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Jack Crossfire's blog
Posted by Jack Crossfire | Jan 06, 2014 @ 03:24 AM | 2,788 Views



Everyone wants to hack a laser tape measure for aircraft navigation. It would indeed make a cheap, extremely accurate, reliable altimeter.

Today, it's the DLR130. It outputs at 1cm accuracy at 3Hz. You need 10Hz for flight, so maybe there's a way to speed it up.




It's very well constructed.


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Posted by Jack Crossfire | Jan 04, 2014 @ 05:10 AM | 2,547 Views



http://www.robotspodcast.com/podcast...episode142.mp3

It's not necessarily quad copter, but tractor based. Did not know Calif*'s mane crop was lettuce or that it produced any vegetables at all, since there hasn't been any rain since 2012. Though quad copters harvesting lettuce is a highly dubious proposition, there's certainly money to be made from tractors.

That guy was rich. Listening to him complain about the lack of PhD's from Stanford to design computer vision algorithms, you thought just stop being a dick & hire people who know how to design computer vision algorithms instead of insisting they have a PhD from Berkeley. Most of the discovering, inventing, engineering, living & dying in this town is done by makers & hackers working in garages. Yet another overstuffed taco salad supported by the federal reserve.

Your other thought was agriculture might actually become a big business as our generation believed 20 years ago. Unlike what we believed, the money is not going to biologists who study genetics, but to designers of robots & businessmen.

There are no jobs for biology majors who learned about robotics on their own, only for engineers who learned about biology on their own or businessmen who can track down farmers with bucks.

It's probably a supply & demand issue. Few people can pull off the engineering side & business side while everyone can do the biology part.

A huge aversion has emerged to the genetic engineering we thought would comprise most of the expansion in food supply. A lot of that is lack of knowledge about genetic engineering & movies, but whatever. For now, you can't use genetic engineering to feed Africa. That leaves using automation to expand the biological system we already have.
Posted by Jack Crossfire | Dec 31, 2013 @ 06:08 AM | 2,636 Views

http://www.the6thstreetbridge.com/commercial-shooting/

The sight of the 6th Street bridge in a music video made it unbearable to not do some running. It's the bridge of despair & the bridge of memories.

There was great despair to cross paths with the Jesus Heroine twice on it, a tiny fraction of a half marathon apart. There was being eyeballed with great intensity on it & longing to be in that parallel race just a few hundred feet ahead. These memories will soon recall a much younger & distant age.


In 2015, it's going to be torn down & replaced by a seismically more robust & hideously ugly piece of warped steel. The asphalt where me & Jesus Heroine ran will be no more. The backdrop seen on those days will never be reproducible again. There will be no trace of what was.

So many other men have memories of that bridge, there's a website about it. http://www.the6thstreetbridge.com/ It's getting more & more common with increasing age, for our past to be erased as structures from our past wear out, become economically unfeasible, & get destroyed.
Posted by Jack Crossfire | Dec 30, 2013 @ 06:37 PM | 2,574 Views





Clicking through some ads reveals there's now a flood of banging good GPS autopilots out there, being marketed towards RC pilots. They're a lot more stable than anything I could afford, owing to the latest GPS module, barometers, & the arducopter source code, which they all undoubtedly copy.


http://www.banggood.com/Walkera-G400...7-p-89151.html


Gone are the days when someone would tear them open & study the part numbers. The new customers are RC pilots with no idea what's inside. It wouldn't be surprising to find uBlox-7 & MS5611 in all of them.



http://helipartsdirect.com/blade-350...l-blh7880.html


Even the mighty Horizon Hobby finally caved in & started selling a GPS autopilot, though marketing it exclusively as a return to home feature.


The trick with autopilots is once you have one, now what? They're good at making timelapse movies. They can fly to places that were impossible for a human to reach manually, but the newest FPV systems make those places accessible for a human.

They're supposed to be good at returning to home when contact is lost, but there's very little evidence of that being used. It's still a lot of trouble to wait for GPS to lock on, make sure everything is calibrated correctly, just for that 1 feature.

There was some energy behind the following camera concept, but they probably weren't accurate enough to do a good job. Now there's hope for massive agricultural demand.

Autopilot for an RC pilot can get pretty boring, once the novelty of seeing it hover wears off. Hobbyists who design robot algorithms still seem to be the mane customers.



It was suprising that the mane media avenues: tested, flite test, rcmodelreviews were completely devoid of the GPS autopilot boom, emphasizing indoor quads instead. Even the mighty black sheep became famous not because of an autopilot but manual control.
Posted by Jack Crossfire | Dec 29, 2013 @ 11:43 PM | 2,604 Views
After 2 days of tracking down dependencies, fixing compiler errors, figuring out the nest of incompatible w objects in boost, mupen64plus finally ran the Robotech ROM image. Figured it would be an interesting study of what being 1 month from completion really means.





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Posted by Jack Crossfire | Dec 29, 2013 @ 04:59 AM | 2,767 Views



There are some poor quality videos of Robotech Crystal Dreams, a failed game from the 1990's. For all the fans gloating over it, it looks pretty bad.



There were a lot of grand ideas for what it was going to be. What kids actually recovered from the demo appeared to be a very simple flight simulator with a small number of models from the Robotech universe, too small to actually see anything.

Like a lot of 1990's software, it was a big idea with only a tiny amount ever getting finished. Modern frameworks may be a lot slower, but are high level enough that programs get a lot farther than they used to.




Robotech crystal dreams (5 min 24 sec)




The developer of the game managed to create some demo footage of some hidden levels & levels the fans never got to. Most of the footage is character animation for unfinished sections.

It looks like a simple flight simulator with some models from the Robotech universe. They also had some elements of Japanese animation. Besides visuals, it's hard to differentiate a game as a Robotech game. The objective must always be shooting & flying.


There is a Robotech DVD somewhere with more demo footage. While all of you were getting married, I spent my 20's buying the 1st Robotech DVD set, which sadly was not the one containing the demo footage. There were at least 3 sets in total.
Posted by Jack Crossfire | Dec 28, 2013 @ 06:29 AM | 2,533 Views
Marcy 1 outrunner flying (8 min 51 sec)



The outrunner with L bracket & slight thrust vectoring increased flight time from 9 minutes to 14 minutes. Can't think of any other vehicle which can hover for 14 minutes on a 450mAh 7.4V. In addition to the flight time, it's very quiet & hypnotic.
Posted by Jack Crossfire | Dec 27, 2013 @ 02:06 AM | 3,308 Views
So like a brushless gimbal motor, a brushless inrunner relies on higher torque to hit lower RPM. That requires a higher turn count. The lowest RPM 12mm inrunner of today uses 20 turns to hit 3800kV. The 3600kV Feigao would have had more turns, making it very expensive. It's now a true collector's item.

The lowest RPM 12mm inrunner still being mass produced is the mightyBA BL1230 4200kv 20 turns.


Flexing of the wing had no effect. The vectored thrust was the next suspect. Unbent the spruce. Ate the weight penalty of an L bracket. Higher coning angle had long been observed to be more stable.



Eliminating the vectored thrust did indeed make it stable but take more energy. It still weighed much less than the inrunner. Adding vectored thrust made it less stable, but take less energy.

There is a sweet spot between efficiency & stability. A maximum functioning angle seems to be 15'. 30' is unflyable. It can be gained by either bending spruce or making a different L bracket. A variable angle bracket would be ideal. There's also adding washers under the motor to tilt it.

A plastic variable angle L bracket could be made with 2 sliding pieces hot glued together & a hinge. Heat it up to adjust it.



The L bracket was dreaded for years, but physics won out, in the end. There was no way to make an elegant bent spruce piece.
Posted by Jack Crossfire | Dec 25, 2013 @ 03:55 AM | 2,785 Views
So every system on Marcy 1 died simultaneously. There was nothing unusual about the circumstances. It was another crash. There was no power cycling.


A very brief, transient high voltage appeared on the 3.3V bus. The transient was caused by probing the I2C bus with a voltmeter & contacting a high voltage solder ball. It's one of those split second events you never actually remember but know happened from doing it hundreds of times before. The PIC survived because it has an internal voltage regulator.


I2C stopped working when a reset routine was added to handle a dead radio. The reset routine on the PIC doesn't reset the I2C driver or peripherals. Most often, they would go into an unknown state & die. There wasn't a problem resetting when a software I2C driver was used, leading to the hardware I2C driver & not the peripheral as the problem.

Like most microcontrollers, the PIC doesn't receive any more UART data if the receive buffer is allowed to overflow. It has to initialize the UART interrupt without delay, on startup. If a character got in before the initialization, it would need a reset to recover the UART. That leaves starting up without I2C, resetting to get the radio to receive something before starting the I2C peripherals.


Adding ballast to the balance beam didn't make it more stable. There's another idea & a theory that having a highly flexible wing is making it more stable. Marcy 1 is a very unusual combination of aerodynamics.
Posted by Jack Crossfire | Dec 23, 2013 @ 09:38 PM | 2,967 Views






In the beginning, there was spyplanes.com. Then there was 3drobotics.com. What a surprise when my recuiter spam feed came up with another one in San Francisco called Airware. They showed a location in Newport Beach, but like so many others, probably had to expand North to save on real estate costs & be closer to the cloud/dot com boom.


It's yet another agriculture quad copter play. Besides tacitly luring photography hobbyists by branding the quad copter as a professional product for agriculture, there's no logic behind all these startups pitching quad copters for agriculture. They can't efficiently image thousands of acres. Sensefly probably had the best model with flying wings, but not the money or the resources to build up a community movement.

Despite not getting any interest, I did manage to get the recruiter to return a phone call, a huge breakthrough. The UAV business has just exploded to the point of not being the domain of makers & self starters anymore. They just want formal masters degrees.
Did the maker movement make the engineering degree mandatory?

In the old days, there was a novelty to someone picking up electronics on his own. It showed the ability to learn without being told what to do & the ability to be motivated without the threat of failing a class. While there were always places like Lockheed which would never touch someone without a formal engineering degree, it...Continue Reading
Posted by Jack Crossfire | Dec 23, 2013 @ 07:56 AM | 2,961 Views

A long coveted spruce bending jig begins operation.



It seemed to achieve the desired bend, but it took a whole day to soak & bend the wood. Bent it to 66' expecting it to settle at 45'. It won't retain its shape in wet weather.

While browsing Kickstarter projects, it became clear that most of them were selling self built kits to get a high volume low price. It would require some massive laser cutting. Preparing instructions & replacing all the parts users screw up would be a bitch.

Every day, there is a new idea, a new price point to calculate, a new design change, so it never is finished.
Posted by Jack Crossfire | Dec 22, 2013 @ 12:48 AM | 2,974 Views


A pair of ADXRS450 gyros arrived in the mail bag. Not sure what kind of IMU you're going to build with only 2 gyros, but these are the duck's guts, compared to Invensense.

The gyros you need for the ultimate flying machine are the ADXRS453. They're more expensive, but 700Hz is what physics requires for a quad copter. The ADXRS450 might be useful in a very expensive balancing robot or as a very expensive replacement for a magnetometer.

There are lots of things which might be more expensive than cheap parts, but not more expensive than all the items as a whole. It would certainly be more productive if instead of a variety of cheap parts, that money was concentrated in 1 expensive part. There are brushless gimbal motors, large drivetrains for a large rover, or just rent.
Posted by Jack Crossfire | Dec 20, 2013 @ 11:29 PM | 3,313 Views
Finally discovered more of the Macross universe. Always wished there was more Robotech material as a kid, but even the mighty Silicon Valley TV stations of the 1980's could barely play the syndicated episodes in order.

Kiwipedia revealed there were in fact several movies, from 1987 onward, starting with Do You Remember Love. Do You Remember Love was an alternate retelling of the Macross series. It was never overdubbed. The Japanese voices are more harsh & monochromatic. All the characters sound the same. The animation is a bit more sparkly but still sometimes reverts to still frames. The music is terrible.

It can get boring to repeat the same old plot device of the Zendraeti being horrified at the sight of heterosexuality, Rick & Min Mae being trapped in an unknown part of the ship, the endless Min Mae singing which was nothing more than a plot device but some Japanese writer thought would sell the movie.

It's interesting to compare how reality for the last 30 years followed the Zendraeti. Heterosexuality became the root of all evil for humans. Heaven forbid the fate of the human race depend on men kissing women.

There are some new scenes that would have been fascinating in the 1980's. They're alternate realities where different characters are captured on the enemy ship. Earth is the wasteland while the SDF-1 in space is the civilization. The male & female aliens are enemies with the male aliens siding with the humans.

Destiny intervened to keep Rick with Lisa Hayes a lot sooner in the movie, but she was a lot more feminine in the movie, while being a lot more strictly military in the TV show until the very end.

Minmay definitely became the Jar Jar of this show. At least the idea of singing a song that was 20,000 years old to defeat the enemy was original. They could have given it an alien quality that you would expect from a 20,000 year old song.



Before:


After:




Posted by Jack Crossfire | Dec 20, 2013 @ 07:23 PM | 3,228 Views


The description of Her is almost like a movie that I wished someone would make for many years, but not exactly. The ultimate movie is about a future where the saying "you have to be a friend before you can be a salesman" has been taken to the ultimate level.

Walmart has created sales robots for the purpose of marrying customers. They're better spouses than humans ever could be. People marry the sales robots & spend the rest of their lives with them, in return generating higher profits than Walmart ever dreamed of.

All human interaction has been replaced by computers designed to raise profits to the point of being better at being human than humans. The devil is in creating a conflict & a mcguffin required to theatricize it.

Perhaps a character could find something lacking in the status quo & want a real human, but be all alone. Maybe he falls in love with a real human & his task is to get her to look away from the robots. Maybe the conflict is between him & other people absorbed in a culture that decrees robots are superior & loving a human is insensitive & shallow. There's probably a decent conflict in Her, but no-one in this blog is going to pay the $20 to watch it in theaters.
Posted by Jack Crossfire | Dec 20, 2013 @ 02:57 AM | 3,206 Views
Having no money definitely stimulates the imagination.


As a kid, I only wanted what wouldn't exist for another 30 years: LED TV screens, 4 propeller electric helicopters, a watch which could play video. I rarely wanted anything that was already being produced.


Now I want an exercise coach robot. It autonomously rolls in front of you to pace you, make a timelapse movie & measure position more accurately than a phone, with a really high quality GPS module. It can carry a certain amount of supplies. Because it's not a human transporter, the cost is greatly reduced & it can roll for many miles with inexpensive batteries.

The challenge is autonomously staying in front of the athlete. No-one has ever tested the range of an unmanned electric rover. If an electric scooter with lead acid batteries can go 10 miles, something unmanned with lipos should go for 30 miles. For all the investment in pedometer wrist bands that don't work, why can't someone invest in a simple rover?
Posted by Jack Crossfire | Dec 19, 2013 @ 07:08 PM | 3,133 Views



Interesting to look at what big named, over hyped projects failed. It ain't the sea of instant $150,000 jackpots on the news.


Another RC controller based on the tilt sensing craze, pitched by guys with a legion of artists who were a little too zealous about an industrial design craze that never happened.


Then, there is something more similar to Marcy 1. 2 guys pledged $100 for a phone controlled copter & it failed.

...Continue Reading
Posted by Jack Crossfire | Dec 19, 2013 @ 12:11 AM | 3,184 Views



Marcy1 Phone Control (3 min 27 sec)



There it is. If there is a Kickstarter campaign, that's going to be the product. Flying with the phone is not as easy as the sticks, but it's cheap. Bluetooth initialization is still a buster. Flight time on a 450mAh, 7.4V battery is 9 minutes.


Interestingly, robugtix.com sells a controller made of a bare circuit board & Xbee.



To get that level of customization, they have to charge a bit more than the price of a standard toy controller.
Posted by Jack Crossfire | Dec 18, 2013 @ 03:58 AM | 2,596 Views
So making a 2 stick controller on a touch screen requires detecting 2 simultaneous touch points. The challenge with a stick controller is keeping a touch point corresponding to a stick applied to that stick, no matter where the touch point moves. If the touch point corresponding to the cyclic was applied to the throttle when it moved to the left side of the screen, it would be disastrous.


Basically, the Goog has tried at least 3 methods for handling multitouch in the Android API. There were ACTION_DOWN, ACTION_POINTER_2_DOWN, ACTION_POINTER_3_DOWN ... macros. Then they tried some really painful ACTION_POINTER_INDEX_SHIFT, ACTION_POINTER_ID_MASK macros which Eclipse says are now depreciated. There's no evidence of what the current, accepted way of doing it is.

The problem is the only way of knowing the current state of the touch screen is to trap a serial stream of MotionEvent events, then construct a table of all the touch spots on your own. There's no way to poll the touch screen or get the current state of the screen with a bunch of gets.

So you get a serial stream of MotionEvent events. The MotionEvent contains an x,y coordinate for every touch point, but there is only 1 action variable describing whether a single touch point in that list was pressed or released. For every press or release of a touch point, a new MotionEvent has to be received with the x,y coordinates for all the points & an action applying to 1 point.

If there is only 1 touch point,...Continue Reading
Posted by Jack Crossfire | Dec 17, 2013 @ 05:42 AM | 2,426 Views
Robotech intro in STEREO (1 min 34 sec)


Discovered selections of the soundtrack, but not all of it, were recorded in stereo. 1 stereo segment was the intro. In the 1995 CD, they combined stereo segments with mono segments in the same track to create the illusion that the entire track was stereo.


Unfortunately, there's no way to get the sound effects from the original intro. There are other goo tube videos with crappy sound effects & lousy clips where kids tried to enhance the intro.


...Continue Reading
Posted by Jack Crossfire | Dec 16, 2013 @ 06:16 AM | 2,852 Views


Best stencil job of them all. A joy to fly, but the spruce isn't retaining its bend.


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