Actuators and Sensors
Actuators are something that control or move things around in a system, for e.g. by actuating a valve we mean to open and close it as per our need. An actuator is requires an energy source and a control signal which can be in the form of an electric or even mechanical signal.
Actuators range from hydraulic, pneumatic to even thermal/ magnetic actuators but in this blog we’ll only be talking about electrical actuators i.e. motors.
Motors
Electric motors operate with the interaction of winding currents with magnetic fields to generate a rotating torque (or motion) thus converting electrical energy into mechanical energy. There are several types of motors some of which are listed below.

DC Motors
Let’s take an example of an RC toy car, we use DC motors to actuate the motion of the wheels of the car, increasing the angular velocity of the left wheel to turn right and vice versa. All you need to do is apply power, and weeeee it spins, to rotate it in reverse direction just rotate the polarity of the input, while to vary it’s speed simply change the input voltage levels.

BLDC Motors
Brush-Less DC motors are more power efficient, with significantly lower noise than DC motors. They are often used in pumps, fans and electric vehicles. Moreover, owing to their lightweight high RPM values, most of the drones these days are predominantly based on BLDC motors.
Servo Motors
Servo motors are not used for continuous rotation (like wheels) instead, they are used for position control systems like robotic arms. There main purpose is to rotate/ move something by a fixed angle/ distance. Unlike DC motors they have a feedback control signal in addition to the power supply.


Stepper Motors
Their working principal is similar to DC motors except for the fact that it has multiple coils. In order to generate motor rotation, these coils need to activated in a particular pattern. They can be used for precise step movements such as in the case of a clock.
Sensors
Sensors are the ones that that detect the changes in a system and send the information to a computer processor (usually a microcontroller). Sensors are used in everyday life like touch sensors in your phone to smoke detectors in our homes, we are completely surrounded by sensors. Let’s take a look at some of the sensors that we might be using in our projects.

Accelerometer
Whenever you use a compass application on your phone, your phone somehow happens to know the direction your phone is pointing. Also, for a VR Headset, you move your head and you happen to be moving in the application too, ever wondered how is your phone able to get this kind of information. Accelerometers are the key to getting this information.
Ultrasonic Sensor (SONAR)
You all have an idea about the working of a SONAR, an ultrasonic sensor works on a similar principle. On receiving a signal from a microcontroller, your sensor emits an ultrasonic wave (f>20KHz) and detects an echo after some time. Based on this time interval, it sends a voltage signal to the microcontroller encoding the information of the distance of the object from the sensor.
Image Source: Google images
