Sounds like the plan is to use the PC comm link as the brains, but with ultrasonic, the data rate will be very slow, and may not be able to react quick enough to make needed flight corrections. My 2 stones worth

Are your not allowed to use a MCU, I guess I should go back and read the old post.

__________________
Pay it forward.

 

Oh, that makes more sense... I will not trust Windows as the host for my AP brain. Most projects have the brain in the airplane and only some basic control commands are sent from the ground station. You will still need some kind of fail safe in the plane if the links is lost to the base.

__________________
How To Ask Questions The Smart Way

 

You say you are living in the middle east, hope you are not planning some one-way low flying (under radar) missions...

__________________
How To Ask Questions The Smart Way

 

Now, now. Besides with an ultrasonic link I think all is safe.

__________________
Pay it forward.

 

Does he want to use the ultrasonic as the link between the base and plane? I thought he want to use it to measure altitude. How are you going to fly a plane in a 6m radius? Maybe I just missunderstood your and his posts... confusing stuff...haha

__________________
How To Ask Questions The Smart Way

 

Yeah I am really not sure either, just been putting pieces together from other post by the op. Multiple post on same project does make things a bit confusing

__________________
Pay it forward.

 

hi again, and thankx for ur responds guys. and about the questions u asked:
no i'm not from the middle east even though that they r very good people , but i'm from libya and it's in north africa, and my project's only mission is to apply what i've learned in my past semsters, so i can have the high deploma in a peaceful way.
about the ultrasonic sensor ,no i'm not going to use it for controlling the airplane from the base.
coz i'm going to control the airplane movements by an RF transmitter "27MHz" which is going to be connected to the PC via an LPT..
if u r wondering about the function of the ultrasonic sensor! it's going to be making sure that the airplane altitude won't axceed 4 meters, and the reason why i chose the altitude rang that way, is bcoz i have an altrasonic sensor in that specific distance range!
so if i send "up command" to the airplane, first it will have to check that it's not flying in the 4 m range, if so it will not take the command ..
so the adjustments of the airplane movement will take place in the receiver part, if u want to see the circuit block diagram, it is as the following:

Attached Images

altitude control.JPG (15.4 KB, 5 views)

 

Ok, my bad. Sorry I misunderstood. Seems like you put some thought into this. Now that we have a better picture we might be able to give better answers. Did you get your PC to remote interface working based on Erics suggestions?
Shoot, I shoulda remembered the RC remote, some reason I started thinking usonic link. duh...
Maybe if you keep all project questions in one link so us memory impaired guys can keep things straight

__________________
Pay it forward.

 

OK, looks like you have the easy part (alt) sorted. How do you plan on using the system. Completely autonomous flight, assisted flight (ie: the sensors in the plane must limit the turn radius and pitch angle to a set safety limit?).
I still don't think you will get anything usable from just the acellerometer alone. If you have a plane with very high dihedral you might get away with only using a gyro on the ussumption that the plane is level if no rudder/ail input is sent to the plane.

__________________
How To Ask Questions The Smart Way

 

Wow, your going a few meters over my head. So if I understand your concerns, your talking about keeping the plane level. Could the gyro or whatever gizmo used provide feedback to the PC and the PC make corrections back to the craft? This stuff is new to me so I dunno squat. Just curious.

__________________
Pay it forward.

 

Yes, that is the short of it. Most DIY autopilots use a gyro/accelerometer combo with Kalman filter. I only know PIC's, which is not really powerfull enough to run a decent kalman filter routine so I opted for the thermopiles to "look at the horizon".
The thermopiles are used on the basis that the earth is always warmer than the sky (even with snow on the ground), so with left and right pointing thermopiles you can see that the plane is tilted when you see more heat on one side and less on the other.

__________________
How To Ask Questions The Smart Way

 

No kidding, thermopiles huh. I will have to look that up. Sounds clever.

__________________
Pay it forward.

 

Have a look here: Thermopile

__________________
How To Ask Questions The Smart Way

 

Thanks for the link. As soon as I saw the photo, I said to myself, so thats what those things were... I had a few devices that looked just like that but I could not figure out what they were for. I will have to check my junkbox for them.

__________________
Pay it forward.

 

i got ur idea boomslang, and yes that was what i'm going to do if i found a gyroscope , i'll use both "if the God will" gyro and accelerometer IC where every sensor will have it's own circuit like the pics display ,but right now i'm trying the altitude control circuit and if it worked i'll do the rest.
but if i don't have much time i guess i'll control the yaw of the airplane by the rate..
anyway thanx for ur reply, u and mike.

Attached Images

	altitude & pitch control.JPG (19.2 KB, 3 views)
	yaw control.JPG (14.9 KB, 2 views)