does that make sense?

[ecalis]

hi there,

in my other thread "inclinometer", i asked for help in finding a relatively low-cost inclinometer for my (distant!) uav-project and doni gave me a link to the paparazzi-project and their thermopile-based inclinometer.

i studied the paparazzi-system in detail now and i found out, that with their method of "sensing the horizon with thermopiles", the minimum amount of sky/earth seen by the sensor is 20%, right?
(http://www.ctie.monash.edu.au/hargrave/horizon_sensing_autopilot.pdf)
in addition, this system does not work in clouds...

so, based on the idea of the "movable roll plate sensor" as to be seen in the pdf, i had the idea to instead of mounting two thermopile sensors, mount one two-axial MEMS accelerometer, which is moving the plate it is mounted on level when the plane around it is changing inclination.
based on the inclination of the movable plate inside the plane, it is then possible for the plane to calculate the zero-point.
sensor-costs will be about the same, only the programming might turn out to be a bit more complicated..

what do you think? is that possbile or nonsense?
(i*m an absolute newbie in this sensor-uav control stuff, so excuse me, if i'm being too out of touch with reality.. ;) )

[JettPilot]

that with their method of "sensing the horizon with thermopiles", the minimum amount of sky/earth seen by the sensor is 20%, right?
in addition, this system does not work in clouds...

so, based on the idea of the "movable roll plate sensor" as to be seen in the pdf, i had the idea to instead of mounting two thermopile sensors, mount one two-axial MEMS accelerometer, which is moving the plate it is mounted on level when the plane around it is changing inclination.
based on the inclination of the movable plate inside the plane, it is then possible for the plane to calculate the zero-point.
sensor-costs will be about the same, only the programming might turn out to be a bit more complicated..



You are totally wrong about a lot of things. The thermopile is very cheap, and you are saying an inertial sensor MOVING a plate accurately will be the same price ?? Not to mention size, complexity, and it would be very fragile... What have you been smoking ??

Also inertial sensors drift constantly, quite a bit at times.... That is a FAR BIGGER problem than the few times in clouds for the thermopile....

You talking about % of sky the thermopile must see.... You have obviously never used one. The thermopile works very well, with no big limitations on the sky it sees. Using thermopiles backed up by a pizo gyro for the times its in clouds... Its simple, cheap, and much better than what you are talking about.

[ecalis]

ok, i see

i told you that i've never used such a thing before, nor did i use a gyro or some other sort of sensor, so i don't see why u r flipping like that?

edit (about that %-thing: the thermopile is measuring the temperature of something and it can detect the horizon because the sky has a different temperature than the earth.. doesn't it? so if it cannot see a certain percentage of either sky or earth, it cannot calculate how the plane is situated.. this is at least how i understood it.. i might be wrong again, if i am, please tell me)

[AntonK]

Alright let me shed some light on this. As far as the Thermopiles go, yes your misled. That 20% comes from the saturation limit of the sensors, meaning if your trying to go past say 45-50 degrees bank angle. The sensors are not fully linear, they seem to be fairly linear up to about 35-40 degrees, then go exponential from there. As far as cheap, well thats all a matter if opinion. An FMA 2 axis board runs $80, 1 axis accels are much cheaper I believe, but gyros would be more than the accels(not too familiar with prices). Now, that paper talked about mounting the board on a servo, this isnt done anymore as its really silly. Now the data is taken directly and used. As far as inertials being easier, read up on anything that says (kalman filter inertial) to start to get a handle on how inertial sensors work.

Anton,

PS. About the % again. Thermopiles can sense I think its a .2 degree F change... well I know its some number lower than 1 degree of temperature. depending on the conditions that should give you at most +- 5 degree error (stab in the dark) which for a large UAV isnt a problem if it banks 25 degrees instead of 20.

[clolson]

An FMA 2 axis board runs $80

I've run one of these on my Kadet Sr. ARF and it works really well. It's sensitive to ground calibration (i.e. you need to calibrate it correctly on the ground or it will not hold you exactly level.)

My thought was that if you put one of these on a stable airplane (such as a trainer) you could probably bluff your way through the clouds on gps track alone ... as long as you keep your control surface movements less than some threshold you won't leave stable flight.

That said, if you do venture up into the clouds you better have full permission from whomever is in charge of the airspace in your country. Once you are in the clouds, "see and avoid" goes out the window (so to speak) and you are into the realm of instrument flight rules so you better be playing nice with everyone else who is allowed to be there.

Curt.

[mwraight]

I've run one of these on my Kadet Sr. ARF and it works really well. It's sensitive to ground calibration (i.e. you need to calibrate it correctly on the ground or it will not hold you exactly level.)

My thought was that if you put one of these on a stable airplane (such as a trainer) you could probably bluff your way through the clouds on gps track alone ... as long as you keep your control surface movements less than some threshold you won't leave stable flight.

That said, if you do venture up into the clouds you better have full permission from whomever is in charge of the airspace in your country. Once you are in the clouds, "see and avoid" goes out the window (so to speak) and you are into the realm of instrument flight rules so you better be playing nice with everyone else who is allowed to be there.

Curt.

Please, in the name of all that is holy, do not fly any RC plane or UAV into the clouds...unless you are working with Air Traffic Control. In fact you shouldn't be flying anything out of your line of sight. There is no reason to operate anything of this sort in Instrument Meteorological Conditions and you are putting full scale planes in extreme hazard if you do so. The quickest and surest way for private UAVs to be banned is by doing anything like that...or worse, causing an accident that results in loss of property or life.

Also, you might want to know that the FAA can and will prosecute you for violating controlled airspace or IMC. Just because their is no specific legislation at the moment does not mean they can't get you for endangering full scale operations or any other thing they want to.

When the legislation is finalized you are probably going to find that any UAVs heading into IMC will need a transponder with encoding altimeter, as well as a trained operator that is in communications with ATC at all times and can follow any commands given by ATC.

People operating UAVs at the moment should have a good understanding of airspace, restricted airspace, TFR (temp. flight restriction areas), MOAs (military operating areas), controlled airspace, ADIZ (air defense identication zones), etc. etc. And the aircraft should always be within your sight and have the ability to be controlled if evasive maneuvers are needed. Flying blind through the national airspace is bound to cause problems.

It will only take 1 UAV being sucked into the intake of a 757 and causing loss of life - and I can almost promise you the only UAVs flying will be government UAVs.

[HELModels]

That is good advice mwraight and must be followed by anyone fiddling with these things. I read lots of posts where disclaimers are added regarding mission, but obviously the capability is there to cause problems. why else would someone feel it necessary when discussing their setup, to emphasize they dont fly in the clouds or out of sight, unless their platform had the capability? If you dont fly illegally, then there is no disclaimer needed.

You are right for emphasizing to ecalis the necessity to stay legal. I also understand that ecalis is curious and wants to go high tech like everyone who ever operates an RC plane. It is a tough reality, but it is reality.

[ecalis]

JettPilot: i thought about what you said and i now i see your point.. i haven't thought too much about precision of the gear moving the sensor-plate.. just an idea ;)

with flying in clouds i didn't actually mean performing high-altitude flights in clouds, even with a clear sky i wouldn't go that high, but we often have fog or at least limited sight and since i read in that paper that apparently the thermopiles are sensitive to the waterdroplets in clouds/fog/similar things, this would make thermopiles not the optimum solution for me.

this +- 5° error, is there any way to overcome this and to make it more precise?

[kd7ost]

with flying in clouds i didn't actually mean performing high-altitude flights in clouds, even with a clear sky i wouldn't go that high, but we often have fog or at least limited sight and since i read in that paper that apparently the thermopiles are sensitive to the waterdroplets in clouds/fog/similar things, this would make thermopiles not the optimum solution for me.


ecalis,

I have issues like that as well. You're new to the site based on your post count so you'll learn how to word things. It can be pretty easy to ruffle tail feathers, (pun intended :D ) here. The guys really working on UAV's tend to understand that a vague comment shouldn't be used to beat a guy up. Most of us understand what it's like to have a platform start to ice up at 100' agl. We aren't all fair weather only flyers. But if you come out here and ask, "How do I keep the ice off my wings", you will get beat up by guys who will swear you must be dodging 747's. That's also why some people coming here issue disclaimers. A post above states "if you have to disclaim, you must be doing something wrong". Hmmmm. Truth is, If I came here and asked how to keep the ice off and I'm only flying in ground fog on a 30 degree day, I just issued a disclaimer to keep people aware of what I'm doing so they understand. You issue the disclaimer because you know guys are reading that will take it the wrong way. There's generally no nefarious activity. The disclaimers happen naturally these days because you know guys are reading over your shoulder, ready to hit you with a verbal club.

Unfortunately, to some people that doesn't matter. I have never posted anywhere else where I've learned to analyze my post as carefully as possible before hitting the "Submit reply" button. This place can erupt in about 2 seconds if someone doesn't understand you. Some of us know when it's deserved, but some of us don't.

That being said, We (UAV pilots) don't advocate flying in a dangerous way or doing anything that violates any rules, laws, safety standards or whatever. Yes that is a disclaimer. No it doesn't mean I fly my UAV to the clouds. :D

Chose your words carefully. ;)

Dan

[JettPilot]

JettPilot: i thought about what you said and i now i see your point.. i haven't thought too much about precision of the gear moving the sensor-plate.. just an idea ;)

with flying in clouds i didn't actually mean performing high-altitude flights in clouds, even with a clear sky i wouldn't go that high, but we often have fog or at least limited sight and since i read in that paper that apparently the thermopiles are sensitive to the waterdroplets in clouds/fog/similar things, this would make thermopiles not the optimum solution for me.

this +- 5° error, is there any way to overcome this and to make it more precise?

Ecalis, thermopiles work better than you think they do, in practice they are really great and do not go crazy because of a water drop, peice of dirt. etc etc. You can buy an entire FMA stabilization setup and it is pretty cheap. I would recommend buying the FMA FS8 and try it out yourself and you will be suprised how well it works. As far as being precise, it does not have to be. Use GPS for your navigation, and that will keep any small bank errors from ever becomming a problem, because the track is constantly adjusted even if the bank is not perfect. Use a pressure altitude hold board to maintain your altitude, and again, even if the pitch gets a bit off, the altitude hold board will keep it where it is supposed to be.

By the way, welcome to the forum :) . I hope we did not scare you, its just easy to get carried away typing sometimes and forget we are talking to real people out there ;) . But building and flying a UAV is great fun, and you can get lots of help and good information here. Dont be afraid to ask questions, that what this forum is here for :D

Now how do I get my glow engine to run reliably at 37,000 feet :confused:

JettPilot

[Iraqigeek]

This is something I wanted to ask about, is it the thin air that makes it hard to run internal combustion at such high altitudes? or is it low oxygen levels (lower % level of O2 per volume unit)?

if its only because the air is so thin at such altitudes, wouldnt some form of supercharger enable the engine to operate at such altitudes???

[mwraight]

This is something I wanted to ask about, is it the thin air that makes it hard to run internal combustion at such high altitudes? or is it low oxygen levels (lower % level of O2 per volume unit)?

if its only because the air is so thin at such altitudes, wouldnt some form of supercharger enable the engine to operate at such altitudes???

The short answer to your question is yes. A supercharger or turbo will enable an engine to operate more efficiently at higher altitudes. The low air density at higher altitudes is what reduces performance. If you can force denser air (by turbo or super charging) into the engine, you increase performance.

[mwraight]

ecalis,

I have issues like that as well. You're new to the site based on your post count so you'll learn how to word things. It can be pretty easy to ruffle tail feathers, (pun intended :D ) here. The guys really working on UAV's tend to understand that a vague comment shouldn't be used to beat a guy up. Most of us understand what it's like to have a platform start to ice up at 100' agl. We aren't all fair weather only flyers. But if you come out here and ask, "How do I keep the ice off my wings", you will get beat up by guys who will swear you must be dodging 747's. That's also why some people coming here issue disclaimers. A post above states "if you have to disclaim, you must be doing something wrong". Hmmmm. Truth is, If I came here and asked how to keep the ice off and I'm only flying in ground fog on a 30 degree day, I just issued a disclaimer to keep people aware of what I'm doing so they understand. You issue the disclaimer because you know guys are reading that will take it the wrong way. There's generally no nefarious activity. The disclaimers happen naturally these days because you know guys are reading over your shoulder, ready to hit you with a verbal club.

Unfortunately, to some people that doesn't matter. I have never posted anywhere else where I've learned to analyze my post as carefully as possible before hitting the "Submit reply" button. This place can erupt in about 2 seconds if someone doesn't understand you. Some of us know when it's deserved, but some of us don't.

That being said, We (UAV pilots) don't advocate flying in a dangerous way or doing anything that violates any rules, laws, safety standards or whatever. Yes that is a disclaimer. No it doesn't mean I fly my UAV to the clouds. :D

Chose your words carefully. ;)

Dan


KD7: I didn't intend to make my statements about flying in the clouds as a flame, and please don't take them as such. I simply wanted to point out what many people don't know about airspace and regulations. There are a lot of things to take into consideration when operating something with the unique capabilities of a UAV. And I do work with UAVs...in fact I'm developing the training program for a UAV currently in pre-production. I'm also a full scale pilot. I see both sides very clearly - and care very much about both sides of the issue.

If my post seemed terse, I apologize for the tone of it. But I won't apologize for the content.

Again, I have no intent to start lobbing flames at anyone in this forum.

[JettPilot]

Hahaha, I was just joking about making my glow engine run at 37,000 feet ;) If I wanted to go that high I would just use a 32 pound thrust RAM turbine engine :p

Besides, what fun is a UAV if it does not climb straight up out of sight...

[AntonK]

Let me add to the GPS idea a little bit. If you get a decent GPS, and not attempting autonomous landings or even if you are on a plane without gear or that can take a firm landing, a pressure sensor is not necessary. Good GPS, especially WAAS enabled gives good enough resolution to fly. a 10 foot error at 500 foot AGL is nothing. Somethign to consider.

Anton

[ecalis]

thanks for the advices, everybody!

i think, slowly i get the point about the 'rules' in this forum :)

i looked at that FMA FS8 and its features are brilliant (especially when keeping the price in mind) to get used to use autopilots..
for my final idea, i would need something "more open" in order to integrate all my planned features..

but autoland is one of the must-haves, so a pressure sensor is the only way forward.. :P

[HELModels]

Reminds me of that George Thoroughgood song in which he rants that "Everybody Funny... So Out the door I went..."

FAR/AIM

[AntonK]

Well, I should note that a pressure sensor still might not have the resolution needed, you may need to look into untrasonic or radar.

Anton

[kd7ost]

If my post seemed terse, I apologize for the tone of it. But I won't apologize for the content.


No apology needed at all. I think we both got our desired effect. You have nothing but support in regards to safety. ;)

Dan

[kd7ost]

KD7: And I do work with UAVs...in fact I'm developing the training program for a UAV currently in pre-production.

Do you mind telling us a little about that? Most of us do this as hobby guys developing micro stuff or small time AP operators trying to scrape up extra dollars while we do what we enjoy. Not many get the envious task of doing this for a living. :D

Dan

[wadiprawita]

Hi Ecalis,

back to the topic, as a matter of fact, in my current AP, I use 2 FMA co pilot sensor, tim LA GPS receiver, gyro ADXRS401 in yaw axis, and 2 axis accelerometer in roll and pitch axis. You can see it here :

http://wadiprawita.myphotoalbum.com/

I send both attitude data from thermopile and accelerometer (as inclinometer), one problem with accelerometer is we have to separate the dynamic and static acceleration (we can use low pass digital filter), second problem we have centripetal force during coordinated turn, to solve this we have to have absolute attitude reference (thermopile will do it), or yaw rate and forward speed information, there several other problems actually (mis alignment, coriolis effect, etc). So, in order to measure attitude (roll and pitch), you cannot use accelerometer alone, we have to combine it with other sensor (gyro, thermopile, gps, etc).

In my application I limit the roll and pitch to 50 degree (because the FoV of thermopile I used is 100 degree), and the use online calibration from vertical channel is very helpful for long operation.

regards

-doni-

[mwraight]

Do you mind telling us a little about that? Most of us do this as hobby guys developing micro stuff or small time AP operators trying to scrape up extra dollars while we do what we enjoy. Not many get the envious task of doing this for a living. :D

Dan

Well it is a hell of a lot of fun! I started out helping the engineers slap the UAV together for a demonstration to potential customers. Working with them was great...its a lot of fun to be able to bounce ideas around in that atmosphere. I filled in wherever and whenever they needed me to. From pointing antennas to safety pilot. Of course the few minutes of manual flight I logged were a bit scary - since the autopilot had put the plane in a dive and I had to pull out. The canopy managed to come off, go through the propeller and then drift over a road and land 1000' away!

Now I've been put to the task of the documentation and training program for the plane. Basically I'm going to take people who have no experience with RC planes and teach them how to operate the beast. Navigation, limitations, airspace, etc. etc.

The plane itself is a fairly compact 'man portable' plane - with a wingspan under 6'. It's basically a Zagi with a fuselage...and thats in the most basic sense. Its aimed more at the private sector - rather than the more common military applications. Its extremely suitable (and designed for) carrying camera equipment and IR camera equipment. Its a good fit for replacing things that are still commonly done by full scale aircraft - like pipeline or powerline patrol, or aerial survey. The things that haven't gone to satellite quite yet! Its called the CyberEye. If you Google it you'll probably find an article or two and maybe a picture. I know that there is some information out there. There is another CyberEye, but it is much larger than this one.

For those of you who don't get to work in this field. I feel your pain. I have had some very boring, uninspiring, low paying, terrible jobs in the past. Imagine what I felt when I saw an ad in the newspaper seeking someone who had experience building and flying model planes. I first called some of my flying buddies to make sure it wasn't a hoax...as I had said 2 weeks before "I wish I could find a job flying RC planes". It wasn't a hoax and I got the job! I'm extremely excited about it and I actually don't feel much like I'm working. For once I feel like I have an amazing amount to contribute and devote myself to. It feels more like a career.

For all of you out there that are interested in a job like this...I say look far and wide and see what you can find. The field is only getting bigger and there's probably going to be more opportunities available where unique expertise is needed!

I hope that gives you an idea of the experience!

[CenTexFlyer]

The plane itself is a fairly compact 'man portable' plane - with a wingspan under 6'. It's basically a Zagi with a fuselage...and thats in the most basic sense. Its aimed more at the private sector - rather than the more common military applications.

Yep, that's pretty amazing since you you guys have been visiting my website since for several years now. (according to my web snoop) Coincidental how it looks so much like our Shaker, and finally the Photon model, isn't it? There are un-associated third parties on this forum that can attest to seeing our design well before your "release". No worries though... it's just a matter of who gets it to market first and produces the best product, eh? A risk you take when you post here on Whole World Wide (copy it if you can) Web....

[kd7ost]

I hope that gives you an idea of the experience!

Indeed it does. Thank you

We should probably allow this thread to stay on original course. ;) I'll send you a PM.

Dan

[kd7ost]

Hmmmmm, interesting. ;)

Dan

[HELModels]

A basic requirement of copyright is to not publish before claiming rights.
Knowingly publish more than 5 times before making a claim and it is considered public domain. I would bet more than 5 independant hits on a website constitutes a published release.

...Out the door I went

[mwraight]

Yep, that's pretty amazing since you you guys have been visiting my website since for several years now. (according to my web snoop) Coincidental how it looks so much like our Shaker, and finally the Photon model, isn't it? There are un-associated third parties on this forum that can attest to seeing our design well before your "release". No worries though... it's just a matter of who gets it to market first and produces the best product, eh? A risk you take when you post here on Whole World Wide (copy it if you can) Web....

I have never seen the Shaker nor have I seen the Photon. So I personally have no clue as to what they look like. As to the description I gave of the CyberEye, it eludes me how anyone could take that and form an adequate enough view of the vehicle to begin making claims of infringement. It would be like having Cessna claim you stole the designs for the 172 when you stated you developed a "4 place, semi-monocoque, semi-cantilever aluminum aircraft fitted with tricycle landing gear and an internal combustion, horizontally opposed, normally aspirated engine driving a fixed pitch propeller.

There are a heck of a lot of planes that look a heck of a lot of other planes in this world. Yet, they are not the same plane. The Tu-154 sure looks a lot like a B-727. Come to mention it, the Russian space shuttle sure looks a lot like the NASA's space shuttle. And the Tu-144 is very similar to the Concorde.

Its one thing to claim that such-and-such a plane was conceived first...another thing entirely to back it up. And in this country at least, the burden of proof is on the person making the claim. So if you would like to take your complaints to the PROPER forum, PM me and I'll be happy to get you the phone number to the legal department.

[CenTexFlyer]

OK, maybe my post was a bit too confrontational.....and for that I apologize.

I posted a fact, two opinions and a rhetorical question, which as I understand it, define what a "forum" is. There is no question as to where the development of the full size versions sprang from and their many iterations thereafter. There is NOTHING protected by any means in reference to our airframe, although we could have applied for an application patent. (Opinion : What a waste of money!)

So.... on a different note.... do you guys need any test pilots or R & D work done? :) :cool:

[ecalis]

regarding that resolution problem for autoland:

i thought of having one radar/ultrasonic sensors in each wing, so the plan also can adjust its attitude to the terrain, preventing landings on just one gear and probably damaging it.
complete nonsense or worth it?

so if i want to use the radar/infrared sensor for low altitudes and gps roughly for the high altitudes, what kind of gps-module would be "decent" enough to provide a suitable resolution?

[AntonK]

Any unit that is WAAS enabled would be great! And Mike, I think you have said enough for now... Stop by soon though we miss ya :)

Anton

PS. CenTex, I can without a doubt say it is a coincidence that the airframes look similar. period, end of story, no need to continue.

[CenTexFlyer]

No worriess, AntonK.... let's just keep 'em flying!

[ecalis]

here in europe, the waas-equivalent is called egnos.. r they fully compatible with each other? because i didn't manage to find a gps unit which is specifically egnos-compatible.. in addition i'm not too sure whether egnos is running already.. anyone from europe already using that system and has an idea for a gps-unit capable of this?

[Iraqigeek]

From my experience with GPS devices (based on SiRF Star II and IIs chipset), they tend to have a relatively lower error margin when in motion. The algorithms on those devices are optimized for in-motion location calculation since they are usually used in navigation systems.

I did some testing back in Iraq where I took logs from two CF GPSs with my PDA while driving around the city, and then plotted those logs on a calibrated high resolution satellite image of the city (1.2GB @1 meter resolution) and found that error was 3-4 meter while driving around at speeds between 20 and 120km/h, increasing to ~6 meter at 10km/h, and 12 meter when standing still. I used an external magnetic antenna mounted on outside the car to improve signal reception since the city suffers from a good amount of interference in the L-Band.

From what I read on the net, the new SiRF Star III has similar accuracy values when moving, but error tends to increase at lower speeds and when standing still. I believe this is due to the xtrac algorithms used on the chipset, but from my understanding you can turn this feature off.

If your wing span is around two meters, I suggest putting a GPS reciever at the tip of each wing. Then you can use simple algebra to obtain sort of a differential reading which would further reduce your error.

In any case, even with a 10 meter error, I wouldn't worry that much. If you are planning on a fullly autonomous landing, you shouldnt rely on GPS anyways (unless you have access to military grade GPS). You will need a combination of barometric altimeter, an accelerometer to calculate descend rate, and some sort of short range - high accuracy range finder (ultrasound or IR based) for the final stage of the landing (the last 20ft of altitude or so before touchdown).

[ecalis]

cheers iraqigeek!
i'm planning at least 2 metres of wingspan, more like 2,5 metres, so two gps receivers would work, which device would you recommend for fairly high stability paired with low weight?

what do you think about the ultrasound/radar sensors for each wing? (it is going to be a low-wing aeroplane)
should i use ultrasound or radar?

(sry about that lot of questions :o )

[Iraqigeek]

Any GPS board based on the SiRF Star II or III chipsets would be just fine. The Star III has a quite impressive signal sensativety (which doesnt make any difference for a UAV, but its still impressive). Generally, GPS positional stability is highly depandant on the number of satellites locked (as long as you have over 4 satellites locked, things should be fine).

Regarding the ultrasound/radar sensors, I don't think its a good idea to depend on them for horizontal stability. Use the thermopiles for absolute roll control, and a gyro to keep the plane level when it comes too low for the thermopiles to operate effectively.

Another alternative for absolute attitude control would be to use a 3 axis magnetometer, though there are many issues with such an attitude system that need to be taken under consideration (for example, if the UAV is flying east at 90 degrees or west at 270 degrees, the magentometers wouldn't be able to detect pitch).

[ecalis]

what do you guys think of the ublox SAM-LS smart antenna?
i know, it hasn't got a Sirf II / III chipsets, but it supports WAAS/EGNOS, has low energy consumption and apparently a number of people use it.
I also found a model from Holux based on a Sirf III chipset, but there wasn't a note about the price..

any other recommendations on what GPS module/receiver to use?

greets, ecalis