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Posted by Jack Crossfire | Nov 22, 2008 @ 11:06 PM | 4,961 Views
Raytheon Active Kill System (1 min 3 sec)

So this video of a guided missile shooting down another rocket got us thinking, a missile that flies up, turns 90 deg, & flies sideways in a fraction of a second is a super high speed UAV. What else can U do with a super high speed UAV?

Maybe instead of massive vehicles with massive batteries & hour long flight times, U have tiny airborn robots that take off, perform tasks in a fraction of a second & land with just a tiny amount of energy.

Used to wonder if there was a way to launch billions of tiny payloads into space real fast, each payload consisting of maybe a fraction of a gram of raw materials & launched using lasers or some super cheap vehicle. Then these billions of tiny payloads would self assemble in space to form massive structures.

What if U could put a small rocket in a handheld launcher & make it fly out 1m, reverse direction & fly back real fast. Maybe U could make it fly out & back hundreds of times in a second. Every time it flew back to the launcher it would recharge. A perpetual 1m linear orbiting rocket guided by a handheld launcher. U could aim the handheld launcher & the rocket's 1m linear orbit would always point where U aimed it.

Maybe instead of a rocket, it was a mirror with some mode of propulsion & U beamed a high powered laser at it to make a laser saber that was bounded by the rapidly oscillating, flying mirror. Not as clumsy or random as...Continue Reading
Posted by Jack Crossfire | Nov 22, 2008 @ 02:57 AM | 5,123 Views
The quad rotor bailout isn't working. Time for drastic measures. Got to elect a quad rotor despot & implement more regulation on the PIC. We're going to need to nationalize not just all the subprime aircraft, but the prime aircraft too. That's right. All your functioning aircraft now belong to Jack Crossfire, to rescue the broken aircraft. Give em up.

Some photos of Oakland telescopes seem to have missed the Jack Crossfire show, so U still get some content, this time....Continue Reading
Posted by Jack Crossfire | Nov 20, 2008 @ 03:36 AM | 5,194 Views
The quad rotor finally got in the air. Not enough power to control altitude. Cyclic oscillation in the dumpy apartment is the same as in the air. A few seconds in the air with that oscillation & the IMU drifts too much, U start going sideways faster & faster out of control, flip, & engine shutdown. Looks like better propellers R a start.

Higher cyclic gains may reduce oscillations, but these R prone to flipping without more kludges.

Quad tests (0 min 56 sec)

Posted by Jack Crossfire | Nov 19, 2008 @ 02:14 AM | 4,806 Views
Depressed over the quad crisis, it's time to worship The GOOG.

It's time to look over The GOOG's Time Warner photo archive & compare great depression #1 with great depression #2. Mainly the family living in poverty. After photographing our dumpy apartment, in our age of endless propaganda about government safety nets, total regulation & centralization, was surprised to find the typical apartment of the modern 50 hour/week programmer looks exactly like the poverty stricken apartment of the 30's.

U know you're taxed at 70% when U work, under Oooobs consisting of 30% marginal taxes, 20% FICA, 13% sales tax, 1% property tax, assorted infrastructure taxes, & "recycling fees" on everything U buy.

During the unemployed times, & U R going to have a lot of unemployed times, you have no savings. Your purchasing power is provided by unemployment insurance & other government programs. The property, sales, infrastructure, & recycling taxes on those purchases may come out of entitlements, but they easily exceed the 30% of your income U had left during employment, so the total tax you're paying during your lifetime is over 100% of what U earned. U pay over 100% of your income in taxes.

Unlike depression #1, there R no private war chests to start businesses & hire people. That money, over 100% of your income, has been paid into government programs to eliminate the need to start businesses & hire people.

Now what do U do when U can't get yaw damping to work? U bring back the vertical test stand. Most people use lazy susans to test yaw damping, but we only have enough room for a single piece of aluminum which can be reused for a vertical test stand & wind screen. U know the wind screen.

Quad rotor vs. vertical test stand (1 min 31 sec)

Notice heading in the video is fixed except when commanded by the pilot. Cyclic damping is still in crisis.
Posted by Jack Crossfire | Nov 18, 2008 @ 03:30 AM | 4,976 Views
Now that we're not flopping anymore, can see the quad is still capable of nasty vibration. Propeller balancers will be in attendance.

Decided to forget about manual cyclic & begin implementing a full time orientation hold & switchable position hold on top of that. That is a buster to get all 3 modes to coexist simultaneously for quad rotor & single rotor craft.

With enough software functioning between commutes, test flight #2 was still disasterous. Cyclic rate damping is good enough for the computer to hold the attitude, but still not for a human. There is no yaw authority. Yaw damping is ineffective & it takes very large deflections for the computer to try to hold a heading, which it never quite does before 1 of the 2 motor pairs stops.
Posted by Jack Crossfire | Nov 16, 2008 @ 05:18 AM | 5,048 Views
Looks like all quad rotors have to overclock their PWM way above the usual 50Hz. Mikrocopter uses I2C to get still higher update rates. The answer is yes. Suppo/Super Simple ESC's can do 100Hz, but it requires shrinking the resolution. The standard resolution only goes to 60Hz.

Nonlinear feedback curves, lighter propellers, higher gyro bandwidth, & higher frequency PWM has all contributed a bit to stability. It's never going to be as stable as an articulated rotor.

In today's video, U can see the rate is damped enough for a human to hold the angle, but the stick response is prone to violent rotation.

Quad rotor rate damping 2 (1 min 35 sec)

Forget about having enough money for any new parts in November. The Suppos R what U get.
Posted by Jack Crossfire | Nov 14, 2008 @ 01:50 AM | 5,288 Views
Well, Microdrones raised the bar with an 8.5lb quad rotor capable of 50 minute flights on battery power. Dual redundant IMU's & flight computers. Must figure out how Germans got so loaded compared to US.

Anyways, back to bailing out SUV manufacturers.

Decided blogs based on user content R really boring now because no-one's buying anything but T bills, so here R some rate damping efforts. Unfortunately, Goo Tube audio synchronization doesn't convey the relation between movement & throttle changes & sure enough, Goog stock is only $300.

Quad rotor rate damping (2 min 35 sec)

See. No rate damping at all. Disappointed to find the "New 1000mm Quad Copter Design" was using Turnigy ESC's at only double the price, not the 10x price U would expect for the ESC to be the problem. The next step is really full time attitude hold. Everyone uses full time attitude hold. Disable lowpass filtering completely & U start to get some rate damping but it's very erratic.

Also, these props R 72% heavier than successful quad rotor props. Haven't sold the T-Rex yet.
Posted by Jack Crossfire | Nov 13, 2008 @ 03:29 AM | 5,052 Views
That didn't go so well. Throttle control isn't fast enough for rate damping to work at all. It's a complete, unflyable, quad disaster. The Suppo ESC's either don't have the response time or don't have enough throttle steps. That's what U get for being sucked into super low prices.

There's much less vibration in the quadrotor than the unirotor. With virtually no noise in the IMU, U don't have the drift anomalies that plagued us & U can probably use the accelerometer for some velocity estimation.

Not surprising that with all these advantages, Mikrocopter has solved most of the problems of autonomous VTOL in the last year & you'd now be hard pressed to bother with all we did when U can just buy a Mikrocopter. They're hauling in some serious dough with those parts.

Mikrocopter does it all on an 8 bit Atmel. It needs no Kalman filters, quaternions, ground based computing, crazy communication schemes, neural networks, or anything. Just straight gyro integration on all 3 axes, using integer math. Unfortunately the source code is in German & it depends on some crazy fixed point optimizations, so your hacking mileage may vary.

If the dynamic forces are low enough, a very high accelerometer blend & slow yaw rate can eliminate the need for a quaternion attitude estimate. High wind still might give U problems. Suspect quaternions & Kalmans will come to Mikrocopter soon enough, which is the biggest reason to still bother with VicaCopter:...Continue Reading
Posted by Jack Crossfire | Nov 12, 2008 @ 06:02 PM | 4,314 Views
When spare parts for our Corona dried up, it seemed Lite Machines was gone. They shifted completely to an extremely painful suppository shaped VTOL device that seemed doomed.

The biggest problem was the requirement for hand launches & landings. For years, no-one was willing to reach into the whirling mass of blades to grab it, but thanks to some recent bank layoffs, that's not a problem anymore & now the mighty Lite Machine VTOL lives.

Lite Machines' Voyeur VTOL UAV - the real thing (1 min 2 sec)

Posted by Jack Crossfire | Nov 12, 2008 @ 02:47 AM | 4,358 Views
PIC debugging complete. There was a bug where DAMPING_SIGN variables interfered with analog readings, but just moved the DAMPING_SIGN variables somewhere else & it started working. Maybe it'll explode over some yellowjackets.

IMU calibration complete. Throttle range calibrated. Rate damping & control directions tested. Engine cutoff & failure testing complete. Threadlocking applied. Ny-ties tied. LED's lighting. Went back to engine cutoff switch + throttle stick since there isn't enough off margin when the transmitter is on & the rate damping is active. Now those propellers R really off when they're off. Running out of things to do without flying.
Posted by Jack Crossfire | Nov 10, 2008 @ 01:49 AM | 4,718 Views
The answer is yes. There is now a yellowjacket hive behind the dumpy apartment complex. If U go there to photograph or fly, you'll be stung over 10 times by a swarm, mainly in the head & have excruciating pain for the next 6 hours, followed by bearable pain. You'll need to run back to the nearest water supply as fast as possible & spray yourself in freezing weather to try to get rid of the monsters.

Still had enough unaffected skin after the attack & extreme pain to finish the quad assembly. Engine testing is already disasterous. Propellers spin up randomly from gyro noise. Prop savers break. Nuts & washers R falling from the fuselage.

Quad rotors R real dangerous. Unirotors don't have any starting torque. Quad rotors can go from 0 to full RPM instantly. Battery connector is too close to the rotors....Continue Reading
Posted by Jack Crossfire | Nov 08, 2008 @ 06:24 AM | 4,572 Views
Getting the quad rotor powered up is going to take another week. Going to 4 engines makes things very complicated & unreasonable. It's a matter of commuting back & forth every 2 hours, learning as much as possible between commutes, getting a missing part or tool down in the valley. We have 1 defective prop saver.

To test the rate damping, need to unplug all but 1 of the motors & wiggle it bare handed with the propeller spinning. IMU mounting isn't going as well as planned either. The total cost is heading more into the $250's than the $132 envisioned....Continue Reading
Posted by Jack Crossfire | Nov 06, 2008 @ 03:23 AM | 4,595 Views
the quad rotor.

Motor mount & mockup #2 was sturdier but not perfect. Final assembly will be foam tape intensive. The plywood fuselage is soft indeed. Time to fabricate this: 4 hours & it's back in the car & back to Silicon Valley.
Posted by Jack Crossfire | Nov 05, 2008 @ 03:18 AM | 3,051 Views
Enough parts arrived from China to mock up with actual motors & materials. The motors were half the expected size & really really flimsy. Looks like our revolutionary theory of metal wires clamping motors to CF rods is busted. It works for a stationary object like the contact lens agitator magnet, but not an aircraft. Looks like it's going 2 B big, heavy wooden vices like everyone else.

Only got CF rods because they were the cheapest & strongest. Need to crash what we have before going to proper square tubing.

Speaking of revolutions, how bout that human nature? U don't need 2 B a psychology major to predict how humans will respond to mass media. Your world is going to be a lot more like...Calif*. If U don't know what Calif* is like, U haven't been reading the Jack Crossfire blog. 450 sq ft of living space is going 2 B a victory 4 U indeed. Better get rid of those savings accounts....Continue Reading
Posted by Jack Crossfire | Nov 04, 2008 @ 04:11 AM | 2,773 Views
Quad rotors R a return to the past.

Our first campaign to build a UAV anything was a quad rotor in Fall of 1988. The quad rotor would be solar powered & recharge a bank of NiCd batteries. It would use discrete electronics & brushed motors. It would be made of a sheet of plywood. It would fly under FPV control using some kind of wireless camera that we would design, & signals sent over 2 way short wave radio. If the NiCD's didn't have enough capacity, it would land & recharge several times during a mission.

Its mission was to fly 12 miles over the east bay hills & bring U telepresence from your true love. You see, we didn't have cars in those days. Also didn't know about microcontrollers, rate damping, counter rotating props, camera systems, wireless systems, brushless motors, solar panel efficiency, battery efficiency, amputation by propeller, & economics. However, it was legal in 1988.

The technology & economics wouldn't exist for another 20 years. In 1988, it might have been barely possible if we used a motor glider or ground vehicle, but our quad rotor compassion would not be denied.

The mission could probably just barely be done today. It would take a very very long time. The quad rotor would fly 15 minutes at a time, recharge on solar power for 7 days, & fly another 15 minutes. It would have to be very autonomous. It would use the cell phone network for video & control, but be entirely GPS guided.

Nowadays we do that exact 12 mile mission every day in a car for our day jobs & the true love is long gone. Ironically, after 20 years of gas & single rotors being economic reality, the electric quad rotor we originally envisioned has emerged as the most practical vehicle.
Posted by Jack Crossfire | Nov 03, 2008 @ 02:02 AM | 2,662 Views
Should note it was only 13 months ago when our vehicles started hovering autonomously. Oct 10, 2007 was the first time anything stayed in the same position on its own. 1Hz GPS wasn't fast enough to do the job, yet neural networks created just enough inferrence to keep it in the air. It was rough going. Forget about any wind. The first year was all about increasing the maximum wind speeds, waypoint tracking, & bringing up airframe #2.

It was only 9/22/06 when we got anything to fly at all: the Picco Z. It was only Oct 24, 2006 when the Corona started flying at all....Continue Reading
Posted by Jack Crossfire | Nov 02, 2008 @ 03:07 AM | 2,927 Views
It's a race against the Chinese air mail, which is probably on a bus. Software migrated from single rotor to quad rotor. 5V leads removed from servo headers. Quad electronics tray being designed.
Posted by Jack Crossfire | Nov 01, 2008 @ 02:14 AM | 2,794 Views
The remains of the Rex might be 4 sale or might not be. It's completely airworthy except for the electronics. If it is ever sold, the electronics will be removed. The tail struts, flybar, & paddles were barely used. The flybar was crashed once. The foam & carbon landing gear assembly is flightworthy & probably stronger than the Taiwan version.

A new kit with ESC, motor, 2.5Ah battery, & CF blades is $449.99.
Some parts missing from VicaCopter's remains:

2.1Ah Battery: -$55.99
Motor + ESC: -$62.50
CF blades: -$36.99
Landing gear struts: -$6

Most of the stuff is used yet there R a few new & spare parts, so the remains of the Rex would probably be $150 today. Don't feel our main blade collection is airworthy enough to sell.
Posted by Jack Crossfire | Oct 31, 2008 @ 04:10 PM | 3,204 Views
Paypal came through & managed to suck our last paycheck into China, so forget about the VicaGlider budget & get ready 4 VicaCopter III.

Now an embedded update.

Phone fans don't like talking about the CPUs in their corporate branded trophies because they're so damn slow. That's why it was really hard to find this out.

iPhone 3G: 412Mhz ARM CPU No FPU.
gPhone: 528Mhz ARM CPU No FPU.

The 600Mhz Gumstix boards we used R being phased out & replaced by new green themed boards running at, wait for it, 600Mhz! "NEON" FPU.

While advertised as dual core, the gPhone CPU is really a 1.5 core & the half core is for communication.

gPhone is written in Java. iPhone is written in C. The gPhone GUI is less responsive. Corporations don't pass higher clockspeeds to users. They use the clockspeeds to write cheaper software.

So unless you're into programming DSP's & FPGA's, the embedded floating point hasn't gone anywhere.
Posted by Jack Crossfire | Oct 30, 2008 @ 04:03 PM | 3,437 Views
Well, $12 motors R a bit too good 2 B true. U need to pay $30 shipping from China to have them in your lifetime. That is, if U can get your credit card to fund Paypal. Anything beats calling the Bangalore call center & waiting on hold for an hour to unblock Paypal. So unless you're crazy, the motors R $50.

Then of course, there's VicaGlider. Since the quadrotor requires parts that only exist in China, we expect major down times. We've got major mortgage bailout taxes coming up. Because of the difficulty in getting money to China, the overlapping quadrotor & VicaGlider purchases could take 2 months to finish, making the overlapping purchases more like 1 purchase each month.