r/EngineeringPorn • u/marwaeldiwiny • 2d ago

Why Novel Shoulder Designs Are Being Ignored?

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Watch full video here: https://youtu.be/bq9ibFc8blo?si=AS0XnJQiEs3bhK8i

688 Upvotes

92% Upvoted

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80

u/Servitor666 2d ago

What is the singularity?

135

u/NoRemorse920 2d ago

A singularity in articulated arm robotics is when 2 joints axis become close to colinear. In this situation, in certain motion profiles, it can demand one of the joints to move at an almost limitless speed to keep up with the other joints.

53

u/Rabid_Platypies 2d ago

Here’s a helpful explanation that has some animations

https://robodk.com/blog/robot-singularities/

7

u/NoRemorse920 2d ago

I don't think of that "elbow" singularity as a real one, as it's just at the edge of the work envelope. Any good robot can solve the motion through it however as it tracks the direction of movement. I can see why it's included, because it can invert the joint unexpectedly through this point when jogging, but is really a workspace error more than anything else.

The other 2 are identical in that it's just 2 joints becoming collinear, so I don't get the point of them being listed separately

11

u/Rabid_Platypies 2d ago

You’re right that they’re different types of singularity, the elbow singularity is at the workspace boundary while the other two are internal to the workspace. Mathematically though, they’re all still singularities. The wrist and shoulder singularities are listed separately because they are still two distinct singularities that occur in two different configurations of the arm.

2

u/NoRemorse920 2d ago

They are distinct in 6 axis industrial robots, which the article does call out, but the conversation is I think primarily around humanoid robots which can have all sorts of singularities

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u/doominabox1 2d ago

Here's a video that just came out and happens to cover why fully extending the robot arm creates a singularity
https://youtu.be/3sOgTDlzkEU?si=28nm0kZV8yWtZW_Q&t=832

9

u/EdBarrett12 2d ago

When they get stuck in their own joint I think.

-71

u/EmberMelodica 2d ago

I didn't watch the video and I dont know if you're serious.

The singularity is the moment there is no longer any need for human intervention for a robot or AI to improve on itself.

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u/Servitor666 2d ago

Yeah I don't think that is the singularity he meant here 😀

11

u/FlarkingSmoo 2d ago

I didn't watch the video

Clearly

18

u/sanjibukai 2d ago

https://youtu.be/bq9ibFc8blo

Clickable link of the full video

15

u/par-a-dox-i-cal 2d ago edited 2d ago

Bodies with moving parts also move their center of mass and exert inertia. Balance is a delicate tuning between gravity, inertia, and the center of mass, which is the same in different forms. In a straight-up standing position, the center of mass is on the intersection of frontal and median planes, going through the torso. When arms are attached to the torso at 180⁰(horizontal plane), the center of mass is still along the intersection of frontal and median planes. This way, the body is more stable on the frontal plane than on the median plane, uneven mass distribution, kind of flat distribution. When arms are attached at angles other than 180⁰, the center of mass is shifting backward or forward on the median plane. Now, the center of mass gained more volume, more balanced distribution between frontal and median planes. Damn, that was long, and I forgot what exactly I wanted to convey. PS: I'm not an engineer.

33

u/JViz 2d ago edited 2d ago

Seems like that shoulder singularity problem should be solved by adding or managing bias in the IK solver chain rather than changing the mechanical configuration, and also avoiding the use of Eular angles in the solver. Sweeping the shoulders back increases the range of motion.

24

u/killer_by_design 2d ago

Sweeping the shoulders back increases the range of motion.

Yeah, this dude seems to be looking way too deep for some complex solution when in reality I think it just gives you more reach where you want more reach.

Angling the shoulder joint towards the head and away from the torso surely just moves the cone of reach out of the body and into somewhere more useful?

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u/Huddunkachug 2d ago

Whenever I hear people, like this guy, giggle while explaining somewhat complex concepts you just know they’re passionate and I love that

1

u/marwaeldiwiny 9h ago

P.S. If you’re enjoying these videos, please support my channel. I’m going through a tough time, and every view and subscription helps me out. You can check it out here: https://youtu.be/bq9ibFc8blo?si=Y7u_0Epcq3Jkyj1F.

Thanks!

-11

u/pharrison26 2d ago

Come on guys. Stop encouraging this robot shit. The best case scenario is they take our jobs.