使用伺服马达有什么意义？

Adafruit的高扭矩伺服电机
这是一个有趣的问题。
我们可以看一下伺服电机的历史，但这是对特斯拉和爱迪生时期电动机发明的长期看法。
我们可以看一下伺服电机的发明者，但这并不十分清楚（尽管我更喜欢第一台伺服电机是由James Servo创造的）。
当我们第一次听到“伺服电机”时，我们可以看看有人在想什么。大多数听到“伺服”的人最有可能想到在爱好者套件中发现并用于玩具飞机等的小型伺服电机。
再说一次，如果你在自动化领域工作，你可能会想到你必须为机器人手臂购买的10,000美元电机。
但究竟什么是伺服电机呢？
伺服电机可简单地定义为旋转执行器或线性执行器，读作电机，内置控制电路。
现在这是一个非常简单但含糊的定义。
问题是工业伺服电机和小型直流伺服电机之间的控制水平差异很大。
您还必须注意不要在定义中包含步进电机。
步进器的控制方式不同。
当步进电机逐步移动时，伺服器保持其角度的测量。
这意味着伺服将被告知移动一定角度，而步进器将被告知需要13步。
伺服系统处于闭环控制状态，并具有其位置反馈;
步进器是开环并且已经测量了步骤，但是没有反馈。
松下工业自动化销售'3000 RPM伺服电机
简单的直流伺服电机与工业伺服电机的概念类似，但也非常不同。
你会注意到一个简单的伺服器，它通常有三根线。
工业电动机通常连接到一个特殊的控制器。
简单伺服有一个电源，接地和控制引脚。
控制引脚通常只是一个PWM信号。
脉冲宽度或时间的变化告诉伺服器要做什么。
对于仅转向一定程度的伺服系统，通常沿着0度位置的1毫秒脉冲，90度的1.5毫秒脉冲和180度的2毫秒脉冲。
对于可以转动360度的连续伺服，脉冲通常控制转速和方向。
1.5 ms脉冲停止;
任何大于这个的东西都会决定顺时针运动，而不是那个会决定逆时针运动。
这使伺服电机成为最容易开始使用的电机。
您只需要PWM信号。
大多数微控制器都内置一个定时器，可以很容易地制作PWM信号。
要了解更多关于创建它的信息，您可以访问我们的eewiki Driving Servomotors页面，或者如果您想了解更多有关伺服电机内部工作情况并在Arduino上运行的信息，请查看我们网站上的伺服电机文章。
参考文献：
1  -  Gieras，Jacek F.永磁电机技术：设计与应用，第三版，第1页。
2017年9月20日
2  -  FASTECH，为什么闭环步进系统比伺服系统具有更好的性能，2017年9月20日



以下为原文

Adafruit's High-Torque Servo Motor
That’s an interesting question. We could look at the history of servomotors, but that is a long look at the invention of electric motors in the time of Tesla and Edison. We could look at the inventor of servomotors, but that is not exactly clear (though I prefer the idea that the first servomotor was created by James Servo). We could look at what someone thinks about when they first hear “servomotor.” Most people who hear “servo” most likely think about the little servo motors found in hobbyist kits and used in toy airplanes and such. Then again, if you work in the automation world, you probably think of the $10,000 motor you had to buy for the robot ARMs.
But what really is a servomotor? Servomotors can be defined as simply as a rotary actuator or linear actuator, read as motors, with built-in control circuitry. Now that is a very simple but vague definition. The problem is the level of control is very different between an industrial servomotor and a little DC servomotor. You also have to be careful not to include stepper motors in your definition. Steppers differ in how they are controlled. A servo keeps a measurement of its angle while a stepper motor moves in steps. This means that a servo will be told to move a certain angle while a stepper will be told to take 13 steps. The servo is in a closed loop control and has feedback of its position; the stepper is open loop and has measured steps, but has no feedback.
Panasonic Industrial Automation Sales' 3000 RPM Servo Motor
Simple DC servomotors are similar in idea of industrial servomotors, but also very different. One thing you will notice with a simple servo is it usually has three wires. An industrial motor has many more that usually connect into a special controller. The simple servo has a power, ground, and control pin. The control pin is usually just a PWM signal. The change in the width or timing of the pulse tells the servo what to do. For servos that only turn to a certain degree, it is usually along the lines of a 1 ms pulse for the 0 degree position, a 1.5 ms pulse for 90 degrees, and a 2 ms pulse for 180 degrees. For a continuous servo, which can turn 360 degrees, the pulse usually controls the rpm and directions. A 1.5 ms pulse is stop; anything greater than that would dictate clockwise motion and less than that would dictate counterclockwise motion. This makes servomotors the easiest motor to get started working with. All you need is PWM signal. Most microcontrollers have a timer built in that has a very easy way to make a PWM signal. To see more on creating that, you can visit our eewiki Driving Servomotors page, or if you want to learn a little more on the inner workings of servomotors and running it on an Arduino, check out this servo motor article on our website.

References:
1 – Gieras, Jacek F. Permanent Magnet Motor Technology: Design and Applications, Third Edition, pg. 26, Sept 20, 2017
2 – FASTECH, Why the Closed Loop Stepping System Has Better Performance Than The Servo Systems, Sept 20, 2017