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Introduction to home automation

Home automation is a generic term encompassing all the techniques to automate the management of a home, to make it "smart". These techniques rely heavily on computers and connected objects to make life easier for the user. This set of techniques can be used for several things: automating certain tasks to make life easier for the user, increasing the security of the home, or reducing the energy consumption of the home.


The different elements of the system

To operate a house "home automation" requires three distinct elements: a central, sensors / actuators / peripherals and finally a system allowing all this to communicate.

The central is the main element of the home automation system, to make a simplistic analogy with the human body, we could talk about the brain. This element is a small computer that includes all the logic necessary to interact with the user, and to control the various elements present in the home automation system. It is this component that will generally be used to interact with the system, either directly via a keyboard or an embedded screen, or indirectly via a remote device such as a remote control, or directly via a web interface and a smartphone, tablet or computer.

The different elements of a home automation system

Then come the sensors and actuators present on the network. To follow the previous analogy, they can be compared to the muscles and organs of the senses of the human body. Just like the eyes or the ears, their role is to allow the home automation system to interact with the environment in which it is located: raise blinds, measure the temperature, detect the presence of a person, etc.

Finally, all these elements need to communicate with each other. Different solutions exist to achieve this result. The first is to use dedicated cabling. This solution is the most expensive, the most complicated to implement, but the most effective, because no external element can come to disrupt communications. From a security point of view, this is also the best solution because it makes communication between the different elements difficult to intercept or disrupt.

Unfortunately, this solution is not always usable, especially in renovation or it is more difficult to create a dedicated network independent of others. The manufacturers have therefore developed techniques enabling the various elements to communicate using the electrical distribution network: CPL (Line Carrier Current) technology. If at first sight this solution seems very attractive, it still has some limitations: it is not always possible to mix multiple PLC systems together (home automation and computer network for example). In addition, this technique is subject to disturbances that may come from the house itself, or from the power grid.

Finally, a last method is to use radio-wave communications, which avoids using an existing network, but has limitations similar to CPL: risk of interference or interference between different systems using the same frequency ranges, and ability to intercept or disrupt communications.

The problem of standardization

As we have seen, the solutions for the different elements to communicate with each other are multiple at the level of the media used (electromagnetic fields, copper wires...). To this must be added the problem of the protocols used to communicate on a given medium, which considerably limits the possibilities of interoperability. To resume once again, the comparison with the human, the communication protocol is the language used by the device. In practice, this is broken down into a set of overlapping layers.

The physical layer is responsible for the way in which the information is transmitted on the media, it is it that is responsible for converting the digital data to be transmitted into electrical or radio signals. It is also responsible for managing the media: detecting if another device communicates so as not to interfere, etc.

The standardization of home automation

Above this layer will be able to stack one or more layers to govern the exchanges between devices. In the simplest systems this layer will be unique, and reduced to a set of standardized messages that devices will be able to exchange directly: "device X, activates the function Y". In this type of configuration, the communication system is generally of the master / slave type with the control unit in the role of the master, and the peripherals in the role of the slaves. A communication is then generally established at the initiative of the master who will therefore govern the communications between devices. In more advanced systems, devices will be able to take the initiative to communicate, and several layers can stack: encryption, presentation of data, etc. This type of communication corresponds to a model that is close to computer networks or that uses these type of protocols outright. In the latter case, it is called an IP model consisting of four layers: physical layer, network layer, transport layer and finally, application layer.

The whole problem in setting up a global home automation system in a home is therefore to select components capable of interacting with each other using the same protocols or by using bridges between the protocols. Currently, the safest method is to use components from the same provider, but standards are gradually appearing, as in the early days of computer networks...

Home automation and connected objects

Because of the limitations described above, current solutions are generally limited to solutions paced by manufacturers. However, the current enthusiasm of the public for connected objects and for smartphones could greatly push for the adoption of standards for assembling custom-made installations according to a logic similar to that currently leading to the convergence of television, radio and television. internet and communications.

Home automation and connected objects

It would thus be easy to transmit the information collected on the user by his smartphone, the sensors located on the clothes, etc. at the home automation station. Based on the heart and respiratory rate of people in one of the rooms of the house, it is relatively easy to determine if they sleep. From there, the home automation system can decide for itself to reduce the room temperature and close the shutters. This basic example can easily be enriched, but comes up against two points. The first is fairly basic: because of the complexity and richness of the information collected, it is difficult to imagine a system taking into account all these parameters that is both: flexible, easy to use and modular. The second is more insidious: it is the protection of privacy. Indeed, the greater the collection of information, the more it is possible to "profile" a person. In the coming years, it is likely that the CNIL has a lot of work at this level.


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