外文資料翻譯

1、 南 京 理 工 大 學(xué) 紫 金 學(xué) 院畢業(yè)設(shè)計(jì)(論文)外文資料翻譯系： 機(jī)械工程系 專 業(yè)： 機(jī)械工程及自動(dòng)化 姓 名： 周小峰 學(xué) 號(hào)： 100104259 外文出處： Proceedings of International Symposium 附 件： 1.外文資料翻譯譯文；2.外文原文。 指導(dǎo)教師評(píng)語(yǔ)： 該生翻譯了一篇有關(guān)重載伺服電機(jī)設(shè)計(jì)在機(jī)器人中的應(yīng)用的論文，論文內(nèi)容主要涉及重載伺服電機(jī)在機(jī)器人領(lǐng)域的應(yīng)用，在將來(lái)的課題“蜘蛛機(jī)器人兒童玩具設(shè)計(jì)與仿真”中可以借鑒。譯文語(yǔ)句基本通順，專業(yè)術(shù)語(yǔ)基本正確。說(shuō)明該生具備一定的英語(yǔ)水平和翻譯能力。 簽名： 年 月 日附件1：外文資料翻譯譯文重載

2、伺服電機(jī)設(shè)計(jì)在機(jī)器人中的應(yīng)用本文介紹了一個(gè)為機(jī)器人應(yīng)用而設(shè)計(jì)的重型伺服電機(jī)系統(tǒng)。這個(gè)傳統(tǒng)的遙控（R / C）系統(tǒng)是一個(gè)精致的，可被遠(yuǎn)程的裝置。由于傳統(tǒng)控制的的R / C伺服電機(jī)是容易的，它的成本是比較便宜的，所以R/ C伺服系統(tǒng)應(yīng)用于廣泛的領(lǐng)域。然而，一個(gè)R/ C伺服電機(jī)在許多應(yīng)用方面，輸出扭矩是小于需求的。而機(jī)器人設(shè)計(jì)和遙控車或飛機(jī)需要較高扭矩。因此，具有較高扭矩的電機(jī)是易控制的，是有利的。在本文中，齒輪直流電機(jī)作為控制機(jī)和電位器安裝在輸出軸上的位置反饋傳感器。重型的R / C伺服電機(jī)利用一個(gè)單穩(wěn)多諧振蕩器，它產(chǎn)生0.5到2.5毫秒的脈沖寬度調(diào)制（PWM）信號(hào)來(lái)驅(qū)動(dòng)發(fā)動(dòng)。本研究結(jié)果證明一個(gè)重

3、型的R / C伺服電機(jī)在機(jī)器人應(yīng)用方面比商業(yè)的R / C伺服電機(jī)能提供更多的扭矩。 關(guān)鍵詞：遙控電機(jī)，脈沖寬度調(diào)制，重型，伺服發(fā)動(dòng)機(jī)。一 引言 在機(jī)器人控制中的應(yīng)用，設(shè)計(jì)人員通常選擇直流伺服電機(jī)或無(wú)刷伺服電機(jī)作為制動(dòng)器來(lái)驅(qū)動(dòng)各個(gè)關(guān)節(jié)。因?yàn)閺?fù)雜的驅(qū)動(dòng)系統(tǒng)，這兩種類型的伺服電機(jī)較為昂貴的。此外，還需要在機(jī)器人的多個(gè)環(huán)節(jié)設(shè)計(jì)多個(gè)伺服電機(jī)，這會(huì)使機(jī)器人的設(shè)計(jì)過(guò)于昂貴。實(shí)際的使用情況，R / C伺服是一個(gè)包含旋轉(zhuǎn)定位的裝配，最初設(shè)計(jì)來(lái)控制的R / C飛機(jī)或船。R / C伺服電機(jī)的PWM信號(hào)被控制在0.5到2.5毫秒，軸旋轉(zhuǎn)可以被控制在-90度到90度。機(jī)器人關(guān)節(jié)由這樣一個(gè)R / C驅(qū)動(dòng)伺服電機(jī)控制是容易

4、的。機(jī)器人控制系統(tǒng)可以通過(guò)發(fā)送適當(dāng)?shù)腜WM信號(hào)來(lái)控制這些電機(jī)。但是，市場(chǎng)上的R / C伺服電機(jī)大多數(shù)是高扭矩，不合格的。因?yàn)榭捎玫呐ぞ赝ǔ榈陀?千克厘米。此外，大多數(shù)的R / C伺服電機(jī)的齒輪箱是塑料齒輪，容易造成由于重載齒輪的損壞。因此，一種具有扭矩超過(guò)20千克厘米和金屬制成的齒輪箱重型的R / C伺服電機(jī)，在實(shí)際應(yīng)用中對(duì)機(jī)器人有吸引力。在本文中，我們提出了控制PWM信號(hào)，以便在不利的情況下使用高扭矩伺服電機(jī)能高負(fù)荷工作。 圖1：重型伺服電機(jī)系統(tǒng)的配置二 設(shè)計(jì)方案重型伺服馬達(dá)的系統(tǒng)配置示于圖1。碳刷直流減速電機(jī)作為控制電機(jī)，需要合適的減速比。馬達(dá)和齒輪箱被稱為電機(jī)組件，一個(gè)電位計(jì)被安裝在齒

5、輪箱作為輸出軸上位置反饋傳感器。如直流電動(dòng)機(jī)轉(zhuǎn)動(dòng)時(shí)，電位器為讓R/ C伺服電機(jī)與被控制的PWM信號(hào)兼容，在這個(gè)設(shè)計(jì)上，所提出的重型伺服電機(jī)的軸的位置也由PWM被控制。所述控制器是專用電用于產(chǎn)生一個(gè)適當(dāng)?shù)腜WM信號(hào)，用于控制伺服電機(jī)軸的位置。該系統(tǒng)更詳細(xì)的每個(gè)部分討論如下文：（A） 電機(jī)組件 直流碳刷電機(jī)是一種用24伏作為額定電壓和62g -cm額定扭矩的控制電機(jī)。該電機(jī)可以在約5000 rpm的速度在額定電壓下轉(zhuǎn)動(dòng);變速箱用的減速比為1/200，它導(dǎo)致附屬的輸出扭矩額定轉(zhuǎn)速分別6公斤-厘米和28轉(zhuǎn)。精密電位器是采納反饋位置的傳感器。因?yàn)檫@種特殊設(shè)計(jì)而得到的結(jié)果是：一個(gè)內(nèi)徑5毫米的電位，外徑為5

6、毫米變速箱軸。這是相同的電位內(nèi)徑，使電位器可以牢固地連接到直流電動(dòng)機(jī)組件，并且用作電動(dòng)機(jī)的位置反饋傳感器。電動(dòng)機(jī)外觀組件被示于圖2 ，在該齒輪的齒輪箱內(nèi)部是由金屬材料和潤(rùn)滑油，使得該組件可在重負(fù)荷應(yīng)用中使用。圖2碳刷式直流電機(jī)和變速箱總成。 圖2：碳刷式直流電機(jī)和齒輪箱組件（B） PWM模塊常規(guī)的R / C伺服電機(jī)由PWM信號(hào)控制。在本文中，我們還采用PWM信號(hào)作為重型伺服電動(dòng)機(jī)的位置指令，保持PWM指令和傳統(tǒng)的R / C伺服電機(jī)的相容性。該R / C伺服電動(dòng)機(jī)是由一個(gè)PWM信號(hào)在其所期望的位置控制的。R / C伺服電機(jī)的軸位置和相應(yīng)的所需的脈沖寬度被示于圖3 。 圖三：伺服電機(jī)軸的位置和所需

7、要的脈沖寬度用0.5毫秒到2.5毫秒的脈沖寬度時(shí)，R / C伺服電機(jī)可以從旋轉(zhuǎn) - 90度至+ 90度的順時(shí)針?lè)较颉 / C伺服系統(tǒng)是結(jié)合位置反饋與精確目標(biāo)位置的復(fù)雜的設(shè)備。在正常使用中，他們比較0.5-2.5毫秒，50Hz的輸入脈沖信號(hào)內(nèi)部線性脈沖發(fā)生器的反饋伺服位置電位器控制。所不同的在脈沖寬度，該誤差信號(hào)，然后用一個(gè)脈沖展寬器，它提供了伺服控制放大獲得。的脈沖展寬器輸出通過(guò)一個(gè)H橋電路驅(qū)動(dòng)伺服電機(jī)，關(guān)閉伺服環(huán)路，PWM模塊的結(jié)構(gòu)示于圖4。 圖4：PWM模塊的配置雖然這不是很難設(shè)計(jì)出一種基于PWM反饋控制系統(tǒng)，特殊用途設(shè)計(jì)的集成電路是更有利的，可避免使用較大的電路板。我們采用了最新的最新

8、的集成電路板三菱M51660L作為PWM控制器，用于重型伺服電動(dòng)機(jī)2。M51660L被用于檢測(cè)反饋電位計(jì)的電阻變化并由此產(chǎn)生一個(gè)脈沖寬度對(duì)應(yīng)于電動(dòng)機(jī)位置作為反饋信號(hào)。反饋信號(hào)進(jìn)行比較在位置控制系統(tǒng)的總結(jié)點(diǎn)的PWM位置指令。最后，誤差信號(hào)是來(lái)自求和點(diǎn)的輸出，以驅(qū)動(dòng)輸出級(jí)和電動(dòng)機(jī)被驅(qū)動(dòng)的方向上，以減少位置誤差。這種專用芯片還設(shè)有一個(gè)小型的輪廓，少分立元件，以及成本低。然而， M51660L提供電流小于100毫安，這遠(yuǎn)遠(yuǎn)低于一個(gè)規(guī)定重型伺服電機(jī)，該電機(jī)繞組的電流可能高達(dá)數(shù)安培。因此，一電流放大器是需要驅(qū)動(dòng)大電流的電機(jī)。一種電動(dòng)機(jī)，應(yīng)在順時(shí)針或逆時(shí)針的方向根據(jù)旋轉(zhuǎn)是否從位置指令和傳感器反饋中減去位置誤

9、差是正或負(fù)。一般情況下，H橋被采用為電流放大器，用于上述目的的一個(gè)輸出級(jí)。何時(shí)分立元件設(shè)計(jì)的電流放大器，至少四個(gè)功率晶體管和大量的使用電阻器是必需的，導(dǎo)致不僅許多電路板空間的需求，但也有幾個(gè)數(shù)的散熱片。從SGS湯姆遜雙極驅(qū)動(dòng)芯片L298是用來(lái)作為一種替代，以避免這些當(dāng)離散的組件用于缺陷，則沒(méi)有離散的組件是必需的，只有一小需要座位匯 3 。每個(gè)L298由兩個(gè)H橋，每個(gè)橋可以提供電流高達(dá)2安培。如果我們連接這兩個(gè)H橋的輸出端并聯(lián)，輸出電流會(huì)加倍。換句話說(shuō)，所設(shè)計(jì)的電流放大器可提供的電流高達(dá)4安培的重型伺服電機(jī)繞組。與M51660L除了L298 ，一個(gè)復(fù)雜的位置反饋控制系統(tǒng)簡(jiǎn)化，結(jié)果在一個(gè)緊湊的模塊

10、。三。結(jié)果用于測(cè)試的設(shè)計(jì)伺服電機(jī)，電源，以及一個(gè)PWM脈沖產(chǎn)生是必要的。由于碳電刷直流電動(dòng)機(jī)的額定電壓為24伏，電壓調(diào)節(jié)器是需要的調(diào)節(jié)在24V至5V邏輯電源，以便系統(tǒng)可以用一個(gè)電壓，而不是雙電壓操作供應(yīng)。此外，雖然適當(dāng)?shù)腜WM指令可以從一個(gè)微控制器，如產(chǎn)生AT89C2051從ATMEL 4中，使用定時(shí)器芯片LM555的一種更簡(jiǎn)單的電路可以提供一個(gè)可調(diào)節(jié)的脈沖持續(xù)時(shí)間從0.5毫秒到2.5毫秒，以測(cè)試該重型伺服電機(jī)。圖。圖5示出一個(gè)555計(jì)時(shí)器，用于產(chǎn)生PWM脈沖。該方程為555時(shí)是簡(jiǎn)單，易于使用。該等式（1）和（2）如下所示。大腿=0.693（R1 + R2）C TLOW=0.693R3C（2）

11、因?yàn)镽s是可變的，該時(shí)間信號(hào)為高時(shí)為0.52.5毫秒，定時(shí)值是足夠接近，只要有任何舵機(jī)工作為了驗(yàn)證定位控制能力，無(wú)論是傳統(tǒng)的R / C伺服和這個(gè)設(shè)計(jì)重型伺服與所提到的555定時(shí)器電路進(jìn)行測(cè)試。 圖5：555定時(shí)器產(chǎn)生的PWM信號(hào) 每個(gè)被測(cè)試電動(dòng)機(jī)的輸出軸是加上一個(gè)單獨(dú)的角指示器。如果兩個(gè)馬達(dá)的PWM指令輸入端子是一起連接到555的PWM命令輸出，兩個(gè)馬達(dá)將獲得相同的角度命令。一數(shù)字示波器是用來(lái)監(jiān)視在PWM指令的脈沖寬度。的可變電阻PWM發(fā)生器逐漸調(diào)節(jié)和脈沖寬度范圍從0.5到2.5毫秒，它可以是從示波器監(jiān)視，并且兩個(gè)馬達(dá)轉(zhuǎn)動(dòng)相應(yīng)的角度，根據(jù)該脈沖寬度PWM指令的。另一方面，適當(dāng)?shù)拿}沖寬度施加到測(cè)

12、試的響應(yīng)不同的角度，如極左，極右和中心的位置反饋位置。它需要的重型伺服約0.7秒，從最左邊旋轉(zhuǎn)到中心位置時(shí)，比常規(guī)的R / C伺服，也就是大約0.2的長(zhǎng)秒。四 討論在電機(jī)和齒輪箱組件，因?yàn)榭紤]并不是一種工業(yè)標(biāo)準(zhǔn)組件，輸出軸的近似直徑設(shè)計(jì)必須仔細(xì)根據(jù)內(nèi)徑的電位。在該實(shí)驗(yàn)中，通過(guò)修改獲得的與內(nèi)徑的電位電子可變電阻器并不是一件容易的工作。對(duì)于大規(guī)模生產(chǎn)，這種電位器必須可適應(yīng)市場(chǎng)或者必須專門(mén)設(shè)計(jì)的。雖然電路可以通過(guò)多種方式來(lái)實(shí)現(xiàn)，我們使用最少元件數(shù)的標(biāo)準(zhǔn)來(lái)設(shè)計(jì)這原型，結(jié)果是在短短的兩個(gè)組成部分， M51660L和L298中實(shí)現(xiàn)。這個(gè)原型需要兩個(gè)電壓， 24V的額定電壓和5V的邏輯電壓。為的簡(jiǎn)單電源，單

13、電源考慮。在大多數(shù)情況下，電機(jī)的額定電壓高于邏輯供應(yīng)，例如在這種情況下， 24伏。因此，用被嵌有電壓調(diào)節(jié)器的原型電機(jī)的額定電壓來(lái)調(diào)節(jié)邏輯電壓。該步驟的反應(yīng)，電動(dòng)機(jī)發(fā)出90度旋轉(zhuǎn)命令使其旋轉(zhuǎn)到所需的位置。在與其傳統(tǒng)的R / C伺服比較，在設(shè)計(jì)變速箱的還原率上高出0.7秒。但是，這個(gè)缺點(diǎn)可以在采用更快的響應(yīng)直流電動(dòng)機(jī)時(shí)，使用一個(gè)更復(fù)雜的控制算法，如比例和微分（PD） ，通過(guò)在伺服的設(shè)計(jì)控制環(huán)節(jié)。五 結(jié)束語(yǔ)在本文中，我們提出了一個(gè)重型伺服電機(jī)的機(jī)器人應(yīng)用。因?yàn)轳{駛輸出的H橋的容量高達(dá)4安培的工業(yè)直流電動(dòng)機(jī)具有更高的繞組電流以及更高的扭矩可以被納入此驅(qū)動(dòng)程序，并作為一個(gè)功能強(qiáng)大的驅(qū)動(dòng)裝置。此外，在使用

14、重加載情況時(shí)，自擬伺服電機(jī)配與耐磨齒輪比傳統(tǒng)的R / C伺服電機(jī)更具耐用性。在進(jìn)行精度定位的測(cè)試，伺服電機(jī)一旦接收到該P(yáng)WM定位命令時(shí)，可以旋轉(zhuǎn)至所需位置。結(jié)果在本研究中也證明一個(gè)重型的R / C伺服電機(jī)比商業(yè)的R / C伺服電機(jī)可以提供更多的扭矩在機(jī)器人應(yīng)用中。附件2：外文資料原文Proceedings of International Symposium on Automation and Mechatronics of Agricultural and BioproductionSystems, Vol. 2A Heavy Duty Servo Motor Design in Robot

15、 ApplicationsChi-Sheng Chen2, Ton-Tai Pan1, 2, Huihua Kenny Chiang1, Ping-Lin Fan2, Joe-Air Jiang3 1.Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan 2.Department of Electrical Engineering, Kuang-Wu Institute of Technology, Taipei, Taiwan 3.Department of Bio-industr

16、ial Mechatronics Engineering, National Taiwan University, Taipei, TaiwanAbstract This paper presents a design procedure of a heavy-duty servomotor for robot applications. The conventional remote control (R/C) servo is an ingenious device that allows remote, proportional actuation of mechanisms by th

17、e simple movement of a lever of a robot. Because of the control of a conventional R/C servomotor is easy and the cost of it is less expensive, the R/C servos are used in widespread areas. However, an R/C servomotor outputs less torque than required in many applications such as robots design and high

18、 torque requirement for remote control cars or planes. Thus, a motor with high torque which is easy to control, is favorable. In this paper, a DC gear motor is used as the controlled motor and a potentiometer was attached on the output shaft as a position feedback sensor. The proposed heavy duty R/C

19、 servomotor was tested with a mono-stable multi-vibrator, which generates 0.5 to 2.5 ms pulse width modulation (PWM) signals to drive the motor. Results of this study demonstrate that a heavy duty R/C servomotor can provide more torque in robot application than the commercial R/C servomotors.Keyword

20、s: Remote control motor, pulse width modulation, heavy duty, servomotor.I. Introduction In robot control applications, designers usually select either DC servomotor or brushless servomotor as the actuator to drive each joint. Both kinds of servomotors are expensive because the complexity of the driv

21、er system. Moreover, several servomotors are needed in a multi-joints robot design and will make the designed robot too expensive to practical usage. The R/C servo is a self-contained rotational positioning assembly originally designed to control an R/C aircraft or boat. The R/C servo is made up of

22、a DC motor,gear reduction, output shaft with position feedback, and a control personal computer board all built into a small rectangular enclosure. The R/C servomotor can be controlled with a PWM signal ranging from 0.5 to 2.5 ms to rotate the shaft from 90 degrees to 90 degrees. A robot joint drive

23、n by such an R/C servomotor is then easy to control. A robot control system can properly control these motors by sending appropriate PWM signals to each joint. However, most of the R/C servomotors on market are not qualified for high torque applications because the torque available is usually lower

24、than 5 kg-cm. Moreover, most of the gearboxes of the R/C servomotor are made of plastic gear, easily resulting in damage of the gears due to heavy load. Therefore, a heavy duty R/C servomotor, with a torque more than 20 kg-cm and a metal-made gearbox, is attractive to a robot designer for practical

25、usage.In this paper, we present a high torque servomotor controlled with a PWM signal so as to be used in a high load or an adverse circumstances. II. Design SchemeThe system configuration of the heavy-duty servomotor is illustrated in Fig.1. A carbon-brush DC gear motor is used as the controlled mo

26、tor. For the purpose of increasing motor torque, a gearbox with a suitable gear reduction ratio is needed. The motor and the gearbox are termed as motor assembly. On the other hand, a potentiometer was attached on output shaft of the gearbox as a position feedback sensor. As the DC motor rotates, th

27、e resistance of the potentiometer varies accordingly to a value corresponding to the shaft position of the motor assembly. For the compatibility with an R/C servo-motor that is controlled with PWM signal, the shaft position of the proposed heavy-duty servomotor is also controlled by a PWM signal in

28、this design. The controller is a dedicated circuit for generating a proper PWM signal when controlling the shaft position of the servomotor. Each part of the system is discussed in more details below.(A). Motor assembly A DC carbon-brush motor with a rated voltage of 24 volts and a rated torque of 6

29、2 g-cm is used as the controlled motor. This motor can rotate at a speed about 5000 rpm under the rated voltage; a gearbox with a reduction ratio 1/200 is attached from the output shaft of the DC motor, which resulting in an output torque and rated speed of 6 kg-cm and 28 rpm, respectively. A precis

30、ion potentiometer was adopted as a position sensor for feedback. However, the potentiometer is different from a general-purpose variable resistor; the original shaft attached to the wiper was removed. As a result of this special design, a potentiometer with an inner diameter of 5 mm is obtained. The

31、 outer diameter of the gearbox shaft is 5 mm, which is the same as the inner diameter of the potentiometer, so that the potentiometer can firmly attach to the DC motor assembly and serves as a position feedback sensor of the motor. The appearance of the motor assembly was shown in Fig. 2, in which g

32、ears inside the gearbox are made of metal materials and filled with lubricating oil so that this assembly can be used in heavy-duty applications. (B). PWM module The conventional R/C servomotors are controlled by a PWM signal. In this paper, we also adopt PWM signal as the position command for the h

33、eavy-duty servomotor, keeping the compatibility of the PWM command protocol for both conventional R/C servomotors and this designed servomotors. TheR/C servomotor is controlled by a PWM signal, which can direct the motor to a desired position according to the width of the pulse. The shaft positions

34、of the R/C servomotor and the corresponding required pulse widths are illustrated in Fig. 3. With a 0.5 ms to 2.5 ms pulse width, the R/C servomotor can rotate from 90 degrees to + 90 degrees clockwise 1. R/C servos are fairly sophisticated devices that incorporate position feedback with a goal to p

35、rovide precise position control. In normal usage, they compare the 0.5-2.5 ms, 50 Hz input pulse signal with an internal linear pulse generator controlled by the feedback servo position potentiometer. The difference in pulse width, the error signal, is then amplified with a pulse stretcher that prov

36、ides the servo control gain. The pulse stretcher output drives the servomotor through an H-bridge circuit to close the servo loop. The configuration of the PWM module is depicted in Fig. 4. Although it is not difficult to design a PWM based feedback control system, a special purpose designed IC is m

37、ore favorable that a large circuit board can be avoided. We adopted an up-to-date ntegrated circuit M51660L from Mitsubishi as the PWM controller for the heavy-duty servomotor 2. M51660L was used to detect the resistance variation of the feedback potentiometer and thus generate a pulse width corresp

38、onding to motor position as a feedback signal. A feedback signal was compared with PWM position command at the summing point of the position control system. Finally, an error signal was output from the summing point to drive the output stage and the motor was driven in a direction to reduce the posi

39、tion error. This dedicated chip also features a small outline, less discrete components as well as low cost. However, M51660L provides a current less than 100 mA, which is far below the requirement for a heavy-duty servomotor that the current of the motor windings may be up to several amperes. There

40、fore, a current amplifier is necessary to drive a high current motor. A motor should rotate in either clockwise or counterclockwise direction according to whether the position error subtracted from position command and sensor feedback is positive or negative. Generally, an H-bridge is adopted as an

41、output stage of the current amplifier for the above-mentioned purpose. When discrete components are used in designing the current amplifier, at least four power transistors and a lot of resistors are required, resulting in the needs of not only many circuit board space but also several counts of hea

42、t sink. A bipolar driving chip L298 from SGS Thomson is used as an alternative to avoid those drawbacks when discrete components are used, then no discrete components are required and only a small seat-sink is needed 3. Each L298 consists of two H-bridges and each bridge can provides a current up to

43、 2 amperes. If we connect the output terminals of these two H-bridges in parallel, the output current will be doubled. In other words, the designed current amplifier can provide a current up to 4 amperes for thewindings of heavy-duty servomotors. With M51660L in addition to L298, a complicated posit

44、ion feedback control system is simplified and results in a compact module.III. Results For testing the designed servomotor, a power supply as well as a PWM pulse generator is necessary. Since the rated voltage of the carbon-brush DC motor is 24 volts, a voltage regulator is needed to regulate the 24

45、V to a 5V logic supply so that the system can operate with a single voltage instead of dual voltage supply. Moreover, although a proper PWM command can be generated from a micro-controller, such as AT89C2051 from ATMEL 4, a more simple circuit using a timer chip LM555 can provide an adjustablepulse

46、duration ranging from 0.5 ms to 2.5 ms so as to test the heavy-duty servomotor. Fig. 5 depicts a 555 timer for generating PWM pulses. The equations for the 555 timer are simple and easy to use. The equations (1) and (2) are shown as follows.THIGH = 0.693 (R1 + R2) C (1)TLOW = 0.693 R3 C (2)Since Rs

47、is variable, the time the signal is high will vary from 0.5 to 2.5 ms, the timing values are close enough to work with just about any servos. To verify the positioning control ability, both the conventional R/C servo and this designed heavy-duty servo are tested with the mentioned 555 timer circuit.

48、 The output shaft of each tested motor is coupled with an individual angle indicator. If the PWM command input terminal of both motors areconnect together to a 555 PWM command output, both motors will receive the same angle command. A digital oscilloscope is used to monitor the pulse width of the PW

49、M command. The variable resistor of the PWM generator is adjusted gradually and the pulse width ranges from 0.5 to 2.5 ms, which can be monitored from the oscilloscope, and both motors rotate to the corresponding angle according to the pulse width of the PWM command. On the other hand, proper pulse

50、width was applied to test the response of the position feedback of different angles such as extreme left, extreme right and center position. It takes about 0.7 seconds for the heavy-duty servo to rotate from extreme left to centered position, longer than that of a conventional R/C servo, which is ab

51、out 0.2 seconds. IV. Discussion In the design of the motor and gearbox assembly, approximate diameter of output shaft must under carefully consideration since a potentiometer with an inner diameter is not an industrial standard component. In this experiment, the potentiometer with inner diameter is

52、obtained by modifying an electronic variable resistor and the modification is not an easy work. For the purpose of mass production, this kind of potentiometers must be available from the market or must be specially designed. Although the circuitry can be achieved in many ways, we use a criterion of

53、minimal component counts to design thisprototype and results in an implementation of just two components, M51660L and L298. This prototype requires two voltages, 24V for the motor and 5V for the logic. For the simplicity of the power supply, a single power supply is considered. The motor rated voltage is higher than the logic supply in most circumstance such as 24 volts in this case. Therefore, the pr