He can see! What was just an arm is now a partial upper body. This time the head is not so humanoid but more insect like. I didn't really do that on purpose, it just sort of happened because I needed an optics array capable of video based vision, multi-colored spot lamps, and photo sensors, and since form follows function, it received four eyes!
Output Card
Specifically this circuit board is an 8 Channel Servo Driver and 6 Channel Digital Output Card. Like the digital output card used for the arm, this one is also addressable and connects to the same serial communications node.
It's also my first board to operate on an interrupt basis. All my other addressable cards are constantly listening for serial instructions causing them to run their primary code much more slowly than is possible. But this one runs it's code uninterrupted and only prepares to recieve instructions when it's Ready-To-Send (RTS) pin goes high. So basically, from the computer side, before I transmit a packet, I raise the RTS pin on my serial port, then this board will receive the instruction, then when the serial code is done transmitting and the pin goes back low, the board implements the instruction and returns to its steady state operation. This is how all my cards should work but was never really necessary. Well this time it was necessary because this board has to drive servos which require a very steady and precise square wave. And the only way to get the board to run fast enough to be able to vary the width of the pulses (PWM) to control the servos was to program it this way.
The Neck:
Using the mechanical principals learned from the arm, I was able to develope a similar lead screw type actuator to move the neck so I wouldn't have to drop more money on junk yard car seat components. While making my own ended up yielding a slower mechanism, it saved me 15 bucks and a crazy amount of time trying to dissasemble the junk yard car seat frame. So to make this work, by complete luck, the thickest piece of threaded rod from Lowes just happens to fit into the aluminum sides of medical Crutches (I was donated a bunch because they are a good source of free aluminum). And If you punch holes into these aluminum tubes, the area of reduced diameter can become threaded when force turning the rod into it. And bam! You now have a hydraulic like actuator to raise and lower the head.
The Head:
This head is not human like, but is still considered anthropmorphic because even though it has pincers and 4 eyes, it still has the mouth and eyes in the anatomically correct place and because of the eye brows, it can relay the notion of various emotional states.
Related Videos:
In this video I am testing out all the motors. You'll see right at the very beginning that the neck does
not move up or down despite the lead screw turning, this is because right before shooting this video the
stop-pin sheered off, but this is fine because I will probably be abandoning this neck design as it is
too flimsy.
3/3/10: Neck V2.0
I pretty much hated everything about the quality of the first neck. It was flimsy, thin,
and shaky. Not to mention it's response time on the head turning axis was horrible. It
was weak too, infact in the above video you can see one of the axes not functioning, so
of course I built one that was to my standards.
Another Motor Controller:
Here is another one of the modules used to drive the motors. You can see the automotive
relays and the driver circuit. I think my design on these is getting very refined as they
are looking better and better each time.
The Head Mount:
This is 100 times better than the previous one. It can hold much more weight, it's optically
encoded, has a wider degree of freedom, and stronger. Only down side, it's a little slower,
and that's only because it has more torque. The motor here is a dashboard climate servo/actuator from
a Hundai Sonata. They are wonderful little motors. I managed to mount Kinnex gears to the actuator
and the lazy suzan for a smooth rotation. I also have a newly designed optical encoder
attached to this setup. The encoder wheel has more divisions than any other on the robot so far
because this motor moves so slowly.
New Neck Assembled:
Here is the new neck mounted to the sholders. The up/down axis is driven by a windshield
wipper motor. Very strong, the platform can lift up to 15lbs.
11/1/09: Neck and Head
