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wind27382
02-05-2008, 11:27 PM
I belive that my title says it all. I wanted to know the best way to track an object such as a finger and print the values out to a computer. I was researching alittle about magnetic sensors and wanted to know if I could use a magnetic sensor to get the position of objects in 3d space and track their motion.

DresnerRobotics
02-05-2008, 11:34 PM
I'm starting to sound like a broken record but: Roborealm can do this.


http://www.youtube.com/watch?v=f_p60Dt6fSk

wind27382
02-05-2008, 11:37 PM
Thats not quite what I'm after. I'm trying to capture the motion of objects. I am a 3d modeler, and I do freelance graphics works. what I want is to track an object such as a finger. track the rotation and the distance and save the values to the computer. and use the values to move a cg finger. Basically an alternative to motion capture.

wind27382
02-05-2008, 11:45 PM
I had one small Idea and I didn't know if it would work. I anted to place a distance sensor and a rotary sensor on every major joint and use that to triangulate a persons movements.

DresnerRobotics
02-05-2008, 11:45 PM
Not quite sure of a solution using that method then, sorry.

Modern motion capture uses the same basic concept of the roborealm tracking video I just posted... I'm at a loss as to how you could do it effectively without a camera input. Magnetic sensors just don't seem like they would provide the accuracy or planes of movement that a camera can.

It's possible you could do it with a cluster of sensors such as an electronic compass, gyro and accelerometer combination... but how you would tie them all together and produce an accurate tracking program is beyond me.

wind27382
02-05-2008, 11:54 PM
The only problem I that I don't understand how I would use roborealm for this. I know that if you use 6 expensive camera than you can track each limb seperatly. I read an article that said they attached a cluster of gyros and distance sensors and where able to make a cheap, yet accurate version. I will try and post the article If anyone wants to see it

jrowe47
02-06-2008, 12:21 AM
I think you could use the method I described in my thoughts on robot stereoscopic vision. Higher res cameras could handle detail work, such as the initial capture and modeling of an image. You could use low res cameras on high speed servos, along with vector prediction, to allow for some pretty accurate real-time motion tracking.

http://forums.trossenrobotics.com/showthread.php?t=1398


I know there's software out there that does something like this, and it should be free, because it's a university project. If I can find the link to the site with the software, I'll post it here.

DresnerRobotics
02-06-2008, 01:39 AM
The only problem I that I don't understand how I would use roborealm for this. I know that if you use 6 expensive camera than you can track each limb seperatly. I read an article that said they attached a cluster of gyros and distance sensors and where able to make a cheap, yet accurate version. I will try and post the article If anyone wants to see it


I wasn't talking abut using roborealm in my last suggestion.

JonHylands
02-06-2008, 07:16 AM
Do you mean doing something like this?

http://www.cs.cmu.edu/~johnny/projects/wii/

- Jon

wind27382
02-06-2008, 07:53 AM
close but this is what I am trying to achieve

http://youtube.com/watch?v=oXG6PI_yXZY


http://www.youtube.com/watch?v=oXG6PI_yXZY

JonHylands
02-06-2008, 08:37 AM
Do a Google search on:

hack nintendo power glove

- Jon

wind27382
02-06-2008, 01:04 PM
ok still doing internet research and browsing the web for ideas and I wanted to know if I could use this
PhidgetAccelerometer 3-Axis


to track say a person wrist and measure the degree of which it turns, and tilts. such as when they move it up and down. the only question I have is that if i wanted to try and triangulate it would I need to also add a distance sensor.

wind27382
02-07-2008, 09:25 AM
so I guess no one knows if that gyo sensor would work or not, with out a distance sensor.

Alex
02-07-2008, 09:36 AM
Hey wind27382,

Sorry, I've been quite swamped trying to get the chat and this Links Directory stuff up and running in the community here.

Yes, you can use the PhidgetAccelerometer 3-axis to measure the degree of wrist turning. It's actually perfect for that. As far as how to go about doing it, I'm not 100% sure because I haven't done much with them myself. I have seen plenty of customers do some pretty amazing things with them, many of which were involving measuring tilt somehow.

Here's an example of a project someone did with Flash and a Phidget Accelerometer:


http://www.youtube.com/watch?v=FZCwBmueUNI

As far as measuring distance though, triangulation is a bit over my head so maybe someone else can help ya out with that.

This project is totally reminding me of a project Johnny (the wiimote genius) did:


http://www.youtube.com/watch?v=0awjPUkBXOU

It's not exactly what you're looking for, but might give you a different way of looking at the problem:)

Dave
02-07-2008, 12:09 PM
The first video that Alex posted should give you a good idea of what the Phidget accelerometer is capable of. It's good for tracking motion and tilt, but it won't detect yaw (rotation about the vertical axis). Accelerometer's can't detect yaw, because it doesn't represent a change in angle with respect to gravity.

The Wii remote does an incredible job of coping with this by tracking it's position with respect to the "sensor bar."


so I guess no one knows if that gyo sensor would work or not, with out a distance sensor.

I'm going to derail this thread for a moment. A gyro and an accelerometer are two different things. I correct people on this all the time, so don't feel bad. I'm an engineer, so it's my job to be a jerk about technical terms :wink:. An accelerometer measures linear acceleration, which can be broken down into dynamic acceleration (change in velocity) and static acceleration (gravity). A gyro actually measures rotation. More specifically, it measures angular velocity or angular acceleration, depending on the sensor.

[/derail]

Alex
02-07-2008, 12:25 PM
A gyro and an accelerometer are two different things. I correct people on this all the time, so don't feel bad. I'm an engineer, so it's my job to be a jerk about technical terms :wink:.

Yeah, definitely don't feel bad. He was at least nice to you, haha! You should've seen what he said and did to me back when I thought they were the same;)

Dave
02-07-2008, 12:58 PM
Yeah, definitely don't feel bad. He was at least nice to you, haha! You should've seen what he said and did to me back when I thought they were the same;)

I called Alex a worthless Luddite, then I told him that there is no Santa Claus. He wept like a child.

DresnerRobotics
02-07-2008, 01:06 PM
Engineers aren't nearly as bad as IT personnel.

"Identify yourself cretin! Oh, you again? What's wrong now, PC get stuck on a merry go round?"

My clients offer their first born for sacrifice upon placing a call to me. Muahahahaha :mad:

Dave
02-07-2008, 01:53 PM
"Identify yourself cretin! Oh, you again? What's wrong now, PC get stuck on a merry go round?"

Do you answer the phone with "Hello. Is it plugged in? Have you tried turning it off and on again?"

wind27382
02-09-2008, 08:44 AM
thank you all for taking the time to answer my question. and thanks for posting that example. that is exactly what I'm going for. The only other question that I have is that If I want to track it 's position as well as the tilt data, would I need a distance sensor.

wind27382
02-09-2008, 08:55 AM
The first video that Alex posted should give you a good idea of what the Phidget accelerometer is capable of. It's good for tracking motion and tilt, but it won't detect yaw (rotation about the vertical axis). Accelerometer's can't detect yaw, because it doesn't represent a change in angle with respect to gravity.

so my question to you would be could I use to accelerometers so that one could detect the tilt of the wrist, and one separate accelerometer could then be used to track just the yaw.

Alex
02-11-2008, 09:48 AM
The only other question that I have is that If I want to track it 's position as well as the tilt data, would I need a distance sensor.

Position in respect to what?

Dave
02-11-2008, 03:29 PM
You'd need to use either a gyro or a compass to measure yaw.

LinuxGuy
03-22-2008, 03:41 PM
I've been reading this all with great interest.. :happy::happy: I purchased a Honeywell I2C compass module and a 3-axis accelerometer (ADI ADXL330) breakout board from Spark Fun. I have not got a gyro yet though.

If I combine the accelerometer with either the compass or gyro, will I be able to track the 3D position of an object, assuming I have the right software? I would like to know, amongst other things, where the end effector of a 3DOF arm is. The arm will have a sensor array and a gripper on the end.

I'm also planning to get a Wii Remote after seeing those awesome videos of what Johnny Lee can do with it.

8-Dale

Droid Works
03-22-2008, 04:32 PM
You might be able to find some help here:
http://amp.ece.cmu.edu
They have a download section for code, databases and libraries. The are doing similar work.

wind27382
04-02-2008, 07:02 PM
just a quick question has anyone mad any progress yet. or have anything worthy of showing. still trying to get a grasp of it. hopefully i will be able to post my project in a week or two.

cmmguy
04-03-2008, 11:08 AM
Have you guys seen the measuring arms that use ONLY rotary encoders on a 5 segment arm to measure in 3D space? IF you could miniaturize the concept it should do what you want.

This is one company of several that have products to do this: FARO (http://www.faro.com)

http://www.faro.com/FaroIP/Files/Image/Product/Prod_01_All_Arms.jpg


There is also tracking technology out there:

http://www.faro.com/FaroIP/Files/Image/Product/Pro_02_All_Trackers.jpg


The technology exists, it is industrialized and expensive, but you can borrow the concept, reduce the accuracy and "hobby-ize" it.

darkback2
04-03-2008, 06:28 PM
Have you looked at infusionsystems I-cube? Its a sensor input device works through USB or MIDI. They make a data glove which has a number of sensors and outputs data based on that. You could I suppose, and I have been thinking about...build a suit that can capture body movement. I was going to do something like that for an electronic music project but didn't have the time or money...and figured it had already been done. In anycase you could even take the midi input and store it to a sequencer program which could then play back the data at any time. It wouldn't give you tracking per say, but would let you capture body positions like in the video.

I was actually thinking you could make a pretty simple thing that would track body position using potentiometers attached to body parts.

Check out:
http://infusionsystems.com/catalog/index.php

Hope that helps.

Matt
04-03-2008, 07:29 PM
borrow the concept, reduce the accuracy and "hobby-ize" it.

Holy crap, THAT should be the TRC tagline! LOL

Adrenalynn
04-10-2008, 10:57 PM
I've been reading this all with great interest.. :happy::happy: I purchased a Honeywell I2C compass module and a 3-axis accelerometer (ADI ADXL330) breakout board from Spark Fun. I have not got a gyro yet though.

If I combine the accelerometer with either the compass or gyro, will I be able to track the 3D position of an object, assuming I have the right software? I would like to know, amongst other things, where the end effector of a 3DOF arm is. The arm will have a sensor array and a gripper on the end.

I'm also planning to get a Wii Remote after seeing those awesome videos of what Johnny Lee can do with it.

8-Dale

The project you describe is exactly what I'm starting work on, only with a hopefully 5DOF arm instead. I'd like to add a few fun things, like using biowire in the glove to give tactile feedback, make the entire system wireless, and embed as much of the code as possible.

Given a couple weeks from my order, I hope to have a go-no-go on the project...

LinuxGuy
04-10-2008, 11:07 PM
The project you describe is exactly what I'm starting work on, only with a hopefully 5DOF arm instead. I'd like to add a few fun things, like using biowire in the glove to give tactile feedback, make the entire system wireless, and embed as much of the code as possible.
I just got all the servos and the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) for the arm. :happy: Now I have to get all the servos centered and installed into the arm with the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88). I am using Hitec HS-475HB servos for the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) and HS-645MG servos for the arm. I wish I could take credit for planning the way the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) works at the end of the arm, but I can't - there is just enough clearance below the Sharp IR Ranger for the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) to do full wrist rotation. :veryhappy: Sometimes, things just work..

8-Dale

Adrenalynn
04-11-2008, 02:12 PM
I just pulled the trigger on the crustcrawler SG5, the SSC, some accelerometers, and I have plenty of embedded processors laying around. So hopefully the next couple weeks will show some progress on the accelerometer and kinematics-based freespace control...

Alex
04-14-2008, 10:19 AM
I just got all the servos and the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) for the arm. :happy: Now I have to get all the servos centered and installed into the arm with the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88). I am using Hitec HS-475HB servos for the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) and HS-645MG servos for the arm. I wish I could take credit for planning the way the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) works at the end of the arm, but I can't - there is just enough clearance below the Sharp IR Ranger for the Little Grip (http://www.lynxmotion.com/Product.aspx?productID=161&CategoryID=88) to do full wrist rotation. :veryhappy: Sometimes, things just work..

Or you could always pick up the Little Grip (http://www.trossenrobotics.com/store/p/5561-Little-Gripper-Kit-no-servos-.aspx) here:
http://www.trossenrobotics.com/store/p/5561-Little-Gripper-Kit-no-servos-.aspx
:D