First of all I am a total noob but as a project I would really like to get the Ping going on a Arduinio. I have yet to get one but I think I should be fine with the help of youtube.
BUT, to get to the point, I was wondering what the read, write frequency of the sensor and board would be. Sorry if I sound retarded but I'm not exactly skilled in the terminology yet but, to use layman terms; How fast can I get this device to read distance (Hz) and what affects this (i.e code, distance etc)
Ok...I think that is enough for me as my firs post but I'm just pretty excited about all this so I'll get back to studying and ordering the right components.
How fast can I get this device to read distance (Hz) and what affects this (i.e code, distance etc
This depends on the sensitivity of the receiver - the less sensitive it is, the faster you can update BUT the shorter the range.
It may also depend on the environment - if you know that after your first target return any sound will be absorbed by the environment, then you can increase the repetition rate.
What you have to remember is that the receiver can't distinguish returns; the echo could be from the pulse just transmitted, or if the repetition rate is too high, from the last pulse from a more distant object.
With a maximum pulse return time of 18.5ms (from the datasheet), your maximum update will be around 50-55Hz.
@Richard: Yeah, I've been looking at the data sheet but as of yet I am still working on figuring out what I need and what it all means and I want to make sure the parts are the right for my use before getting them. And I want to get the parts as soon as possible so I'm sorry if I'm a bit premature with my eager questions
@Groove: Thank for the info, appreciate it!
The reference I have is this clip (How-To Tuesday: Ping))) ultrasonic sensor - YouTube) and it seems as if the output he's getting is a bit slow. My goal is to get at least 25Hz and write them out with some kind of timecode.
I think the next step will be to get the components and play around with it. Thanks again for taking the time to reply to an excited noob.
Why do you want to read so fast? What are you intending to measure?
I've been playing with one of the SR04 modules - works OK, but without adequate delays you do get whacky results. My vid here shows about 1Hz, but it's faster than that because I'm taking multiple reads and averaging them.
My goal (maybe a bit ambitious but I really would like to try) is to:
Get a reading of a position every 1/25 sec with a timecode (ideally frame number) so that I can use this data to "recreate" the motion in a program. If there are any other ways of getting position data available I would be very interested indeed.
My thoughts were that if I can get one axis (X) working it would be possible to add two more (Y,Z) and get all the information needed but I'm starting to realize that ultrasonic is a bit too unreliable for getting accurate translation readings. As I said, if you have any alternative suggestions I would indeed be interested to hear them
Sorry for my vagueness Richard but I want to track a camera and be able to use the information in a 3D software package.
My idea is that if you can get an accurate reading in (at least) 25 Hz so it can be used as a camera tracker on the actual camera itself instead of using expensive tracking software AFTER it is shot. It would be soo cool if it would be possible to get the data as you are filming but I guess I may be a bit ahead of my time...
J, are you talking about the camera tracking they did with Avatar?? I saw a doco on the making of Avatar and the "virtual" camera they developed was amazing, but I'm pretty sure beyond the scope of a "mere" Arduino...
but I'm pretty sure beyond the scope of a "mere" Arduino...
What do you mean, Arduino can do everything!
J, are you talking about the camera tracking they did with Avatar??
Well not exactly as intricate as to be able to film in 3D space as such but I guess the principles are the same except I'm not in need of instant visual feedback, rather a way to store the position and rotation information.
Still not clear. Are you saying you want to track THE CAMERA, or are you saying you want to track the SUBJECT that the camera is shooting? The people who do that kind of 3D modeling use hard-linked arms and rotary encoders to make 3D tracings of objects.
If you read my post it is pretty clear I want to track the camera. Don't mean to be rude but I can't explain things any further than saying that I'm looking into ways of tracking the camera itself and did not mention motion capture of subjects as that is getting cheaper and easier to use (http://www.ipisoft.com/).
As for the camera I figured accelerometers and gyros can deliver rotation values but what is left is obtaining reliable and accurate position data. I appreciate your comments and I am sure you have a lot more knowledge about these things than I do. I am just trying to get an overview of the available technology to see if my idea is feasible.
you say: what is left is obtaining reliable and accurate position data
and also: I figured ... gyros
if you are going to have gyros on the camera platform, won't something like dead reckoning (Dead reckoning - Wikipedia) be good enough to determine your position? you mention you won't do it online, so you only have to record the gyros data stream somewhere and use it for calculation later.
if you use ultrasound sensor, what would be your frame of reference to determine the position? i think with the gyro information you'll probably track position better than ultrasound.
Thanks jubal! I'll look into it but I think that i itf would be a reliable way of doing it they would have used it in Wii and PS remotes already instead of the IR sensors?
if you use ultrasound sensor, what would be your frame of reference to determine the position? i think with the gyro information you'll probably track position better than ultrasound.
I was thinking (obviously) ground, and (for an indoor environment) walls or one could set up provisional walls for reference. I was thinking that there would be all kinds of trouble with angles for the reflection in regard to the walls but just now it hit me that one could have the translation sensors somehow fixed perpendicular to the walls and not be affected by the rotation (a slight deviation from the camera "center" could be added later).
Wii and PS remotes already instead of the IR sensors?
Wikipedia mentions that IR is used in Wii to detect which way it is pointing, not for position; apparently they use accelerometers for position.
You should research how these work in detail, I am sure there are a lot of references online.
As for reliability, inertial guidance systems are used on all sorts of self-propelled military projectiles. You'd thunk the military knows about reliability.
