Will, I your last video you mentioned reverse schematics to get smoother arm movements. Could you point me to some info on that or quickly explain what that is? I tried looking it up but found nothing useful.

Actually, it's called IK (Inverse kinematics). If you watch this video where I am moving the mock-up of a real leg (3 servos) with a virtual (computer model).

We animate in ARC by using FK (Forward Kinematics) As we move a joint like say a shoulder joint all the other joints like the elbow and wrist follow too as they are attached to the shoulder. In IK, if move the hand by pulling on it, some basic trigonometry is used to determine where the elbow and shoulder rotation will go. Like a real arm.

In IK and robotics, you are creating complex motions that would be difficult to animate by hand.

The best way to imagine this on your B-9, is to have a virtual B-9 model in the computer, and use your cursor to grab the claw and pull on it... your real robot would move his arm out and follow the same motion path that you are doing with the cursor in the computer. The power comes in, as you record that motion live!

There is an object called a "goal or end effector". This object can be anything like a cube or some other object in the computer. In my video its just a small cube. Then there is the IK chain. Imagine the IK chain as being like bones in your arm. As you move the goal the "bones" will try and follow that goal. But they must follow the rules you put into place. As an example, your actual elbow cannot move backward. Same thing for your joints (servos) on your robot. So the arm will try to follow this goal object AND follow the rules and restraints you have set up on your servos (i.e 1-180). The IK chain can never move beyond the limits you have set. All in all, it allows you to record very very complex animations with little to no effort. AND with animation curves, you can very easily edit your motions after recording, fine-tuning your animations, and creating the perfect easing in and easing out.

My experience on robots as big as ours is that ARC doesn't know what size your robot is.  It applies the same rules to every joint. Move from point A to B in a linear motion path as fast as you decide to move it..but with the mass and weight of big robots, you need to have control over acceleration (ease in and out). I think that is why you are using the kangaroo, the ease in and out that is built into the firmware?!

I have a demo video coming up soon, that tackles this issue.

Just realized I didn't make a comment yet. Amazing video Will!

The production value of Thirsty Wars was top-notch, I don't think I've ever seen a video that great in the DIY robotics genre! Loved episode 8 too

Thanks for the detailed explanation Will. You made it very easy to understand this concept. I'm looking forward to that demo video you mentioned on this subject.

Also, yes. The Kangaroo makes the movements it makes look realistic by easing in and out of the movement. I've been calling this effect ramping. However our meanings (easing and ramping) seem to be the same.

Yes, indeed ramping and ease in and out are the same meaning! Glad that was a bit clear. Hard to describe functions in writing. Yeah, I have something very special to demo

Hey, I also realized I just commented only over there on YouTube...this episode was such a great ending to a great first season!! Looking forward to the show evolving!! You are such a great host!!

Will, I have been a subscriber for a while, and totally enjoy your work.  You provide great detail, keep up the great work. Steve S

I've been messing around with speeding up the arm movement on Arbee. I like this animation speed and smoothness, plus he can get drinks poured faster!