Grisbot Design Studies

Posted on May 3, 2013 by engineerzero

side by side

Would grisbot look nicer if the battery was enclosed? I was hoping that I could cut down on the acrylic, but it doesn’t look that way.

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Grisbot ‘light above’ demo

Posted on April 30, 2013 by engineerzero

light_above_screen

In the ‘light above’ mode, when a flashlight is brought close enough to exceed user-specified light intensity (a), the robot will turn in place. When the flashlight is brought close enough to exceed user-specified light intensity (b), the robot will move forward in whatever direction it is pointing. Withdrawing the flashlight beam will cause the robot to stop and wait for new commands.

The upward-aimed photocell is plugged into the ATMega328’s analog input corresponding to A2 on the Arduino. I previously made a photocell ‘assembly‘ consisting of a photocell, resistor, and branching lead. However, when I tested it out, I discovered that the shadows of the servo leads would fall on the photocell and cause the robot to move in fits!

Here’s how the installed photocell assembly looked at that time:

DSCN2770

To preclude shadowing, I needed to elevate the photocell above the servo wires. Hence, I did some solder surgery to lengthen the photocell assembly leads, like so:

DSCN2771

With lengthened leads on the photocell assembly, the robot looks like this now:

DSCN2772

And so without further ado, this is how the ‘light above’ mode works:

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Book Review: Camelot 30K

Posted on April 28, 2013 by engineerzero

51NgNGjjVpL._SY300_

Camelot 30K, by Robert L. Forward.

Camelot 30K is a fascinating novel about a truly alien society of shrimp-like intelligent beings who live on an ice world far beyond the orbit of Pluto. If you like hard science fiction, you’ll appreciate Forward’s meticulous technical detail. If you like stories that take place in exotic settings, this outdoes Avatar.

This book may not be appropriate for children, as it discusses social taboos at length. Some might consider age fourteen to still be too young, but by that age your younglings (Lucas’s word, not mine) have probably seen much more already on the internet. However, unlike the internet, this book treats cultural issues philosophically rather than gratuitously. So actually, this might be a good book to give an older child.

Forward is often criticized for lack of characterization, but I really came to empathize with Merlene, his Wizard of Camalor, as a real person with identifiable emotions and motivations.

The plot was entirely believable — though if I were to explain it here in 25 words or less, you probably would be incredulous. But isn’t the mark of a good plot that it is simultaneously unpredictable and inevitable?

(Warning: Do not read the Kirkus Review on the Amazon page until after you’ve read the novel, as the mark of a bad book review is that it contains a spoiler.)

I like stories that lift the reader out of the mundane world and put you in a totally new world with its own rules and logic, where every sight and sound is different. If you’re looking for a blockbuster-movie-like Super Hero vs. Super Villain grudge match that takes place a few hundred feet above an American city, then you probably will find this book boring. If you find that grudge matches above American cities are coming to be a bit tedious and are looking for original sagas upon bizarre new worlds, then you might want to give this book a try.

It’s the most fun you’ll find below the freezing point of nitrogen, and if you truly are the nerd you claim to be then you know that’s high praise indeed.

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Grisbot One-Click Screen Flash Communications Demo

Posted on April 27, 2013 by engineerzero

Instead of needing three buttons clicked in order to ‘flash’ data, Grisbot now needs only one click. The only ‘tricky’ part is that when the robot’s LED blinks, you have to click at the same time.

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Grisbot Idea Map

Posted on April 26, 2013 by engineerzero

grisbot idea map

Based very closely on Mind Maps, the idea map is probably self-explanatory. I think up an idea for something grisbot could do, then another idea occurs to me, and I write that down with an arrow showing the lineage of inspiration.

As you can see, I ended up with some very un-grisbot ideas like a programmable alarm clock (which no doubt occurred to me at the time because I was randomly remembering that somebody is making a ‘programmable flashlight.’)

Anyhow, I decided it was time to quit and go back to working on my Scratch interface for the ‘above light’ procedure (or whatever I’m calling it at the moment). And that’s where I’ll be Friday afternoon . . . in the Land of Ideas.

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Hardware for Light Above Procedure

Posted on April 25, 2013 by engineerzero

When I was at Big-Brained Superheroes on Monday, I noticed that the kids were aiming the flashlight at the robot from above. So why not have a light-following procedure that responds to light shined from above?

After some somewhat sloppy soldering (keep telling yourself it’s only a prototype), I implemented this breadboard-hole-conserving design for a third photocell which will be aimed upward:

photocell3

It will fit into the breadboard like so:

bb

Tomorrow, I’ll try to get done with the computer/robot software to implement the light-above procedure. Demo to come.

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Grisbot One-Click Transfer

Posted on April 24, 2013 by engineerzero

I have been going with three buttons for the transmit procedure because I needed to calibrate light and dark rectangles before I could read the data. That made it cumbersome and confusing to use the transmit procedure.

Here’s how the old data transmit procedure went:

zzz2

1. Click the hi-cal button.
2. Turn the robot on and hold it up to the screen.
3. The LED blinks once, then twice.
4. Click the lo-cal button.
5. The LED blinks once, then twice, then once again.
6. Click the Transmit button and wait.
7. If the LED blinks twice, it’s a successful transfer.

I would have liked to have had everything done with a single click, but I knew that would require time synchronization between the robot and computer while reading the hi and lo cal rectangles, and I had troubles in the past with time synchronization.

But then . . . I realized that my troubles with robot-computer time-synchronization for data transmission involved mere milliseconds. In the calibration procedure, however, I was dealing with full seconds. The robot and computer surely can’t get out of time synchronization by a full second in only a couple seconds unless their relative velocity to one another is greater than 87% of the speed of light, in which case I have bigger problems.

So here’s how the new procedure goes:

one_click

1. Turn the robot on and hold it up to the screen.
2. The LED blinks once.
3. Click the Transmit button and wait.
4. If the LED blinks twice, it’s a successful transfer.

Instead of having to watch nine LED blinks and click three times, the user need only watch for three blinks and click once.

So simple a 57-year old can do it!

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Grisbot goes into the light

Posted on April 23, 2013 by engineerzero

At the Big-Brained Superheroes Club.

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Batteries: A Cautionary Tale

Posted on April 22, 2013 by engineerzero

screen trans

On Saturday, I took grisbot to the Seattle Robotics Society meeting and showed a demo video of the light-follow mode. After the main presentation, I got out grissy and tried to set up a real-time demo in case someone wanted to come by and talk.

Well, after all these months, suddenly the robot decided not to work. Every time I tried to transmit data from the screen to the robot, I would get a solid flash on the LED — the signal for a data transfer error.

And as luck would have it, somebody did come by to watch. But I had nothing to show him except one failure after another to do the most basic function of the robot. Is there a jinx or what?

Tonight, back home, I tested out a theory, and discovered the following:

battery vs plug

To put in words: the data transfers fine unless I’m using an old battery and have the computer unplugged. Then I learned the hard way.

And at that, while I have identified the physical cause of my problem (ie, old battery plus computer on battery power), I still don’t know the systemic cause (ie, why that causes transfer error).

On Saturday morning, I had left the apartment and realized in the car that I had forgotten to take a back-up 9v battery with me. I stopped to buy stuff at a store but forgot to buy a back-up battery. I stood outside in the parking lot and thought about it but decided not to go back. Nah, what are the odds?

So, Boeing, you have my sympathy.

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A Picture of Resistance

Posted on April 21, 2013 by engineerzero

is futile 02

(Images downloaded from Sketchup Warehouse. CREDITS: Log by Ferrari, shoes by best-lemming, tricycle by Taylor, clover leaf by Super Builder, gloves by MorBius, die by syicreations, calendar by HARBURCOMPUTERS, octopus by [green])

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