Skip to content

Periscope / Borescope Gimbal Lock - Use Top Mount Style Setup

Summary

A Milo periscope setup can create a gimbal lock problem when the camera is pointing straight down and the pan axis lines up with the roll axis. The chat workaround was to turn off the periscope flag, treat the lens like a borescope/top-mount camera, enter the nodal and camera offsets as if the camera were directly behind the 90 degree periscope lens, and set the roll axis as a target tracking type.

This gave better Cartesian behaviour: no strange go-tos and no rumbling axes.

Symptoms

  • Flair warns that Target Tracking must be in Head Level.
  • Head Level would place pan directly in line with roll.
  • Operator expects gimbal lock when trying to track across a tabletop.
  • Periscope setup creates strange go-tos in Cartesian.
  • Axes rumble or behave poorly with periscope enabled.

Community Guidance

[CONFIRMED] Turn off periscope in lens setup

Simon Wakley advised turning off the periscope flag in lens setup for this scenario. Jeremy Andrews then drove the lens as if it was a borescope looking down, with lens pan controlled by roll, and reported that it worked well in Roll Up.

Confidence: 0.86

[CONFIRMED] Set it up like top mount with correct offsets

Enter the nodal and camera offsets as if the camera is directly behind the 90 degree periscope lens. This is not physically a top-mount camera, but it gives Flair a cleaner kinematic model for the lens angle.

Confidence: 0.82

[LIKELY] Use Roll Up and make roll a target-tracking axis

For this layout, the successful setup used Roll Up and set the roll axis to target tracking type. Test slowly and verify the shot path in Cartesian before running.

Confidence: 0.76

[FIELD WORKAROUND] For Raptorscope/periscope, use the imagined sensor position

For periscope-style lenses, one later workflow was to ignore the real camera-body position and imagine the camera body directly attached to the lens. Measure the XYZ offsets from the robot pivot to the periscope reflecting point, then choose the equivalent camera mount direction. This is a field workaround for exact 90 degree periscope orientations.

Confidence: 0.7

WhatsApp Excerpts

Timestamp User Evidence
2021-01-21 10:05 Jeremy Andrews "This would put the pan axis directly in line with the roll axis, and create 'gimbal lock'."
2021-01-21 10:07 Julian Hermannsen "I'd not set it up as a periscope but just as a top mount camera. Gives you a lot more freedom of movement."
2021-01-21 10:13 Simon Wakley "Make sure you turn OFF periscope in the lens setup."
2021-01-21 11:08 Jeremy Andrews "Turning off periscope and driving the lens through as if it was a borescope looking down ... works pretty nicely in roll up."
2021-01-22 02:51 Jeremy Andrews "No strange 'goto's' in cartesian, and no 'rumbling' axes. Periscope flag is 'off' in lens settings, and the roll axis is set to 'target tracking' type."
2026-03-30 00:06 Jeremy Andrews "I'm not using any probe settings at all ... camera sensor is actually the raptorscope 'reflecting point' measured away from Milo tilt and roll centre."
2026-03-30 02:09 Jeremy Andrews "You need to imagine that the camera body is directly attached to the lens, and that the sensor is the 'reflecting point' of the periscope."
2026-03-30 02:09 Jeremy Andrews "I would definitely only try this if you are rotating the raptorscope exactly 90 degrees in any direction."