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1、 南 京 理 工 大 学 紫 金 学 院毕业设计(论文)外文资料翻译系: 机械工程系 专 业: 机械工程及自动化 姓 名: 周小峰 学 号: 100104259 外文出处: Proceedings of International Symposium 附 件: 1.外文资料翻译译文;2.外文原文。 指导教师评语: 该生翻译了一篇有关重载伺服电机设计在机器人中的应用的论文,论文内容主要涉及重载伺服电机在机器人领域的应用,在将来的课题“蜘蛛机器人儿童玩具设计与仿真”中可以借鉴。译文语句基本通顺,专业术语基本正确。说明该生具备一定的英语水平和翻译能力。 签名: 年 月 日附件1:外文资料翻译译文重载
2、伺服电机设计在机器人中的应用本文介绍了一个为机器人应用而设计的重型伺服电机系统。这个传统的遥控(R / C)系统是一个精致的,可被远程的装置。由于传统控制的的R / C伺服电机是容易的,它的成本是比较便宜的,所以R/ C伺服系统应用于广泛的领域。然而,一个R/ C伺服电机在许多应用方面,输出扭矩是小于需求的。而机器人设计和遥控车或飞机需要较高扭矩。因此,具有较高扭矩的电机是易控制的,是有利的。在本文中,齿轮直流电机作为控制机和电位器安装在输出轴上的位置反馈传感器。重型的R / C伺服电机利用一个单稳多谐振荡器,它产生0.5到2.5毫秒的脉冲宽度调制(PWM)信号来驱动发动。本研究结果证明一个重
3、型的R / C伺服电机在机器人应用方面比商业的R / C伺服电机能提供更多的扭矩。 关键词:遥控电机,脉冲宽度调制,重型,伺服发动机。一 引言 在机器人控制中的应用,设计人员通常选择直流伺服电机或无刷伺服电机作为制动器来驱动各个关节。因为复杂的驱动系统,这两种类型的伺服电机较为昂贵的。此外,还需要在机器人的多个环节设计多个伺服电机,这会使机器人的设计过于昂贵。实际的使用情况,R / C伺服是一个包含旋转定位的装配,最初设计来控制的R / C飞机或船。R / C伺服电机的PWM信号被控制在0.5到2.5毫秒,轴旋转可以被控制在-90度到90度。机器人关节由这样一个R / C驱动伺服电机控制是容易
4、的。机器人控制系统可以通过发送适当的PWM信号来控制这些电机。但是,市场上的R / C伺服电机大多数是高扭矩,不合格的。因为可用的扭矩通常为低于5千克厘米。此外,大多数的R / C伺服电机的齿轮箱是塑料齿轮,容易造成由于重载齿轮的损坏。因此,一种具有扭矩超过20千克厘米和金属制成的齿轮箱重型的R / C伺服电机,在实际应用中对机器人有吸引力。在本文中,我们提出了控制PWM信号,以便在不利的情况下使用高扭矩伺服电机能高负荷工作。 图1:重型伺服电机系统的配置二 设计方案重型伺服马达的系统配置示于图1。碳刷直流减速电机作为控制电机,需要合适的减速比。马达和齿轮箱被称为电机组件,一个电位计被安装在齿
5、轮箱作为输出轴上位置反馈传感器。如直流电动机转动时,电位器为让R/ C伺服电机与被控制的PWM信号兼容,在这个设计上,所提出的重型伺服电机的轴的位置也由PWM被控制。所述控制器是专用电用于产生一个适当的PWM信号,用于控制伺服电机轴的位置。该系统更详细的每个部分讨论如下文:(A) 电机组件 直流碳刷电机是一种用24伏作为额定电压和62g -cm额定扭矩的控制电机。该电机可以在约5000 rpm的速度在额定电压下转动;变速箱用的减速比为1/200,它导致附属的输出扭矩额定转速分别6公斤-厘米和28转。精密电位器是采纳反馈位置的传感器。因为这种特殊设计而得到的结果是:一个内径5毫米的电位,外径为5
6、毫米变速箱轴。这是相同的电位内径,使电位器可以牢固地连接到直流电动机组件,并且用作电动机的位置反馈传感器。电动机外观组件被示于图2 ,在该齿轮的齿轮箱内部是由金属材料和润滑油,使得该组件可在重负荷应用中使用。图2碳刷式直流电机和变速箱总成。 图2:碳刷式直流电机和齿轮箱组件(B) PWM模块常规的R / C伺服电机由PWM信号控制。在本文中,我们还采用PWM信号作为重型伺服电动机的位置指令,保持PWM指令和传统的R / C伺服电机的相容性。该R / C伺服电动机是由一个PWM信号在其所期望的位置控制的。R / C伺服电机的轴位置和相应的所需的脉冲宽度被示于图3 。 图三:伺服电机轴的位置和所需
7、要的脉冲宽度用0.5毫秒到2.5毫秒的脉冲宽度时,R / C伺服电机可以从旋转 - 90度至+ 90度的顺时针方向。R / C伺服系统是结合位置反馈与精确目标位置的复杂的设备。在正常使用中,他们比较0.5-2.5毫秒,50Hz的输入脉冲信号内部线性脉冲发生器的反馈伺服位置电位器控制。所不同的在脉冲宽度,该误差信号,然后用一个脉冲展宽器,它提供了伺服控制放大获得。的脉冲展宽器输出通过一个H桥电路驱动伺服电机,关闭伺服环路,PWM模块的结构示于图4。 图4:PWM模块的配置虽然这不是很难设计出一种基于PWM反馈控制系统,特殊用途设计的集成电路是更有利的,可避免使用较大的电路板。我们采用了最新的最新
8、的集成电路板三菱M51660L作为PWM控制器,用于重型伺服电动机2。M51660L被用于检测反馈电位计的电阻变化并由此产生一个脉冲宽度对应于电动机位置作为反馈信号。反馈信号进行比较在位置控制系统的总结点的PWM位置指令。最后,误差信号是来自求和点的输出,以驱动输出级和电动机被驱动的方向上,以减少位置误差。这种专用芯片还设有一个小型的轮廓,少分立元件,以及成本低。然而, M51660L提供电流小于100毫安,这远远低于一个规定重型伺服电机,该电机绕组的电流可能高达数安培。因此,一电流放大器是需要驱动大电流的电机。一种电动机,应在顺时针或逆时针的方向根据旋转是否从位置指令和传感器反馈中减去位置误
9、差是正或负。一般情况下,H桥被采用为电流放大器,用于上述目的的一个输出级。何时分立元件设计的电流放大器,至少四个功率晶体管和大量的使用电阻器是必需的,导致不仅许多电路板空间的需求,但也有几个数的散热片。从SGS汤姆逊双极驱动芯片L298是用来作为一种替代,以避免这些当离散的组件用于缺陷,则没有离散的组件是必需的,只有一小需要座位汇 3 。每个L298由两个H桥,每个桥可以提供电流高达2安培。如果我们连接这两个H桥的输出端并联,输出电流会加倍。换句话说,所设计的电流放大器可提供的电流高达4安培的重型伺服电机绕组。与M51660L除了L298 ,一个复杂的位置反馈控制系统简化,结果在一个紧凑的模块
10、。三。结果用于测试的设计伺服电机,电源,以及一个PWM脉冲产生是必要的。由于碳电刷直流电动机的额定电压为24伏,电压调节器是需要的调节在24V至5V逻辑电源,以便系统可以用一个电压,而不是双电压操作供应。此外,虽然适当的PWM指令可以从一个微控制器,如产生AT89C2051从ATMEL 4中,使用定时器芯片LM555的一种更简单的电路可以提供一个可调节的脉冲持续时间从0.5毫秒到2.5毫秒,以测试该重型伺服电机。图。图5示出一个555计时器,用于产生PWM脉冲。该方程为555时是简单,易于使用。该等式(1)和(2)如下所示。大腿=0.693(R1 + R2)C TLOW=0.693R3C(2)
11、因为Rs是可变的,该时间信号为高时为0.52.5毫秒,定时值是足够接近,只要有任何舵机工作为了验证定位控制能力,无论是传统的R / C伺服和这个设计重型伺服与所提到的555定时器电路进行测试。 图5:555定时器产生的PWM信号 每个被测试电动机的输出轴是加上一个单独的角指示器。如果两个马达的PWM指令输入端子是一起连接到555的PWM命令输出,两个马达将获得相同的角度命令。一数字示波器是用来监视在PWM指令的脉冲宽度。的可变电阻PWM发生器逐渐调节和脉冲宽度范围从0.5到2.5毫秒,它可以是从示波器监视,并且两个马达转动相应的角度,根据该脉冲宽度PWM指令的。另一方面,适当的脉冲宽度施加到测
12、试的响应不同的角度,如极左,极右和中心的位置反馈位置。它需要的重型伺服约0.7秒,从最左边旋转到中心位置时,比常规的R / C伺服,也就是大约0.2的长秒。四 讨论在电机和齿轮箱组件,因为考虑并不是一种工业标准组件,输出轴的近似直径设计必须仔细根据内径的电位。在该实验中,通过修改获得的与内径的电位电子可变电阻器并不是一件容易的工作。对于大规模生产,这种电位器必须可适应市场或者必须专门设计的。虽然电路可以通过多种方式来实现,我们使用最少元件数的标准来设计这原型,结果是在短短的两个组成部分, M51660L和L298中实现。这个原型需要两个电压, 24V的额定电压和5V的逻辑电压。为的简单电源,单
13、电源考虑。在大多数情况下,电机的额定电压高于逻辑供应,例如在这种情况下, 24伏。因此,用被嵌有电压调节器的原型电机的额定电压来调节逻辑电压。该步骤的反应,电动机发出90度旋转命令使其旋转到所需的位置。在与其传统的R / C伺服比较,在设计变速箱的还原率上高出0.7秒。但是,这个缺点可以在采用更快的响应直流电动机时,使用一个更复杂的控制算法,如比例和微分(PD) ,通过在伺服的设计控制环节。五 结束语在本文中,我们提出了一个重型伺服电机的机器人应用。因为驾驶输出的H桥的容量高达4安培的工业直流电动机具有更高的绕组电流以及更高的扭矩可以被纳入此驱动程序,并作为一个功能强大的驱动装置。此外,在使用
14、重加载情况时,自拟伺服电机配与耐磨齿轮比传统的R / C伺服电机更具耐用性。在进行精度定位的测试,伺服电机一旦接收到该PWM定位命令时,可以旋转至所需位置。结果在本研究中也证明一个重型的R / C伺服电机比商业的R / C伺服电机可以提供更多的扭矩在机器人应用中。附件2:外文资料原文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
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