My Site was down early this morning.

I use my computers at home to host my Web-site, including this blog. But the IP address I have at home, is just a regular, dynamically-assigned IP address, which is owned by my ISP. This IP address can be reassigned to be at any moment.

Therefore, I have an update service which makes my changed IP address available to people who may want to access my URLs.

This morning, this update service failed to do its job correctly. And therefore, my Site was unavailable from 4h40 until 6h50.

This problem has now been corrected in an easy way.



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Switched In a Replacement Keyboard

This is a situation which brings back memories of my Late Father, who repatriated to Germany in the late 1990s and early 2000s. He had a habit of giving me gifts that included computers and computer accessories.

During a visit which I made to Germany in 2010, he gave me a laptop that he didn’t need anymore, and which is in fact the Acer Aspire 5020 I mentioned before.

Link to Previous Posting

But his gifts that year included a good laptop bag, and also a keyboard. What I found peculiar about Dad, was that it had seemed very important to him, to find a keyboard in Germany which emulated the standard 105-key, US keyboard layout. Evidently he had been away from Canada and the USA for so long, that he could not remember what the US keyboard layout was. And so specifically for me, he had purchased a new K.B., which had the U.K. layout. This is entirely logical, because of the geographic proximity Germany has to Great Britain.

But Dad seemed struck so sad, when he learned that the K.B. he had bought for me wasn’t really a US-layout board. I tried to explain to him, that a Linux computer can easily be switched from one keyboard layout to another, and that the only challenge we faced, was to identify which layout this keyboard had. Because, we had actually failed to find this out, for which reason I did not make immediate use of it.

And, we did not have the time to solve the puzzle either, because we had his laptop to set up, as well as numerous other things to do in Germany, while my Father was still alive.

But, Not knowing what the keyboard layout is, can do far more damage, than simply having a layout from a nearby country. But Dad felt it was the other way around.

The computer I name ‘Pheonix’ possessed a Hewlett-Packard keyboard which had always served me well. But now the time came to retire that old K.B., which was my occasion this evening to switch in the one which my Late Father had given to me in 2010.

This K.B. is of the brand-name “Cherry”, and just by Googling that, I found out that Cherry was a later generation, high-quality keyboard brand. I tend to appreciate keyboards that have good tactile properties, and high-quality switches. Even though Cherries are not genuine “Clickety Keyboards”, they come close. I expect that this one will last me a long time. It’s quite robust.



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The Drop-Sensors on my Neato XV Vacuuming Robot

I initially had the false impression, that this vacuuming robot, a “Neato XV Signature”, only had three ways to sense its surroundings: The laser which turns in its turret, the pressure-bar in the front with its two switches, and the magnetic sensors in its front corners.

Neato XV _1

But as it happens, this robot also has two optical “drop-sensors” in front, which statically look straight down at the ground.

I think the main purpose of these drop-sensors, is just to allow it to travel in a straight line. With a robot traveling over real terrain, a simple command to its left and right wheels to turn with the same amount of power, is not sufficient. This robot uses the feedback of its front drop-sensors, to measure the speed of the floor passing underneath.

I was watching it today, as it was having problems for the first time to travel in a straight line. And when I intervened, its display told me to “Please Clean My Left Drop-Sensor.”

These sensors can get dusty easily, and need to be wiped from time to time. And the plastic in front of its base-station also needs to be wiped free of dust, so that the robot can find its base-station again when ‘returning home’.

I now think that some of the malfunctions other people have reported, may in fact have been due to some of these panels not having been cleaned.

Also, it was my initial expectation that this robot stored the location of the base-station, when leaving the closest room, to clean farther reaches of its assigned area. In reality, when returning to the base station, this robot needs to find it again each time. Behind the panel of the base-station, there must be some sort of infrared corner-cubes, which glitter especially brightly in response to the laser, for it to recognize. Well it can happen that we have other objects hanging at the right or wrong distance above the ground, such as a set of curtains, which look unremarkable to the naked eye, but which also glitter to the vision of the infrared laser. And this can result in the robot making a mistaken attempt, to try docking in a corner of the correct room, but in a place where the base-station is not. And so such sources of glitter must also be removed from the room of the base-station.



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