Applications for acceleration sensor?
Applications for acceleration sensor?
by NullARC
Mon Dec 14, 2009 3:19 am
I have seen in videos that a Huno with an acceleration sensor installed can sense that it is lying on it's front or back and stand itself up accordingly.
Is is possible to use the acceleration sensor for dynamic stabilization?
As an example, if that question didn't make any sense, I have seen Bioloid humanoids use their acceleration sensor to adjust it's center of gravity to compensate for changes in the angle of the platform that it is standing on.
What might be some other applications for the acceleration sensor.
As always, thanks for your help in advance! =)
- Marc
Is is possible to use the acceleration sensor for dynamic stabilization?
As an example, if that question didn't make any sense, I have seen Bioloid humanoids use their acceleration sensor to adjust it's center of gravity to compensate for changes in the angle of the platform that it is standing on.
What might be some other applications for the acceleration sensor.
As always, thanks for your help in advance! =)
- Marc
"She'll make point five past lightspeed. She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself."
by PedroR
Mon Dec 14, 2009 12:21 pm
Hi NullARC
The Bioloid PREMIUM includes a more complete IMU: it is a combination of Gyro and Acceleration Sensor and therefore is capable of much finer tuning.
Robobuilder only has the the Acceleration Sensor (not the Gyro). It is a simpler approach (and much cheapper) and the sensor can essentially detect the presence of gravity on it's 3 axis.
That's why it is so easy to make it get up on itself after laying it down. It can also sense how it is laying by checking in which axis gravity is.
There are some youtube videos with some real time stabilization techniques using the Acc Sensor.
I think you may be able to do this stabilization (much like the Bioloid Stabilization) with the Acc Sensor only but it is not as accurate as using a combination of Gyro + Acc Sensor.
In this case, you would have to sense the shifting of gravity between the multiple axis. For example when tilting right you would sense gravity on -Y and as the robot tilts right you will theoretically see gravity increasing on +X
However this is quite prone to some noise because the Acc Sensor will sense not only gravity but also external forces (and reports the sum of them). Using a gyro helps in these situations because you can always know the actual position (tilt) of the robot.
This is the typical application for the Acceleration Sensor:
BTW In this video you can see he used ActionBuilder to program the Robot (you see the that by the keys he presses on the Remote).
The youtube video with the dynamic stabilization is this:
I think the author of the video also participates in our forum.
I also think he is using the Acc Sensor to do the balancing but I am not 100% sure.
Pedro.
The Bioloid PREMIUM includes a more complete IMU: it is a combination of Gyro and Acceleration Sensor and therefore is capable of much finer tuning.
Robobuilder only has the the Acceleration Sensor (not the Gyro). It is a simpler approach (and much cheapper) and the sensor can essentially detect the presence of gravity on it's 3 axis.
That's why it is so easy to make it get up on itself after laying it down. It can also sense how it is laying by checking in which axis gravity is.
There are some youtube videos with some real time stabilization techniques using the Acc Sensor.
I think you may be able to do this stabilization (much like the Bioloid Stabilization) with the Acc Sensor only but it is not as accurate as using a combination of Gyro + Acc Sensor.
In this case, you would have to sense the shifting of gravity between the multiple axis. For example when tilting right you would sense gravity on -Y and as the robot tilts right you will theoretically see gravity increasing on +X
However this is quite prone to some noise because the Acc Sensor will sense not only gravity but also external forces (and reports the sum of them). Using a gyro helps in these situations because you can always know the actual position (tilt) of the robot.
This is the typical application for the Acceleration Sensor:
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BTW In this video you can see he used ActionBuilder to program the Robot (you see the that by the keys he presses on the Remote).
The youtube video with the dynamic stabilization is this:
phpBB [media]
I think the author of the video also participates in our forum.
I also think he is using the Acc Sensor to do the balancing but I am not 100% sure.
Pedro.
by Ketchup
Mon Dec 14, 2009 8:56 pm
Hi Pedro and NullARC!
That 2nd vid is of mine. I don't have the 3-axis sensor in mine. I was trying to make it walk slowly by balancing all of its weight on one foot at a time. (I was trying this when I first got it assembled)
It's very difficult to do. A gyro and the right programming would make it easier. (These tools I do not posses
) Look up the Gigantor robot walking vid. (here it is: http://www.youtube.com/watch?v=Oqd_ZvDngi4 )
My Robobuilder has been sleeping in his case for the past month since I got side-tracked with other projects.
I think it would be nice to have the 3-axis integrated into the base operation of the system and not have to use the action builder to make it work. (This is what I'm lead to believe...it can only be used with action builder)
That 2nd vid is of mine. I don't have the 3-axis sensor in mine. I was trying to make it walk slowly by balancing all of its weight on one foot at a time. (I was trying this when I first got it assembled)
It's very difficult to do. A gyro and the right programming would make it easier. (These tools I do not posses
) Look up the Gigantor robot walking vid. (here it is: http://www.youtube.com/watch?v=Oqd_ZvDngi4 )
My Robobuilder has been sleeping in his case for the past month since I got side-tracked with other projects.
I think it would be nice to have the 3-axis integrated into the base operation of the system and not have to use the action builder to make it work. (This is what I'm lead to believe...it can only be used with action builder)
by PedroR
Tue Dec 15, 2009 12:11 pm
Hi Ketchup
In fact the Acceleration Sensor can be used well beyond ActionBuilder.
The Acc Sensor is supported in these scenarios:
- ActionBuilder (you already know)
- Any .Net language using the very nice libraries by l3v3rz
- Using the native RBC protocol (supports virtually any language that can talk to the COM port).
- WinAVR C
The way it works with .Net and the native RBC protocol is that the PC is in control of the robot and queries the Acceleration Sensor in real time, several times per second and the computer "commands" the robot according to the readings.
With AcionBuilder and WinAVR C (custom firmware) you can make use of the Acc Sensor completely onboard the robot.
So as you can see there are plenty of options to go around.
In the past months significant programmability improvements have surfaced for Robobuilder and I think it is now the platform that offers the largest number of programming options.
Pedro.
In fact the Acceleration Sensor can be used well beyond ActionBuilder.
The Acc Sensor is supported in these scenarios:
- ActionBuilder (you already know)
- Any .Net language using the very nice libraries by l3v3rz
- Using the native RBC protocol (supports virtually any language that can talk to the COM port).
- WinAVR C
The way it works with .Net and the native RBC protocol is that the PC is in control of the robot and queries the Acceleration Sensor in real time, several times per second and the computer "commands" the robot according to the readings.
With AcionBuilder and WinAVR C (custom firmware) you can make use of the Acc Sensor completely onboard the robot.
So as you can see there are plenty of options to go around.
In the past months significant programmability improvements have surfaced for Robobuilder and I think it is now the platform that offers the largest number of programming options.
Pedro.
by Felix
Thu Jan 07, 2010 2:53 pm
Could you maybe explain a bit further on how the acceleration sensor works? One thing I have noticed it that if I lower the robot onto it's front really slowly (to keep acceleration low) he still gets up again.
Also if I start my actionbuilder program with it lying still on its front already, it still gets up. In this case there is definitely no acceleration because it is perfectly still!
Does the acceleration sensor measure raw acceleration or its position as interpreted from acceleration?
Felix
Also if I start my actionbuilder program with it lying still on its front already, it still gets up. In this case there is definitely no acceleration because it is perfectly still!
Does the acceleration sensor measure raw acceleration or its position as interpreted from acceleration?
Felix
by l3v3rz
Thu Jan 07, 2010 7:40 pm
Don't forget gravity !
Measured X, Y, Z axis value is indicated by integral
number from -7 to +7.
Integral number 1 can be translated as “1/4g”.
Note) g : gravity acceleration
For instance, Value would be X=0g, Y=0g, Z=-1g if
Robot lies down, because all gravity acceleration
direction is minus(-).
Therefore, you can judge whether Robot is lies
down or not, as long as you check acceleration
data would be
-1< X < 1, -1 < Y < 1, -5 < Z < -3
by l3v3rz
Fri Jan 08, 2010 6:53 pm
Well it is counter-intuitive - we think of acceleration as change in velocity and its is stationary. What's more if it fell of the desk it would it plummet to the ground - (accelerating in our frame of reference) but (I assume - not tried it) the accelerometer would read zero, as in zero g (until it hit the floor of course!). What a genius Newton was ! Should we send a robobuilder to the ISS to try it out? 
by l3v3rz
Sun Jan 10, 2010 11:59 pm
Did anyone see this on the robobuilder.net site ? It a really nice demonstration of use of action builder with the accelerometer.
http://robobuilder.net/eng/board/ucc/bo ... itle_name=
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<embed src="http://web.flv.gabia.com/player/rtmp_skin.swf?file_key=910d9b4080864a8e0d6b42280c8f09c0&allowmaximize=YES'" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
http://robobuilder.net/eng/board/ucc/bo ... itle_name=
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