Denavit–Hartenberg (DH) parameters are a convention used by robotics experts to mathmatically describe the size and range of a robot’s bones. Today we’re going to look at what they mean and how they’re used.
(more…)Today I’d like to show you how to use Gradient Descent to solve Inverse Kinematics for your robot arm with a practical example. I used GDIK to improve the movement planning of the SIXI robot arm and I was blown away by how much simpler it was to understand and implement. Read on to see how it works so good.
The Sixi robot arm can reach 80cm (31.5in) and carry 2kg (4.4lbs). That’s a lot of power and versatility! In the wrong hands it could be trouble. Here’s a list of things that you should NEVER do with a Sixi robot arm.
Some ideas we have tested under very strict safety guidelines to show you why they’re a bad idea.
Some ideas we read about… then we folded the paper and put it in a fire.
Look, I get it, secret agents are getting all up in your base. Please! Resist the urge. Your Sixi will get PTSD. Also, the Secret Agent union is really mean.
It’s all good clean fun until it isn’t, and then you can count only to 512. Segue: I want to point out the Bishop pulled an Andy Dufresne – before it was cool – and saved the remaining humans from that space hell. That should go on the DO list.
While we are all in favor of villainy, the human imagination is nearly limitless. Please don’t stab, slice, burn, scar, tattoo, shave, tenderize, cook, melt, or do other unpleasant things with humans, pets, or other living things. If you’re not sure what this means, draw a picture of what you want to do and show it to your parents or a lawyer. Do they approve? Cool.
Remember: all accidents can be traced back to at least three mistakes. A little paranoia is totally acceptable here, it’s okay to let it off leash here.
If you’re still not sure if your task is safe (or how to do it safely), ask in our forums.
This will only get better with time. I’m currently coding a way to record & play back the sixi simulation.
Oh! If only I had a kinect bar! I could put the point cloud into the simulation, and then the driver could see the block in the app. I will have to settle for a raspicam and VLC on the local net.
After nearly a week of screaming at my monitor, I finally got a new system for rotating and translating Sixi2’s hand.
Which (technically) worked, but was super hard to do well.
In the future I may even remove the need for the shift key so that everything can be done with a mouse or a touch pad or maybe even a sip+puff.
I tried several things that didn’t work out, like using OpenGL’s Select Buffer. I also notice the rotation handles don’t stay inside the grey circle when they are in the far corners of the screen and I don’t have an answer for that yet.
If you want to read the code in the open source project, start in org.marginallyclever.robotOverlord.DragBall
Also much love to https://www.scratchapixel.com/. Their 3D graphics tutorials kept coming up when I searched for things I needed in Robot Overlord. If you want to learn 3D graphics it is a clean, simple, effective resource.
