Hi, this is Wayne again with a topic “Skill Buider: Servo Basics – a practical guide”.
[ Applause ]: these are servos and they’re an excellent way to add motion to your electronics projects, not to be confused with industrial grade servos. These dc hobby servos can be really useful in a variety of different projects, from model planes and cars to even robotic arms and understanding how they work, how to choose one and finally, how to control one is essential. Hi, i’m allison check out my channel linked down below, and this is our practical guide to dc hobby servos. Mechanically servos are pretty simple and consist of three basic parts: the dc motor and gears, the encoder or potentiometer, and the control board. At the basis of a servo. We have a dc motor that spins a shaft generating torque. However, as is this, torque output is pretty low. To fix this, a typical servo uses a set of gears that, while reducing the rotational speed of the servo increases, its torque servos also use encoders sensors that tell the servo about the position and speed of the motor. Many modern servos use rotary encoders, which convert the motion and position of the shaft to an electrical signal allowing us to both know and control.
These aspects of the servo using the control board, some of the more simple servos – will use resistive potentiometers, instead of rotary encoders to achieve a similar result. All you really need to know is that the encoder or potentiometer is constantly sending signals to the servo’s controller, which allows you to monitor and control its position. Your servo will also generally come with a set of attachments, called horns for mounting to different parts of your projects allowing for actuation and movement when choosing a servo for your project. You first want to consider the range of motion that you require most commonly you’ll find positional servos, which have a range of around 0 to 180 degrees and come with the ability to control position.
But if you need to you can always find continuous rotation servos, which can rotate continuously in any direction, the trade-off being that you can only control, speed and direction, not position. Another thing you’ll want to consider is the torque and power requirements of your servo, a micro servo like this one picks up less space and requires less power to run, but also provides less torque. While this standard size, servo is capable of providing more torque but requires more power in space in general, micro servers are great for smaller projects, but if you’re doing something more, you’ll want to calculate your own torque requirements and compare it to the stall torque rating.
For your servo to ensure it can do what you need it to do in terms of price. The lower quality servals will definitely be cheaper, but with the trade-off of using mainly plastic parts which impacts, longevity and torque higher quality servos usually come with metal gears and last longer, but are also more expensive. Hey you are you subscribed to make magazine? Yet if you like this kind of video of projects and stuff to build, you are gon na love, make magazine, it comes out quarterly and it is packed full of tips and tricks, full projects that you can recreate and feature pieces explaining. How makers are changing the world for the better? You can find information on how to subscribe in a multitude of ways, digital or get the actual print edition in your mailbox at the link above the link below in the description now back to the video. Now, let’s get into actually controlling your servos servos are controlled by pulse width, modulation or pwm signals.
Essentially, you send your servo an electronic pulse of variable width and the controller uses this width to determine the position it should move to 180 degree. Positional servo typically expects these pwm signals to be sent at a frequency of 50 hertz or with a period of 20 milliseconds, with the actual width of the pulse being between 1 and 2 milliseconds. So a pulse with a 1 millisecond width will turn 0 degrees. A pulse with a 1.5 millisecond width will turn 90 degrees and a pulse with a 2 millisecond width will turn to its 180 degree position in the case of continuous servos. This pwm signal controls, speed and direction rather than position also, for the most part, the timing and width of your servo signal is standardized, but you’re going to want to check your spec sheet just to be sure. As an example, let’s control the position of this 180 degree servo using an arduino we’ve connected up the power and ground pins of the servo to an external 5 volt power source, while feeding the signal line of the servo into pin 9 of our arduino. Now we can start sending it pwm signals using arduino’s built-in servo library. We can test its full range of motion by sending it commands to move to 90 degrees, 0 degrees and 180 degrees, and that’s it.
Hopefully. Now you have a better understanding of dc hobby servos. How to choose one and how to use them in your own projects? If you do, let us know in the comments below also feel free to check out my own channel, also linked down below, and if you like. This type of content, make sure to subscribe.
To make magazine and makes youtube channel and we’ll see you in the next one you .