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Archive for May, 2013 - Page 2
Posted by Jack Crossfire | May 14, 2013 @ 03:08 AM | 6,626 Views

The 1st board which didn't have any defects. It worked on the 1st power up. It makes sense, because after that, you realized you didn't have as much money as you thought you did.
Posted by Jack Crossfire | May 13, 2013 @ 02:05 AM | 6,609 Views
Posted by Jack Crossfire | May 11, 2013 @ 04:43 PM | 6,083 Views
Jaron Lanier Asks Who Owns the Future?

Interesting commentary on how the information economy has caused a new feudalism & deterioration in human wellbeing. Key to the new feudalism is the "big computer," a computer which has a massive collection of private data: bank statements, browsing history, private photos, private relationships. In the past, it was benign, but now the information is being turned into profit, the largest source of profit in all history. The big computer uses your private information & ever more advanced algorithms to direct advertizing, collect bank loans, trade stocks.

The problem is the big computer is not a democratic technology & never will be. Only a very small number can exist, since you would never share your private information with John Smith the taxi driver. That information is only for the most powerful, prestigious, trusted people in the world: Google, Facebook, JP Morgan, Bank of America, your government.

You can't effectively trade real estate because you don't know where the rich people live, but ah, Google does. You can't become a wedding photographer because you don't know who's banging who, but ah, Zuckerberg does.

A case in point was Facebook buying Instagram for $1 billion. 1 very trusted guy aggregated the private memories of a lot of people on a big computer & sold it for $1 billion, so the $1 billion of value that originally belonged to a lot of people was...Continue Reading
Posted by Jack Crossfire | May 11, 2013 @ 12:57 AM | 4,491 Views
Optical flow insanity (8 min 0 sec)

Flying waypoints over the floor pattern, using pure optical flow odometry & sonar: any altitude seems very stable, over the pattern. Stability over carpet, with some manual intervention: 0.5 meters is all you get, over carpet. At least the MB1240 does an excellent job managing altitude over any material.

Went back to position->velocity->tilt feedback. That was done in 2007, then changed to position->tilt in 2008, when GPS got good enough. For indoor navigation, position->velocity->tilt feedback seems to be better. Originally saw position->tilt in Mikrokopter when it was open source, thinking it was going to be the standard design. That might explain the lifetime of toilet bowl effect.

Vision guidance doesn't have doppler shift. Also, the IMU drifts too much to clamp tilt at a reasonable value. You have to clamp velocity so a long movement doesn't go out of control.

Increased the frame rate back to 50. There is always a hunt for the highest frame rate before the minimum speed becomes too high, yet not too slow to have too much error. Those improvements made it pretty damn stable.

The room will most certainly now be leased by someone, now that the floor pattern is taped down.

Posted by Jack Crossfire | May 09, 2013 @ 11:12 PM | 4,311 Views
Boeing offers voluntary buyouts to employees in its space division

Drone maker AeroVironment sputters as defense spending dries up

Raytheon announces plans to eliminate 200 jobs

So avoid LA if you want to be employed. With the civilian layoffs & 6th consecutive year of downsizing, the area around LAX must be a ghost town, by now. Getting paid to design drones is now so competitive, you end up with a lot of experience that must be thrown away because you don't have the right degree & now they can ignore anyone who doesn't have an MS in CS just to fill the garbage bag unrolling position.

It never was supposed to be more than a hobby, but you always get caught up in just the news you want to see. In our lifetime, there probably won't be a practical use of drones outside of life or death military scenarios, because

#1 the energy storage technology doesn't exist. All 600 battery breakthroughs since the LiPo haven't amounted to anything. Even A123 Lithium Phosphate cells went away.

#2 The energy involved & reliability of the components to make something fly autonomously are too dangerous for an unattended appliance or require too much skill to manage.

There is always the environmental science, a very small market. There will be a boom in autonomous toys, but only generating very low Chinese wage level profit.

This hobby originally came from a desire to work on space vehicles. latimes.com had a word about that, too. Boeing...Continue Reading
Posted by Jack Crossfire | May 08, 2013 @ 11:54 PM | 5,878 Views

There were some cheap optical flow floor covers at the dollar store. Unfortunately, there's not enough room in the apartment to paint them. It takes 3 to create a reasonable flying space.

No better than unrolled garbage bags, but the most compact material. Can't imagine who would ever use them as table covers.

...Continue Reading
Posted by Jack Crossfire | May 08, 2013 @ 01:43 AM | 6,018 Views

These died, yet again. They're 27 years old. The right speaker finally became disconnected. They were originally $80 + 7.25% tax. Now, they're $55 + 10% tax. They are the best sounding phones of them all. Very clear at all frequencies.

They are the perfect tightness. The head band only gets painful without a mane. They were shredded from wearing glasses. Eventually they'll need new ear pads, maybe some RC foam.

...Continue Reading
Posted by Jack Crossfire | May 07, 2013 @ 11:26 PM | 6,622 Views
Half pixel or full pixel motion searches in optical flow is a highly contested issue. Half pixel takes a lot more software & clockcycles. Optimizing it to run on a pinhead takes a lot of coding.

The same thing can be done by doubling the camera resolution, doubling the focal length, halving the frame rate, or averaging all the motion vectors. It's really a logarithmic search at double the resolution. It's only effective when all other options have been used & you need the last bit of accuracy.

Optical flow has a problem where movement isn't detected below a threshold, but there's always wobbling movement above the threshold. There might be long term accumulations of movement that only half pixel can detect.

The next problem is at high altitude & small derivative size, you get oscillations. The gyro timing & optical measurements aren't accurate enough to get rid of angular movement. You need a derivative that gets longer with increasing altitude.

Optical flow is believed to have 2 weeks of life left in it. It would only be useful for job interviews, after that. It might have some use, augmenting GPS. It would only work in daylight, at low altitude. GPS in an urban environment has never improved. It's always going to need something.

It might have some use augmenting a front facing camera for absolute positioning, indoors. Absolute position with downward optical flow & front facing object matching might end up the way indoor navigation is done.

It's still the only method which can be completely independent of any navigational aid. No satellites, no ground based camera, just a textured floor.
Posted by Jack Crossfire | May 07, 2013 @ 03:52 AM | 9,184 Views
Opening the recruiter spam for the 1st time since the college application revealed the same old wank words, every buzzword ever known required to apply, but it would have been the same, even after another degree. Each of those positions is getting many applications & they're very undesirable jobs.

The job market & your lack of money can make you feel like you've lost your way, gotten distracted by robots & electronics that can't possibly be useful without a formal engineering degree. Then you saw a blog post by a coworker you consider to have the kind of focus on software that someone with formal degree in CS & not engineering needs to have.

"maybe itís because I havenít written enough code in the last few years"

So what would you see if you saw yourself from a 3rd person for the last 3 years? You would see a skinny guy spending 12 hours, 7 days a week, sitting at a computer. Most of the productive time is programming. Sometimes Eclipse is running with an Android project. Sometimes a text editor is running with a C/C++ project.

There is a lot of time laying out boards & fabricating, but every project is designed to rely on software to get the most out of the least amount of hardware. It's not the 100% focus on software of 1999, but it's not a total shift to hardware, nor is it obviously far less than those who are gainfully employed in software.

You're not investing in any relationships. Your destiny was not to get married. The coworker also got a few cases of wine. You're not an expert in wine like everyone else, because you can't afford it, not because of beliefs.
Posted by Jack Crossfire | May 06, 2013 @ 05:16 AM | 4,509 Views
As expected, I was rejected from the EE program. That was a competitive program. Since it was the only 1 in the state for 2nd BS degrees & so many people are unemployed, it was probably more competitive than for high school students in 1993.

I thought long & hard about selecting CS as an alternative, but jobs for CS majors don't normally require the formal degree like EE jobs, just learning the language of the week. It would not justify the amount of debt & time required. There was the idea of getting into any easy program, then transferring to EE, but I suspected that wouldn't be possible for 2nd BS degrees.

Then there was applying elsewhere, out of state, or private schools. It wasn't considered a high enough priority to justify the extra money. There's applying elsewhere next year, but a new degree gets rapidly less valuable after 40.

So there will be no move to the southland, no living 30 miles from Jesus Heroine again, no going back into debt, no $1400 rent, no nightly runs to the beach, no goofing off in school for 2 years, no larger apartment, no gold coast, no weekly drive to Venice beach. I considered moving there no matter what, but the rent & cost of moving ended up simply unaffordable. Job hunting revealed there aren't any jobs there like Silicon Valley. What there is much more often requires the formal degree.

No matter how much you logically know the only possible outcome, you still somehow get into a mindset that you're going to be...Continue Reading
Posted by Jack Crossfire | May 05, 2013 @ 02:20 AM | 5,102 Views
Finally put sshdroid on the tablet. That includes some busybox tools.

ssh [email protected] -p 2222

Unfortunately, sshdroid doesn't have all the tools. You still need to copy some files from busybox non-root.


It has some very useful tools:

vi, xz, ifconfig, iwconfig, free, wget

vi is much easier for config file editing than the graphical text editors.

Modern Android products get software updates for 1 year & that's it. The last version of Android they port is what you get, bugs & all. Unlike the days of generic operating systems on standard computers, it takes too much work to port Android to a gadget for it to forever be supported.

We've gotten to a point where consumers own very little of the gadget they pay for. You can't access all the data on it. You can't install anything on it that's not approved. There aren't the open source projects for phones that there are for servers. There isn't the overwhelming interest in having full ownership of software that there was, 20 years ago.

There is no way to root the Transformer Prime anymore. They hardened most devices over the years until rooting no longer worked. The mane need was to get at the application data, but users also wanted to disable adsense, which The Goog wouldn't tolerate.

All the email apps store your email in private directories. The only way to get that data is now

adb backup -f mybackup.ab -all

That copies the entire flash to a PC, where it can be extracted. http://nelenkov.blogspot.com/2012/06...d-backups.html

The relevant command was:

dd if=mybackup.ab bs=1 skip=24|openssl zlib -d > mybackup.tar

Sadly, the email is not in a decipherable format. Reading it will always require having the working gadget & backup file around. There might be a way to restore the backup file to an emulator, but the official emulator never worked.

It's interesting to see how an application you wrote actually stores its data, since this is all normally hidden. Preferences are stored in an XML file.
Posted by Jack Crossfire | May 04, 2013 @ 04:59 AM | 4,329 Views
So another idea to make something more crash resistant ended up another bodge job, but it was slightly less fragile. Noted the power output with brushed motors varies greatly between aircraft. This one had a lot less power.

The 1cm accuracy of the MB1240 made no obvious degradation to the altitude. It was much better at 1m altitude than the MB1042.

So now there are differences between exact copies of aircraft & there are some with internal guidance, some with ground guidance, necessitating many different config files.

They're now stored in /sdcard/DCIM/copter/ on the tablet & copter/ on the PC. There are so many parameters, having an Android user interface for configuration isn't practical. It's easier to edit a text file, but the Android file manager can't open .conf files in a text editor & you don't want to call them .txt files. You need a text editor with its own file picker to open it.

Finally, having a PC ground station allows video screen capture for debugging, but no tactile interface for manual mode. Having the Android ground station makes it much easier to give demos, but configuring wifi after every reboot is very time consuming. There's no way to force it to use 1 access point.

Porting changes between the 2 ground stations is a buster. It's about time to start using a preprocessor to share code.
Posted by Jack Crossfire | May 03, 2013 @ 10:42 PM | 4,549 Views
With 9V batteries heading to $10 & beyond, it was time to convert the scale to a Lipo. Its alkaline Won Hung Lo battery lasted 3 years, mostly in standby, but you don't have any money anymore for a new battery.

It uses 10uA in standby mode & 15mA when on. The battery warning comes on at 5V & it runs at over 8.4V, perfect for a lipo.

There is a steel lever mechanism transferring most of the weight of the enclosure to 4 feet & some of the weight to a steel flexing bar.

That is a real nice LED panel. There is a larger LED panel on a clock, suitable for scavenging, in the apartment. There was once a desire to make a large, GPS speedometer out of one.

...Continue Reading
Posted by Jack Crossfire | May 03, 2013 @ 12:39 AM | 4,693 Views
So the ultimate voltage regulator died, the moment the motors were started. What probably happened is back EMF spiking the battery over 6V. The MIC5353 only goes to 6V. The MIC5205 goes to 16V & didn't have a problem. So put high Vin on the list of requirements & forget about hooking a camera directly to a battery.

MIC5237 0.5A 16V 300mV TO-263

MIC5239 0.5A 30V 350mV MSOP-8 3x5, SOIC-8 4.93x6, SOT223 7x6.5

LT1763 0.5A 20V 300mV SOIC-8
Posted by Jack Crossfire | May 02, 2013 @ 05:46 AM | 5,363 Views

So that is well into its software debugging. You'd be amazed how much debugging is required just to clone something that previously worked.

The MB1240 is being used on this one. With its oddly placed transformer, it needs to be mounted in a sub optimal place.

...Continue Reading
Posted by Jack Crossfire | May 01, 2013 @ 04:44 AM | 4,551 Views
Another revision of the Marcy 2 flow board was spun. It's a tried & true autopilot, the smallest capable of downward looking optical flow. The mane change was including the microcontroller hack required for I2C. That was a real surrender.

The other change was using the mighty MIC5353, a super regulator in a bastard 1.6mm, 0.5mm spacing, leadless package. That outputs 3.3V 500mA with only 200mV in voltage drop, enough to drive wifi on a dead battery & hopefully present a less noisy voltage for sonar. The green tech movement has drastically improved voltage regulators.

Then there was the star routing that caused many days of torment. It still has no reverse voltage protection or motor capacitor.

Shouldn't use magnet wire for jumpers on the top. It's not insulated enough to contact anything but itself.

Anyways, the Marcy 2 flow system was yet another autopilot to require rotating the cyclic to defeat the toilet bowl effect. This has happened on every autopilot. They all need 25-45 deg of cyclic rotation. Without it, they're stable for a while, then get kicked into a toilet bowl pattern. There's no logic for it to happen on a quad.

The best idea is the lead compensation has a resonant point it sometimes hits & giving feedback that's not totally symmetric to the motion is a way of dampening the resonance. It makes the translations less accurate, but makes the hovers much more stable. Haven't seen it or the lead compensation on any other autopilot. They just rely on the extremely tight GPS modules that came after this algorithm was written. They use the Mediatek & uBlox 6.

Without lead compensation, toilet bowl effect was guaranteed.