{"id":101,"date":"2017-11-20T12:22:15","date_gmt":"2017-11-20T11:22:15","guid":{"rendered":"http:\/\/em-company.fr\/blog\/?p=101"},"modified":"2017-11-29T17:10:04","modified_gmt":"2017-11-29T16:10:04","slug":"sensor-fusion-controller-fuzzy-logic","status":"publish","type":"post","link":"https:\/\/www.em-company.fr\/blog\/index.php\/2017\/11\/20\/sensor-fusion-controller-fuzzy-logic\/","title":{"rendered":"Sensor Fusion controller using a Fuzzy Logic approach (intro)"},"content":{"rendered":"

The recent rise of MEMS and Microsensors have posed a new and interesting problem to designers. Before MEMS, you barely had one temperature sensor, maybe one pressure sensor in your system. Then you would put some code around … Et Voila ! your device was capable of measuring Temperature and Pressure.<\/p>\n

Now with the advent of MEMS, nothing prevents you to have a lot of sensors, of different types, at different positions in your system. The issue has become “How do I combine all these together to produce something useful” ?\u00a0 This what Sensor Fusion is about.<\/p>\n

\"sensor
(Courtesy of STMicroelectronics.)<\/figcaption><\/figure>\n

Your smartphone has typically\u00a0 several temperatures sensors, several light sensors, several accelerometers. Modern accelerometers often implement smart functions like “Significant Motion detection”, “No Motion detection”, etc .. . This is even an OS requirement (see here<\/a>, for Android).<\/p>\n

My own definition:<\/strong> A Sensor Fusion Controller is a piece of Software and\/or Hardware that implements some smart algorithms out of a variety of inputs (the sensors), essentially to derive a richer information than the sum of all the inputs.<\/p><\/blockquote>\n

The following describes an implementation of an off-arm detection based on sensor fusion. The Wearable Device I was working on was an arm-worn type of device. Is it very important to understand, in those kind of devices, whether it is actually worn by the User, or simply left aside on a table or within a bag. All kind of Power Saving scenarios can then be implemented.<\/p>\n

So in this specific case, it looked simple ! Put a Proximity Sensor and you got it. Those components are available, one example here<\/a>.\u00a0 But he problem was that, the manufacturer wanted to shave off the 1 dollar of component ….\u00a0 so Software had to find a solution. Easy \ud83d\ude41<\/p>\n

Problem description<\/h5>\n

The basic question was:<\/p>\n

“Are we able to infer that the device is worn or not, based on all those sensors ?”.<\/p><\/blockquote>\n

And of course, the corollary design constraint:<\/p>\n

“We shall NOT infer it is worn when it is not …”.<\/p><\/blockquote>\n

We very rapidly agreed that, we’d better concentrate on a few “solid” cases, like: the device is laying on a table, facing up, since more that 5 minutes<\/em><\/strong>. For all the difficult cases (for example, Worn but not moving ),\u00a0<\/strong><\/em>we can just not do anything.<\/p>\n

In the next<\/a> articles, I will detail the rationale in using a Fuzzy Logic approach for solving this problem,\u00a0 the implementation of the whole thing … and some results \/ possible improvements.<\/p>\n

References<\/span><\/p>\n

    \n
  1. Original paper<\/a> from Pr. Lofti Zadeh, 1965<\/li>\n
  2. Introduction to Fuzzy Logic\u00a0, by\u00a0Franck Dernoncourt (MIT)<\/li>\n<\/ol>\n
    This article is a very modest tribute to the work of Pr. Zadeh who passed away last month. R.I.P.<\/em><\/div>\n","protected":false},"excerpt":{"rendered":"

    The recent rise of MEMS and Microsensors have posed a new and interesting problem to designers. Before MEMS, you barely had one temperature sensor, maybe one pressure sensor in your system. Then you would put some code around … Et Voila ! your device was capable of measuring Temperature and Pressure.<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18,20],"tags":[42,41],"class_list":["post-101","post","type-post","status-publish","format-standard","hentry","category-architecture","category-embedded","tag-fuzzy-logic","tag-sensor-fusion"],"yoast_head":"\nSensor Fusion controller using a Fuzzy Logic approach (intro) - Embedded<\/title>\n<meta name=\"description\" content=\"Description of a fuzzy logic approach for implementing a sensor fusion controller. 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