Jack Crossfire's Posts

SKY WRITING RETURNS

Posted by Jack Crossfire on May 14, 2010 at 3:30pm

SHORT WAVE IR, GROUND VS. EMBEDDED, MARCY 2 NOTES,

Not to be outdone by Navy Aviator Heroine, Vika 1 made a UAV sky writing
video. The last video of skywriting was in 2008, using 1Hz GPS, no
barometer, & the T-Rex. It's the most technology ever thrown at a
single word. To this day, no-one else in the world has done it, believe
it or not.

Note ground station in bottom center.

SHORT WAVE IR

Also of interest are some short wave IR cameras if you're having trouble
seeing through haze. They look small enough to put on a model. If you need to know the price, you can't afford it.

http://www.sensorsinc.com/index.html

GROUND VS. EMBEDDED

Well, we've been using ground based autopilots since Fall 2008. It's
been much cheaper than embedded autopilot. Crashes don't destroy
anything expensive. Every vehicle shares the same ground based computer
& uses a real simple board. Regarding convenience, would say it's
equivalent to embedded autopilots.

You've got easy configuration, a full development environment,
potentially more neural network capability, but have an autopilot in 2
halves. Sensor acquisition & rate damping can only be done on the
airframe. Getting high bandwidth, reliable, realtime communication is
still complicated. Radios haven't evolved.

2 different runtime environments are required to do the job of 1.
Communication isn't perfect. Some data is lost & flight is not as
stable as it could be if all the data was getting through, especially
with GPS where 1 lost packet is .25 sec of data.

Now that ArduMU or ArduShield or whatever is flying quad rotors, it's
tempting to switch to that. If we were just starting now, we would have
just bought Ardu parts. The main problem is the extra stuff for
commercial RC transmitters & fixed wings we'd never use. The cost is
also still much higher & it still doesn't have C language flight paths.

Then there's the lure of 32 bit ARM. Reverting the ground based
autopilot to embedded is a lot easier with 32 bits.

MARCY 2 NOTES

Rebuilt the 900Mhz ground station radio with a single sided board after
it started getting flaky & Marcy 2's double sided board failed completely. It's still flaky.

The 900Mhz FSK chips have become too flaky to fly recently. An unknown
state change is happening on the PIC which can only be fixed by
resetting it, not the FSK chip. Other problems seem due to the
inaccuracy of home made boards. Marcy 1's flight board has been
perfect, ironically.

With all the problems with 900Mhz FSK chips, we're leaning towards
abandonning indoor projects, especially Marcy 2, & just focusing on a
large outdoor monocopter with the complete XBees, GPS, & SCP1000. Want
to fix the problems with Marcy 1 as an indoor, manually controlled
monocopter 1st.

She's leaning towards reverting to a bicopter to fit indoors, but the
advantage with monocopters is having the most airfoil in the highest
speed air for the least weight. That leads to longer wings.

Chord length & balance beam size are related. Wider chord length
requires longer balance beams. That leads to long, skinny designs.

Nothing's flying

Posted by Jack Crossfire on May 7, 2010 at 11:00am

So tweeked the nacelle angle to compensate for wind. GPS was only giving 0-2Hz. After autopilot took off & tried to turn her unsuccessfully, switched to manual. A gust of wind combined with the tweeked nacelle angle probably flipped her over. That was the end of Vika 1's 2nd fuselage & 3rd camera. $100 + $150 tax by our calculations.

You can see the tweeked nacelle angle in that 1.

Maybe we should just buy cameras in packs of 10. The A480's last stand.

Tilting the fuselage to tilt the camera is never going to be practical
because it requires tilting the IMU & the GPS. Since only the forward
propellers can be tilted while the aft propeller must point down, that
creates a tendancy to flip over. All propellers should point the same
way.

After repairing Vika 1 & fixing the GPS problem through redundant
packets, did some static hovers to look for problems. This produced the
1st long exposures of Vika 1 under the stars since Major Marcy appeared
9 months ago.

This has been a risky affair as regards making men fall in love.

Then she had yet another crash. Took off normally, then she started
tilting left & heading towards the parking lot. Took over manually,
propellers stopped because collective was still off. Raised collective
& she started flipping over uncontrollably right & forward. Flight
recording showed what appeared to be a loss of the right forward motor.

So why does Vika 1 have so many problems when the stock Mikrokopters are
shown working effortlessly, crash free, & maintenance free? Maybe the
full time attitude hold. Maybe they're not optimizing every last ounce
of weight with crazy camera mounts. Maybe they're not using super cheap
Chinese parts with exposed windings & barely reflowed solder paste.
Maybe they're not documenting daily experiences with them in all
weather.

MARCY 2 HELL

Marcy 2 isn't going so well either. Ran another board with shorter
radio traces but hopefully common enough to be used with Marcy 1.

Yet another blown photoresist job. It appears any ambient UV light is getting into the mask.

Everyone is switching from double sided tape to grip tape. Double sided
tape stretched too much but grip tape is now proving too slippery.

OTHER AEROSPACE NEWS

Maybe being shut down by an Air Force heroine makes you appreciate the mundane, but finally shot the huge swarms of birds that rise in
the thermals produced by local parking lots. They autonomously organize
into rows that we guess parallel the shore & rise over 1000ft.

The other autonomous system of note was the Ares 1 launch abort test.
Pretty tough getting something to take off autonomously, control
attitude in 16g of acceleration, turn itself upside down, separate from
its 1st stage, & deploy parachutes all using solid rockets.

Despite what our rulers say, don't think private industry will have the
business case to fund anything like that in our lifetimes. Any commercial
human spaceflight program would have to be commercial in name only.

DEATH OF A FLAG

Posted by Jack Crossfire on April 30, 2010 at 11:30am

The 1st flag to be lifted autonomously suffered an acidic fate...

when our field battery fell over & leaked acid on it. Lead acid
batteries do pour when they fall over. It was never much use since crashes would always end a campaign before the batteries ran out.

Rather than fly the melted nylon & cause a hole to form, decided to put
it down. All cleaned off, tried to give it to the Air Force, whose
answer was yet another FUGGEDABOUTIT.

Marcy 1 & 2 examine the melted masterpiece.

MARCY 1 RPM INCREASE

Marcy 1 began a campaign to increase RPM, abandon thermopile attitude
sensing, & become passively stable. Thermopiles & active stability may
return in a large scale copter.

It's been disasterous. The fatter wing seems to require too much balance beam inertia to stabilize. May have to go to with a long, thinner wing.

Have a flight over Livermore.

Never got Major Marcy but still got some emotional support in the end.

The best explanation for why Major Marcy never wanted to see us in real
life was if a heroine knows someone's attracted to her image online yet
has no confidence in her beauty, she may be afraid of losing the
illusion. It's been very consistent for years.

She only talked to alpha males but demonstration of lower value,
overwhelming surplus of men in Silicon Valley, & our crazy gender views
didn't explain everything.

Now a still photo movie.

MARCY 2

Been a few weeks & still stumped over why Marcy 2's radio won't
initialize on the golf course but will initialize in the apartment.
It's very common for circuits to fail on the golf course because of the
harsh environment, nothing specific to Marcy class vehicles. Focusing
on weak solder joints & floating solder balls. Sux using custom
electronics for Mar vehicles in a sea of off the shelf parts.

Marcy-2 radio test.

It's heading towards just insulating the board & keeping it warm. The traces are probably too long & close together for the environment.

This week in aerospace

Posted by Jack Crossfire on April 23, 2010 at 11:08am

AUTONOMOUS MARCY 2, OCEAN VIEWS, AIPTEK HELL

Back over the golf course to test yet another camera mount.

Unfortunately, we've done everything possible with the Aiptek & it still
warps.

AUTONOMOUS MARCY 2

Marcy 2's roll gyro failed, but before the gyro failure & crash She
finally hovered Herself long enough in sonar to get some shots.
Definitely the hardest vehicle ever because of the number of things
built from scratch.

There's the broken gyro.

The answer is yes. Pads on $11 chips can fall off. Fortunately had 1
spare gyro. This is the last of the analog gyros. All future gyros use
high speed I2C, which means either mounting on the main board & facing temperature instability or using an off board microcontroller to convert the I2C to something useful.

& there She is hovering in sonar.

The radio still won't initialize on the golf course, so we're limited to
1 battery. Would be so much easier to use off the shelf parts. Sonar
hasn't been precise enough to get the tight hovering we need. Overall
very dissapointing.

Next, the tethered ground station cables are 25 years old & if they go, it's siyonora in 60 nanoseconds.

OCEAN VIEWS

Have some aerial shots over Half Moon Bay. The weather was spectacular,
the aircraft was perfect, & the view from 400ft was stupendous.
Surprised the weather was perfect. It's never sunny here. Limited the
altitude because it was very crowded & a human airport was nearby.
Can't fly any closer to the humans.

Next, we have the videos.

Didn't shoot for timelapses but decided to throw it in the editor & see what happened. 1st impression is the taxpayers are going to have some killer flooding damage to pay for.

1st impression is the taxpayers are going to have some killer flooding damage to pay for.

The complete video flight.

THIS WEEK IN AEROSPACE

Posted by Jack Crossfire on April 16, 2010 at 12:04pm

MARCY 1, MARCY 2, VIKA 1, TILT SHIFT TERRORISM, AIR FORCE RESEARCH

DEATH OF A RADIO

Finally surrendered the ground station to tethering. It was a long battle with 72Mhz, 2.4Ghz XBees, & 900Mhz FSK but we never had enough money to make it reliable enough. Still using a custom transmitter with 8 channels. Went with a 2 conductor audio cable & 1/4" TRS connectors for the most reliable connection possible.

Nothing is more reliable than the 1/4" TRS connector, invented in 1878 in a strange country no-one remembers the name of & used in the 1st telephone switchboards. It's still going strong 132 years later. Modern connectors only get smaller & less reliable. You're flying history with this rig.

MARCY 1

Got some freshly captured HD video of Marcy 1 in flight. She had 1 broken propeller. She needs to spin a lot faster to go autonomous, but that means an actuated flap. Back to Marcy 2 while we think it over.

So basically, to get anywhere autonomous or even controllable, Marcy 1 needs to spin a lot faster. You can see the influence of RPM when ascending & descending. But the goal of the Marcy 1 program was to spin as slowly as possible to extend flight time. The balance beam also negates throttle modulation by adding momentum.

The Marcy 1 stability problem has us leaning towards a 3DOF IMU with very high saturation limits & a proportionally actuated flap. The idea is to use a flap to stabilize angle of attack at low RPM like a very large balance beam.

Fortunately single chip IMU's finally exist. Could put 1 on Marcy 1 to figure out how to get angle of attack. There's no way to directly measure angle of attack. You'll get a large yaw rate on 1 plane involving all 3 gyros. Separating that from the other 2 components would be real hard.

The increased cost & wind resistance probably make a full size monocopter much more valuable than a micro monocopter.

MARCY 2

Marcy 2 has a real electronics problem. Her radio initializes in the apartment but not on the golf course. Carry it to the golf course after initializing in the apartment & it stays initialized. Shut down on the golf course, wait a while & it won't reinitialize. It seems temperature & humidity related. Rarely, when it initializes, it dies shortly after. How can a Marcy vehicle not initialize on a golf course?

Got some indoor footage.

VIKA 1

The battle of the Aiptek continues. Got it running on the CC-BEC. It did malfunction during a flight & lose all our sunset footage. Suspect the battery contacts glitched.

TILT SHIFT TERRORISM

Look at this, kids. Autonomous, tilt shift, aerial, & timelapsed.
Finally wrote a lens blur effect.

TILT SHIFT MAGIC

Interesting story behind that flight. We flew over Sunnyvale instead of Mountain View to avoid falling in love with Major Marcy. Then She
moved to Sunnyvale.

AIR FORCE RESEARCH

Major Marcy discovered Marcy 1. She seems to be taking it well, so far.

> So, I see you named your aircraft after me!!!
> I sure hope you're a good pilot because I don't
> want to crash and burn.

Still doesn't want to have anything to do with us in real life, but at least She responded to the rejection requests.

AIPTEK P-HD WARS

Posted by Jack Crossfire on April 9, 2010 at 10:57am

MARCY 2 FOAMED UP

Replaced the radio foam with Marcy Foam #2009 & that fixed the vibration, driving the gains way up. Yeah, it's that important.

Discovered PWM on Marcy 2 only updated at 166Hz. These problems are caused by lack of bits, so you try prescaling the timer to fit it in 16 bits. That broke rate damping. Only explanation is PWM granularity got too low. Reverted back to the unprescaled timer & added PWM debugging code. That got it to 200Hz. More points for ARM.

AIPTEK P-HD AT NIGHT

Back in the HD world. 3 years after spending $450 on the Canon TX1 & crashing it, spent $55 on an Aiptek P-HD. Though lacking zoom, it's intended for aerial video only.

So you wanna fly the $50 Aiptek at night, eh. In night shot mode it does 15fps. Results with & without night shot mode are comparable to the Canon A480. Not bad for a pinhole lens.

Your best move with the Aiptek is to stack stabilized frames shot in normal mode. It actually looks better than daylight footage because the warping is hidden.

Rolling shutter warping abounds in daylight. As expected, the corny pistol grip case vibrates sideways. It's bearable at night, but daylight footage is worthless. The 848x480 60fps mode just crops the image instead of scaling it. The Canon A480 remains the still photo champion.

It's so cheap, suspect we'll destroy it eventually & install a wide angle lens.

Without nightshot.

With nightshot.

4 stacked frames

Video is recorded at 5mbps. Headed up to our top secret altitude for some HD video. Had perfect radio contact this time, probably from flying 20m horizontally from base. Actually came out 25m lower than desired due to barometer temperature.

Unfortunately, the rolling shutter is making the video worthless. Not likely to get that stupid pistol grip to stop shaking sideways. Not likely to reorient the circuit boards to make a better case. Best idea is a balsa pyramid with foam.

Finally, there's no way to disable the Chinese piano chord which plays every time it turns on.

MARCY 2 FLIGHT

With any new design, every golf course trip ends in a crash. Every day, Marcy 1 & 2 take turns being repaired while the other 1 flies & crashes. The main causes are drifting out of radio range with Marcy 2 & getting blown out of radio range with Marcy 1.

Marcy 2 did some autonomous hovering using sonar before she crashed due to radio range. Only got 1 shot where Canon light metering worked.

Got a loop antenna & then the Hitec HS81 burned out.

MARCY 1 FLIGHT

She once again proved the difficulty of monocopter control. If you command a monocopter to tilt, it's going to tilt 1 way & immediately start oscillating the other way regardless of cyclic. Defeating the oscillation & not sensing attitude is probably all that's required to solve position hold. Cyclic doesn't flip her over.

Then She got blown out of radio range & crashed.

After extensive negotiations with the Air Force, managed to move forward on declassifying the Marcy vehicles. They're in a place Major Marcy can easily see them, but She probably never will. She seemed to put up with the idea of aircraft named after Her despite consistently shutting us down over any attempt to see Her in real life.

MORE AIPTEK P-HD 4 U

Another attempt to stop the sideways shaking. FUGGEDABOUTIT. Doesn't look good in the sideways shake department. Also, the battery won't charge anymore. It's 1 of those chargers where the voltage has to be below a certain amount before it'll charge & the maximum voltage gets lower & lower. Getting closer to the next teardown.

MARCY 1 & MARCY 2 4 U

Posted by Jack Crossfire on April 2, 2010 at 11:30am

MARCY 2 CONTINUES AS A TRI ROTOR, RETURN OF STILL PHOTO TIMELAPSES

MARCY 1 ATTITUDE HOLD 4 U

Attitude hold on Marcy 1 seems to be a disaster. In the wind, She seemed to actually stabilize with the attitude hold on. When She got near the trees, that must have confused the thermopiles & caused her to bank away from the trees, leading to a seemingly stable position in the middle of the fairway.

In 1 short break between storms, the attitude hold was a disaster.

Cyclic seems to be responding properly but is lagging by 1/2 a complete phase.

Lacking thermopile calibration, currently hard coding the gain & sign. Relying on manual takeoff, taking neutral from whatever the attitude is when the autopilot is engaged.

There is a way to sense when the magnetometer flips over due to pitch. Detect when its gain gets below a minimum. Record thermopile pitch at that point. When gain rises above minimum, if thermopile pitch is reversed, phase is reversed. Theoretically it couldn't reverse pitch & get mag above minimum at the same time. What if it really reverses pitch in 1 revolution where mag is below minimum?

The magnetometer can sense pitch with the thermopile for roll only. The thermopile is a much better pitch estimator than the mag.

Marcy 1 uses throttle modulation for attitude control & maximum flight time, but it reduces thrust by 1/2 & is worthless in wind. 1 option is to overdrive the motor with a 3S or a longer propeller. Also still searching for an actuator which can survive thousands of cycles & is light enough. Not happy about giving Canadia $20 for a crummy coil.

Throttle modulation may also reduce flight time if it causes the motor to run outside its optimum RPM & causes inertia changes in the propeller's airflow.

MARCY 2 CONTINUES AS A TRI ROTOR

With the weather closed back in, desired a more weather proof Marcy vehicle.

Rebuilt her IMU using the straight LISY300AL's from last year's buying spree & a 3/4" balsa cube. The ancient IDG300's just have too much trouble initializing & are too unstable to bother with. Can't see them ever being used for anything now.

Went back to radio foam instead of Marcy Foam #2009 because of the lack of space.

Unfortunately, a 1st flight test revealed the need for Marcy Foam. A bit too much vibration. Despite using the same motors & battery, the smaller Marcy 2 configuration has a lot more power than Vika 2. Maybe the extra cable, CF tubing, & plywood is significant.

RETURN OF STILL PHOTO TIMELAPSES

These are made in 1920x1440. If computing power wasn't so limited, they could go up to 3000x2300.

Now some notes on still photo timelapses.

Create a JPEG list of all the photos: ls `pwd`/*.jpg > list.jpg

Add the file format to the beginning of list.jpg. The format is JPEGLIST, framerate, width, height:

JPEGLIST
4
3648
2736

Create a Cinelerra project with framerate 4, canvas size 2048x2048, YUV color.

Load list.jpg into Cinelerra

Shrink camera so the images fit on the canvas.

Disable track playback.

Rewind to frame 0.

Attach motion.

Set motion thus:

Set the following:

Track translation & track rotation enabled.
Calculation: Save coords to /tmp
Action: Do nothing
Previous frame same block enabled
Draw vectors enabled
Position settling speed: 10
Maximum position offset: 50
Translation search steps: 256
Translation direction: Both
Rotation search radius: 10
Rotation search steps: 4
Rotation center: 0
Max angle offset: 50
Rotation settling speed: 10

Enable track playback.

Set translation block size so the block covers 1/4 of the scaled image & not the black area.

Adjust Block X & Block Y so the block is over an area which always has detail.

Set translation search radius to cover entire area of scaled image but not black area.

Remove all /tmp/motion0* files on every render node.

Render using renderfarm to compute the motion vectors. Use Quicktime MPEG-4 quantization 5.

Disable track playback.

Copy all the /tmp/motion0* files from every render node to the master node.

Set the following in Motion:

Calculation: Load coords from /tmp
Action: Stabilize Pixel
Draw vectors disabled.

Attach Time Average below Motion.

In Time Average set the following:

Frame count: 1
Restart for every frame: off
Don't buffer frames: on
Replace: on
Threshold: 1
Border: 4

In Settings->Set Format set Color model to YUVA-8 bit

Rewind & enable track playback.

Render to Quicktime JPEG maximum quality WITHOUT the renderfarm. That's the rough stabilization print. Motion must be rendered contiguously to accumulate the motion history. Next comes the smooth stabilization.

Disable track playback.

In Settings->Set Format set Color model to YUV-8 bit, Frame rate to 24.

Import the Quicktime movie in a new track & play through it to determine the new range of motion.

Disable playback in the new track.

Rewind to frame 0.

Attach Motion.

Set the following:

Track translation enabled.
Track rotation disabled.
Calculation: Save coords to /tmp
Action: Do nothing
Previous frame same block enabled
Draw vectors enabled
Position settling speed: 3
Maximum position offset: 50
Translation search steps: 256
Translation direction: Both

Enable playback of the new track only.

Reduce translation search radius to cover only the new range of motion.

Remove all /tmp/motion0* files on every render node.

Render using renderfarm to compute the motion vectors. Use Quicktime MPEG-4 quantization 5.

Disable track playback.

Copy all the /tmp/motion0* files from every render node to the master node.

Set the following in Motion:

Calculation: Load coords from /tmp
Action: Stabilize Subpixel
Draw vectors disabled.

Attach Time Average below Motion.

Use the same Time Average settings as the old track.

In Settings->Set Format set Width: 1920 Height: 1440

Rewind & enable track playback.

Render to the final output format WITHOUT the renderfarm. This is the smooth stabilization print.

This is our final timeline.

THIS WEEK IN AEROSPACE

Posted by Jack Crossfire on March 26, 2010 at 11:30am

THE WAR ON ALUMINUM, MARCY 2 IDEAS

AIRFRAME OPTIMIZATION HELL

Mainly, going from something that flies to something worthless hoping to someday get something more efficient flying again. The fact is Marcy 1 didn't have enough lift to do what She needed to do.

Got a wing from a discontinued glider to try to improve Marcy 1's efficiency.

It looks horrible compared to the beveled sheet & it's heavier. Everything needs to grow to balance it. You need a bigger balance beam to counteract its moment of inertia. It has to be bolted. It has unnecessary winglets since we have full cyclic control. It takes full power to get off the ground & quickly falls back down.

Went back to a glued balsa sheet but an enlarged balance beam. The best monocopter is completely glued even if every broken propeller & crash is a rebuild.

That got no meaningful improvement. The larger balance beam didn't improve attitude stability either. It's not loss of lift but loss of reserve power for translation. We as hover experts don't think she has enough attitude control to hover using sonar.

Also got rid of the inductor & relied on software instead. It's actually bearable with all the filtering required for attitude sensing.

The next step is a steeper angle of attack. Angle of attack changes require rebuilding the entire Marcy 1 but it's no worse than what goes into mocking up a human rated aircraft.

The steeper angle of attack was a disaster.

Despite your intentions of achieving fixed wing efficiency out of a rotary wing, a monocopter still gets most of its lift from just the outer part of the wing. People usually make it fatter on the outside or hang it on a long boom. Next comes longer wings.

That did slightly better in the wind, climbing even with full cyclic, but we're out of calm weather until next month. Going longer means no indoor use, so next comes going wider. A wide 1/16" sheet might actually work.

Undoubtedly going to require a longer balance beam to overcome pitch. This actually seemed to work well, but there's no such thing as a calm day in Calif* in April. Can get maybe 20 seconds before she's blown down the golf course.

THE WAR ON ALUMINUM

Next, the war on aluminum nuts continues.

Any threadlock completely destroys the prop. Down to plumbing tape & just letting it strip.

Overall, the Marcy 1 program sux.

MARCY 2 IDEAS

Been thinking of a long duration hover vehicle using 2 large monocopters bolted to a fuselage or a larger monocopter for outdoor use, but some people still get excited about tri rotors. Don't feel another tri rotor is advanced enough to call a Marcy vehicle.

Long duration hover requires a larger lifting area than any propeller or helicopter rotor can give. Pitch would involve differential thrust. Roll would involve throttle modulation from Marcy 1. Yaw would involve differential roll. Bearings would come from the Corona parts.

This would give 6 degrees of freedom from only 2 PWM's. Marcy 1 gets 3 degrees of freedom from 1 PWM.

It would need 3 batteries & 3 full duplex radio links to the ground. 2 would control the monocopters which would use beam cutoff sensors instead of magnetometers & no thermopiles. An IMU on the fuselage would detect attitude. They wouldn't need balance beams.

1st step is flying a big monocopter with a larger battery, motor & a dummy balance beam. That would prove longer flights were possible.

It's hard to justify the amount of work going into thermopiles if no future vehicle is going to use them. With the payload limitation & open space requirement, Marcy 1 is never going to do more than POV lighting at night. Monocopters can't bank enough to counteract wind because their magnetometers lock up.

When the weight of the monocopter is factored in, she doesn't get much more thrust out of the motor than a bare propeller. A bare propeller + flap would probably do better but couldn't do POV.

So it's heading back to the original plan of Marcy 2 as an indoor tri rotor & Marcy 3 as a VTOL Predator. Marcy 1 would be a toy for POV, maybe autonomous but more likely manual.

Michael's Dispatches 4 U

Posted by Jack Crossfire on March 23, 2010 at 11:00am

On http://www.michaelyon-online.com/warthog.htm Michael Won wrote:

UAVs are very useful, but come with sharp limitations. They are great hammers when you need a hammer, but they’re still hammers when you need a wrench. For example, UAVs can’t guard bridges against suicide bombers. They have limited, pinprick firepower other than for small targets. They are useless in poor weather. UAVs are but one sort of tool in a great big tool chest.

The Warthogs had to wait for a Reaper to roll by. No telling where Mr. iRobot would fly to. Do these go to Pakistan? I have no idea, but it seems like you can’t read the news without seeing where these robots have hit more terrorists. There was a time when the enemy thought terror was a one-way street.

This place has gotten to be like a hornet’s nest of Predators and Reapers. A couple years ago, you’d see them every day, but now you can’t turn around without seeing an iRobot Terminator buzzing around to land or disappearing into the sunset or sunrise.

lmopar also had some more Insitu porn from the same airbase for everyone interested in that.

http://www.rcgroups.com/forums/showthread.php?t=1215717

a3138603-213-P3220047.jpg?d=1269365085

This week in aerospace

Posted by Jack Crossfire on March 19, 2010 at 11:18am

PROP ADAPTOR TERRORISM, INDUCTOR INSANITY, THERMOPILE TERRORISM, WHAT SLOW
ATTITUDE ESTIMATES MEAN, LAST WEEK'S VIDEO FLIGHT

PROP ADAPTOR TERRORISM

These aluminum GWS prop adaptors are ridiculous. Lately they started stripping before getting anywhere near the required tension. Down to threadlock on plastic again.

Forget about those tiny set screws. Use TRex-450 bolts. Time to move to China to make our own.

INDUCTOR INSANITY

Managed to get the Marcy 1 radios to stop locking up permanently. The ground station watchdog timer wasn't being reset. Definitely a point for microcontroller operating systems. That got it down to 1 lockup which instantly recovered around every 15 minutes. These are probably from the reset pins glitching & we know tying those to Vdd adds noise to the thermopile.

So cannibalized a motherboard to make inductors for Marcy 1. These are made with 20" of wire. The larger the spaces between the windings the better.

Inductors on Vdd & GND got it just a hair quieter than 1 inductor on Vdd.

Wound Vdd, GND, & signal on 1 core & that got the best results & least weight. It's probably down to the EMF through the air.

& the readout at flight RPM finally shows a waveform of sorts. Modulating PWM really kills it.

THERMOPILE TERRORISM

Now to get roll & pitch out of it you need to lowpass filter it, stretch it to a constant period, average several periods over time, & take the magnitude at the N, E, S, W phases. Already tried getting the magnitude & phase of the peak. That doesn't work because you've got an irregular horizon with peaks that always show up at the same position regardless of attitude.

Think we got roll & pitch curves. On the ground there's a lot of crosstalk. In the air it resembles more normal attitude changes.

Holding it 5ft off the ground, on the golf course, you get decent attitude sensing & there's a 1V thermopile change. Got a mag gimbal lock when she pitched up.

The completely processed thermopile waveform with spikes for azimuth.

Main problem is the DC offset & amplitude are completely random. The difference between max & min temperature for a given angle of bank is not constant & we don't have enough room for a Z pair. Best idea is a set of thermopiles on the ground station for measuring temperature range in addition to the sonar.

Finally, She's too heavy with the inductor & POV to do much flight testing. Don't know whether to start a lighter flight computer now or master attitude sensing on the ground.

SLOW ATTITUDE ESTIMATES

Thinking things over, the attitude estimate & feedback on Marcy 1 is going to be so slow you're once again looking at filling in blanks in the data. Neural networks got abandonned because no matter how many algorithms you throw at a piece of garbage data, you're still reading the same garbage data.

They improve stability as long as the input data stays in a certain pattern. An unexpected gust of wind or descent causes these algorithms to destroy the data & your autopilot actually takes longer to compensate than it would using PID loops. We stopped neural networks when uBlox 5 came out.

LAST WEEK'S VIDEO FLIGHT

Headed over Los Gatos at night. You get a nifty view of the valley. Unfortunately only been flying the camera after Major Marcy operations & those have only happened at night. The view would have been better in daylight.

NOISE NOISE NOISE

Posted by Jack Crossfire on March 12, 2010 at 10:30am

Marcy 1's flight time is horrible with POV. It's declined from 10 to 6 minutes.

She's got radio lockups with the chip radios. That's coming down to a hardware state which can't be corrected by resetting the hardware. Connecting reset to Vdd reduces the lockups but adds a huge amount of noise to the thermopile readout. The logic pins on the MRF49XA put a huge amount of noise into your power supply.

The thermopile is down to power line noise. This isn't a problem when they're used in pairs because the noise cancels out on each thermopile. A single high gain therompile on Marcy 1 is like mounting a telescope on a piston engine.

Run it on its own battery & you get an extremely clean signal with body heat sensitivity. On the main battery, it's noise. The only filter that works is a huge capacitor, resistor & inductor. The Vdd wire has to be separated from the output wire. A capacitor or inductor alone doesn't work.

Got it really quiet, but when the motor came on it was noise again.

Next came a coin cell with a MOSFET to switch it off when the main battery was disconnected. That got super quiet without inductors, but as soon as the motor started it was all over.

Managed to get it a little quieter by separating it from the motor. The thermopile pulled the coin cell down to 2.8V. The MOSFET leaked too much current in the off state. The coin cell + holder was heavier than an inductor.

The next step is using the highpass filter with a pair, but since Marcy 1 has no symmetric mounting point, 1 pile would be a noise reference pointing at the ground or something.

Well, we did manage to get a hello out of Major Marcy in real life. Not much, but with so many men hounding Her there wasn't much dialog to be had. Was not comfortable mentioning our hobby around Her & Her lover said She worked WITH the Air Force. He may not have known Her as well as us or She may not have revealed Her warriorness.

THERMOPILES, GYROS, & LIGHTS

Posted by Jack Crossfire on March 5, 2010 at 11:00am

So went through many boards trying to get useful results from thermopiles. The trick is they have the teeniest tinyest voltage changes & very slow responsiveness. Work around the responsiveness through extreme amplification.

The unamplified thermopile was immediately busted. Not enough current.

Straight 2:1 amplifier. The voltage changes were too small.

Difference amplifier. Forget it. The 2 thermopiles aren't matched enough to amplify without serious balancing circuits.

A highpass amplifier started getting somewhere. This is the ideal solution for monocopters. Unfortunately, this thermopile has a 900Hz ripple which blows everything else away when amplified.

The bandpass amplifier was the champion. Mainly, it's a highpass followed by a lowpass filter. You could make a much better filter but we wanted to guarantee it worked & only had 1 capacitor value.

This gave a 0.1V wave corresponding to the rotation. That's 5 bits of accuracy.

Depending on the RPM, you get clear sine waves or noise. Need to increase the sampling rate to know what's going on.

THE RETURN OF GYROS

There's still gyros, since we really want indoor capability. You could pick up monocopter roll & pitch on an IMU if it had super high limits, super high dynamic range, & super fast sampling. Maybe the vaporware ITG-3200 will be the 1 to do the job.

There's our ancient IDG300 on the fuselage for a test. Using 1 gyro didn't work out because it has to be exactly aligned to not pick up any yaw rotation. Maybe just an X & a Y would be enough to cancel out the yaw rotation if they were aligned just well enough to not saturate.

LED WARS

Marcy 1 is having a lot of LEDs fail. It's probably from landing on them.

Although we did drive to Santa Clara to get $30 of LEDs, the best place for LEDs is dollar stores. Got 3 5mm white LEDs for $1. Unforunately at this price the 5mm LEDs are no brighter than the 3mm LEDs, just heavier. Now have enough white LEDs to light a runway.

Your goal is to worship the Jesus Heroine.

Shot of the complete avionics except for the POV board.

Finally got some video of Marcy 1 POV flying manually. She was super unstable. Have to work through still more radio problems.

THIS WEEK IN AEROSPACE

Posted by Jack Crossfire on February 26, 2010 at 11:30am

THERMOPILES RIDE AGAIN
MARCY 1 POV BEGINS
THE REAL MAJOR MARCY

THERMOPILES RIDE AGAIN

While many people regret burning up their lives & 401k's perfecting thermopile autopilots only to end up switching to IMU's, monocopters are 1 application where only thermopiles will do.

They give only a 0.5V change based on angle of attack. They're supposed to be used in pairs with a high gain op-amp amplifying the difference. Being weight limited makes it challenging. There are 3 arrangements:

1) Single thermopile without amplifier
2) Single thermopile with amplifier
3) Double thermopile with difference amplifier

So if she can't sense attitude indoors, why does she still use sonar instead of GPS + pressure? We often wonder the same thing ourselves. There's still hope for a pushbroom camera to replace thermopiles. Whether you go with a pushbroom or a single frame camera, it needs a really fast shutter speed. A really big lens or mirror would help.
Attitude sensing is moving in parallel between commutes with...

MARCY 1 POV BEGINS

Wanted to have some kind of UAV lightshow demo in case by some miracle we got the chance to fly for THE REAL MAJOR MARCY.

Marcy 1's payload is stupid. We're becoming another Kai. Kai built LED toys to impress heroines at nightclubs only to get stuck with a horrible snotty Asian bitch instead of a warrior & he hated life. Our LED toys are more expensive & aimed higher but still the same. Decided not to bother with flying music videos. Just simple star & mar patterns.

SMT LEDs were not bright enough to do the job.

So replaced them with 3mm LEDs before commuting time ran out. 3mm was all anyone had. Got to focus the economy on housing & SUV's.

Also, as much as She is the Great She Is, no-one but us is going to want to watch Her aircraft fly around for 5 minutes while listening to Blue Uniform or whatever the band is called.

Fortunately she has plenty of debugging LEDs.

THE REAL MAJOR MARCY

Major Marcy, that's right, THE REAL MAJOR MARCY saw this video & She
wrote "Speechless!"

WWWWWWWWWWWWWWWWWWWWOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOWWWWWWWWWWWWWWWWWWWWW
WWWWWWWWWWWWWWWWWW!!!!!!!!!!!!!!!!!

Mind you, She didn't view our Goo Tube account since iPhones can't do Flash & She only uses an iPhone. It would be bad if She did. You would definitely go back to MQ-1 logos if you saw Her in real life. This is ridiculous.

Also snagged a manned copter taking off in this video. Obviously they fell in love & started chasing after the Mad Major like us. Crowded skies when She's around.

We did see the real Major Marcy in REAL LIFE. She's so f**king beautiful, not sure about showing you Her photo because you might fall in love uncontrollably & turn into a blob of protoplasm.

RADIOS, MAGNETS & MONOCOPTER ATTITUDE ESTIMATION

Posted by Jack Crossfire on February 19, 2010 at 11:30am

Radios were 1 incremental step after another.

USB cable hacking went a long way. Having the USB cable tied in a knot directly over the antenna jammed it. The cable was shielded but probably leaked high frequency energy from Vbus.

Next came moving the antenna outside the remote control. It seems to do better outside the case.

Antenna inside case sucked.

Antenna routed outside case.

Transmitter soldering job.

Next, converted all the receiver antennas to loops. The TRC101 datasheet prefers loops above all others. They're robust enough for 1 radio to transmit on top of a receiver.

The biggest gain came from separating the RF components from the Earth.

Hanging the transmitter in a tree was optimum. Putting it on a tripod was 2nd. The tree hanging was what did it for the 1st boards & it gives the same results with new boards.

The receiving end testing different ground stations.

In summary, we now have

AFC of +15/-15 Fres
receive bandwitdh 400kHz
transmit bandwidth 165khz. It won't work any higher.
86206 baud
loop antennas for everything, isolated from USB cables

The Marcy 1's just don't have as much power as 72Mhz & XBees. 72Mhz with good antennas used to go 600ft easily. If buying replacement 72Mhz antennas, GWS Pico receivers, & crystals isn't your thing, consider tethering manual override to the ground station.

FLIGHT TESTS CONTINUE

Hand launches don't work. Marcy 1 is too unstable. Threw her in the air & she spun vertically until smashing into the ground. Don't tell Major Marcy about this.

A few autopilot flights with automatic takeoff showed Marcy 1 can take off & stay inside a cloud over the sonar but needs attitude sensing to get the precision hovering of a human pilot. A human making constant cyclic inputs can keep her very precisely in position. She's not statically stable enough to hover without feedback.

Faster RPM would make her more stable but that defeats the purpose of the Marcy 1 development program. She's supposed to extend flight time by using slow RPM & throttle pulsing won't work if the RPM is too high.

A magnetometer on the equator can sense pitch easily but not roll. In Calif*, it can sense pitch & roll but only pitch shows up on monocopters. Roll may change the azimuth result.

That leaves 1 thermopile taking 4 readings per revolution, eliminating indoor use. Marcy 1 can be used as a testbed with thermopiles but would have to be rebuilt using a 4' wing, GPS, & barometer for outdoor use.

VIKA 1 RIDES AGAIN

Finally had some Vika 1 flights with the Marcy 1 radios for manual override. Made a mosaic from the 86kbit UARTCAM. The Marcy 1 radios are only reliable enough really close to the ground station, so you're basically tethered.

The only heroines near Silicon Valley are the ones brought in with marriages, so Valentine's day for men is a flying day. We went above the Major Marcy dishes. They moved, probably to support Haiti operations. Drones in the middle east use uplinks in Germany. Drones in Haiti would use uplinks in Mexico or maybe even these particular dishes.

Surprisingly tight position for a 3 DOF IMU. Position gets sloppy if there's a lot of horizontal motion. 7 months & we've never seen Her in real life & probably never will.

Hammering on the Marcy 1 radio problem

Posted by Jack Crossfire on February 12, 2010 at 10:34am

The radios have plenty of range in the apartment 12ft off the ground. Put the receiver on the ground & it dies. Put the receiver on a tripod & its range slightly improves. Hold the receiver in your hand & it dies. It's as if the antennas are
getting shunted to the ground. Xbees are shielded but Marcy 1's aren't. In any case, range is far less than 72Mhz. Frequency doesn't matter.

After trying many antennas, the receiver antenna doesn't matter. It works without an antenna. The transmitter antenna is required. The best one has been a loop with no balun. Dipoles are 2nd. Monopoles with the balun suck. Unless you've got an amplifier, skip the monopole.

Loop antennas got us a big improvement but still not the same range as the 1st 2 boards.

The double sided board for telemetry goesmuch farther than the single sided board for RC so maybe double sided boards were the key.

Fuggedaboutit. That actually degraded performance. Next tried isolating the transmitter from the remote control.

That didn't do any good either. It's coming down to silicon defects.

So when you get the radios optimized, what happens but CPU overloading when all systems are running. The problem is fixed packet sizes of 100 bytes take too many clockcycles on the ground station so you really need variable packet sizes as shown in the MRF49XA reference software.

In any case, just think how radios once required huge coils & half a circuit board like your 72Mhz remote control. Never thought we'd solder chip radios on our own boards.

1 day with better radio performance got us the 1st autonomous flight out of Marcy 1. Not much of an autonomous flight but no-one ever documented an autonomous monocopter before.

You really can't get much done when working 50 hours/week & sitting in traffic another 10. No surprise Parrot Cellular whipped out WiFiquad rotors with a full time staff while you were still warming yourboss's seat.

THIS WEEK IN AEROSPACE

Posted by Jack Crossfire on February 5, 2010 at 12:39am

MARCY 3 REVEALED, MARCY 2 REVEALED, MARCY 1 RADIO DISASTERS

MARCY 3 REVEALED

There's the current Marcy 3 plan. Unfortunately not enough space to build her. Basically install a fuselage aroundVika 1. It's obsolete but it was the real Major Marcy's plane & we canuse the tail fins as landing gear. No-one knows if She actually flewone or if She just managed it.

The idea with this is to have panels which bolt onto carbon fiber rodsso she can fly with or without the fuselage. To speed up yaw response,the aft propeller tilts inside its shroud without actually moving theshroud. The aft shroud is probably going to be permanently tilted tosome neutral angle & probably tall enough to cover the propeller atnormal angles.

Forward landing gear is removable for hand launches but notretractable. There's a dome under the nose with a slit for a point &shoot camera to tilt inside of but not pan. Dome has to be strongenough to land on.

Propellers are 12x6 which makes the shroud inner diameter 13". Wings & fuselage between the wings & tail are variable length, probably made of removable sections. Aft fins contain CF rods & are used as landing
gear.

The exact dimensions are a long way from being known. The more rent increases, the smaller she gets. May use aluminum angle rods because
they're longer.

MARCY 2 REVEALED

The next indoor sonar demonstrator, since the monocopter ended up too big & unstable.

Swapped Vika 2's flight computer & shrunk her to the smallest possiblesize to make Marcy 2. She's the smallest vehicle we can make economically. A smaller vehicle using Feigau motors like theParrot demo would be more expensive so it's cheaper to bury our 1 Feigauthan buy 2 more to make a tri rotor. Turnigy/Towerpro 2410-9's are thelow point in motor prices when they're in stock.

Time to get rid of our 3 year old IDG300's. They had troubleinitializing on 1 axis. The pair could still be used in a flat IMU buttheir temperature sensitivity was horrible. Nowadays it's not worthhoarding gyros. They were free samples at a time no-one ever heard ofUAV's. Invensense thought their only use was phone cameras but we knewbetter.

Time to use up the LISY300AL's we got last April in a cube IMU.

MARCY 1 RADIO DISASTERS

The Marcy 1 ground station is basically a scratch built USB radio with 2 channels & a 224khz soundcard, sending 1.8Mbits of telemetry & sonar tothe laptop & 9600bits of commands to the aircraft.

Radio failures explain some of her instability. The Marcy 1 radios havenever performed as well in the fully integrated ground station as theydid in this test:

this-week-in-marcy-1-aviation

They sometimes work & sometimes drop out for no reason. There seems tobe no difference between straight dipoles, impedance matching baluns,plastic enclosures, bare circuit boards, low baud rates, isolatingcapacitors, & choke inductors for Vbus.

These radio parameters improved on the reference software.

Set the AFC range to +15/-16 Fres.
Use the highest receive bandwidth.
Use the highest FSK deviation.

The choke inductor on Vbus got rid of a lot of sonar noise.

Stepped up the remote control to 115000 baud but the flight computeronly has enough horsepower for 86000 baud. Now it's coming down tointerference from through hole parts.

She didn't crash there. It's a radio test.

New 900Mhz -> PCM receiver with a balun.

Without wind & with perfect radio contact she can hover in a smallarea. Cyclic effectiveness ramps up with very small magnitude & seemsto decrease with higher magnitude until she falls out of the sky.

STEVE STABILIZATION

Finally ran a stabilization pass on some Steve Morris helmet cam footage to see if it did any good for helmet cam footage. It looks a bit more like flying than clinging to someone's head but he needs a TASE gimbal & a head tracker.

Asian air space Eclipses North America As World’s busiest

Posted by Jack Crossfire on February 2, 2010 at 7:54pm

So much for America's over crowded airspace as a reason for banning UAV's.aero-newsTheoretically the region between Japan & India contains most of the world's traffic, has more aircraft per square mile than US, yet is more flexible for unmanned traffic.

THIS WEEK IN AEROSPACE

Posted by Jack Crossfire on January 29, 2010 at 10:30am

A MATERIAL THAT BONDS TO PLASTICAfter years of JB Weld, Cyanoacrylate, & epoxy failures, someone in China finally invented a material that bonds to plastic: SHAPELOCK You might even bypass the shipping costs by driving to Sunnyvale & getting it from this guy's house.http://shapelock.com/Heat it to 150F & it permanently sticks to plastic, allowing repairs to ever broken T-Rex landing gear. It can also be hand molded into arbitrary shapes. Skip the makerbot & use Shapelock to make camera mounts, sensor mounts, antenna mounts, battery holders, carbon fiber joints, fuselage brackets, servo mounts, maybe even motor mounts.Apparently it's equivalent to teflon & can be drilled & tapped. Our main use would be carbon fiber joints & propeller guards.PROPELLER SURGERY

Grinding the 3x2's down to 2.5x2's got them to last 20 minutes instead of 10 before breaking. 3x3's ground to 2.5x3's haven't broken after 30 minutes. The 2S 800mAh battery has a 10min flight time. Got used to the power management to the point where she feels like a slowly responsive copter. Unlike a normal copter, release cyclic & she sort of stabilizes in a hover.She's extremely unstable dynamically. Throttle derived attitude control doesn't seem enough for any tight position hold. She's not likely to stay inside the sonar radius on autopilot. May just put a uBlox on her & retire her.An RPM governer would be nice. Tried a simple PID loop & realized the RPM is too slow & requires too much variation to get very far. An RPM governor works best for constant, fast RPM.Got some long exposures showing position changes in no wind.

SONAR DISASTERSHaving sonar & telemetry on separate boards ended up busted. Sonar can't use laptop beacons for synchronization if the sonar & radio ground stations are on separate boards.Tried using the laptop clock but there's too much latency. The idea with clock synchronization is to broadcast a beacon from the laptop to every microprocessor to get the clock differences.With that, the Marcy 1 ground station was triple busted & we had a joyous time reverting hardware to Vika 1. It would have been better to give the Marcy 1 radio its own microprocessor & have it communicate over UART with the Vika 1 ground station.Fortunately synchronization with Marcy 1 radios works much better than XBees. The XBees added random latency.Properly calibrated sonar gives decent results.

After some sonar flight tests.

Nicely bent from water landings.MARCY-1 FIGHTS THE WIND

Got some progress against wind by reducing RPM to get more horizontal thrust. Minimizing RPM gives more horizontal force at the expense of instability. Unfortunately the radio connections are real lousy & lost contact in the end. Not sure if it's having telemetry & remote control on 900Mhz or the use of dipole antennas.THROTTLE INDUCED BANK

This one shows changes in angle of attack caused by Marcy 1's throttle modulation algorithm. Not much bank because she's bolted on a test stand & also because throttle modulation doesn't cause much banking.The magnetometer derived azimuth is sloppy but flyable. The problem is modulating throttle to bank changes the RPM.Now some long exposures showing the extent of throttle induced banking.

Getting clearer that the single PWM monocopter is a lousy indoor sonar demo because of the rotor diameter & the instability required for single PWM control. A large GPS guided monocopter which spins just fast enough to stabilize pitch yet maximize horizontal thrust might work outside.

Went through many ideas for Marcy 2. A partially fabricated single fan with servo controlled vanes was busted on efficiency. A large monocopter that converts into a flying wing was busted because the CG has to change. Steve Morris did that with a clumsy tractor mechanism. Transforming aircraft certainly aren't new.A compact tri rotor using Vika 2 parts is gaining popularity for Marcy 2.M.M.M.

Made a slideshow of our early flying photos with real Major Marcy Music. Apparently 1 other human in the world used Major Marcy as a username on a music service so how could we resist making a video. Maybe it was a Jack Crossfire reader.

THIS WEEK IN MARCY 1 AVIATION

Posted by Jack Crossfire on January 22, 2010 at 1:27am

Decal applied.

Ground station packed in. Battery sensor calibrated.

This design did not achieve horizontal control. The pitch oscillationfrom not having enough balance beam inertia offset any horizontal force.

This redesign did achieve 2 horizontal changes of direction using onlythrottle modulation. Unfortunately she threw a propeller &disintegrated upon crashing.

Marcy-1 was already very prone to throwing propellers, her 5300kV motorseemingly at the limit of Chinese plastic. We have a 4' monocopterplanned for extremely long duration hovers with normal RPM.

There it is. XYZ positioning using only throttle on the Marcy 1 vehicle.Unfortunately not enough authority to move upwind, so we only gotcrosswind translations & a slower downwind drift than if cyclic wasneutral.As Mike Bakula recommended, used raw magnetometer output & detected whenthe halfway point in the waveform was crossed. Much better than usingderivatives like MIT since the derivatives are very noisy.Very important to have the balance beam loaded as much as humanlypossible to prevent pitch oscillation. Having the motor & battery onthe balance beam is the easiest way to load it. She did indeed bank inthe direction of the translation from throttle alone.An aileron servo would do better against the wind but it would be heavy,expensive, & wear out fast. No way a servo would cycle 6x a second forvery long. If you're gonna use 2 PWM, there's no point in a monocopteranyways but it's probably unavoidable for any long duration, outdoorvehicle.PROPELLER TERRORISMFinally got a flight in no wind & drizzle & she was easily controllableusing only 1 PWM. She was very sensitive to breezes.1 problem was power level changes when applying cyclic which we actuallylearned to handle. Greatest horizontal thrust comes from gliding herwhen applying cyclic. You can stall the motor this way so she justapplies thrust in 1 direction yet stays in the air. Greatest verticalthrust comes from releasing cyclic. Power management on a monocopter isa new artform.

The mane problem was broken propellers after 6 minutes. That's right.The GWS 3x2's are just not strong enough to provide hovering power.Marcy 1 is perfect in every way but dead without a stronger propeller.Ideas range from griding them down to 2.5x2 & using 3x3 if the weatherever improves.

3x2 ground into a 2.5x2SONAR REVIVALGetting sonar working on a new flight computer & new radio is nevereasy. The mane problem is actually the microcontrollers & tools. Everynew microcontroller has a different register set. If you want SPI,magnetometer, & 3k of RAM that means capture compare & analog need to berewritten.Also, the MRF49XA takes so much more CPU time to service than the XBee,sonar had to go on a dedicated USB device, making it more expensive touse 8 bit PICs than 32 bit ARMs.3 years ago ARMs were $10 & really tough to solder. Now they're $2 &easily soldered. PICs are only still around because of code reusethough ARMs need a lot more pins for programming.Building a 100Mhz computer from scratch using an ARM has always beenalluring, but the only motivation now would be going back to embeddedautopilots or a huge price advantage with ARMs.SONAR THEORYThe trick with sonar is to synchronize the clocks on the ground station& aircraft. Vika 2 did it by sending 1 beacon to the ground station &aircraft simultaneously. Marcy 1 doesn't have sonar on the same USBport so there's a significant rewrite already.

The complete Marcy 1 sonar guided kit, applying all the sonar knowledgegained from Vika 2.

The standalone sonar board is the simplest possible.Now more views of the machine with 3x2's & loaded balance beam.

Sonar installed, magnetometer in the stock & this thing which tellstime. Wow that sounds neat.

Making the sonar crash resistant is going to require a new fuselage.

Aren't you glad you didn't need to solder this. This is standard forChinese toys though not Air Force grade except for the name.

Balancing act.

Final look before crashing.

MARCY-1 LIFTS OFF

Posted by Jack Crossfire on January 15, 2010 at 10:30am

There it is. Marcy-1's first free flight on the golf course.The 900Mhz RC transmitter interferes with the telemetry receiver even though they're on opposite ends of 915Mhz. You need to keep them separated or on different bands, which requires rebuilding the entire transmitter.The notoriously fickle capture compare on the PIC is still extremely hard to get working in the field.

Salute the Mar.

By now, we realized she had a serious roll oscillation which is probably from not having enough weight on the balace beam.

Longest flight.

Last flight, ending in a tree impact.

Marcy-1, warrior copter.THE 900MHZ NIGHTMARE

Tracked down the SI4421 problem to a floating solder joint. The SI4421is electrically identical to the MRF49XA.

Dual 900Mhz receivers for Vika 1 & Marcy 1.

Ancient 72Mhz converter from 3 years ago.

900Mhz converter fits inside the case.

Much better.

900Mhz converter has resistors for all the inputs to prevent overloading.The 900Mhz conversion runs at 9600bps. Manual control now has the full60Hz of the RC transmitter. It was reduced to 50Hz when it was 72Mhz.

After being plagued by broken wires & floating solder joints, the Marcy1 ground station was finally capable of flight.

Vika 1 is also beginning a long hard 900Mhz upgrade. Since the MRF49XAhas only a 16 bit buffer being consumed at 86000bps, getting VikaCopter to output data fast enough requires buffering an entire packet on the flight computer & sending it in 1 shot instead of sending data as it's collected.MICROMAG3 RIDES AGAINSince we didn't win the free $parkfun hibache knife set & no-one knowsif Marcy-1 will work, that leaves digging the old Micromag3 out of thegadget graveyard & fabricating a new Marcy-1 flight computerspecifically for it.A 3rd revision will be necessary. Depending on traffic, these boardscan be fabricated in 1 commute & since we're tax paying renters, thechips are fully recycled.

Spent $30 to find out only Mane Clog Remover, only at Walmart works.Other drain cleaners have additives which prevent the NaOH fromdissolving photoresist. Mind you, you're supposed to use batchpcb.

Etching skills are a bit rusty after the draino experiments.

Size comparison. Went back to single sided boards because they'relighter with our methods.

This one has a simple dipole with choke inductors, no decouplingcapacitors, 1 digital line under the chip & it still works. Filling aground patch & using 3 decoupling capacitors is only necessary formaximum range.

Suspect any inductors above 8nH would do the job but these were whatthe balun had.

Marcy 1 phase 2 with magnetometer grafted on.

& this is the raw & derivative of the magnetometer output at flight RPM. Flight RPM has 144 samples per period. The limiting factor is radio bandwidth, not the magnetometer. It takes 20000bps of radio bandwidth to downlink that. Monocopters take the zero crossings of the derivative to get azimuth & angular rate, but it's not so easy in realtime.