{"id":63786,"date":"2022-04-16T07:50:22","date_gmt":"2022-04-16T12:50:22","guid":{"rendered":"https:\/\/www.bjultrasonic.com\/measuring-distance-with-sound-waves\/"},"modified":"2025-01-27T06:14:47","modified_gmt":"2025-01-27T11:14:47","slug":"measuring-distance-with-sound-waves","status":"publish","type":"post","link":"https:\/\/www.bjultrasonic.com\/cs\/measuring-distance-with-sound-waves\/","title":{"rendered":"M\u011b\u0159en\u00ed vzd\u00e1lenost\u00ed pomoc\u00ed zvukov\u00fdch vln: Princip a aplikace"},"content":{"rendered":"<p>M\u011b\u0159en\u00ed vzd\u00e1lenosti pomoc\u00ed zvukov\u00fdch vln je fascinuj\u00edc\u00ed oblast fyziky s \u0161irok\u00fdm spektrem aplikac\u00ed, od jednoduch\u00fdch m\u011b\u0159en\u00ed vzd\u00e1lenosti a\u017e po sofistikovan\u00e9 syst\u00e9my pro autonomn\u00ed navigaci. Z\u00e1kladem t\u00e9to metody je m\u011b\u0159en\u00ed \u010dasu, kter\u00fd zvukov\u00e1 vlna pot\u0159ebuje k uraz\u011bn\u00ed cesty k objektu a zp\u011bt.  Rychlost \u0161\u00ed\u0159en\u00ed zvuku je zn\u00e1ma a z\u00e1vis\u00ed na prost\u0159ed\u00ed (nap\u0159. vzduchu, vod\u011b, pevn\u00fdch l\u00e1tk\u00e1ch), tak\u017ee po zm\u011b\u0159en\u00ed \u010dasu m\u016f\u017eeme snadno spo\u010d\u00edtat vzd\u00e1lenost.<\/p>\n<h3>Princip m\u011b\u0159en\u00ed<\/h3>\n<p>Z\u00e1kladn\u00ed princip spo\u010d\u00edv\u00e1 v vysl\u00e1n\u00ed zvukov\u00e9 vlny (impulsu) sm\u011brem k c\u00edlov\u00e9mu objektu.  Tento impuls se odraz\u00ed od objektu a vr\u00e1t\u00ed se k senzoru. \u010cas mezi vysl\u00e1n\u00edm a p\u0159ijet\u00edm impulsu se zm\u011b\u0159\u00ed a n\u00e1sledn\u011b se vypo\u010d\u00edt\u00e1 vzd\u00e1lenost pomoc\u00ed jednoduch\u00e9ho vzorce:  <code>vzd\u00e1lenost = (rychlost zvuku * \u010das) \/ 2<\/code>. D\u011bl\u011bn\u00ed dv\u011bma je nutn\u00e9, proto\u017ee zvuk uraz\u00ed cestu tam i zp\u011bt.  P\u0159esnost m\u011b\u0159en\u00ed siln\u011b z\u00e1vis\u00ed na p\u0159esnosti m\u011b\u0159en\u00ed \u010dasu a na znalosti rychlosti zvuku v dan\u00e9m prost\u0159ed\u00ed.  Vliv m\u00e1 i okoln\u00ed \u0161um a odrazy od jin\u00fdch objekt\u016f.<\/p>\n<h3>Typy zvukov\u00fdch vln<\/h3>\n<p>Pro m\u011b\u0159en\u00ed vzd\u00e1lenosti se pou\u017e\u00edvaj\u00ed r\u016fzn\u00e9 typy zvukov\u00fdch vln, v z\u00e1vislosti na po\u017eadovan\u00e9 p\u0159esnosti a dosahu.  N\u00edzk\u00e9 frekvence maj\u00ed v\u011bt\u0161\u00ed dosah, ale ni\u017e\u0161\u00ed p\u0159esnost, zat\u00edmco vysok\u00e9 frekvence (ultrazvuk) umo\u017e\u0148uj\u00ed p\u0159esn\u011bj\u0161\u00ed m\u011b\u0159en\u00ed, ale s krat\u0161\u00edm dosahem.  Ultrazvukov\u00e9 senzory se hojn\u011b pou\u017e\u00edvaj\u00ed v r\u016fzn\u00fdch aplikac\u00edch, nap\u0159\u00edklad v automobilov\u00e9m pr\u016fmyslu pro parkovac\u00ed senzory, v robotice pro navigaci a v pr\u016fmyslu pro automatizovan\u00e9 \u0159\u00edzen\u00ed.  V n\u011bkter\u00fdch p\u0159\u00edpadech, zejm\u00e9na p\u0159i m\u011b\u0159en\u00ed v\u011bt\u0161\u00edch vzd\u00e1lenost\u00ed, se pou\u017e\u00edvaj\u00ed i zvukov\u00e9 vlny v ni\u017e\u0161\u00edch frekven\u010dn\u00edch p\u00e1smech.<\/p>\n<h3>Vliv prost\u0159ed\u00ed na m\u011b\u0159en\u00ed<\/h3>\n<p>Rychlost zvuku se m\u011bn\u00ed v z\u00e1vislosti na teplot\u011b, tlaku a vlhkosti vzduchu.  Pro p\u0159esn\u00e9 m\u011b\u0159en\u00ed je proto nutn\u00e9 kompenzovat tyto vlivy.  Voda a pevn\u00e9 materi\u00e1ly maj\u00ed obecn\u011b vy\u0161\u0161\u00ed rychlost zvuku ne\u017e vzduch, co\u017e je t\u0159eba zohlednit p\u0159i m\u011b\u0159en\u00ed vzd\u00e1lenosti v t\u011bchto prost\u0159ed\u00edch.  N\u00e1sleduj\u00edc\u00ed tabulka ukazuje p\u0159ibli\u017en\u00e9 rychlosti zvuku v r\u016fzn\u00fdch materi\u00e1lech p\u0159i standardn\u00edch podm\u00ednk\u00e1ch:<\/p>\n<table class=\"table table-striped table-bordered\">\n<thead>\n<tr>\n<th>Materi\u00e1l<\/th>\n<th>Rychlost zvuku (m\/s)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Vzduch (20\u00b0C)<\/td>\n<td>343<\/td>\n<\/tr>\n<tr>\n<td>Voda (20\u00b0C)<\/td>\n<td>1481<\/td>\n<\/tr>\n<tr>\n<td>Ocel<\/td>\n<td>5960<\/td>\n<\/tr>\n<tr>\n<td>Aluminium<\/td>\n<td>6420<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>Aplikace m\u011b\u0159en\u00ed vzd\u00e1lenosti pomoc\u00ed zvukov\u00fdch vln<\/h3>\n<p>M\u011b\u0159en\u00ed vzd\u00e1lenosti pomoc\u00ed zvukov\u00fdch vln m\u00e1 \u0161irok\u00e9 uplatn\u011bn\u00ed v mnoha oblastech.  Parkovac\u00ed senzory v autech jsou jedn\u00edm z nejzn\u00e1m\u011bj\u0161\u00edch p\u0159\u00edklad\u016f.  V pr\u016fmyslu se ultrazvukov\u00e9 senzory pou\u017e\u00edvaj\u00ed pro m\u011b\u0159en\u00ed hladiny kapalin v n\u00e1dr\u017e\u00edch, detekci objekt\u016f na v\u00fdrobn\u00edch link\u00e1ch a pro automatick\u00e9 \u0159\u00edzen\u00ed robot\u016f.  V medic\u00edn\u011b se ultrazvuk pou\u017e\u00edv\u00e1 pro diagnostick\u00e9 zobrazov\u00e1n\u00ed.  V oce\u00e1nografii se pou\u017e\u00edvaj\u00ed sonarov\u00e9 syst\u00e9my k mapov\u00e1n\u00ed mo\u0159sk\u00e9ho dna a k detekci podmo\u0159sk\u00fdch objekt\u016f.  I v geofyzice nach\u00e1z\u00ed tato metoda uplatn\u011bn\u00ed, nap\u0159\u00edklad p\u0159i pr\u016fzkumu ropn\u00fdch a plynov\u00fdch lo\u017eisek.<\/p>\n<h3>Omezen\u00ed metody<\/h3>\n<p>P\u0159esnost m\u011b\u0159en\u00ed je ovlivn\u011bna mnoha faktory, v\u010detn\u011b okoln\u00edho \u0161umu, odraz\u016f od jin\u00fdch objekt\u016f a nep\u0159esnost\u00ed v m\u011b\u0159en\u00ed \u010dasu.  V prost\u0159ed\u00ed s vysok\u00fdm \u0161umem m\u016f\u017ee b\u00fdt obt\u00ed\u017en\u00e9 spolehliv\u011b detekovat odra\u017een\u00fd sign\u00e1l.  M\u011b\u0159en\u00ed v prost\u0159ed\u00ed s mnoha p\u0159ek\u00e1\u017ekami m\u016f\u017ee v\u00e9st k chyb\u00e1m, proto\u017ee odrazy od t\u011bchto p\u0159ek\u00e1\u017eek mohou ru\u0161it m\u011b\u0159en\u00ed.  D\u00e1le je t\u0159eba br\u00e1t v \u00favahu, \u017ee metoda je vhodn\u00e1 pro m\u011b\u0159en\u00ed vzd\u00e1lenost\u00ed od relativn\u011b bl\u00edzk\u00e9ho objektu.  U vzd\u00e1len\u011bj\u0161\u00edch objekt\u016f se sign\u00e1l zeslabuje a jeho detekce se st\u00e1v\u00e1 obt\u00ed\u017en\u011bj\u0161\u00ed.<\/p>\n<p>M\u011b\u0159en\u00ed vzd\u00e1lenosti pomoc\u00ed zvukov\u00fdch vln je robustn\u00ed a relativn\u011b levn\u00e1 metoda s \u0161irok\u00fdm spektrem aplikac\u00ed.  A\u010dkoliv existuj\u00ed omezen\u00ed, jej\u00ed v\u00fdznam v mnoha oblastech z\u016fst\u00e1v\u00e1 nezpochybniteln\u00fd a neust\u00e1le se vyv\u00edj\u00ed a zdokonaluje.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>M\u011b\u0159en\u00ed vzd\u00e1lenosti pomoc\u00ed zvukov\u00fdch vln je fascinuj\u00edc\u00ed oblast fyziky s \u0161irok\u00fdm spektrem aplikac\u00ed, od jednoduch\u00fdch m\u011b\u0159en\u00ed vzd\u00e1lenosti a\u017e po sofistikovan\u00e9 syst\u00e9my pro autonomn\u00ed navigaci. Z\u00e1kladem t\u00e9to metody je m\u011b\u0159en\u00ed \u010dasu, kter\u00fd zvukov\u00e1 vlna pot\u0159ebuje k uraz\u011bn\u00ed cesty k objektu a zp\u011bt. Rychlost \u0161\u00ed\u0159en\u00ed zvuku je zn\u00e1ma a z\u00e1vis\u00ed na prost\u0159ed\u00ed (nap\u0159. vzduchu, vod\u011b, pevn\u00fdch l\u00e1tk\u00e1ch),<\/p>\n","protected":false},"author":1,"featured_media":5770,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6415],"tags":[],"class_list":["post-63786","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","prodpage-classic"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/posts\/63786","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/comments?post=63786"}],"version-history":[{"count":0,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/posts\/63786\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/media\/5770"}],"wp:attachment":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/media?parent=63786"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/categories?post=63786"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/tags?post=63786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}