Ferrero Rocher Trees & Computational Geometry

This little hazelnut tree is growing in a farm in Northern Italy.

hazelnut

When mature, it will produce lots of these

choc

But meantime it needs lots of tender loving care.

The care will be provided by a robot tractor driving carefully between the rows of trees, as seen from space

space

and converted to a mathematical guide

path

To ensure no tree is neglected because it grows in an awkward corner requires solving a notoriously challenging problem, the convex decomposition of a concave polygon, in computational geometry.

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Talking to People and Robots

In these days of COVID19 and AI, when face to face communication is avoided and Alexa lurks in the corner of every room, people are beginning to sound like robots and robots sound ever more like humans.  Still, sometimes a translator is needed.

Over the years I have developed many applications that “talk” to devices attached to  a Windows desktop computer.  The devices range from half a dozen different sensors on a racing sailboat to an infra-red spectrometer the size of a pinhead. For a list, see.

Such applications have two essential tasks, talking to the human user and talking to the device.  Neither the human nor the device are very patient – they expect an instant response no matter what else is going on.   So the application must be split into two separate threads of computation, one looking after the user and one looking after the device.  The trick is synchronizing the two threads so that whatever is said by the user is translated and sent to the device, while anything communicated from the device is displayed to the user, without descending into confusion and chaos.

Developing multithreaded applications is a challenge.  Ideally, the application developer should be able to concentrate on the translation tasks, employing a well tested library to keep track of the different threads and their inter-dependencies.  The application code should run in exactly one thread, and the communications library should create and run the required threads so that the robots do not block communications with the user, or vice versa.

This week I added a class called com to the windex framework which does just this for robots that are connected to a serial port ( USB, COM, RS232, etc ).  If this sounds like it might be useful, check it out

 

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Bin Packing

Capture

For many years I have maintained open source code to optimize the arrangement of small items in larger bins in two and three dimensions.

My interest in this problem has been maintained by requests from several clients to provide front and back ends that adapt the bin packing engine for their particular needs.

  • Cutting panels from plywood sheets with minimum waste.  2D problem. Client in the Philippines .
  • Packing ECCO shoe boxes into cartons to minimize shipping costs.  3D problem. Client in the USA.
  • Packing Canon camera boxes into cartons to minimize shipping costs. 3D problem.  Client in Italy.
  • Cutting panels from plywood sheets with minimum waste. 2D problem. Client in India.

The Indian client was kind enough to share test results comparing my results with those from a commercially available system ( Cut Rite ).  The test involved 32 unique packing problems requiring in total  926 panels to be cut from 124 sheets. On 26 of the 32 packs the results were identical, requiring the same number of sheets to cut the panels. For 4 packs the Cut Rite arrangement needed fewer sheets, and for 2 my packing engine gave a better result.

As always with optimization problems, my focus is on providing answers that are good enough in an extremely short time.  The Cut Rite bin packer required several seconds to generate a solution, my engine delivered in 300 milliseconds or about 10 times faster.

Bin Packing Engine code.

 

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A little intelligence, artificially.

KMeans is a windows console application to find clusters in data with any number of columns ( attributes ) using the KMeans algorithm ( https://en.wikipedia.org/wiki/K-means_clustering )

Usage: KMeans <data dimension> <data file path> <number of clusters>

The iris data set ( http://archive.ics.uci.edu/ml/datasets/Iris ) has 4 attributes

1. sepal length in cm 
2. sepal width in cm 
3. petal length in cm 
4. petal width in cm

The application outputs

KMeans.exe 4 ..\data\bezdekIris.data 3

Total distance 103.982
Total distance 97.249
Total distance 97.2046

Cluster 0 means 5.006 3.428 1.462 0.246
mins: 4.3, 2.3, 1, 0.1,
maxs: 5.8, 4.4, 1.9, 0.6,
sds: 0.348947, 0.375255, 0.171919, 0.104326,

Cluster 1 means 5.90161 2.74839 4.39355 1.43387
mins: 4.9, 2, 3, 1,
maxs: 7, 3.4, 5.1, 2.4,
sds: 0.462633, 0.293885, 0.504774, 0.295091,

Cluster 2 means 6.85 3.07368 5.74211 2.07105
mins: 6.1, 2.5, 4.9, 1.4,
maxs: 7.9, 3.8, 6.9, 2.5,
sds: 0.48761, 0.28625, 0.482118, 0.276165,

I have used this code to locate servers among clients to minimize the total distance between clients and their nearest server, when there was too many clients to calculate the absolute optimal locations directly.

The open source code for this can be seen at https://github.com/JamesBremner/KMeans

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Talking to satellites

Starting work on SpaceCom  to enable error free communication between satellites and the ground using the  NASA TC SPACE DATA LINK PROTOCOL CCSDS 232.1-B-2

SpaceDataLink

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New Mexico Senate Webcaster

Every session of the New Mexico state senate since 2009 has been webcast using a computer application designed and coded by SpeakerToRobots.

The chair recognizes one of the senators. When the senator begins to speak, one of three cameras has already swung into position and is webcasting the perfect image. The application stores over 50 preset positions for each camera, automatically selecting and moving the cameras into position whenever the speaker changes, using the VISCA protocol over RS232.

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SWEEPEM

In the 1980s this Canso flying boat was photographed over the Gatineau Hills searching for ore deposits using a new electromagnetic system called SWEEPEM.  Built in the 1940s to hunt submarines under the North Atlantic, the aircraft’s ability to flow low, slow and long was ideal for detecting metallic ores buried deep underground.  I developed the signal processing and real time control software for SWEEPEM and operated the system aboard the Canso for the calibration flights.  In this article written for Survey Magazine and published in 1985 I described the work.

sweepem_article

 

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PELEX-MAX

A showcase for some recent work on real time signal processing

http://pinmed.net/wireless_mri-compatible_12-lead_ecg_pressure_oximetry/

There are five applications comprising the heart of the software in this system:

  1.  Mixer which does the signal processing
  2.  GUI which helps the user to edit the 100 plus configuration parameters
  3.  PDG which produces the pretty graphs seen in the showcase video
  4.  WV ( waveform visualizer ) which enables user to monitor and “teach” the Mixer how to identify cardiac signals.
  5.  Unit Tester

Added together these have 40,000 lines of pure code, excluding comments and white space.

 

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Nana

Nana is a cross-platform library for GUI programming in modern C++ style.

v1.5.5 was released this week and includes a small contribution from me that allows application code to set the default width of text entry fields.

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Hour of Code

Two little kids with big grins came to fetch me.  Roy and Kasha looked as delighted as I felt to be rescued from the grey busyness going on among the grey adults in the school admin office.

Up the stairs and along the corridors lined with lockers, just like the ones seen in tv shows, the classroom held two dozen more kids grouped in threes and fours.  Their postures were terrible.  It was not just that they slouched.  Their arms and lags stuck out at odd angles like rose bushes that needed pruning, many heads were resting on desktops just as if they had marched for a week to get here and faces were sheltered behind a hand or shoulder as if they were so many shy Victorian maidens. It was all a bit of a shock for someone who was last in school in rural Scotland where we sat in ordered ranks, backs straight and facing forward.

So, anyway, I launched into my introduction. When I am working on Computer Science I call myself ‘Speaker To Robots’.  I write code that lets people control their robots.  Robots speak one language and people understand a completely different language, so they need me to help out.  Let me tell you about a few of the robots I have spoken to …

Glancing around the untidy heaps of limbs that were my audience, I was caught by a bright flash of white from every pair of eyes.  I realized that they were all paying close attention. Suddenly I was enjoying myself.

I finished up. Time for you to talk to some robots yourself.  These are the characters that move around and interact in the world of Minecraft.  The world is not real, it is a simulation, but the robots that populate the world are real robots – they work in the same way as real-life robots and you can talk to them, control them, in just the same way

They plunged in without hesitation.  They zoomed.   The room filled with a happy hubbub. These kids knew what they were doing, they were focused on getting it done, and with a speed that astonished me the puzzles were ticked off.  I wandered around looking for someone who was stuck, but really I only needed to offer praise.

The best thing was the energy and application.  The kids were busy trying this and that.  No-one was hung up on what I have seen so many adult novice programmers hung up on: looking for the problem.  Instead of sitting, waiting for inspiration to strike, they were busy.

It was a short hour and when the bell rang they all rushed off for lunch.

Hour of Code

 

 

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