CSF117 Module 4 IoT Actuators

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Welcome to the IoT actuators module. This module aims to facilitate learning of the different types of actuators and how they can be used in creating IoT solutions. We will look at several actuators to see how to interface those with Arduino.
Welcome to this module where we will learn about the different types of actuators that are used in IoT. It helps to have gone through the previous modules of IoT architecture and components as well as IoT protocol stack as well as IoT sensors. After reading the state of the environment through sensors, it may be necessary to perform an action in that environment. Actions are performed by use of actuators, which act based on a desired signal. Those signals may come from sensors or processed information collected from various sources. Actuators therefore convert an electric impulse to a physical phenomenon. Outputs for IoT are manifested by actuators such as motors, servos, segment displays, speakers and so on. In this module we will learn about sensors. Actuators are part of the IoT ecosystem that help to bridge between the physical world and the digital world. They modify the state of the environment. When sourcing for the type of actuator for your project, there are several considerations you need to make. The first one is the purpose of the component. For example, you may want to move an item. This would require a component that converts electrical signals to motion. Another consideration is the power rating of the actuator. Actuators will have an operating voltage and current. Some actuators need much more power than a microcontroller can provide. That makes it necessary to include hardware drivers that are able to deliver higher power ratings to drive the actuator. Another consideration is the accuracy and precision of the actuator. For example, motor actuators come in several designs. Some offer fast rotations but with low precision. Others offer low speed but are very precise. Depending on the project you are working on, it is important to get the right actuator. Additionally, you may want to choose between a digital actuator and an analogue one. Digital actuators tend to make it easier for you to send data, from a programming standpoint and also from the logistical perspective because some Arduino and other boards tend to have few analog input pins. Also, some analog actuators might require additional analog components such as resistors, capacitors, transistors and so on to regulate the signal from your Arduino output pin. Another important consideration for digital actuators is how to address a specific component from a pool. We have three main types of actuators: Electric actuators, Pneumatic actuators and Hydraulic actuators. These three types of actuators come from the energy sources that drive the actuator component. Each type has its advantages and disadvantages. Hydraulic actuators for example, allow for fast thrust motion that is also very accurate. Their downside is that they tend to be expensive to acquire and have routing maintenance such as changing of O-rings and fluid. Electric actuators use electricity to power the component. Current for such actuators can be direct current or alternating current. Some even have gears such as worm gears, among others. This means there is a need to lubricate them with some form of grease. They are best used in situations where few actuators are needed in a project. Their initial cost is the highest among the other two actuators. Though the maintenance costs are very low. For pneumatic actuators, compressed air is used as the energy source. These have the lowest initial cost but have the highest maintenance cost. Electric motors exist as three types: DC motors, servo motors and stepper motors. DC motors are very basic. Once connected, they simply rotate. At times, it is necessary to control the speed and angle of rotations. For example, for use in printers and robotic arms that need very high precision movement. Stepper motors are relatively low cost and readily available. They are good at holding good torque without being powered. They have numerous stopping points where they can stop without being powered and therefore useful in high holding torque requirements, but have low speed. They provide high accuracy in positioning and have good repeatability. To control a stepper motor, pulses are sent to the device and it moves a precise angle or step of rotation. Servo motors have feedback to control motion and torque. They allow movement to a particular angle and speed. Some servo motors support digital signals. Sometimes they require tuning or calibration to achieve the desired accuracy and precision. They run more smoothly than stepper motors and also provide about more than double the speed. Servo motors have low torque at lower rpm but have better torque at high rpm over 1000 rpm. This is achieved because they make use of gears. Due to the feedback requirement, servo motors need a controller device or component to run so as to detect the position and speed of the motor.