Key Technologies for Intelligent House Implementations
There are various elements of the Intelligent House system that creates the overall functionality. Those are the sensors that gather the data from the house, the network technology that allows sending the date between sensors and a central computer and between the central computers and the controlled equipment and finally the software capable of learning habits of inhabitants. There are different properties of each solution and in the following section those properties will be addressed shortly. Additionally some references to the sources, where more information can be found will be provided.
Sensors
The sensors that are available on the market are in most cases quite cheap and can be bought in most of the specialised hardware shops.
The most important sensors for the Smart Houses are the movement sensors. They result in the valuable data about the location of the person and they are reliable. By the proper placement of those sensors so that their ranges overlap it is possible to find the exact location of any person. There are different kinds of such sensors on the market and the most popular are passive infrared sensors. Such sensors have usually the range between 12 and 15 meters and the angle of 90 degrees. Still there are models that offer different ranges or angle. There are also some improved types like dual sensors that decrease the probability of environmental conditions triggering the sensor. There are also other movement sensors like ultrasonic, microwave, video imaging and piezometric sensors. Still there is no need for any advanced movement sensors as normal infrared sensor has a desired reliability for the house applications.
Second kind of sensor that could be very helpful is the video camera. Such a sensor can be for example used instead of a movement sensor. Such sensors can track the position of a person with great precision, can identify a person and finally it can also recognise the situation or the activity that the person is performing. The capabilities of the sensor itself can be high enough, the problem with the reliability is rather related to the software that process the data form the camera. It has to be both capable of complex computations and has to contain a sophisticated algorithms that would perform the analyse process. As it can be known from different projects, the recognition can be achieved, but the reliability is not always at the satisfactory level. On the other hand also the cameras that are used in different experiments are usually internet cameras or some standard surveillance cameras that does not have a perfect image quality as well.
There are many other sensors that are available on the market, are reliable and can extend the functionalities of an Intelligent House. Those are for example dusk sensors, thermometers, humidity sensors or pressure sensors. The last ones are very interesting as they can cooperate with movement sensors and video cameras or even replace them and provide complete person location functionalities. Such sensors can be placed in the sofas or armchairs, but also like in a Smart Floor project carried out by the AHRI group the whole floor can consist of pressure sensors.
Wireless Communication
The next element of the implementation of an Intelligent House is a network technology that would connects all the sensors and devices with the central processing unit. Again different technologies can be chosen for this purpose.
One of them is the Bluetooth technology. This technology for wireless transfer was introduced in 1994 by Ericsson, but it was quite recently that the technology gained the popularity. The technology was designed to provide the radio at the 2.4 GHz. The main properties are that the technology is cheap, has low power consumption, is of small size and additionally it is designed for the small ranges. The range is supposed to be around 10 meters which is completely enough for the inside the house exchange of data. The small range additionally has an influence on the security and privacy issues. The probability that someone outside the house could percept or generate a signal is very small while using the bluetooth technology. Additional advantage is that the technology is quite popular and widespread nowadays and many mobile phones, PDAs and notebooks are already equipped with Bluetooth and could easily be used to interact with a house.
Another quite similar technology is called HomeRF. The Home RF Shared Wireless Access Protocol is a standard created by the Home Radio Frequency Working Group. The technology has similar technical properties like the Bluetooth technology as both operates at the frequency of 2.4GHz, are low cost and low energy consuming. The difference is that the homeRF technology is designed for use in the house environments what gives it a great advantage. On the other hand the standard was created in the main purpose of carrying the sound around the house and all the functionality was made to support it. This would make some features of that technology rather useless in the Intelligent House implementation. Still the technology could be used in a Controllable House where such features could be used. It is also important to state that the HomeRF Working Group does not exist any more, thus the evolution of the standard is not certain.
Yet another technology similar to the previous one is ZigBee technology. This technology is also working in the 2.4 GHz freqenecy and is a low power consuming technology intended for the house applications. Any differences can be easily seen on the figure 2.3.
Another network technology for the houses is the Z-Wave technology offered by Zensys Company. The technology is again a low cost and low power consuming one. It is intended to send just control commands or statuses as the bandwidth is only 9.6 Kbps. Still such a bandwidth is enough for most of the applications of the Intelligent house, as the information sent by for example movement sensor has just to distinct values - (detects or does not detect). What is particularly interesting is the fact that the Zensys Company is not only creating a standard for the network protocol, but also the actual equipment for various house applications in the house that are using the Z-Wave technology.
Another technology that is quite different than the ones presented above is the IrDA infrared technology. It is a standard defined by the Infrared Data Association consortium. Such a communication in the latest version can transfer the data with transfers up to 1.5 Mbps. Such a speed is enough for a successful implementation but a problem lies with the range of infrared signal. To transfer the data reliably the range cannot exceed 1 meter. That makes the technology much less usable as one meter is a very small distance even in a small room. Moreover the infrared signal can be interfered by the ambient light, what makes the possible range even smaller. Still there are some advantages of such technology as well. One of them is the directional nature of the signal. Thus the signal would be received only by the piece of equipment that is intended to receive it. This would simplify the implementations and again would have a great security benefits, as the possibility to intercept the signal from outside the house would be practically impossible.
The other technologies that are worth mentioning here are the wired technologies. Those are much difficult to implement, as the wires has to be placed inside the walls. But eventually the new houses being build will have an extended set of cables inside the walls so there would be no problem with such issue anymore. First advantage of such technology is the lack of hundreds of radio waves around inhabitants that could potentially affect people's health. Second advantage is that the problem of security and privacy is solved. As there is no way that someone with the radio waves receiver could intercept some data.
Wired Communication
An interesting example of a wired technology can be the X-10 technology. Similarly to the Zensys Company, the standard for the network is just a small part of the X-10 technologies. The most important parts are the different pieces of equipment that are created. The devices range from the sensors, switches, lamp modules to the entertainment equipment. All of those with the functionalities of connection with the home network and with some simple programmable functionality are available to buy with a low price.
There are many others companies creating products that are similar to the ones mentioned before or that are not very convenient for the Intelligent House implementation. Moreover some technologies disappear while others enter the market. Hence there will be always a need to do a small research to check the current state of the market.
House Intelligence
Implementing the intelligence of a house in not a straightforward task. There are no products available on the market or standards that could be easily implemented. The area of Artificial Algorithms and Neural Networks that could be applied is still a work in progress that does not have any easy to implement results. Of course, this does not imply that creating house intelligence is an impossible task. It is possible to create some simple or more sophisticated learning algorithms, but still that is not an easy task and there are not simple solutions that can be presented in such places. Of course if someone is interesting in such subjects can check the papers about the learning algorithms and neural networks that are available on the website of the Adaptive house project or check the SNEuroNet website.
Tool Prototype for Creating Smart House simulations
The scenarios that were presented earlier on the site were created using a special software tool. The tool in Flash MX 2004 allows for creation of various animations and simulation of Intelligent Houses and their sensros and equipement. More detailed description with the source .fla file is available behind the following link.