that look identical in the 3D view produce different physical rig positions
- Changing the camera mount from Top to End causes previously working moves to misbehave
Root Cause¶
Inverse kinematics (IK) for a robotic arm commonly produces two solutions for any given camera position in 3D space — commonly called the "elbow up" and "elbow down" configurations (or front/back for Bolt-family rigs). Both solutions are mathematically correct; only the physical arm position differs.
Flair must choose one solution at initialisation and then follow that solution through the move. If the initialisation is set incorrectly, Flair may start in the wrong configuration and flip to the other solution when it encounters a position where only the other solution is reachable.
End Mount exacerbates this because the camera's offset from the arm wrist is reversed — the sweet spot where both solutions are reachable changes, and the default Init Scaling (designed for Top Mount) may not be optimal.
Resolution¶
Adjust Init Scaling in Miscellaneous Setups¶
- Open Setups → Miscellaneous Setups (Classic) or Setups → Miscellaneous (Flair 7).
- Find Init Scaling (sometimes called Initialisation Scaling or similar — location varies by Flair version).
- Try different Init Scaling values:
- Positive value (e.g. +1): prefers one arm configuration at init
- Negative value (e.g. -1): prefers the opposite arm configuration at init
- Apply, then re-run the move and check whether the flip still occurs.
"Adjust Init Scaling in Misc. Setups to control which solution the kinematics prefers at initialisation." — Simon Wakley / Community (paraphrased)
Position the rig to avoid the dual-solution zone¶
If Init Scaling alone does not resolve the issue:
- Physically position the rig/track so the programmed move avoids the boundary between the two solutions.
- In End Mount, this often means:
- Ensuring the arm does not cross directly overhead or directly below during the move
- Keeping the target in front of the rig rather than behind it
- Placing track to the side of the subject rather than shooting straight along the track axis
Use Elbow Inversion safety awareness¶
If the arm does flip unexpectedly during a move: - This is related to the known Arm Elbow Inversion hazard - See AXIS arm elbow inversion DANGEROUS for safety implications and prevention
Arm inversion is a safety hazard
When the arm flips between configurations unexpectedly, it can move violently and unpredictably. Keep the area clear of people and fragile equipment when testing moves where dual-solution conflicts may occur.
WhatsApp Excerpts¶
"Init Scaling in Misc. Setups is the way to tell Flair which solution to prefer. Especially important in End Mount where the default may not match your rig orientation." — Community consensus
"Switching camera mount from Top to End changes where the dual-solution zone falls — always test Init Scaling after changing mount type." — Tom D / Community (paraphrased)
Related Issues¶
- See also: Arm Elbow Inverting / Camera Dropping on Forward Run — Arm elbow inversion hazard (same root cause: IK dual solutions)
- See also: Camera Orbital Incompatible with Roll Up for Vertical Orbits — Camera Orbital limitation (related: kinematics constraints)
Related Tutorials¶
Revision History¶
| Date | Change | Editor |
|---|---|---|
| 2026-05-24 | Initial extraction | Tom D / Claude Code |