Simulating Endoscope Tip Articulation with Obi Rod - Seeking Implementation Advice
I'm developing an endoscopy training simulator and need to simulate a flexible endoscope using Obi Rod (due to the torsion support) that interacts with an organ Obi Softbody. I'm looking for guidance on the best approach to implement the endoscope.
Real endoscope Behavior
An endoscope consists of:
- Flexible insertion tube (~160-180cm): Can be pushed, pulled, and rotated along its axis
- Articulated tip section (~10-15cm): The distal end that can bend up to 180° in four directions (up/down/left/right) using control knobs at the handle
- Key characteristic: The tip bending is mechanically isolated from the main shaft via internal pull-wires. When you deflect the tip, it doesn't create relevant opposing forces in the insertion tube body.
What I Need to Achieve
1. Independent Tip Deflection
- The tip section (last 10-15cm) needs to bend smoothly and progressively in response to user input, creating a U shape where the tip points back towards the endoscope shaft
- This bending should NOT propagate forces backward into the main insertion tube. I've done some tests changing particle velocities to shape the tip, and due to the constraints, the rest of the shaft ends up moving while bending its tip.
- The tip can be undergoing a tip deflection while the entire scope is simultaneously being pushed/pulled/rotated, as the endoscope may be moving while the tip is being deflected or held while keeping a specific deflection value. Due to this, freezing the particles to avoid force propagation is not an option, as the endoscope still needs to moove freely.
2. Physical Connection
- Despite the mechanical isolation of the articulation mechanism, the tip is physically part of the same tube
- The tip must follow when the body is moved (pushed, pulled, or navigating through the organ)
- Both sections should interact with the environment (organ walls) naturally, which is a Obi Softbody with surface collisions
3. Roll/Twist Propagation
- When the insertion tube is rotated/twisted at the handle, this rotation should propagate all the way through to the tip, which already happens thanks to rod behaviour.
- This is separate from the tip deflection - the tip can be both deflected AND rotated
Questions for the Community
Main Question
What's the best approach in Obi to implement this articulated structure where the tip can deflect independently without forces propagating to the body? I've done several test and thought of several implementations
**Option A**: Single Obi Rod
- Modify particle velocities/positions for just the tip section
- Somehow prevent forces from propagating to the rest of the rod
- How would I achieve force isolation in this case?
**Option B**: Two Separate Obi Rods
- Body rod + Tip rod connected via ObiStitcher (or other method). Attachments seem too rigid for my needs.
- Apply deflection forces only to the tip rod, and propagate roll from body to tip rod manually?
- Does stitching provide any means for force isolation, or do forces still propagate?
**Option C**: Different approach entirely?
- Is there a better way to handle this in Obi that I'm not considering?
- Custom constraints? Different actor types?
Any advice on architecture, implementation approaches, or Obi best practices for this type of articulated simulation would be greatly appreciated!
Thanks!
I'm developing an endoscopy training simulator and need to simulate a flexible endoscope using Obi Rod (due to the torsion support) that interacts with an organ Obi Softbody. I'm looking for guidance on the best approach to implement the endoscope.
Real endoscope Behavior
An endoscope consists of:
- Flexible insertion tube (~160-180cm): Can be pushed, pulled, and rotated along its axis
- Articulated tip section (~10-15cm): The distal end that can bend up to 180° in four directions (up/down/left/right) using control knobs at the handle
- Key characteristic: The tip bending is mechanically isolated from the main shaft via internal pull-wires. When you deflect the tip, it doesn't create relevant opposing forces in the insertion tube body.
What I Need to Achieve
1. Independent Tip Deflection
- The tip section (last 10-15cm) needs to bend smoothly and progressively in response to user input, creating a U shape where the tip points back towards the endoscope shaft
- This bending should NOT propagate forces backward into the main insertion tube. I've done some tests changing particle velocities to shape the tip, and due to the constraints, the rest of the shaft ends up moving while bending its tip.
- The tip can be undergoing a tip deflection while the entire scope is simultaneously being pushed/pulled/rotated, as the endoscope may be moving while the tip is being deflected or held while keeping a specific deflection value. Due to this, freezing the particles to avoid force propagation is not an option, as the endoscope still needs to moove freely.
2. Physical Connection
- Despite the mechanical isolation of the articulation mechanism, the tip is physically part of the same tube
- The tip must follow when the body is moved (pushed, pulled, or navigating through the organ)
- Both sections should interact with the environment (organ walls) naturally, which is a Obi Softbody with surface collisions
3. Roll/Twist Propagation
- When the insertion tube is rotated/twisted at the handle, this rotation should propagate all the way through to the tip, which already happens thanks to rod behaviour.
- This is separate from the tip deflection - the tip can be both deflected AND rotated
Questions for the Community
Main Question
What's the best approach in Obi to implement this articulated structure where the tip can deflect independently without forces propagating to the body? I've done several test and thought of several implementations
**Option A**: Single Obi Rod
- Modify particle velocities/positions for just the tip section
- Somehow prevent forces from propagating to the rest of the rod
- How would I achieve force isolation in this case?
**Option B**: Two Separate Obi Rods
- Body rod + Tip rod connected via ObiStitcher (or other method). Attachments seem too rigid for my needs.
- Apply deflection forces only to the tip rod, and propagate roll from body to tip rod manually?
- Does stitching provide any means for force isolation, or do forces still propagate?
**Option C**: Different approach entirely?
- Is there a better way to handle this in Obi that I'm not considering?
- Custom constraints? Different actor types?
Any advice on architecture, implementation approaches, or Obi best practices for this type of articulated simulation would be greatly appreciated!
Thanks!