【正文】 電能。 直流電機(jī)工作原理： 直流電機(jī)里邊固定有環(huán)狀永磁體，電流通過(guò)轉(zhuǎn)子上的線圈產(chǎn)生安培力，當(dāng)轉(zhuǎn)子上的線圈與磁場(chǎng)平行時(shí)，再繼續(xù)轉(zhuǎn)受到的磁 場(chǎng)方向?qū)⒏淖儯虼舜藭r(shí)轉(zhuǎn)子末端的電刷跟轉(zhuǎn)換片交替接觸，從而線圈上的電流方向也改變，產(chǎn)生的洛倫茲力方向不變，所以電機(jī)能保持一個(gè)方向轉(zhuǎn)動(dòng)。要使電機(jī)運(yùn)轉(zhuǎn)，必須導(dǎo)通對(duì)角線上的一對(duì)三極管。按圖中電流箭頭所示，該流向的電流將驅(qū)動(dòng)電機(jī)順時(shí)針轉(zhuǎn)動(dòng)。 北京化工大學(xué)北方學(xué)院畢業(yè)設(shè)計(jì)（論文） 22 圖 H 橋驅(qū)動(dòng)電機(jī)逆時(shí)針轉(zhuǎn)動(dòng) 使能控制和方向邏輯 驅(qū)動(dòng)電機(jī)時(shí)，保證 H橋上兩個(gè)同側(cè)的三極管不會(huì)同時(shí)導(dǎo)通非常重要。 圖 所示就是基于這種考慮的改進(jìn)電路，它在基本 H橋電路的基礎(chǔ)上增加了 4個(gè)與門和 2 個(gè)非門。） 北京化工大學(xué)北方學(xué)院畢業(yè)設(shè)計(jì)（論文） 23 圖 具有使能控制和方向邏輯的 H 橋電路 采用以上方法，電機(jī)的運(yùn)轉(zhuǎn)就只需要用三個(gè)信號(hào)控制：兩個(gè)方向信號(hào)和一個(gè)使能信號(hào)。根據(jù)設(shè)計(jì)的要求，和前面描述的控制系統(tǒng)硬件設(shè)計(jì)的具體情況，單片機(jī)控制系統(tǒng)軟件程序流程圖如圖 所示： 圖 程序流程圖 北京化工大學(xué)北方學(xué)院畢業(yè)設(shè)計(jì)（論文） 26 第 節(jié) 程序 設(shè)計(jì) C 語(yǔ)言是一種計(jì)算機(jī)程序設(shè)計(jì)語(yǔ)言。 所以本次設(shè)計(jì)采用 C語(yǔ)言編程 。被激活后的 DHT11 進(jìn)入接收內(nèi)存訪問(wèn)命令狀態(tài)，內(nèi)存訪問(wèn)命令完成溫濕度轉(zhuǎn)換、讀取等工作（ 單總線在 ROM命令發(fā)送之前存儲(chǔ)命令和 控制命令不起作用）。被激活后的 DHT11 進(jìn)入接收內(nèi)存訪問(wèn)命令狀態(tài)，內(nèi)存訪問(wèn)命令完成溫度轉(zhuǎn)換、讀取等工作（單總線在 ROM 命令發(fā)送之前存儲(chǔ)命令和控制命令不起作用）。當(dāng)傳動(dòng)桿碰到位置開關(guān) J3 時(shí)。 RP3 電位器代表光敏傳感器 (光敏電阻 )， RP2 用于調(diào)節(jié)光敏電阻的靈敏度，當(dāng)陽(yáng)光充足時(shí)，光敏電阻阻值下降．使運(yùn)放 U3 輸出低電平，經(jīng)過(guò) C4 和 R12 的微分電路，再通過(guò) U4(555 集成電路 )單穩(wěn)觸發(fā)電路，輸出高電平，定時(shí)時(shí)間 T=，其中 RP4 用于調(diào)節(jié)定時(shí)時(shí)問(wèn)， J6 為行程開關(guān) (常閉觸點(diǎn) )，用于控制衣架伸出的幅度， U4 輸出高電平使 V2飽和導(dǎo)通。 J5為手動(dòng)控制開關(guān)，用于人工控制晾衣動(dòng)作。仿真器自帶 64K 程序存儲(chǔ)器和64K硬件斷點(diǎn)存儲(chǔ)器等很多強(qiáng)大功能。 北京化工大學(xué)北方學(xué)院畢業(yè)設(shè)計(jì)（論文） 32 結(jié) 論 本設(shè)計(jì)采用 AT89S52 作為主控芯片，設(shè)計(jì)了一種智能的溫濕度自動(dòng)晾衣桿 。北京化工大學(xué)北方學(xué)院畢業(yè)設(shè)計(jì)（論文） 33 參考文獻(xiàn) [1] 盧艷軍主編 .單片機(jī)基本原理及應(yīng)用系統(tǒng) [M].北京：機(jī)械工業(yè)出版社 ,2020. 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[16] Atmel AVR Microcontroller with 16K Bytes InSystem Programmable Flash Atmega16L data Corporation,2020. [17] Spasov,Peter. Microcontroller technology[M].Prentice Hall， 2020. [18]Katsuhiko Ogata. Modern Control Engineering[M].New York： Electronics industry, 2020. [19] Lang, Walter. Reflexions on the future of microsystems[J].Sensors and Actuators, A, Physical, 1999. [20] Amato a revolution,in miniature[J]. Science,1998. 北京化工大學(xué)北方學(xué)院畢業(yè)設(shè)計(jì)（論文） 34 致 謝 歷時(shí)半載，從論文選題到搜集資料，從開題報(bào)告、寫初稿到反復(fù)修改，期間經(jīng)歷了喜悅、 聒噪、痛苦和彷徨，在寫作論文的過(guò)程中心情是如此復(fù)雜。 卜 老師淵博的專業(yè)知識(shí)，嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度，精益求精的工作作風(fēng)，誨人不倦的高尚師德，嚴(yán)以律己、寬以待人的崇高風(fēng)范，樸實(shí)無(wú)華、平易近人的人格魅力對(duì)我影響深遠(yuǎn)。在整個(gè)的論文寫作中，各位老師、同學(xué)和朋友積極的幫助我查資料和提供有利于論文寫作的建議和意見(jiàn)，在他們的幫助下，論文得以不斷的完善，最終幫助我完整的寫完了整個(gè)論文。 exactly how early it would be difficult to say, but in the course of centuries it was greatly added to and modified. It contains about 200 chapters, but no plete papyrus has been found. The chapters are quite independent of one another, and were probably all posed at different times. The main subject is the beatification of the dead, who were supposed to recite the chapters in order that they might gain power and enjoy the privileges of the new life. The work abounds in magical references. The whole trend of the Book of the Dead is thaumaturgic, as its purpose is to guard the dead against the dangers they have to face in reaching the other world. As in most mythologies, the dead Egyptian had to encounter malignant spirits and was threatened by many dangers before reaching his haven of rest. He also had to undergo judgment by Osiris, and to justify himself before being permitted to enter the realms of bliss. This he imagined he could in great part acplish by the recitation of various magical formula and spells, which would ward off the evil influences opposed to him. To this end every important Egyptian of means had buried with him a papyrus of the Book of the Dead, containing at least all the chapters necessary for encountering the formidable adversaries at the gates of Amenti, the Egyptian Hades. These chapters would assist him in making replies during his ceremony of justification. First among these spells were the words of power. The Egyptians believed that to discover the secret name of a god was to gain plete ascendancy over him. Sympathetic magic was in vogue in Egyptian burial practice, which explains the presence, in tombs of people of means, of paintings of tables laden with food and drink, with inscriptions attached conveying the idea of boundless liberality. Inscriptions like the following are extremely mon— To the ka [essential double or soul] of soandso, 5,000 loaves of bread, 500 geese, and 5,000 jugs of beer. Those dedications cost the generous donors little, as they merely had the objects named painted upon the wall of the tomb, imagining that their ka or astral counterpart would be eatable and drinkable by the deceased. This of course is merely an extension of the Neolithic conception that articles buried with a man had their astral counterparts and would be of use to him in another world. Pictorial representation played a considerable part in the magical ritual of the Book of the Dead. One of the pleasures of the dead was to sail over Heaven in the boat of Ra, and to secure this for the deceased one must paint certain pictures and mutter over them words of power. Regarding this belief, E. A. Wallis Budge states in his book Egyptian Magic (1889): On a piece of clean papyrus a boat is to be drawn with ink made of green abut mixed with anti water, and in it are to be figures of Isis, Thoth, Shu, and Khepera, and the deceased。 but Ra was supposed to travel in one boat (called Atet) until noon, and another (called Sektet) until sunset, and provision had to be made for the deceased in both boats. How was this to be done? On one side of the picture of the boat a figure of the morning boat of Ra was to be drawn, and on the other a figure of the afternoon b