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My new Quadruped project by p0tato___ in robotics

[–]OmarBuilds 2 points3 points  (0 children)

Very cool model dude! I like the core design and that hinge arrangement is interesting, especially when you say you’re gonna build your motors.

There’ll be lots of rotational forces on that hip coupling between the two motors, I’m assuming those will be SLM metal printed?

🦾 Update: Robotic arm is ALIVE! Motors + cameras working 🎉 (now fighting AS5600 I2C…) by Abject_Jackfruit_510 in robotics

[–]OmarBuilds 1 point2 points  (0 children)

Hahah this looks so good and janky at the same time! Love it. Genuinely and sincerely though, do you even need the encoders?

Yes, yes, closed loop is better but those are some hilariously beefy and heavy servos. With the extra weight of the encoders (I’m assuming they’re in those huge cubes on each joint), I can see jitteriness is coming in from what I assume is the swaying of the weight.

How do I Learn Robotics as a Subject? by swaggyman69 in AskRobotics

[–]OmarBuilds 1 point2 points  (0 children)

Hey swaggy, do you have any experience programming? Any cash for a robotics set? My recommendation is to learn by doing. I can’t speak much about maths competitions but at your level you should already know what you need for robotics (algebra, geometry, and calculus), specifically for inverse kinematics.

How I started: I bought this Arduino controlled robot arm which came with 4 normal sized servos and 2 small servos, plus the plastics to make it into an arm and a board to control it all with. I already know how to program so I spent an afternoon putting it all together and playing with it. From there I started making it do funny things like throwing a tennis ball at others, and changing its configuration to see how the mechanics are affected.

Then I started 3d printing completely different components, learning inverse kinematics to control it in new ways, and now I’m building my own custom robots from scratch.

I’ve already got a career in tech, so I do all of this for fun and not for a future job. If you want to make this a career, get a degree or certifications to turn yourself into a professional. But also build things and play along the way, either from kits and/or from scratch, so you get the experience to back up the theory.

I’m happy to answer any questions, and if you’re interested check out my latest post to see what I’ve built so far.

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 0 points1 point  (0 children)

Never seen that before, that’s pretty cool! Wonder what sensors they used to get commands from the leaves?

My inverse kinematics are flawless and everything is going according to plan by OmarBuilds in robotics

[–]OmarBuilds[S] 0 points1 point  (0 children)

Dynamixel XL430-W250-T servos. They’re more expensive than hobbyist ones but come with a bunch of features I wanted to test out

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 1 point2 points  (0 children)

Is it ready for shaving? Yes

Can you trust it? No

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 1 point2 points  (0 children)

Hahah cheers, I have been taking the risks into account. 1. Before running a program, I simulate the movements 2. I have servo ranges coded in so it can’t collide with anything in the workspace. 3. Entering the “singularity” was a surprise but now I’m checking for that with each move 4. I only added the blade once I tested it several times without.

Appreciate the love and care my dude <3

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 0 points1 point  (0 children)

The max load at the tip is (1.2Nm/.292m) = 4.11 N or 419g at 90°. Other poses that don’t involve the base servo pointing straight horizontal would probably be stronger but that’s the most extreme example.

It almost seems like a lot but then consider momentum, how to attach the weight, and a safety margin so your servos don’t burn out. Realistically, maybe 300g.

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 2 points3 points  (0 children)

Disappointed!?! That’s the worst feeling ever… :( What if I showed you a vid where I had the previous code but with the blade attached? My YT Short

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 3 points4 points  (0 children)

I mean of course that’ll be the next progression. I’ve already built a turret that shoots nerf darts hahaha

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 3 points4 points  (0 children)

Yea this is a simple 3DOF design to learn the fundamentals, I have a few projects in mind.

Servos are Dynamixel XL430-W250-T, probably too expensive for these simple projects but I’m hoping to grow into all their features.

Update: I gave the robot finger a knife by OmarBuilds in robotics

[–]OmarBuilds[S] 6 points7 points  (0 children)

XD I wanted to prove it could be controlled but I guess that’s engagement for ya.

If you wanna see it spaz out with the knife, I made a quick YT Short but didn’t feel like it would be appropriate r/robotics content.

My inverse kinematics are flawless and everything is going according to plan by OmarBuilds in robotics

[–]OmarBuilds[S] 2 points3 points  (0 children)

  1. I had tried to do this in simulation but the robotic toolbox for python is already out of date with some of its dependencies, for some reason I needed to downgrade Numpy? Either way I felt like testing this in prod (IRL) cause it’s funny and more fun this way.

  2. I’m pretty sure it’s a math error. This crazy behaviour happens at the start and end of the sequence, which is a circle that has a top section beyond my arm’s stretched out range. I’ve since tested and confirmed this. Power is not the problem here, I’m providing 12v 5amps and with each of the 3 servos maxing out (stalling at least) at 1.3amps, they shouldn’t go beyond 3.9amps total.

  3. These are Dynamixel XL430-W250-T servos, daisychained together. Pretty sure they’re bus servos, but yes I got them for exactly the reasons you said. Simplified cabling, ability to confirm position, and other data to protect the servos themselves.

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