tag:blogger.com,1999:blog-8214401912480503366.post8619412713282216592..comments2023-08-10T13:35:15.093+02:00Comments on My life with Android :-): Detecting speed bumps with accelerometerGabor Pallerhttp://www.blogger.com/profile/14307475522972458932noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-8214401912480503366.post-72158895233883868222016-12-17T21:21:42.850+01:002016-12-17T21:21:42.850+01:00Harsh: bw_0_9, etc. are the resampled variants of ...Harsh: bw_0_9, etc. are the resampled variants of the prerecorded speed bump signal whose graph can be found in the post (below the text "This is the pre-recorded sample I used for cross-correlation"). The signal was slowed down (bw_0_9) in case the car crosses the speed bump more slowly than the case when the reference signal was recorded. bw_1_0 is the original signal and bw_1_1 is the case when the signal was sped up to simulate when the car crosses the speed bump faster. As the post says, this way of measurement is not very efficient, see the continuation of this saga <a href="http://mylifewithandroid.blogspot.hu/2013/10/sensor-fusion-between-car-and-smartphone.html" rel="nofollow">here.</a>Gabor Pallerhttps://www.blogger.com/profile/02390936870056951146noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-14364406086165115552016-12-12T20:04:20.031+01:002016-12-12T20:04:20.031+01:00What is bw_0_9 bw_1_0 .. in code?What is bw_0_9 bw_1_0 .. in code?Harshnoreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-26083855077596756512016-03-16T22:28:57.649+01:002016-03-16T22:28:57.649+01:00Karthick, the post is about vertical acceleration ...Karthick, the post is about vertical acceleration ("vibration") and yes, I detect this kind of acceleration using the Android accelerometer. If you are interested in the motion acceleration, I recommend the car's speedometer, <a href="http://mylifewithandroid.blogspot.com/2013/03/data-capture-application-for-car-speed.html" rel="nofollow">click here for a post</a> or <a href="http://mylifewithandroid.blogspot.com/2013/10/sensor-fusion-between-car-and-smartphone.html" rel="nofollow">click here for a presentation.</a>Gabor Pallerhttps://www.blogger.com/profile/02390936870056951146noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-26938623819422083592016-03-15T10:05:15.668+01:002016-03-15T10:05:15.668+01:00Hi Gabor Paller Are u detecting the car accelerati...Hi Gabor Paller Are u detecting the car acceleration using android accelerometer?Karthickhttps://www.blogger.com/profile/14618619205690928262noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-23650407521383644532016-02-11T23:02:37.306+01:002016-02-11T23:02:37.306+01:00Kevin, this issue is discussed briefly in this blo...Kevin, this issue is discussed briefly in <a href="http://mylifewithandroid.blogspot.com/2010/05/movement-patterns.html" rel="nofollow">this blog post</a>. You are right that if the phone is fixed so that its Z axis corresponds to the vertical axis then only the Z axis should be considered. However, I took the habit in earlier experiments (mostly human movements) not to assume anything about the position of the phone because it may be positioned in any way wrt. the human body. The situation is similar in the car too. E.g. the phone may be correctly positioned so that its Z axis corresponds to the vertical axis - if the car does not tilt. If it does, then the phone's Z axis is not vertical anymore but the gravity vector always is. So I used the simplification that I look for the amplitude and don't deal with the direction of the vibration. Gabor Pallerhttps://www.blogger.com/profile/02390936870056951146noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-60875616473827684242016-02-11T07:50:04.914+01:002016-02-11T07:50:04.914+01:00Thanks for the quick reply! Helped reinforce my co...Thanks for the quick reply! Helped reinforce my confidence in my endeavour :)<br /><br />I just have one more question, which might sound a little stupid. The pre-recorded signal that you have used, contains positive as well as negative values. However, in your application code, you take the amplitude value of the acceleration sensor (Root(x^2+y^2+z^2)) which is always a positive value, and compare it to the pre-recorded signal. Have you just taken the actual z-axis vibrations as your pre-recorded signal, or is there some other calculation I am missing? Because if I use the amplitude of the pre-recorded signal, I will always get a positive value.Kevinnoreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-76896672718759461542016-02-10T22:08:43.801+01:002016-02-10T22:08:43.801+01:00Hi, Kevin,
My experiments with car vibrations wer...Hi, Kevin,<br /><br />My experiments with car vibrations were summarized in <a href="http://mylifewithandroid.blogspot.com/2013/10/sensor-fusion-between-car-and-smartphone.html" rel="nofollow">this presentation (starting from slide 34)</a> My conclusion is that road damage detection is quite possible but the general detection of speed bump is not feasible. The difference is between the two is the behavior of the driver: while road damage normally happens to driver unprepared (this means that you have a nice, strong acceleration signal which is bad news to the car's suspension system but good news for our detection algorithm), speed bump is normally approached carefully which results in a small acceleration signal which is hard to detect in the vibration cacophony of the car. Of course, if you assume that the driver gets through the speed bump with full speed, without slowing down then the situation is different but not many of us have drive permits for tanks. :-) <br /><br />Regarding the capture problem, I shared some capture programs (like <a href="http://mylifewithandroid.blogspot.com/2010/03/sensors.html" rel="nofollow">in this post, the post also refers to an app on Google Play that has the capture functionality</a>). Also, <a href="http://mylifewithandroid.blogspot.com/2013/03/data-capture-application-for-car-speed.html" rel="nofollow">I shared the data capture application I used in many of these car experiments.</a><br />Gabor Pallerhttps://www.blogger.com/profile/02390936870056951146noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-49383957631564104782016-02-10T12:36:54.677+01:002016-02-10T12:36:54.677+01:00Hi,
Amazing work with the Speed Bump detection! :...Hi,<br /><br />Amazing work with the Speed Bump detection! :)<br />I just have a couple of questions:<br />1. How did you obtain the perfect pre-recorded speed bump signal?<br />2. Is it possible to obtain a similar pre-recorded signal for detecting potholes, and filter out the speed bumps?<br /><br /><br />Kevinnoreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-91843555650929628102015-10-29T14:59:28.552+01:002015-10-29T14:59:28.552+01:00Hi everyone can anyone give me bump detection algo...Hi everyone can anyone give me bump detection algorithm?<br />Anonymoushttps://www.blogger.com/profile/06767178485892127053noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-74843818796081382732015-10-10T06:55:38.260+02:002015-10-10T06:55:38.260+02:00Wow! There are way too many close calls and traged...Wow! There are way too many close calls and tragedies that could be prevented by drivers doing the right thing. Thanks for sharing your post!!<br /><a href="http://www.highway1.co.nz/" rel="nofollow"> speed bumps </a>Highwayhttps://www.blogger.com/profile/17063739426520601199noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-62783353255783402452013-06-29T17:55:11.012+02:002013-06-29T17:55:11.012+02:00Tejaswini, are you placing the device casually (in...Tejaswini, are you placing the device casually (in any position relative to the car) or do you have the possibility to fix the device to the car? E.g. usual handsfree kits fix the device in such a way that the device's Z axis points more or less to the main axis of the car (axis of driving). In this case the accelerating/braking acceleration can be measured only on the Z axis of the device and road problems (potholes, etc.) would cause acceleration only on the Y axis.<br /><br />I don't understand your reference to the interrupt duration.Gabor Pallerhttps://www.blogger.com/profile/02390936870056951146noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-62930322452963518722013-06-28T14:14:36.115+02:002013-06-28T14:14:36.115+02:00Hi,
I am using LIS3DH accelerometer to detect Ha...Hi,<br /><br /> I am using LIS3DH accelerometer to detect Harsh acceleration and Harsh breaking.<br /><br />The device is working for Harsh breaking perfectly but i am facing difficulty in Harsh acceleration,<br />With this bump,elevation's are appearing, How to remove the bump?<br />if i increase interrupt duration of my device i can able to detect only Harsh breaking,i cant detect HA.<br />Please suggest me for this problem??Anonymoushttps://www.blogger.com/profile/11735742496935350243noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-71345389614695056722013-02-21T10:07:54.212+01:002013-02-21T10:07:54.212+01:00Alexander: I my tests it was a suburban setting. S...Alexander: I my tests it was a suburban setting. So I drove quite slowly, say 30km/h and slowed down to about 10 km/h before the speed bumps (that I knew very well). That's a speed difference of about 20 km/h, about 5.5 m/s. But the deceleration phase took more than 1 sec - hard to estimate, let it be about 3 sec. That yields an acceleration of about 1.8 m/s^2. <br /><br />I checked my samples and acceleration in random direction of about 1 m/s^2 was quite common in my samples. The car was shaking on the road because it was not perfectly smooth. In short: I was not able to extract that horizontal negative acceleration (the slowing down) from the noisy background caused by vibrations.<br /><br />Maybe we can redefine the task so that we are interested only in dangerous passing of speed bumps. Then we can assume much larger deceleration and "knock".Gabor Pallerhttps://www.blogger.com/profile/02390936870056951146noreply@blogger.comtag:blogger.com,1999:blog-8214401912480503366.post-48404463244569278262013-02-20T09:58:53.272+01:002013-02-20T09:58:53.272+01:00You should consider driver's behavior too!
Al...You should consider driver's behavior too!<br /><br />Almost all drivers will actually slow down in front of those bumps (it's their goal anyways). So, instead of looking just at the acceleration magnitude, check its projections too.<br /><br />It might look like:<br />- slowing down (acceleration towards driving direction)<br />- stopping slowing down (common good practice to unload front wheels)<br />- front wheels bump and high osscilations<br />- rear wheels bump and lower osscilations<br />- car accelerationAnonymoushttps://www.blogger.com/profile/17553756844046168482noreply@blogger.com