Ch-1 Things & Connections
closed loop control system
A closed-loop control system uses feedback to determine whether the collected output is the desired output. A closed-loop system measures output using a sensor. Using control theory, this measurement is compared to a reference that represents the desired state (input). The result is then "fed back" into a controller. This feedback is used by the controller to adjust the controls into the plant for the next iteration of output, and the process repeats.
control systems
A control system includes a controller that uses inputs and outputs to manage and regulate the behavior of the system in an attempt to achieve a desired state. The input specifies what the output should be for the whole process. The controller indicates what specific changes are needed to achieve the desired output based on the input. The controlled portion of the system, the process and the actuator, is often called the plant. The input is used by the plant to produce the desired output. Control systems can be open-loop or closed-loop systems. The difference between these two systems is based on whether it uses feedback or not.
controllers
A controller can collect data from sensors without human intervention or network connectivity. As an example, a sensor determines that the temperature in an apartment has dropped below a pre-set level. The controller will process the data and send output to cause the heater (the actuator) to turn on. The controller may also act as a gateway to an IP network and pass the sensor data to be stored or analyzed on servers in the fog or the cloud. The collected data and analyses can be used to trigger actions by people, systems, or machines.
Sensors
A sensor is a device that can be used to measure a physical property by detecting some type of information from the physical world. This information could be light, moisture, motion, pressure, temperature, or any other environmental condition. A sensor may be connected to a controller either directly or remotely. Sensors and controllers are usually connected by means of analog or digital circuits. Sensors send data to a controller. That controller could react to the sensor data immediately and change the actuator settings.
actuators
An actuator is a basic motor that can be used to move or control a mechanism or system, based on a specific set of instructions. Typically, in the Industrial IoT, there are three types of actuators: • Electrical - Powered by a motor that converts electrical energy into mechanical operations • Hydraulic - Uses fluid pressure to perform mechanical movement • Pneumatic - Uses compressed air to enable mechanical operations Regardless of how the actuator causes the movement to be performed, the basic function of an actuator is to receive a signal from the controller, and based on that signal, perform a set action.
Device to Gateway to Cloud Application
Another connection option supports smart device data collection and transfer through a gateway to a local IP network. The data then flows to the fog or the cloud and is then available for users to export and analyze. The data is often analyzed in combination with data from other sources or other cloud services. Knowledge of the four basic levels of connections will ensure that consideration is given to device interoperability and open standards. These are key considerations when developing an internetworked IoT system.
Cisco IoT System
Cisco IoT System consists of new and existing products and technologies to help reduce the Complexities of digitization.
cloud computing
Cloud computing refers to the ability to store data and retrieve it from off-site locations. It's how your smart phone got so smart; phones don't have enough built-in storage to maintain all the information they need for all their apps and functions, so they're constantly transmitting and receiving data in order to provide you with the services you want. The problem with cloud computing — as anyone with a slow data connection will tell you — is bandwidth. According to the World Economic Forum, the U.S. ranks 35th in the world for bandwidth per user, which is a big problem if you're trying to transmit data wirelessly. And as the Internet of Things continues to expand, with more and more physical objects connecting wirelessly to transmit and receive data, the problem is only going to increase.
derivative controllers
Derivative controllers (PID) - These proportional, integral, and derivative controllers include data about how quickly the system is approaching the desired output. In an HVAC system, the derivative function of a PID controller looks at the rate of change in temperature. This allows the controller to quickly adjust the output as the system approaches the desired output, as shown in the PID graph.
IoT Feedback Loops
Feedback loops are used by the IoT device to provide real-time information to its controller based on current behavior. A closed loop exists when the feedback is continuously being received by the controller from its sensors. The controller analyzes and processes information, and if necessary, it can use actuators to modify conditions. This process is continuously repeated and adjusted.
TCP & OSI Models
Network connections are most often described as using the OSI and TCP/IP models. Both models use layers, and each layer has a function. Whereas the TCP/IP model layers are referred to only by name, the seven OSI model layers are more often referred to by number rather than by name. For instance, the physical layer is referred to as Layer 1 of the OSI model.
M2M
Figure displays a sample IoT topology that highlights how controllers are used in fog computing. Imagine smart traffic lights that contain sensors and actuators. The sensors detect and report traffic activity to the controller. The controller is able to process this data locally and determine optimal traffic patterns. Using this information the controller will send signals to the actuators in the traffic lights to adjust traffic flows. This is an example of machine-to-machine (M2M) communication. In this scenario, the sensors, actuators, and the controller all exist within the fog. That means that the information is not sent beyond the local network of end devices.
fog vs edge computing
Fog computing is different from edge computing in a subtle, but important way, and it has everything to do with where the computational power is located. In fog computing, computational power is centered on fog "nodes" and IoT gateways ; in edge computing, the entire network itself functions as a computational powerhouse, distributing the share between all devices and the resultant automation controllers.
fog computing
Fog computing, also sometimes called edge computing, solves the problem by keeping data closer "to the ground," so to speak, in local computers and devices, rather than routing everything through a central data center in the cloud. Fog computing, also sometimes called edge computing, solves the problem by keeping data closer "to the ground," so to speak, in local computers and devices, rather than routing everything through a central data center in the cloud. In our modern, western world, we exist with a huge amount of computing power around us all the time.
Device to Cloud IoT Architecture
In a device-to-network-to-cloud communication model, the IoT device connects through a local network directly to an Internet cloud service using traditional wired Ethernet or Wi-Fi connections. This model establishes a connection between the device, the IP network, and the cloud to allow the exchange of data and control messages.
integral controllers
Integral controllers (PI) - These proportional and integral controllers use historical data to measure how long the system has deviated from the set temperature. The longer the system has deviated from the set temperature, the larger the response from the controller. In an HVAC system, the controller would account for historical data and time when adjusting the system. Although integral controllers will also overshoot the set temperature, the variation will decrease overtime, as shown in the PI graph.
IoT
Internet of Things = The IoT is helping industries including manufacturing, utilities, oil and gas, transportation, mining, and public and private sector organizations increase operationally efficiency.
Device to Device IoT Architecture
IoT solutions often support one smart object connecting directly to another via a wireless protocol such as Bluetooth or Zigbee. An example of this level is a sensor that is located in a vineyard and detects dry soil. It sends a signal to an actuator that triggers the watering system.
IoT Reference Model
Like the OSI model, the IoT Reference Model has seven parts. However, the parts are called levels instead of layers. The IoT reference model was developed as a common framework to guide and to help accelerate IoT deployments. The model is the result of a collaborative effort of the 28 members of the IoT World Forum's Architecture, Management and Analytics Working Group. It is also endorsed by the Industrial Internet Consortium (IIC). The intent of the IoT reference model is to provide common terminology and help clarify how information flows and is processed for a unified IoT industry.
Device to Gateway to Cloud IoT Architecture
Many smart devices, such as fitness trackers, are not IP-enabled and do not have the native ability to connect directly to the fog or the cloud. For these devices, there is application software operating on a local gateway device which acts as an intermediary between the device and the cloud service. The gateway may also provide security and data or protocol translation. For devices, like fitness trackers, the gateway is often an application running on a smartphone.
negative feedback loop
Negative feedback - Feedback cancels out or counteracts the original input. Negative feedback diminishes the effect of the previous result. It tends towards stabilization, reaching some level of equilibrium.
open loop control systems
Open-loop control systems do not use feedback. The controller instructs the plant to perform a predetermined action without any verification of the desired results. Open-loop control systems are often used for simple processes where the relationships between the input and the plant are well-defined. The job of the engineer is to determine how to manipulate the inputs so that the plant will generate the desired outputs.
positive feedback loop
Positive feedback - Feedback reinforces the original input. Positive feedback accelerates the transformation of the output in the same direction as the previous result. It tends toward either exponential growth or decline.
proportional controllers
Proportional controllers (P) - These controllers look specifically at the difference between the measured output and the desired output. The amount of change sent to the plant by the controller is proportional to the size of the error from the last iteration. For example, in an HVAC system the controller would activate 50% of the chillers if the sensor detected a one degree deviation from the set temperature. At 2 degrees deviation, 100% capacity would be activated. Proportional controls will usually overshoot the set temperature, as shown in the P graph because they are only looking at the deviation from the set point at any given time
microcontrollers
The Arduino microcontroller, shown in Figure , and the Raspberry Pi (RaPi), shown in Figure, are both types of controllers. They can both operate without the Internet and are used by hobbyists and professionals. The key difference between the two is physical size, available processing power, memory, and OS. Typically the Arduino requires less power than the RaPi and is more suitable for analog input. The application should dictate which controller is the best to use. The two controllers are commonly used together. For instance, you can acquire data with the Arduino and then process the data using the Raspberry Pi.
IP-enabled controllers
The IP-enabled controller forwards information across an IP network, and allows individuals to access the controller remotely. In addition to forwarding basic information in an M2M configuration, some controllers are able to perform more complex operations. Some controllers can consolidate information from multiple sensors or perform basic analysis of data received.
TCP/IP protocol
The TCP/IP protocol model for internetwork communications was created in the early 1970s. It defines four categories of functions that must occur for communications to be successful. The architecture of the TCP/IP protocol suite follows the structure of this model which is why it is called a protocol model. The TCP/IP protocol model is commonly referred to as the Internet model.
IoT Topology Sample
The figure displays a sample IoT topology consisting of sensors, controllers, routers and data centers. To reach the more powerful computers in the data center, the controller will first send data to a local router. This router is the interface between the local network and Internet. It can send data back and forth between them.
Processes of IoT
a process uses inputs to execute the right actions to achieve the desired output. More formally, a process is a series of steps or actions taken to achieve a desired result by the consumer of the process. A system is a set of rules that govern the series of steps or actions in the process.
IoT enabled devices
most IoT devices use sensors, controllers, and actuators to perform functions.
Cisco Tech Pillars
the Cisco IoT System identifies six technology pillars that help simplify and secure an IoT deployment: 1. Network Connectivity 2. Fog Computing 3. Cybersecurity and Physical Security 4. Data Analytics 5. Management and Automation 6. Application Enablement Platform