Lynxmotion AL5D Arm Inverse Kinetics reference material

The best theoretical analysis of inverse kinetics for the Lynxmotion AL5D robotic arm can be found here.

Furthermore, someone has already coded up the AL5D arm inverse kinetics code for Arduino.  I've ported this to Python and a quick test shows it appears to be sane (with some hack tweaks to make up for different initial angles of my servos), but I need to do more extensive testing.  I suspect the initial angles of my servos are different than most typical AL5D applications as I've set everything up to maximize reach for moving chess pieces, so I'll have to calibrate those angles into the code.

Arm Movement and Need for Inverse Kinetics

I extended my Arm controller Python program to be able to map and save the locations of chess board positions.

So here is a video of the "Mechanical Turk" arm moving a chess piece across the board using forward kinetics:

And here is the result of trying to move to another square:

Oops, I crashed into the board!  So I think I may have a go at calculating the inverse kinetics to avoid the arm from crashing into the board or (more likely) neighboring chess pieces.  The arm has to move the end effectors pretty much straight up a few inches to clear all the pieces, then it needs to move above all the pieces until it is directly above the destination square, then it needs to move directly vertically down.

I could probably heuristically do this with forward kinematics (for example, move up and down first by just using the elbow or such), but if I can get the inverse kinematics working OK it would give me a lot more control over the system.

Dorkbot SoCal @ Crash Space Sunday, June 9

Dorkbot SoCal 53

***** Sunday, June 9, 2013
***** 1:00pm to 3:00pm
***** Crash Space
***** 10526 Venice Blvd.
***** Culver City, CA 90232
***** (Directions)
***** No cover charge / donations to venue welcome

Come to Crash Space and learn about the hackersapce and some of their exciting projects:

Flipbookit
Mechanical animation kit.

 

Crash Library
Arudino-powered outdoor mini-library that tweets when people take out a book.



Crash Inspired
Mobile interactive night club experience - 2K RGB LEDs - on a truck - controlled with Twitter!

New end effector

I added a new end effector to "The Turk" arm.  The Lynxmotion Little Grip has screw holes for 4-40 bolts, so I added two pieces of copper pipe hanger that just happened to be the right thickness.