Out of 40 papers at the conference, there will be just one paper that looks at human factors
There is a reason for this: the conference is about security. A large part of security is defining news ways of keeping systems secure, and usability is just one of the myriad factors. I think having even this one paper is overkill - I read it and don't think that it contributes very much.
Before you mod me down as flamebait, read the paper and honestly ask yourself if it tells you anything new at all.
Do they need to know how to install the OS first, or should I let them look that up on their own while I make them power-users?
What distributions of Linux and BSD should they be first introduced to? (I'm only familiar with Debian, and I know virtually nil about *BSD.)
Initially, do they need to be more adept at the GUI, or do they first need to know how to use the shell?
Should I give away Debian CDs no-questions-asked, or should I talk with the almighty Parents so little Daniel doesn't install Linux over Dad's 'work computer.'
Are there any other key issue I need to think about?"
Seriously though, I think he's looking for input on any issues we can think of, issues that might help influence kids to use and embrace open software early in life.
I think the point that was being made was that China has a vested interest in blocking sites about Taiwan (which China claims as an integral part), but there is no obvious reason for it to block the remaining sites like Red Lobster.
Unfortunately the lack of stereo vision that this results in means that the picture is now no longer 3D. However, there is a solution: alternately open and shut your left and right eyes around 24 times a second.
Oh wait...
Isn't this already happening?
on
Virtual Simerica
·
· Score: 3, Interesting
Correct me if I'm wrong, but hasn't this been a problem for a long while? I remember reading stories about people who play EverQuest 10 hours a day. Someone I knew was fired from his job because he used to sneak an hour out of every workday playing EQ.
I don't see any specific reason why the sudden advent of The Sims is going to create a big enough blip in the social landscape that we need to start worrying afresh.
The whole point of the Internet Archive project is to document the growth of the Internet - in all its glory or lack of it thereof. There has never been an opportunity like this before. To be able to study the growth and maturity of a massive social phenomenon like the internet - something that affects the way humanity communicates on an elemental scale - is the dream of every social scientist.
Picking and choosing what goes into the archive does not solve the purpose of the archive in any way.
Here. They seek to create physical items (clocks and libraries are two items they name) that will last for very, very long periods of time. This diagram shows what is meant by the "long now", and this is a link to their first prototype clock that is on display in the Science Museum in the UK (the second clock on the page).
Re:+1 Informative?YES IT IS FUCKING +1 INFORMATIVE
on
Living with Darth Vader
·
· Score: 0, Flamebait
It seems to me that keeping a Jar-Jar like character in the game is one of the smartest things that LucasArts could do - just from reading the posts on this thread so far, I can see that there are likely to be a large number of people who play the game just to see if they could kill Jar Jar.
They're kind of limited by the movies, aren't they?
No, they are not - take a look at the zillion books written about the Star Wars universe. Some of which have even been pretty good - like Timothy Zahn's first trilogy. The whole point of it being set in a universe is that it is limitless, and this limitlessness gives immense scope for expansion. Too many players? Lets just announce the discovery of a new planet!
So no, I don't believe that they are limited by the movies - the movies just give them a firm pseudo-reality to start from.
It is the simplest thing in the world for power to the robot to be automatically cut off as soon as transmissions frmo the surgeon to the robot cease, and I'm pretty sure that the system has at least that elementary failsafe built in. So this, at least, would not be something to get nervous about.
November 12, 13, 15, and 16 (busy week!) meeting notes
Flight Unsuccessful
We prepared for and conducted our first remote flight test at the Oklahoma Spaceport facility in Burns Flat this week. Several lessons were learned.
We built a checklist for our flight operations, which was a very good idea. Going through it before setting off caught several things we almost forgot.
The five hour drive from Dallas to Burns Flat was rougher on the equipment than expected. The tarp we put over everything to keep people from staring was damaged by the wind in several places, and the wooden cradle we transport the vehicle on actually broke one of its 2x4 support bars. We are probably going to arrange some hoops for the trailer so we can tarp it like a covered wagon in the future. I may consider an enclosed trailer with a suspension in the future.
Everyone was extremely helpful in Oklahoma, and we set up in the middle of a service road well off from the main airport runway. Our expected altitude with only five gallons of peroxide was under 1500', and our parachute drift range with 13 mph winds was only about 2000', so we had plenty of room. Bill Kourie from OSIDA stayed with us to communicate with the air traffic control tower during our launch activities.
Our setup was a bit slower than we expected, but everything got done fairly smoothly. The VOX on the radios we brought was more trouble than it was worth, often triggering with wind noise, but this was our first time using radio communication.
We did a full water test, then loaded up five gallons of peroxide. The engines all warmed quickly, and ran perfectly clear, even though it was in the mid 50s.
When we were cleared for our launch, I smoothly throttled up the engine over a two second period. The vehicle tilted a little bit on liftoff, but seemed to straighten out, but it then continued tipping, eventually tipping all the way over and flipping into the ground from a hundred or so feet up.
There was still peroxide left in the vehicle tank, but all the pressure had drained out by the time we reached it. We tipped it up to allow the remaining peroxide to drain down into the main engine and slowly catalyze away, then we carried the vehicle back to the road to run some low pressure water through it to clean it up.
http://media.armadilloaerospace.com/2002_11_16/f li ghtUnsuccessful.mpg
We drove the remains to our bunker to strip off the good parts, and left the main body there.
http://media.armadilloaerospace.com/2002_11_16/b un ker.mpg
Analysis
The telemetry cut off only four seconds after throttle-up, indicating that the computer died, but there was very valuable data.
Immediately after liftoff, there was a +Z angle rate kick, probably caused by the funny takeoff aerodynamics underneath the tail flare. The piece of aluminum sheet metal we put under the rocket for ground protection was folded in half and crumpled up after liftoff, which was completely unexpected. You can briefly see that in one of the liftoff video frames. The rate peaked at 22 deg/s, with the opposite attitude engine full on, then it started coming back down. The liftoff test last week did not show this behavior, but the feet were changed, and the surface was different this time. It is also possible that the main engine mount was slightly distorted by the travel.
The Crossbow stopped updating 1.25 seconds before telemetry ceased.
The vertical acceleration was right at one G when the Crossbow stopped updating, and very smooth. This was slightly higher than expected, indicating about 600 pounds of thrust from the engine at 280 psi takeoff tank pressure. The plumbing on the test stand was definitely limiting performance compared to the straight shot on the vehicle. The welded catalyst pack continues to perform very well.
The battery voltage started dropping rapidly at this point, but the computer continued operating for another 1.25 seconds, until the battery voltage reached 9v, at which point telemetry ceased. The 15v power converter for the Crossbow probably suffered a voltage drop before the 5v power converter for the main computer. The main engine feedback potentiometer reading fell off as the 5v supply dropped below 5v, and the engine pressure transducer started falling off faster than it should as the supply voltage dropped below 10v. All of this points to a general power system failure, rather than just a computer power failure (which has triple redundant connections to the main power supply from the manned lander work).
During the last 1.25 seconds of operation, the computer continued using the last valid Crossbow data, which caused it to hold the same two attitude engines on, which built up momentum on all three axis. Presumably the attitude solenoids all closed when the computer died and stopped sending an active signal to the solid state relay boards, but quite a bit of momentum could be built up in that time. The main engine would remain in the full-open position. As the vehicle did its flip, you could see it slowing down while it was pointed upwards.
The flight control code has in the past had stop-all-engines behavior when the crossbow stops updating, but on this flight there was no cutoff checks, which was a mistake. If there had been, the rocket would have just dropped from about 20' in the air, and suffered much less damage. The exact timing for deciding the crossbow isn't working is a tough judgment call, but a quarter second should certainly be enough time to decide that the attitude engines should cut off. The decision to cut the main engine is harder, because the vehicle should be able to continue flying as an unguided, aerodynamically stabilized vehicle if it is going fast enough, but right-off-the-pad, it could turn into a land shark.
There was one GPS update after liftoff, showing it at three meters above the ground, but with only a small vertical velocity. The processing latency on GPS velocity and position may be different.
My initial thought was that something had shorted, perhaps in the motor drive feedback or pressure transducer, which have power running to them from the main bus. When we opened the electronics box, the cable to the battery positive terminal was not connected. The battery still had full voltage in it, so we believe that the terminal came off during the flight, causing the voltage drop that led to the failure, rather than during the crash. It is unfortunate that it seemed to work during the water test and warm-ups, but the drive from Texas probably loosened the connection to the point that it was barely hanging on. The batteries have slip-on connectors, which have bothered me for quite a while, but screw terminal batteries are not available until much larger sizes. We are going to drill our own screw terminals in the lugs of future batteries, and possibly solder them as well.
The Damage
The important thing is that the Crossbow IMU survived, because that costs more than everything else put together, and can have an 8 week lead time. I am going to buy a backup, in case we aren't so lucky next time. Crossbow is now offering (but not shipping yet) an improved fiber optic gyro IMU with half the drift rate, but they jacked up the price a few thousand dollars.
The main tank actually seems to be ok, but we are not going to trust pressurizing it again.
The fiberglass nose and tail cones were both broken.
The engines casings for the parachute tower still look OK, I guess they bent away before the body hit them.
The tower was mangled, of course.
The pressure transducer at the top of the tank was broken.
Our aluminum engine frame at the base was bent a fair amount.
One attitude engine broke the jet holder fitting off inside, but we can probably remove it.
The main engine servo valve had the half inch pipe fitting permanently bent in it, but we were able to swap that section of the valve with scrap from a valve broken in a different way, so it seems to have been saved, but we haven't leak checked it yet. The plastic connectors on the valve were very brittle from the cooking they took on our hover tests that stuck to the ground, and broke when disassembled. We are going to run Tefzel wire all the way to the valve motors in the future, instead of using the supplied pigtail connectors.
All the plumbing survived, except for the two fittings that jammed in engines.
All the engines look ok, but we will have to carefully check that the main engine hasn't bent its inlet connector.
The WinSystems SBC computer seems dead. The memory SIMM was ripped out of the socket, which also partially detached, and even after reseating everything, it won't boot. The flash drive still works fine in another system, which saves me the effort of building a new linux system from my last backup.
The antenna connector on the Esteem wireless unit is broken, but the unit looks OK. Taking the case apart showed that we can save a large amount of electronics area and several pounds by just mounting the guts and ditching the case.
Both batteries have cracked cases, although neither one spilled any acid gel in the box.
The fan over the power supplies was wrecked.
The A/D breakout board was smashed by the batteries.
New Vehicle Work
We are going to proceed with the next vehicle design, as if this test had succeeded, rather than rebuilding an identical vehicle. The major change is to move to four large engines that are differentially throttled, instead of the single large engine and four solenoid controlled attitude engines. This goes back to the control style of our very first lander, and is motivated by the fact that we are bumping up against vehicle size limits for being controlled by the thrust we can get from solenoid based attitude engines.
The vehicle will pay much more attention to streamlining, with the intention of being capable of supersonic flight. The nose will be 10 or 15 degrees, and we will be using a honeycomb composite constructed box fin arrangement for stability instead of the tail flare. There will be no external protrusions or loose cables along the sides. We are going to try a rear parachute ejection system, with an intentionally crushable top nose section
The propulsion system will have a master cutoff valve, run by a separate watchdog computer. We have talked about this for ages, but not yet implemented it. If implemented on the last vehicle, it would have dropped it from a much lower altitude.
We are going to make many changes in the electronics to improve reliability.
There will be a backup 9600 baud telemetry radio, in addition to the Esteem 802.11b.
No more solid core wire for DB connectors, move to 22 ga stranded Tefzel wire. All 18 gauge wire is already Tefzel, but I had been using solid wire for soldering serial cables, which is a known poor practice. I am moving to mil-spec double-crimp terminals for all flight hardware, instead of the single-crimp industrial terminals we have been using.
Mount all the electronics, except for the inertial unit, on a vibration isolated board.
New A/D breakout board
The breakout board that WinSystems sells for their A/D board takes up a lot more space than necessary, and uses bare wire screw terminals for input, so we are going to replace it with a custom board that is smaller and takes ring terminals.
16 signal inputs with #6 ring terminals, one ground is common to all signals measured.
The range is +/- 10V, so we need to cut the main battery voltage in half before sampling. It is a toss up if this should be done on the A/D breakout board, or on the power supply board. There should be a grid of holes for soldering in random resistors or capacitors to modify signals.
The grounds are common to all the signals, so I think all we need is a single ground ring terminal that we will run back to the power supply.
The connector going to the A/D board is a 26 pin ribbon cable with the following pinout:
1: ch0 2: ch8
3: ch1 4: ch9
5: gnd 6: gnd
7: ch2 8: ch10
9: gnd 10: gnd
11: ch3 12: ch11
13: gnd 14: gnd
15: ch4 16: ch12
17: gnd 18: gnd
19: ch5 20: ch13
21: gnd 22: gnd
23: ch6 24: ch14
25: ch7 26: ch15
Watchdog Board
Trivial microcontroller that watches a continuous signal from the main computer, and uses a private motor drive to open the master cutoff valve only when the main computer is healthy.
Input:
One optically isolated digital line from the main computer
Private +12v / GND
Output:
Two #6 ring terminals to control the master cutoff servo valve (the main computer will still read the pot feedback of that valve)
Power supply board
Multiple, diode isolated batteries for redundancy, with an additional port for running on external power
External charging ports for each battery, so the electronics don't need to be taken out of the vehicle for charging.
Short run from batteries to boards, no in-line power switch. Use the power pin on the DC/DC power converters for switch-on. Use redundant switches to prevent a switch glitch under vibration from turning everything off.
Run nothing from the unregulated power supply, except for the A/D line for current voltage level. We previously ran a couple things from the unregulated 12v supply, like the Esteem wireless unit, and the pressure transducer. It is possible we were losing telemetry momentarily earlier than the computer died, depending on the details of their power use.
Instead of running wires from the power supply board to jumpered barrier strips for distribution as we previously did, build plenty of terminals directly onto the power supply board. At a minimum:
Lots of grounds.
Unregulated +12v: Battery A/D line
+5v: computer (two lines)
+5v: 6 motor drive potentiometer feedbacks
+5v: several spares
+6v: laser altimeter
+12v: pressure transducer
+12v: GPS
+12v: Panel-PC LCD display
+12v: Several spares
-12v: Panel-PC LCD display
+15v: Crossbow IMU
We might want to use a higher voltage for the IMU, as the range is 15v-30v, and we have been warned by someone about running avionics at their minimum recommended voltages. Today's result seem to corroborate that it is closer to going out than the rest of the systems.
Current draw signal for telemetry? If we ever have a short somewhere, this would be helpful in diagnostics.
Isolated voltage signals for each battery? If we don't have that, telling when a battery has failed will be difficult.
Actuator Boards
Our current solid state relay board still has bare wire terminals (although they are high quality ones that haven't yet given problems), it still has the old power supply on it that we don't use, and one bit on the input connector is flaky, so it needs to be replaced.
Isolated voltage signal for A/D telemetry?
Isolated continuity checks for each actuator? The motor valves can be self-tested by watching the potentiometer feedback, but solenoids and pyro would need a low-current test signal. The actuator battery needs to be completely isolated from the main battery to avoid noise problems, so a continuity sensor would need to be isolated as well.
We have known needs for up to six solid state relays and six motor drives, so building for eight and eight is probably good planning.
From the article: It does, however, share capabilities, such as inking and handwriting recognition, with the more expensive machines.
There seems to be no information about how these machines support handwriting recognition. The Tablet PCs perform this task using capabilities in Windows XP Tablet PC edition - i.e., the OS itself. Since these products claim to support handwriting recognition over a wide variety of OSs, is there some hardware support for this feature?
I was terribly excited when I read that bit too, but some digging into google revealed this fact: You won't be able to keep your phone number when you switch until November 2003, which is more than a year away. So there go all my hopes of keeping my number when my contract ends next April.
Slashdot Mirror
Read the article: he created counterfeit cashiers checks.
Out of 40 papers at the conference, there will be just one paper that looks at human factors
There is a reason for this: the conference is about security. A large part of security is defining news ways of keeping systems secure, and usability is just one of the myriad factors. I think having even this one paper is overkill - I read it and don't think that it contributes very much.
Before you mod me down as flamebait, read the paper and honestly ask yourself if it tells you anything new at all.
Aren't they up on the post?
Do they need to know how to install the OS first, or should I let them look that up on their own while I make them power-users?
What distributions of Linux and BSD should they be first introduced to? (I'm only familiar with Debian, and I know virtually nil about *BSD.) Initially, do they need to be more adept at the GUI, or do they first need to know how to use the shell?
Should I give away Debian CDs no-questions-asked, or should I talk with the almighty Parents so little Daniel doesn't install Linux over Dad's 'work computer.'
Are there any other key issue I need to think about?"
Seriously though, I think he's looking for input on any issues we can think of, issues that might help influence kids to use and embrace open software early in life.
likely to go out and earn $80,000/yr in a post-90s economy
:)
Have you looked at the stock market lately?
Some of them are even on Slashdot. I want to give the rest a boost in the right direction."
Aren't the kids in the first group the dangerous ones?
here.
I think the point that was being made was that China has a vested interest in blocking sites about Taiwan (which China claims as an integral part), but there is no obvious reason for it to block the remaining sites like Red Lobster.
Unfortunately the lack of stereo vision that this results in means that the picture is now no longer 3D.
However, there is a solution: alternately open and shut your left and right eyes around 24 times a second.
Oh wait...
Correct me if I'm wrong, but hasn't this been a problem for a long while? I remember reading stories about people who play EverQuest 10 hours a day. Someone I knew was fired from his job because he used to sneak an hour out of every workday playing EQ.
I don't see any specific reason why the sudden advent of The Sims is going to create a big enough blip in the social landscape that we need to start worrying afresh.
Nothing much - I'd be too busy scraping myself off the surface of the moon.
The whole point of the Internet Archive project is to document the growth of the Internet - in all its glory or lack of it thereof. There has never been an opportunity like this before. To be able to study the growth and maturity of a massive social phenomenon like the internet - something that affects the way humanity communicates on an elemental scale - is the dream of every social scientist.
Picking and choosing what goes into the archive does not solve the purpose of the archive in any way.
Here. They seek to create physical items (clocks and libraries are two items they name) that will last for very, very long periods of time. This diagram shows what is meant by the "long now", and this is a link to their first prototype clock that is on display in the Science Museum in the UK (the second clock on the page).
Hmm.. this from a very brave anonymous coward.
I'm quaking in my boots.
It seems to me that keeping a Jar-Jar like character in the game is one of the smartest things that LucasArts could do - just from reading the posts on this thread so far, I can see that there are likely to be a large number of people who play the game just to see if they could kill Jar Jar.
Oops, and here I thought this was a joke. Must've missed something...
PLEASE don't moderate a comment a certain way unless you understand what the poster is trying to say.
They're kind of limited by the movies, aren't they?
No, they are not - take a look at the zillion books written about the Star Wars universe. Some of which have even been pretty good - like Timothy Zahn's first trilogy. The whole point of it being set in a universe is that it is limitless, and this limitlessness gives immense scope for expansion. Too many players? Lets just announce the discovery of a new planet!
So no, I don't believe that they are limited by the movies - the movies just give them a firm pseudo-reality to start from.
It is the simplest thing in the world for power to the robot to be automatically cut off as soon as transmissions frmo the surgeon to the robot cease, and I'm pretty sure that the system has at least that elementary failsafe built in. So this, at least, would not be something to get nervous about.
Flight Unsuccessful
f li ghtUnsuccessful.mpg
b un ker.mpg
November 12, 13, 15, and 16 (busy week!) meeting notes
Flight Unsuccessful
We prepared for and conducted our first remote flight test at the Oklahoma Spaceport facility in Burns Flat this week. Several lessons were learned.
We built a checklist for our flight operations, which was a very good idea. Going through it before setting off caught several things we almost forgot.
The five hour drive from Dallas to Burns Flat was rougher on the equipment than expected. The tarp we put over everything to keep people from staring was damaged by the wind in several places, and the wooden cradle we transport the vehicle on actually broke one of its 2x4 support bars. We are probably going to arrange some hoops for the trailer so we can tarp it like a covered wagon in the future. I may consider an enclosed trailer with a suspension in the future.
Everyone was extremely helpful in Oklahoma, and we set up in the middle of a service road well off from the main airport runway. Our expected altitude with only five gallons of peroxide was under 1500', and our parachute drift range with 13 mph winds was only about 2000', so we had plenty of room. Bill Kourie from OSIDA stayed with us to communicate with the air traffic control tower during our launch activities.
Our setup was a bit slower than we expected, but everything got done fairly smoothly. The VOX on the radios we brought was more trouble than it was worth, often triggering with wind noise, but this was our first time using radio communication.
We did a full water test, then loaded up five gallons of peroxide. The engines all warmed quickly, and ran perfectly clear, even though it was in the mid 50s.
When we were cleared for our launch, I smoothly throttled up the engine over a two second period. The vehicle tilted a little bit on liftoff, but seemed to straighten out, but it then continued tipping, eventually tipping all the way over and flipping into the ground from a hundred or so feet up.
There was still peroxide left in the vehicle tank, but all the pressure had drained out by the time we reached it. We tipped it up to allow the remaining peroxide to drain down into the main engine and slowly catalyze away, then we carried the vehicle back to the road to run some low pressure water through it to clean it up.
http://media.armadilloaerospace.com/2002_11_16/
We drove the remains to our bunker to strip off the good parts, and left the main body there.
http://media.armadilloaerospace.com/2002_11_16/
Analysis
The telemetry cut off only four seconds after throttle-up, indicating that the computer died, but there was very valuable data.
Immediately after liftoff, there was a +Z angle rate kick, probably caused by the funny takeoff aerodynamics underneath the tail flare. The piece of aluminum sheet metal we put under the rocket for ground protection was folded in half and crumpled up after liftoff, which was completely unexpected. You can briefly see that in one of the liftoff video frames. The rate peaked at 22 deg/s, with the opposite attitude engine full on, then it started coming back down. The liftoff test last week did not show this behavior, but the feet were changed, and the surface was different this time. It is also possible that the main engine mount was slightly distorted by the travel.
The Crossbow stopped updating 1.25 seconds before telemetry ceased.
The vertical acceleration was right at one G when the Crossbow stopped updating, and very smooth. This was slightly higher than expected, indicating about 600 pounds of thrust from the engine at 280 psi takeoff tank pressure. The plumbing on the test stand was definitely limiting performance compared to the straight shot on the vehicle. The welded catalyst pack continues to perform very well.
The battery voltage started dropping rapidly at this point, but the computer continued operating for another 1.25 seconds, until the battery voltage reached 9v, at which point telemetry ceased. The 15v power converter for the Crossbow probably suffered a voltage drop before the 5v power converter for the main computer. The main engine feedback potentiometer reading fell off as the 5v supply dropped below 5v, and the engine pressure transducer started falling off faster than it should as the supply voltage dropped below 10v. All of this points to a general power system failure, rather than just a computer power failure (which has triple redundant connections to the main power supply from the manned lander work).
During the last 1.25 seconds of operation, the computer continued using the last valid Crossbow data, which caused it to hold the same two attitude engines on, which built up momentum on all three axis. Presumably the attitude solenoids all closed when the computer died and stopped sending an active signal to the solid state relay boards, but quite a bit of momentum could be built up in that time. The main engine would remain in the full-open position. As the vehicle did its flip, you could see it slowing down while it was pointed upwards.
The flight control code has in the past had stop-all-engines behavior when the crossbow stops updating, but on this flight there was no cutoff checks, which was a mistake. If there had been, the rocket would have just dropped from about 20' in the air, and suffered much less damage. The exact timing for deciding the crossbow isn't working is a tough judgment call, but a quarter second should certainly be enough time to decide that the attitude engines should cut off. The decision to cut the main engine is harder, because the vehicle should be able to continue flying as an unguided, aerodynamically stabilized vehicle if it is going fast enough, but right-off-the-pad, it could turn into a land shark.
There was one GPS update after liftoff, showing it at three meters above the ground, but with only a small vertical velocity. The processing latency on GPS velocity and position may be different.
My initial thought was that something had shorted, perhaps in the motor drive feedback or pressure transducer, which have power running to them from the main bus. When we opened the electronics box, the cable to the battery positive terminal was not connected. The battery still had full voltage in it, so we believe that the terminal came off during the flight, causing the voltage drop that led to the failure, rather than during the crash. It is unfortunate that it seemed to work during the water test and warm-ups, but the drive from Texas probably loosened the connection to the point that it was barely hanging on. The batteries have slip-on connectors, which have bothered me for quite a while, but screw terminal batteries are not available until much larger sizes. We are going to drill our own screw terminals in the lugs of future batteries, and possibly solder them as well.
The Damage
The important thing is that the Crossbow IMU survived, because that costs more than everything else put together, and can have an 8 week lead time. I am going to buy a backup, in case we aren't so lucky next time. Crossbow is now offering (but not shipping yet) an improved fiber optic gyro IMU with half the drift rate, but they jacked up the price a few thousand dollars.
The main tank actually seems to be ok, but we are not going to trust pressurizing it again.
The fiberglass nose and tail cones were both broken.
The engines casings for the parachute tower still look OK, I guess they bent away before the body hit them.
The tower was mangled, of course.
The pressure transducer at the top of the tank was broken.
Our aluminum engine frame at the base was bent a fair amount.
One attitude engine broke the jet holder fitting off inside, but we can probably remove it.
The main engine servo valve had the half inch pipe fitting permanently bent in it, but we were able to swap that section of the valve with scrap from a valve broken in a different way, so it seems to have been saved, but we haven't leak checked it yet. The plastic connectors on the valve were very brittle from the cooking they took on our hover tests that stuck to the ground, and broke when disassembled. We are going to run Tefzel wire all the way to the valve motors in the future, instead of using the supplied pigtail connectors.
All the plumbing survived, except for the two fittings that jammed in engines.
All the engines look ok, but we will have to carefully check that the main engine hasn't bent its inlet connector.
The WinSystems SBC computer seems dead. The memory SIMM was ripped out of the socket, which also partially detached, and even after reseating everything, it won't boot. The flash drive still works fine in another system, which saves me the effort of building a new linux system from my last backup.
The antenna connector on the Esteem wireless unit is broken, but the unit looks OK. Taking the case apart showed that we can save a large amount of electronics area and several pounds by just mounting the guts and ditching the case.
Both batteries have cracked cases, although neither one spilled any acid gel in the box.
The fan over the power supplies was wrecked.
The A/D breakout board was smashed by the batteries.
New Vehicle Work
We are going to proceed with the next vehicle design, as if this test had succeeded, rather than rebuilding an identical vehicle. The major change is to move to four large engines that are differentially throttled, instead of the single large engine and four solenoid controlled attitude engines. This goes back to the control style of our very first lander, and is motivated by the fact that we are bumping up against vehicle size limits for being controlled by the thrust we can get from solenoid based attitude engines.
The vehicle will pay much more attention to streamlining, with the intention of being capable of supersonic flight. The nose will be 10 or 15 degrees, and we will be using a honeycomb composite constructed box fin arrangement for stability instead of the tail flare. There will be no external protrusions or loose cables along the sides. We are going to try a rear parachute ejection system, with an intentionally crushable top nose section
The propulsion system will have a master cutoff valve, run by a separate watchdog computer. We have talked about this for ages, but not yet implemented it. If implemented on the last vehicle, it would have dropped it from a much lower altitude.
We are going to make many changes in the electronics to improve reliability.
There will be a backup 9600 baud telemetry radio, in addition to the Esteem 802.11b.
No more solid core wire for DB connectors, move to 22 ga stranded Tefzel wire. All 18 gauge wire is already Tefzel, but I had been using solid wire for soldering serial cables, which is a known poor practice. I am moving to mil-spec double-crimp terminals for all flight hardware, instead of the single-crimp industrial terminals we have been using.
Mount all the electronics, except for the inertial unit, on a vibration isolated board.
New A/D breakout board
The breakout board that WinSystems sells for their A/D board takes up a lot more space than necessary, and uses bare wire screw terminals for input, so we are going to replace it with a custom board that is smaller and takes ring terminals.
16 signal inputs with #6 ring terminals, one ground is common to all signals measured.
The range is +/- 10V, so we need to cut the main battery voltage in half before sampling. It is a toss up if this should be done on the A/D breakout board, or on the power supply board. There should be a grid of holes for soldering in random resistors or capacitors to modify signals.
The grounds are common to all the signals, so I think all we need is a single ground ring terminal that we will run back to the power supply.
The connector going to the A/D board is a 26 pin ribbon cable with the following pinout:
1: ch0 2: ch8
3: ch1 4: ch9
5: gnd 6: gnd
7: ch2 8: ch10
9: gnd 10: gnd
11: ch3 12: ch11
13: gnd 14: gnd
15: ch4 16: ch12
17: gnd 18: gnd
19: ch5 20: ch13
21: gnd 22: gnd
23: ch6 24: ch14
25: ch7 26: ch15
Watchdog Board
Trivial microcontroller that watches a continuous signal from the main computer, and uses a private motor drive to open the master cutoff valve only when the main computer is healthy.
Input:
One optically isolated digital line from the main computer
Private +12v / GND
Output:
Two #6 ring terminals to control the master cutoff servo valve (the main computer will still read the pot feedback of that valve)
Power supply board
Multiple, diode isolated batteries for redundancy, with an additional port for running on external power
External charging ports for each battery, so the electronics don't need to be taken out of the vehicle for charging.
Short run from batteries to boards, no in-line power switch. Use the power pin on the DC/DC power converters for switch-on. Use redundant switches to prevent a switch glitch under vibration from turning everything off.
Run nothing from the unregulated power supply, except for the A/D line for current voltage level. We previously ran a couple things from the unregulated 12v supply, like the Esteem wireless unit, and the pressure transducer. It is possible we were losing telemetry momentarily earlier than the computer died, depending on the details of their power use.
Instead of running wires from the power supply board to jumpered barrier strips for distribution as we previously did, build plenty of terminals directly onto the power supply board. At a minimum:
Lots of grounds.
Unregulated +12v: Battery A/D line
+5v: computer (two lines)
+5v: 6 motor drive potentiometer feedbacks
+5v: several spares
+6v: laser altimeter
+12v: pressure transducer
+12v: GPS
+12v: Panel-PC LCD display
+12v: Several spares
-12v: Panel-PC LCD display
+15v: Crossbow IMU
We might want to use a higher voltage for the IMU, as the range is 15v-30v, and we have been warned by someone about running avionics at their minimum recommended voltages. Today's result seem to corroborate that it is closer to going out than the rest of the systems.
Current draw signal for telemetry? If we ever have a short somewhere, this would be helpful in diagnostics.
Isolated voltage signals for each battery? If we don't have that, telling when a battery has failed will be difficult.
Actuator Boards
Our current solid state relay board still has bare wire terminals (although they are high quality ones that haven't yet given problems), it still has the old power supply on it that we don't use, and one bit on the input connector is flaky, so it needs to be replaced.
Isolated voltage signal for A/D telemetry?
Isolated continuity checks for each actuator? The motor valves can be self-tested by watching the potentiometer feedback, but solenoids and pyro would need a low-current test signal. The actuator battery needs to be completely isolated from the main battery to avoid noise problems, so a continuity sensor would need to be isolated as well.
We have known needs for up to six solid state relays and six motor drives, so building for eight and eight is probably good planning.
Whenever I use this OS, i just have to wince.
It does, however, share capabilities, such as inking and handwriting recognition, with the more expensive machines.
There seems to be no information about how these machines support handwriting recognition. The Tablet PCs perform this task using capabilities in Windows XP Tablet PC edition - i.e., the OS itself. Since these products claim to support handwriting recognition over a wide variety of OSs, is there some hardware support for this feature?
Also, while he's post comments on articles, perhaps Hemos can also perform tense-consistency checks on what he writes.
Looks like the load balancing didn't work as well as planned.
Oh. wait, you mean the release called Woody.
Sigh