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SRF08

5/5/2007 7:13:53 PM

Shaggy

13 posts

SRF08

I was looking over the .NET class for this sensor, and noticed that you can only get a distance. The sensor provides data on the first 17 echoes detected. After testing it for a bit, I realized that in an indoor environment, only the first four or five are meaningful, but that is still more than 1. Is there any way with the .NET interface to get the other echo data?

5/7/2007 11:46:30 AM

jason

158 posts

Re: SRF08

Shaggy,

Yes, this constraint goes all the way down to the firmware. Hence we didn't bother adding it to the .NET or Serializer Services interface. Are the additional readings really that useful?

Jason Summerour
President,
Summerour Robotics Corp
Microsoft MVP
www.roboticsconnection.com

5/7/2007 7:07:57 PM

Shaggy

13 posts

Re: SRF08

I've been studying that at some length. I feel that the first four or five readings are VERY useful, while the ones above those first four or five are very doubtful. My purpose is to use three pairs of SRF08 sensors to act as binocular "eyes", which is an idea that may or may not even work. I don't expect to see an image like our eyes do, because, for one thing, you get a single return off of a 3D object. However, one of the modules will be storing hits to a database, while another module will be using the database records to construct images of objects. Basically, while one ping shows very little, several pings, from several angles, will eventually build up a picture. For this, I feel that the more information the better, but out beyond the fourth or fifth echo, the two sensors in a pair tend not to line up well (all the echos are paired, but one or the other sensor has an 'extra' echo). The real advantage of using the first four or five would be in increasing the data obtained. For echolocation, this could be crucial once a map has been built. Multiple echoes would allow for something possibly akin to triangulation, though I still have plenty to work on before I can even say how well that will work. My goal is to map my house, then be able to set the robot anywhere in the house, and have it figure out its location. I'm still working on that first step at the moment.

10/18/2007 10:37:24 AM

rpg

35 posts

Re: SRF08

Hi Jason and Shaggy,

I too would find it useful to have access to the other 16 echo readings from the SRF08. I have been reading some papers on using sonar profiles for object recognition and apparently it can be quite accurate, so it would be nice to be able to point the SRF08 at an object, collect the 17 echos, store them as a pattern vector, then do some clustering analysis to test object recognition.

The BrainStem controllers by Acroname have support for all 17 echo readings but they do not have a .NET interface. The 3rd party .NET interface for Brainstems found at http://www.bespokesoftware.org/wordpress/?page_id=8 unfortunately does not have support for the SRF08!

--patrick

10/18/2007 11:15:20 AM

jason

158 posts

Re: SRF08

We'll be glad to add this functionality, however, it might be about a month before we can get to it. We have five new products launching over the next 3 weeks, and the Christmas shopping season is on the way, so we're going to be swamped. I will put it on the TODO list, though.

I can just add an optional switch to the 'srf08' command so that you can specify the number of echoes that you want returned. That way it won't break the current interface.

Example:

>srf08 n:17

In the mean time, you should be able to use the Generic I2C interface (either via direct protocol usage, or via the .NET lib) to retrieve the readings. To learn how to do this, please refer to the I2CDevice class under Namespace.RoboticsConnection.Serializer.Sensors topic on the Serializer .NET Library MSDN Help pages.

Jason Summerour
President,
Summerour Robotics Corp
Microsoft MVP
www.roboticsconnection.com

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