14 replies to this topic

[Michel Trahan]

As anyone thought of using the Forward Star data structure and algorithm (to find the shortest path) for autonomous robots ? I have implemented a VB version many years ago (1995) and I could rewrite it for C# to use in autonomous robots ... Everything in .Net MF ... any interest in such an algorithm ? very very efficient data structure (minimalistic, one node per node and one link per link, no wasted structure) and it is a very very fast algorithm. Example of usage : in a defined environment resembling a network of connecting nodes, allow a robot to find the fastest way to get there (emergency, security (using cameras on a quadcopter), etc). You can recalculate new paths when encountering closed paths ... could probably be used to repath power just like in Terminator movie lol Mike discovering quadcopters and netduino ! p.s.: I'll also work on a Kalman Filter using a complete set of sensor data as well as user commands. Everything in .Net MF

[demonGeek]

I'd be interested in that - I don't know anything about it but I'm slowly progressing towards building an autonomous robot and it sounds like this could be really useful. - Adam

[Troll feeder]

As anyone thought of using the Forward Star data structure and algorithm (to find the shortest path) for autonomous robots ?

I have implemented a VB version many years ago (1995) and I could rewrite it for C# to use in autonomous robots ... Everything in .Net MF ... any interest in such an algorithm ? very very efficient data structure (minimalistic, one node per node and one link per link, no wasted structure) and it is a very very fast algorithm.

Example of usage : in a defined environment resembling a network of connecting nodes, allow a robot to find the fastest way to get there (emergency, security (using cameras on a quadcopter), etc). You can recalculate new paths when encountering closed paths ... could probably be used to repath power just like in Terminator movie lol

Mike discovering quadcopters and netduino !

p.s.: I'll also work on a Kalman Filter using a complete set of sensor data as well as user commands. Everything in .Net MF

I'd be interested in the code as well.

[Michel Trahan]

I'd be interested in the code as well.

I just started to learn .Net (I know so many languages ... and yeah, I know, late learning) so give me time.

My project is to build a complete quadcopter from scratch and include in it the Kalman filter (KF). Once done, I'll work on it being autonomous ... and add the Forward Star (FS) data structure and the label setting shortest path algorithm.

If someone already has an autonomous quadcopter (or anything autonomous that would need such a fonctionnality) and would like to add the FS data structure, please contact me and I'll rewrite it sooner. If only newbies like me, then I'll take the time to learn first

If I wait long enough, we probably could have it in VB.Net on .Net MF lol (I'm a VB fanatic, so easy to program) but I'll try it in C# ...

Mike surprised about your fast reply !

[demonGeek]

I just started to learn .Net (I know so many languages ... and yeah, I know, late learning) so give me time.

If I wait long enough, we probably could have it in VB.Net on .Net MF lol (I'm a VB fanatic, so easy to program) but I'll try it in C# ...

One word of advice, since you're just starting out with .NET - make sure you develop the code in a .NETMF (Netduino) project and not a regular .NET project. NETMF is a subset of the full framework and I'm continually running into things that I can do in one but not the other.

VB.NET and C#.NET are much more closely related than VB is to VB.NET. I found the transition from VB to VB.NET to be hard work mostly because of the effort required to learn the framework. The syntactic differences between all three are not particularly significant.

- Adam

[Michel Trahan]

- make sure you develop the code in a .NETMF (Netduino) project and not a regular .NET project.

Don't worry, I also program for the windows phone 7 in silverlight (vb and c#) and I always get confused LOL

I tested my old vb program and it works like a charm ... 1995 code ! wow !

I tried to convert using Artinsoft Visual Basic Upgrade Companion (free for msdn member) but only the c# translation worked ... so I'm ok for the netduino I have to test the class a bit before posting the code

Keep you posted ... now is time to get out and play pool !

[Michel Trahan]

Small Update :

- The code was transfered to VB.Net like a charm
- Now trying to translate to C# (Full .Net first, then .Net MF ... but with the N+ since there is file access)

Question : how do we write/read files in C# ?

Here is the code using the Microsoft.VisualBasic assembly that I want to remove the dependency ... to write the Nodes and Links to files and loading them from files

filenum = FileSystem.FreeFile();
FileSystem.FileOpen(filenum, s, OpenMode.Input, OpenAccess.Read, OpenShare.LockWrite, -1);
FileSystem.Input(filenum, ref k);
FileSystem.FileClose(filenum);

int filenum = FileSystem.FreeFile();
FileSystem.FileOpen(filenum, s, OpenMode.Output, OpenAccess.Write, OpenShare.LockReadWrite, -1);
// Write the number of nodes and links.
FileSystem.WriteLine(filenum, bGraphicalInfoAttached, iNumNodes, iNumLinks);
FileSystem.WriteLine(filenum, Nodes[i].Name, Nodes[i].FirstLink, 0, 0);

And I have to verify why I am using this ...

s = Strings.Left(s, s.Length - 2);

And this ...

Conversion.ErrorToString()

I Think I can replace the last one with a catch (Exception e) in a try catch and using e.Message ... I am right ?

Keep you posted.

[demonGeek]

Hi Michel,

There are a lot of ways to do file I/O depending on what you need to do. Here's some code that I'm using to read/write to the SD card on the Netduino:

using System.IO;

public byte[] Read(string fileName)
{
	byte[] buffer;
	using (FileStream file = File.OpenRead(fileName))
	{
		buffer = new byte[file.Length];
		int bytesToRead = (int)file.Length;
		int bytesRead = 0;

		while (bytesToRead > 0)
			if (file.Read(buffer, bytesRead, bytesToRead) == 0) break;

		file.Close();
	}

	return (buffer);
}

public void Write(string fileName, byte[] data)
{
	using (FileStream file = File.Open(fileName, FileMode.Append))
	{
		file.Write(data, 0, data.Length);
		file.Flush();
		file.Close();
	}
}

The only word of warning would be that the read buffer in the above code could overflow on a platform with limited memory such as the Netduino. The code really needs to check the file size before allocating the buffer and then chunk the data if necessary.

Conversion.ErrorToString()

I Think I can replace the last one with a catch (Exception e) in a try catch and using e.Message ... I am right ?

Yes, you're right, use a try...catch and parse the exception like this:

try
{
	// something...
}
catch (IOException ex)
{
	// Catch a specific type of exception
	Debug.Print(ex.ToString());
}
catch (Exception ex)
{
	// Catch any exception
	Debug.Print(ex.ToString());
}
finally
{
	// clean up here, if necsessary
}

Hope that helps.

- Adam

[Michel Trahan]

The only word of warning would be that the read buffer in the above code could overflow on a platform with limited memory such as the Netduino. The code really needs to check the file size before allocating the buffer and then chunk the data if necessary.

Thanks ! I'll check that in april ... work load too heavy but wow ! Thanks !

And I am right in assuming that the FLASH memory access is automatic ? or do we need to do some special access to read/write to it ?

Mike away from the computer for the next few days ...

[demonGeek]

And I am right in assuming that the FLASH memory access is automatic ? or do we need to do some special access to read/write to it ?

Yes, that's right (assuming your SD Card is compatible). Just prefix the path with \SD like this:

File.OpenRead(@"\SD\myfile.txt");

[Michel Trahan]

Thinking of modifying the saving to file functionality to write xml file instead of an old coma seperated values (didn't find a way to read it and store it in variables yet ...). I prefer XML files ... anyone argue ? Anyone know of a XML Spy equivalent on the open source community ?

[Arawn]

Thinking of modifying the saving to file functionality to write xml file instead of an old coma seperated values (didn't find a way to read it and store it in variables yet ...).

I prefer XML files ... anyone argue ?

Anyone know of a XML Spy equivalent on the open source community ?

Haven't used it myself, so I have no idea if it will suit your needs but there's the free version of the Serna XML editor at http://www.syntext.c...cts/serna-free/

[Michel Trahan]

Haven't used it myself, so I have no idea if it will suit your needs but there's the free version of the Serna XML editor at http://www.syntext.c...cts/serna-free/

My Prefered tool for XML / XSD (Schema definition) is XML Spy but it is not given ... I'll buy (when budget permits) the professionnal version ... I used to do a lot of XSD and XML with it, very efficient.

[Michel Trahan]

There will be 6 versions - one main class with no file access - one with one type of file access (suggestions on csv or else?) - one with xml files (defining my own schema for it ... suggestions ? I'll post it here when defined OK ?) In two programming languages VB.net and C# The VB.net version with XML access is for my needs and will take priority. Any takers for that version ? Who wants to have a C# version ? With file acces or not ? If so, which one, XML (might not be appropriate for .net mf) ? Mike.

[Michel Trahan]

Wanted to give you a peak at an XML Schema for the Forward Star Network file representation but I can't upload an XSD file ... why ? (Tried XPS too to no avail ...) In the XSD file I separated the graphical info from the rest since if it only run in code, no graphical information is attached (only used when designing the directed network through a specialised editor). I ask for comments from those interested. How do I show this type of file here ? XSD, or XPS Here is a look at what a file would look like ...

Attached Files

•  FSNetworkTest20110406.xml   4.38KB   0 downloads