<link>https://people.skolelinux.org/pere/blog/</link>
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+ <item>
+ <title>OpenSnitch in Debian ready for prime time</title>
+ <link>https://people.skolelinux.org/pere/blog/OpenSnitch_in_Debian_ready_for_prime_time.html</link>
+ <guid isPermaLink="true">https://people.skolelinux.org/pere/blog/OpenSnitch_in_Debian_ready_for_prime_time.html</guid>
+ <pubDate>Sat, 13 May 2023 12:10:00 +0200</pubDate>
+ <description><p>A bit delayed,
+<a href="https://tracker.debian.org/pkg/opensnitch">the interactive
+application firewall OpenSnitch</a> package in Debian now got the
+latest fixes ready for Debian Bookworm. Because it depend on a
+package missing on some architectures, the autopkgtest check of the
+testing migration script did not understand that the tests were
+actually working, so the migration was delayed. A bug in the package
+dependencies is also fixed, so those installing the firewall package
+(opensnitch) now also get the GUI admin tool (python3-opensnitch-ui)
+installed by default. I am very grateful to Gustavo Iñiguez Goya for
+his work on getting the package ready for Debian Bookworm.</p>
+
+<p>Armed with this package I have discovered some surprising
+connections from programs I believed were able to work completly
+offline, and it has already proven its worth, at least to me. If you
+too want to get more familiar with the kind of programs using
+Internett connections on your machine, I recommend testing <tt>apt
+install opensnitch</tt> in Bookworm and see what you think.</p>
+
+<p>The package is still not able to build its eBPF module within
+Debian. Not sure how much work it would be to get it working, but
+suspect some kernel related packages need to be extended with more
+header files to get it working.</p>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+</description>
+ </item>
+
<item>
<title>Speech to text, she APTly whispered, how hard can it be?</title>
<link>https://people.skolelinux.org/pere/blog/Speech_to_text__she_APTly_whispered__how_hard_can_it_be_.html</link>
<p>I am one of the Norwegian Bokmål translators of this book, and we
have just started. Your contribution is most welcome.</p>
-<p>As usual, if you use Bitcoin and want to show your support of my
-activities, please send Bitcoin donations to my address
-<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
-</description>
- </item>
-
- <item>
- <title>Automatic LinuxCNC servo PID tuning?</title>
- <link>https://people.skolelinux.org/pere/blog/Automatic_LinuxCNC_servo_PID_tuning_.html</link>
- <guid isPermaLink="true">https://people.skolelinux.org/pere/blog/Automatic_LinuxCNC_servo_PID_tuning_.html</guid>
- <pubDate>Sat, 16 Jul 2022 22:30:00 +0200</pubDate>
- <description><p>While working on a CNC with servo motors controlled by the
-<a href="https://en.wikipedia.org/wiki/LinuxCNC">LinuxCNC</a>
-<a href="https://en.wikipedia.org/wiki/PID_controller">PID
-controller</a>, I recently had to learn how to tune the collection of values
-that control such mathematical machinery that a PID controller is. It
-proved to be a lot harder than I hoped, and I still have not succeeded
-in getting the Z PID controller to successfully defy gravity, nor X
-and Y to move accurately and reliably. But while climbing up this
-rather steep learning curve, I discovered that some motor control
-systems are able to tune their PID controllers. I got the impression
-from the documentation that LinuxCNC were not. This proved to be not
-true.</p>
-
-<p>The LinuxCNC
-<a href="http://linuxcnc.org/docs/html/man/man9/pid.9.html">pid
-component</a> is the recommended PID controller to use. It uses eight
-constants <tt>Pgain</tt>, <tt>Igain</tt>, <tt>Dgain</tt>,
-<tt>bias</tt>, <tt>FF0</tt>, <tt>FF1</tt>, <tt>FF2</tt> and
-<tt>FF3</tt> to calculate the output value based on current and wanted
-state, and all of these need to have a sensible value for the
-controller to behave properly. Note, there are even more values
-involved, theser are just the most important ones. In my case I need
-the X, Y and Z axes to follow the requested path with little error.
-This has proved quite a challenge for someone who have never tuned a
-PID controller before, but there is at least some help to be found.
-
-<p>I discovered that included in LinuxCNC was this old PID component
-at_pid claiming to have auto tuning capabilities. Sadly it had been
-neglected since 2011, and could not be used as a plug in replacement
-for the default pid component. One would have to rewriting the
-LinuxCNC HAL setup to test at_pid. This was rather sad, when I wanted
-to quickly test auto tuning to see if it did a better job than me at
-figuring out good P, I and D values to use.</p>
-
-<p>I decided to have a look if the situation could be improved. This
-involved trying to understand the code and history of the pid and
-at_pid components. Apparently they had a common ancestor, as code
-structure, comments and variable names were quite close to each other.
-Sadly this was not reflected in the git history, making it hard to
-figure out what really happened. My guess is that the author of
-<a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/at_pid.c">at_pid.c</a>
-took a version of
-<a href="https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/components/pid.c">pid.c</a>,
-rewrote it to follow the structure he wished pid.c to have, then added
-support for auto tuning and finally got it included into the LinuxCNC
-repository. The restructuring and lack of early history made it
-harder to figure out which part of the code were relevant to the auto
-tuning, and which part of the code needed to be updated to work the
-same way as the current pid.c implementation. I started by trying to
-isolate relevant changes in pid.c, and applying them to at_pid.c. My
-aim was to make sure the at_pid component could replace the pid
-component with a simple change in the HAL setup loadrt line, without
-having to "rewire" the rest of the HAL configuration. After a few
-hours following this approach, I had learned quite a lot about the
-code structure of both components, while concluding I was heading down
-the wrong rabbit hole, and should get back to the surface and find a
-different path.</p>
-
-<p>For the second attempt, I decided to throw away all the PID control
-related part of the original at_pid.c, and instead isolate and lift
-the auto tuning part of the code and inject it into a copy of pid.c.
-This ensured compatibility with the current pid component, while
-adding auto tuning as a run time option. To make it easier to identify
-the relevant parts in the future, I wrapped all the auto tuning code
-with '#ifdef AUTO_TUNER'. The end result behave just like the current
-pid component by default, as that part of the code is identical. The
-<a href="https://github.com/LinuxCNC/linuxcnc/pull/1820">end result
-entered the LinuxCNC master branch</a> a few days ago.</p>
-
-<p>To enable auto tuning, one need to set a few HAL pins in the PID
-component. The most important ones are <tt>tune-effort</tt>,
-<tt>tune-mode</tt> and <tt>tune-start</tt>. But lets take a step
-back, and see what the auto tuning code will do. I do not know the
-mathematical foundation of the at_pid algorithm, but from observation
-I can tell that the algorithm will, when enabled, produce a square
-wave pattern centered around the <tt>bias</tt> value on the output pin
-of the PID controller. This can be seen using the HAL Scope provided
-by LinuxCNC. In my case, this is translated into voltage (+-10V) sent
-to the motor controller, which in turn is translated into motor speed.
-So at_pid will ask the motor to move the axis back and forth. The
-number of cycles in the pattern is controlled by the
-<tt>tune-cycles</tt> pin, and the extremes of the wave pattern is
-controlled by the <tt>tune-effort</tt> pin. Of course, trying to
-change the direction of a physical object instantly (as in going
-directly from a positive voltage to the equivalent negative voltage)
-do not change velocity instantly, and it take some time for the object
-to slow down and move in the opposite direction. This result in a
-more smooth movement wave form, as the axis in question were vibrating
-back and forth. When the axis reached the target speed in the
-opposing direction, the auto tuner change direction again. After
-several of these changes, the average time delay between the 'peaks'
-and 'valleys' of this movement graph is then used to calculate
-proposed values for Pgain, Igain and Dgain, and insert them into the
-HAL model to use by the pid controller. The auto tuned settings are
-not great, but htye work a lot better than the values I had been able
-to cook up on my own, at least for the horizontal X and Y axis. But I
-had to use very small <tt>tune-effort<tt> values, as my motor
-controllers error out if the voltage change too quickly. I've been
-less lucky with the Z axis, which is moving a heavy object up and
-down, and seem to confuse the algorithm. The Z axis movement became a
-lot better when I introduced a <tt>bias</tt> value to counter the
-gravitational drag, but I will have to work a lot more on the Z axis
-PID values.</p>
-
-<p>Armed with this knowledge, it is time to look at how to do the
-tuning. Lets say the HAL configuration in question load the PID
-component for X, Y and Z like this:</p>
-
-<blockquote><pre>
-loadrt pid names=pid.x,pid.y,pid.z
-</pre></blockquote>
-
-<p>Armed with the new and improved at_pid component, the new line will
-look like this:</p>
-
-<blockquote><pre>
-loadrt at_pid names=pid.x,pid.y,pid.z
-</pre></blockquote>
-
-<p>The rest of the HAL setup can stay the same. This work because the
-components are referenced by name. If the component had used count=3
-instead, all use of pid.# had to be changed to at_pid.#.</p>
-
-<p>To start tuning the X axis, move the axis to the middle of its
-range, to make sure it do not hit anything when it start moving back
-and forth. Next, set the <tt>tune-effort</tt> to a low number in the
-output range. I used 0.1 as my initial value. Next, assign 1 to the
-<tt>tune-mode</tt> value. Note, this will disable the pid controlling
-part and feed 0 to the output pin, which in my case initially caused a
-lot of drift. In my case it proved to be a good idea with X and Y to
-tune the motor driver to make sure 0 voltage stopped the motor
-rotation. On the other hand, for the Z axis this proved to be a bad
-idea, so it will depend on your setup. It might help to set the
-<tt>bias</tt> value to a output value that reduce or eliminate the
-axis drift. Finally, after setting <tt>tune-mode</tt>, set
-<tt>tune-start</tt> to 1 to activate the auto tuning. If all go well,
-your axis will vibrate for a few seconds and when it is done, new
-values for Pgain, Igain and Dgain will be active. To test them,
-change <tt>tune-mode</tt> back to 0. Note that this might cause the
-machine to suddenly jerk as it bring the axis back to its commanded
-position, which it might have drifted away from during tuning. To
-summarize with some halcmd lines:</p>
-
-<blockquote><pre>
-setp pid.x.tune-effort 0.1
-setp pid.x.tune-mode 1
-setp pid.x.tune-start 1
-# wait for the tuning to complete
-setp pid.x.tune-mode 0
-</pre></blockquote>
-
-<p>After doing this task quite a few times while trying to figure out
-how to properly tune the PID controllers on the machine in, I decided
-to figure out if this process could be automated, and wrote a script
-to do the entire tuning process from power on. The end result will
-ensure the machine is powered on and ready to run, home all axis if it
-is not already done, check that the extra tuning pins are available,
-move the axis to its mid point, run the auto tuning and re-enable the
-pid controller when it is done. It can be run several times. Check
-out the
-<a href="https://github.com/SebKuzminsky/MazakVQC1540/blob/bon-dev/scripts/run-auto-pid-tuner">run-auto-pid-tuner</a>
-script on github if you want to learn how it is done.</p>
-
-<p>My hope is that this little adventure can inspire someone who know
-more about motor PID controller tuning can implement even better
-algorithms for automatic PID tuning in LinuxCNC, making life easier
-for both me and all the others that want to use LinuxCNC but lack the
-in depth knowledge needed to tune PID controllers well.</p>
-
<p>As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
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