ANNOUNCING: navX MXP Robotics Navigation Sensor

[bmammen]

We started playing with the example code tonight, trying to use the navX to Auto-Rotate to an angle but we're having an issue where no matter what values we use for PID, the bot rotates to the angle and constantly shakes back and forth trying to reach the exact angle.

I can post our code if that helps, we're using C++ and have a 4 motor/4 transmission tank drive configuration on our test chassis. Hoping someone might have some ideas for us. Thx.

[cjl2625]

Originally Posted by bmammen

We started playing with the example code tonight, trying to use the navX to Auto-Rotate to an angle but we're having an issue where no matter what values we use for PID, the bot rotates to the angle and constantly shakes back and forth trying to reach the exact angle.

I can post our code if that helps, we're using C++ and have a 4 motor/4 transmission tank drive configuration on our test chassis. Hoping someone might have some ideas for us. Thx.

I once had a similar problem with rotating swerve modules with PID.
The problem ended up being that the loop time was really long, like 300 ms.
Since it took so long to update, it repeatedly overshot the target and shook back and forth.
In my case, it turned out that this was being caused by an error, because I didn't configure something correctly in the drive encoders. So the code seemed to be quietly throwing errors which drastically slowed down the iteration time.

[jojoguy10]

Not sure about anyone else, but the NavXMXPUI program isn't working for our team. When I try to run the .bat file, it says it can't find a file.

Is there a KNOWN working version somewhere?

Thanks!

[slibert]

Originally Posted by jojoguy10

Not sure about anyone else, but the NavXMXPUI program isn't working for our team. When I try to run the .bat file, it says it can't find a file.

Is there a KNOWN working version somewhere?

Thanks!

The navXMXPUI 64 bit windows version is known working, tested on Windows 7 64-bit. Please post details on the error message you are seeing. Note that Java is required to be installed, too.

[jojoguy10]

I'm using 64-bit Windows 8.1 (that might be the issue?)

Here is the command prompt window text

Catched FileNotFoundException: C:\Users\Joe\Desktop\navx-utilities\navXMXPUI\app
lication.windows64\lib\gluegen-rt-natives-windows-i586.jar (The system cannot fi
nd the file specified), while addNativeJarLibsImpl(classFromJavaJar class com.jo
gamp.common.os.Platform, classJarURI jar:file:/C:/Users/Joe/Desktop/navx-utiliti
es/navXMXPUI/application.windows64/lib/gluegen-rt.jar!/com/jogamp/common/os/Plat
form.class, nativeJarBaseName gluegen-rt-natives-windows-i586.jar): [ file:/C:/U
sers/Joe/Desktop/navx-utilities/navXMXPUI/application.windows64/lib/gluegen-rt.j
ar -> file:/C:/Users/Joe/Desktop/navx-utilities/navXMXPUI/application.windows64/
lib/ ] + gluegen-rt-natives-windows-i586.jar -> slim: jar:file:/C:/Users/Joe/Des
ktop/navx-utilities/navXMXPUI/application.windows64/lib/gluegen-rt-natives-windo
ws-i586.jar!/
Exception in thread "Animation Thread" java.lang.UnsatisfiedLinkError: Can't loa
d library: C:\Users\Joe\Desktop\navx-utilities\navXMXPUI\application.windows64\g
luegen-rt.dll
        at java.lang.ClassLoader.loadLibrary(Unknown Source)
        at java.lang.Runtime.load0(Unknown Source)
        at java.lang.System.load(Unknown Source)
        at com.jogamp.common.jvm.JNILibLoaderBase.loadLibraryInternal(JNILibLoad
erBase.java:551)
        at com.jogamp.common.jvm.JNILibLoaderBase.access$000(JNILibLoaderBase.ja
va:64)
        at com.jogamp.common.jvm.JNILibLoaderBase$DefaultAction.loadLibrary(JNIL
ibLoaderBase.java:96)
        at com.jogamp.common.jvm.JNILibLoaderBase.loadLibrary(JNILibLoaderBase.j
ava:414)
        at com.jogamp.common.os.DynamicLibraryBundle$GlueJNILibLoader.loadLibrar
y(DynamicLibraryBundle.java:388)
        at com.jogamp.common.os.Platform$1.run(Platform.java:203)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.jogamp.common.os.Platform.<clinit>(Platform.java:173)
        at javax.media.opengl.GLProfile.<clinit>(GLProfile.java:82)
        at processing.opengl.PJOGL.initSurface(PJOGL.java:238)
        at processing.opengl.PGraphicsOpenGL.initPrimary(PGraphicsOpenGL.java:59
88)
        at processing.opengl.PGraphicsOpenGL.requestDraw(PGraphicsOpenGL.java:16
00)
        at processing.core.PApplet.run(PApplet.java:2177)
        at java.lang.Thread.run(Unknown Source)

If I just try to run the .exe file, it's just a blank, white window. I've tried downloading the NavX_Utilities different times and I've tried this on 3 different laptops (granted, all running 64-bit Win8.1) with no success.

Thanks!

[slibert]

Originally Posted by jojoguy10

I'm using 64-bit Windows 8.1 (that might be the issue?)

Here is the command prompt window text

Catched FileNotFoundException: C:\Users\Joe\Desktop\navx-utilities\navXMXPUI\app
lication.windows64\lib\gluegen-rt-natives-windows-i586.jar (The system cannot fi
nd the file specified), while addNativeJarLibsImpl(classFromJavaJar class com.jo
gamp.common.os.Platform, classJarURI jar:file:/C:/Users/Joe/Desktop/navx-utiliti
es/navXMXPUI/application.windows64/lib/gluegen-rt.jar!/com/jogamp/common/os/Plat
form.class, nativeJarBaseName gluegen-rt-natives-windows-i586.jar): [ file:/C:/U
sers/Joe/Desktop/navx-utilities/navXMXPUI/application.windows64/lib/gluegen-rt.j
ar -> file:/C:/Users/Joe/Desktop/navx-utilities/navXMXPUI/application.windows64/
lib/ ] + gluegen-rt-natives-windows-i586.jar -> slim: jar:file:/C:/Users/Joe/Des
ktop/navx-utilities/navXMXPUI/application.windows64/lib/gluegen-rt-natives-windo
ws-i586.jar!/
Exception in thread "Animation Thread" java.lang.UnsatisfiedLinkError: Can't loa
d library: C:\Users\Joe\Desktop\navx-utilities\navXMXPUI\application.windows64\g
luegen-rt.dll
        at java.lang.ClassLoader.loadLibrary(Unknown Source)
        at java.lang.Runtime.load0(Unknown Source)
        at java.lang.System.load(Unknown Source)
        at com.jogamp.common.jvm.JNILibLoaderBase.loadLibraryInternal(JNILibLoad
erBase.java:551)
        at com.jogamp.common.jvm.JNILibLoaderBase.access$000(JNILibLoaderBase.ja
va:64)
        at com.jogamp.common.jvm.JNILibLoaderBase$DefaultAction.loadLibrary(JNIL
ibLoaderBase.java:96)
        at com.jogamp.common.jvm.JNILibLoaderBase.loadLibrary(JNILibLoaderBase.j
ava:414)
        at com.jogamp.common.os.DynamicLibraryBundle$GlueJNILibLoader.loadLibrar
y(DynamicLibraryBundle.java:388)
        at com.jogamp.common.os.Platform$1.run(Platform.java:203)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.jogamp.common.os.Platform.<clinit>(Platform.java:173)
        at javax.media.opengl.GLProfile.<clinit>(GLProfile.java:82)
        at processing.opengl.PJOGL.initSurface(PJOGL.java:238)
        at processing.opengl.PGraphicsOpenGL.initPrimary(PGraphicsOpenGL.java:59
88)
        at processing.opengl.PGraphicsOpenGL.requestDraw(PGraphicsOpenGL.java:16
00)
        at processing.core.PApplet.run(PApplet.java:2177)
        at java.lang.Thread.run(Unknown Source)

If I just try to run the .exe file, it's just a blank, white window. I've tried downloading the NavX_Utilities different times and I've tried this on 3 different laptops (granted, all running 64-bit Win8.1) with no success.

Thanks!

Ok, that helps. To help narrow things down, what version of Java is installed?

Also, you might try installing the processing IDE, using the instructions at the bottom of this page: https://code.google.com/p/navx-mxp/wiki/navXMXPUI

[jojoguy10]

Originally Posted by slibert

Ok, that helps. To help narrow things down, what version of Java is installed?

Also, you might try installing the processing IDE, using the instructions at the bottom of this page: https://code.google.com/p/navx-mxp/wiki/navXMXPUI

I have Java 8 Update 31 installed on my main computer.

I have the Processing IDE installed (v2.2.1) When I try to run the navXMXPUI.pde, it says:

No library found for com.kauailabs.navx_mxp
No library found for com.kauailabs.navx_mxp
Libraries must be installed in a folder named 'libraries' inside the 'sketchbook' folder.

[slibert]

Originally Posted by jojoguy10

I have Java 8 Update 31 installed on my main computer.

I have the Processing IDE installed (v2.2.1) When I try to run the navXMXPUI.pde, it says:

No library found for com.kauailabs.navx_mxp
No library found for com.kauailabs.navx_mxp
Libraries must be installed in a folder named 'libraries' inside the 'sketchbook' folder.

We may have an issue with Java 8 (we tested with Java 7).

You'll need processing IDE v 2.1.

Also the sketch folder in the processing IDE needs to be set to point to the directory that has the navXMXPUI.pde file in it.

[jojoguy10]

Originally Posted by slibert

We may have an issue with Java 8 (we tested with Java 7).

You'll need processing IDE v 2.1.

Also the sketch folder in the processing IDE needs to be set to point to the directory that has the navXMXPUI.pde file in it.

Rolling back to Java 7 worked! Thanks!

[slibert]

Originally Posted by jojoguy10

Rolling back to Java 7 worked! Thanks!

Great to hear, congratulations.

Did a little research on the error message re: the missing file; it looks like the previous Java system thought it was 32 bits, so perhaps previously the 32-bit version of Java 8 was installed. We will do some testing with Java 8 and the navXMXPUI to try to get this sorted out.

[jojoguy10]

Originally Posted by slibert

Great to hear, congratulations.

Did a little research on the error message re: the missing file; it looks like the previous Java system thought it was 32 bits, so perhaps previously the 32-bit version of Java 8 was installed. We will do some testing with Java 8 and the navXMXPUI to try to get this sorted out.

Hmmmm...I guess that's possible.

Thanks again for the help. The NavX is VERY responsive at 60Hz! It's awesome!

[ayeckley]

Originally Posted by bmammen

no matter what values we use for PID, the bot rotates to the angle and constantly shakes back and forth trying to reach the exact angle.

That sounds like a classic case of the Proportional gain being set too high. Keep in mind that it might require surprisingly small values, depending on your exact implementation. If you haven't already, the recommended PID tuning process starts with the I and D gains set to zero and the P gain set to a very low value. If you still get oscillation, then it is probably(*) necessary to decrease the P gain. If the robot "under-turns", then increase the gain incrementally. Generally speaking, once tuning is complete the P gain value should be just below the point at which you get oscillation. This can be very tricky with drives that have to overcome a large amount of stiction (static friction) in their drive systems (Mechanum drives are a good example) and robots that have relatively high angular moments of inertia (all of them?). It's highly unlikely that the navX unit is the source of the problem. You'll get very different behaviors if your robot is on a hard floor vs. carpet; try to use the most-FRC-realistic surface you can obtain.

* You might also get the symptoms you've described if there is some binding or other non-uniform drag in your drivetrain.

[bmammen]

Originally Posted by ayeckley

That sounds like a classic case of the Proportional gain being set too high. Keep in mind that it might require surprisingly small values, depending on your exact implementation. If you haven't already, the recommended PID tuning process starts with the I and D gains set to zero and the P gain set to a very low value. If you still get oscillation, then it is probably(*) necessary to decrease the P gain. If the robot "under-turns", then increase the gain incrementally. Generally speaking, once tuning is complete the P gain value should be just below the point at which you get oscillation. This can be very tricky with drives that have to overcome a large amount of stiction (static friction) in their drive systems (Mechanum drives are a good example) and robots that have relatively high angular moments of inertia (all of them?). It's highly unlikely that the navX unit is the source of the problem. You'll get very different behaviors if your robot is on a hard floor vs. carpet; try to use the most-FRC-realistic surface you can obtain.

* You might also get the symptoms you've described if there is some binding or other non-uniform drag in your drivetrain.

We started with the P value but no matter what its set at (low or high) the turn is still at the same velocity - it does hit the angle though before gyrating back and forth trying to reach accuracy. We've also tried changing the % SetTolerance which yields no change. It must be something with the way we are handing the PID output. Thanks for the suggestions.

[Alan Anderson]

Originally Posted by bmammen

We started with the P value but no matter what its set at (low or high) the turn is still at the same velocity - it does hit the angle though before gyrating back and forth trying to reach accuracy.

What P values were you using for "low" and "high"?

It sounds to me like you need to set the P constant lower yet. Remember that it's using the error in robot heading and turning that into a motor command. Motor values are between -1 and 1, and you probably want it to go to less than ten percent power when you're within several degrees of the target. I'd try a Kp of 0.01 to start with and go from there.

[ayeckley]

Scott,

I too am having difficulty running the UI. If I execute navXMXPUI.bat (edited as specified to point to COM4, which is where the ST VCP is connected), I get an error "Could not find or load main class NAVXMXPUI". I am able to run navXConfig (setup.exe) with no issues which leads me to believe both the PC and navX hardware are configured properly.

I'm using Win 7 (64 bit), and have Java 1.7 runtime enabled under User settings (1.8 is also installed, but I have disabled it). I've also installed Processing 2.2.1 (BTW, 2.1 is not listed as a downloadable release) and have merged the UI "processing" directory to the [user]\Documents\Processing location. I can open the Sketch successfully however when I attempt to compile it I get the same library errors as a previous poster reported (no library found for com.kauailabs etc.). When I "Show Sketch Folder", the navXMXPUI folder (and its subfolders) is displayed as one would expect.

Where have I gone wrong? I suspect it's something in my Java configuration.