It isn't rocket science but it is a start.

[Peter Nachtwey]

The Phoenix Mars Lander will land tomorrow. The article below explains Delta's small contribution to the Controlled Descent System testing system used by Vertigo inc. Basically, it is a hydraulic brake that allow simulating martian gravity and air resistance. This was done by taking difference the non-linear differential equations from earth and mars and using that to compute the drag on the hydraulic brake as a function of velocity. From the generated motion profile a cam table was made to get the desired motion profile. They had to take into account the stretch of the cable when figuring the altitude. Dennis Ritola did most if not all the math for this part of the test. This project did not use our latest controller so the calculations had to be done ahead of time.
See the article
http://pdf.aiaa.org/preview/CDReadyMADSTC07_1443/PV2007_2537.pdf
The AIAA is the aerospace equivalent of ISA or IEEE.
On page 4 you can see the velocity profile as a function of elevation. Notice the increase in speed at 500 m. This is where the Phoenix is separated from the parachute and free falls until the landing thruster start. The Phoenix must use its landing thrusters to stabilize the probe and control the descent.
This method of testing by using a helicopter and hydraulic brake is new. It gives the other engineers a better idea of how the probes radar will perform as the probe falls. There was a lot of testing even before dropping the mock up probe from the helicopter. This saved time and money later because the helicopter time cost about $2000/hour.
Dennis Ritola, our engineer that co-authored the article ( pages 10-12 ), will attend the landing party at JPL in Pasadena tomorrow evening.
Now lets hope the Phoenix lander lands and doesn't make a crater.

 

[Mickey]

WOW!! exciting.
The link only has one page.

 

[Peter Nachtwey]

I didn't realize the AIAA pdf was only a preview

Here is the full article
www.vertigo-inc.com/aiaa/AIAA-2007-2537a.pdf

 

[CharlesM]

You guy's are way too cool. I just love the things you guy's work with. I've been reading about the landing all week. An air bag landing would have better odds but at some point you have to use thrusters. I would say if this works we will see a lot more of this type of landings.

 

[Bruce99]

Fun stuff

Thanks Peter,
Many of us are watching and waiting. This is better than the bouncing ball...

 

[TConnolly]

It isn't rocket science

Yes it is.

Fascinating. I'll be watching the news.

 

[surferb]

Thanks for the heads up

Cool! Here's an article from the San Diego Tribune. I've got my fingers crossed.

 

[Peter Nachtwey]

Phoenix appears to have landed OK

I was watching CNN where they are at JPL telling us what is happening.

 

[Bruce99]

She made it...

Looks like a safe landing... Hope everything still works...

 

[kamenges]

OK, that's pretty cool. I'm not sure I would have wanted to be the guy flying the helicoptor. The force rates on accel and decel must have kept him(er) on his(er) toes. Manufacturing, entertainment, aerospace. You guys do a little bit of everything, don't you?

The article mentioned that the hydraulic circuit needed a pretty significant tweak to make it work at high flow rates. Is that something you saw coming or did that catch you by surprise also?

Nicely done.

Keith

 

[Peter Nachtwey]

OK, that's pretty cool. I'm not sure I would have wanted to be the guy flying the helicoptor. The force rates on accel and decel must have kept him(er) on his(er) toes.

Yes, my first concern is that that the cable snaps and springs back up into the rotors.

Manufacturing, entertainment, aerospace. You guys do a little bit of everything, don't you?

Motion control is used in many industries. It helps to be diversified. Right now our main industry, saw mills, is in the dumps because of the mortgage/housing mess.

The article mentioned that the hydraulic circuit needed a pretty significant tweak to make it work at high flow rates. Is that something you saw coming or did that catch you by surprise also?

Ideally we just sell the motion controllers and just answer a few questions about the motion controller. We leave the hydraulic desing to the system houses or hydraulic distributors. If all goes well we are not involved. [rant]If the start up doesn't go right then the motion controller is almost always a fault. It certainly can't be the hydraulic or mechanical design. [/rant] We eventually get called because we can do the engineering the others didn't. Many times the engineering services exceed the cost of the motion controller.

 

[fluidpower1]

The article mentioned that the hydraulic circuit needed a pretty significant tweak to make it work at high flow rates. Is that something you saw coming or did that catch you by surprise also?

You could blame it on the Fluid Power Engineer if there ever is anyone trained to do the Hyraulic circuit design.

 

[TConnolly]

[rant]If the start up doesn't go right then the motion controller is almost always a fault. It certainly can't be the hydraulic or mechanical design. [/rant]

Oh come on! The system house guys don't ever make mistakes, at least not any really big ones.

If you're ever in the area and decide to take me up on my invitation to drop by I'll show you a system that came out of China. It s a real piece of art. [/sarcasm] I'm trying to phase it out though.

 

[fluidpower1]

But then again, Who Needs Fluid Power Engineers since Hydraulics and Pneumatics is so simple ANYONE CAN DESIGN CIRCUITS for that EQUIPMENT!!!!!!

 

[BudW]

Just let the controls engineer fix it in the software!!