An integrated, flexible, and Internet- based control architecture for home automation system in the Internet Era

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1 An integrated, flexible, and Internet- based control architecture for home automation system in the Internet Era Neng-Shiang Liang, Li-Chen Fu, Chao-Lin Wu Department of Computer Science & Information Engineering, National Taiwan University, ROC Abstract Because of the advanced development in computer technology, the microprocessors are not only on the desktop but also exist everywhere. It is obvious that microprocessors are embedded in electronic appliances (EAs) in our home today. In the past, the EAs are working stand-alone and cannot cooperate with one another. But in the recent years, these appliances can be monitored and controlled by embedded microprocessors and be displayed on terminals, but they are still in lack of integration. Since the present home automation (HA) system is not equipped with efficient integration mechanism, it cannot fully manifest the worth of these developments. In order to achieve this goal of integration, many appliance manufacturers focus on the development of intelligent (or information) appliances to be integrated into a complete HA system for monitoring and controlling. Due to the advent of advanced computer and wide-band network, the personal computer-based environment seems to be a very suitable platform for system integration. The personal computers can be linked by the network and are capable of powerful computation and easy display. We can take advantage of such abilities to develop an integration system. 1 Introduction A HA system is an integration of the current hardware and software technologies. Thus, development of the current HA can be classified into three categories. Information appliance The development of information appliances (IA) is a hot topic in the recent years. The definition of IA is in [3]. An IA is dedicated to performing a function and has the ability to share information with others. This kind of appliance is different from the traditional EA and plays an important role in the field of HA. Home control network A home control network is designed to control all the EAs including traditional EAs and IA in the home environment. The main job of a home control network is to make all the EAs have the features of modern IA. It means that every EA can be controlled and can share information with one another via the communication protocol in the control network. There are some home control networks proposed today, like LonWorks[5], Jini[4], and BACnet[6]. Software architecture for the HA system Despite that the development of software architecture is not prized as much as the development of hardware currently, it is believed that the software architecture must be an important issue for establishing the HA system architecture. It is clear that the home environment is a complex environment and we expect that an excellent HA system should be a flexible system. In order to achieve the goal flexible, we must consider how to solve the problem by applying software technology. In this paper, we propose a software architecture that makes our HA system fit to various home environment. This is an integrated control architecture for HA system based on the multi-agent concept. This architecture is composed of five main components respectively named space agents, function agents, personal preference agents, environment variables sever, and resource access right control kernel. The integrated home control architecture has the following features: Scalable Inhabitants always expect their house become smarter. It is quite likely that they may want to attach new devices and add new functions by themselves if necessary. This proposed integrated home control architecture should be a scalable architecture to facilitate them to do those. Reconfigurable Even two identical EAs will play different roles in different home environments. For example, somebody wants the lamp in his living room to be turned on when he gets into the house, but contrarily another one may expect it to be turned off under the same condition. The control architecture should be reconfigured easily. Internet-based Internet should play an important role in the HA architecture absolutely. If our HA system is compatible with Internet, we can expand its functionality easily. This paper consists of four sections. In section 2, the entire architecture is explained in detail, which turns out to be the most important part in this paper. In section 3, the proposed integrated home control architecture is actually implemented. In section 4, conclusions are made and some future work discussed. 2 An Integrated Control Architecture for Home Automation (HA) System 2.1 Architecture Overview In this section, we will propose an integrated control architecture for HA system based on the multi-agent concept. This architecture is composed of five main

2 components, respectively, named as space agents, function agents, personal preference agents, environment variables sever, and resource access right control kernel. In the following, Figure 2.1 gives an overview of the integrated HA system proposed in this paper. #1 #M Space Agent #1 Direct Control Operation Register Operation Physical Connection Internet Environment Variable Server Resource Access Right Control Kernel Space Agent #N Personal Preference Agent #1 Personal Preference Agent #K Figure 2.1 Overview of the integrated control architecture 2.2 Important Components in the Integrated Home Control Architecture As has been mentioned earlier, the integrated home control architecture consists of five components. In this architecture, both environment variable server and resource access right control kernel have only one entity for each, but the other components may have more than one entity individually. Each of the five components has its special responsibility to handle particular kind of job. In the following subsections, we will explain the complete architecture and functionality of each component in detail Space Agent It is obviously that there are many kinds of home control network under development currently, which also means that a widely accepted and used standard has not been established yet. Therefore, if we now want to develop a general mechanism to control all EAs, then there will be problems because no single solution exists that can take care of all EAs which may be attached to various home control networks. In order to alleviate this problem, we proposed a component called Space Agent. Referring to the architecture as shown in Figure 2.1, space agents are the only components that are physically connected to the real EAs. The space agents have the following responsibilities: Maintain and update information of electronic appliances which are attached in this zone Because the configuration of home environment is always dynamic, the space agents naturally must be able to keep and update information of EAs in this zone. Inhabitants always want to attach new EAs or detach old ones if necessary. When this action occurs, all the associative space agents should change their register information of EAs rapidly, and we must guarantee the whole control system have the correct configuration of the real home environment. Report data change to the Resource Access Right Control Kernel In the integrated control architecture, space agents are the only mechanism that accesses the EAs directly. When one EA changes its state, for example, a lamp is turned off, we have to get information of this change at almost the same time. If we fail to dominate the status of these EAs, we will also fail to control these EAs efficiently. Receive control commands for electronic appliances The space agents must receive control commands from the resource access right control kernel. Actually they do not care where the control commands come from. When a space agent receives a control command from the resource access right control kernel, it will decode the control command and take some corresponding control actions. The process of generating a control command is complex and it usually results from the cooperation among different components in this proposed architecture. Guarantee some user defined rules will be executed We claim that a space agent should be able to execute some basic rules. For example, if we attach a gas sensor, we may expect the HA system to provide a safety measure in conjunction with this sensor and the hot plates. That is, when this sensor is activated, the hot plates should be turned off anywise. This functionality of executing rules guarantees that some safety or necessary rules can be realizable in any situation. That makes the integrated HA architecture reliable Inhabitants always expect their HA system to achieve various control goals, for example, security, alarm, and energy saving. In the proposed architecture, we claim that inhabitants can make this system adaptable and fit to various environments. In order to establish this feature, an important component called function agent is proposed. The function agents have the following responsibilities: Interpret low level device data to high level meaningful context (named condition variable) describing the home environment What is a condition variable? Simply speaking, condition variables are high level description of this home environment. These condition variables are meaningful words but not general variables in programs. Function agents generate condition variables, and every function agent has different condition variables. According to this definition, function agents must have some expertise in it. It is obviously that function agents have ability to provide some meaningful information by analyzing the data collected from related EAs. Figure

3 is an example of generating a condition variable. HVAC Energy Saving Function Agent Thermometer Energy is wasting!!! Analyze Sensor Figure 2.2 An example of generating condition variables Accomplish some complex tasks and control real electronic appliances Because each function agent has some special expertise, it can handle several kinds of tasks according to the assigned expertise. The role of this agent is pretty like a servant. If we want to acquire some service, we simply ask our servants to do it, for example, cleaning our house. We ourselves do not have to know how to finish the aforementioned task in detail, and our servants will work together to accomplish it by exploiting each expertise. As has been mentioned, the function agents will broadcast their services and wait for the request messages from the other components in the system. When they receive a request of service, they will execute a list of actions to accomplish this job. Certainly, the function agents will send control messages to all associated space agents, which take charge of the EAs we want to control Personal Preference Agent The personal preference agent is a special mechanism that preserves the personal preference, because a home environment usually has many inhabitants and each person has his particular preference. An ideal HA system should claim that each inhabitant is quite satisfied with use of this architecture. It means that different person needs different automation functions. In order to realize this concept, a component called personal preference agent is proposed to preserve the personal preference in the integrated HA architecture. The personal preference agents have the following responsibility: Execute control strategy according to preference Every personal preference agent represents individual inhabitant preferences. Naturally, the most important job of the personal preference agents is to execute the control strategy of this personal preference agent. Based on our previous statement about condition variables and services of function agents, we will now explain how a personal preference agent can take advantage of those designed features and how a control strategy can be guaranteed. One example is shown in Figure 2.3 In this example, we have a lighting control agent, one personal preference agent and two space agents. The space agent A holds a brightness sensor and the space agent B holds a lighting device. The lighting control function agent provides a condition variable and one service Brighten the room. The strategy of the personal preference agent is If is "Dark" Then "Brighten the room". Cooperation between the lighting control function agent and the personal preference agent is demonstrated in this example. As shown in this figure, the personal preference agent only contacts the function agent. It reads the condition variables from the function agent and makes decision according to its strategy. In this example, if the value of the condition variable is Dark, the personal preference agent will send a service request to the function agent to turn on the lighting devices in the room. But if the value of the condition variable is Bright, the personal preference agent will send a service request to the function agent to turn off the lighting devices. We can easily understand that the personal preference agents only access the interpreted high level data (condition variables) and request some high level services. This explains what we said that a personal preference agent executes strategies. Reading Data Condition Variable (Bright or Dark) Sensor Data Space Agent A Sensor Personal Preference Agent Control Strategy : If is "Dark" Then "Brighten the room" Brighten The Room Space Agent B Device ON/OFF Direct Control Figure 2.3 An example of making strategy Resource Access Right Control Kernel The resource access right control kernel is a mechanism that manages the communication among all components in the architecture. The resource means space agents, function agents, personal preference agents, the environment variable server, the information about EAs, condition variables, services and environment variables. We have introduced three main components in the

4 integrated home control architecture, and it is obvious that sometimes they must communicate with one another to finish some jobs, which implies that there might be some conflicts that need to be resolved by some sort of coordination mechanism. Therefore, we need this special component called resource access right control kernel to avoid conflicts, and it has the following responsibilities: Maintain register information of all the components and route messages between components In order to make this architecture flexible, we hope that every component in the architecture can be moved from one machine to another easily. For example, we may want to disable one working function agent in a slower machine and enable it in another faster machine. If we do not have any special mechanism, we must reconfigure all the other components in this architecture, and it will be a boring job if our system is very large. To achieve this goal without heavy effort, the answer is to use a central communication center, resource access right control kernel. In order to make the architecture reconfigurable, we claim that the resource access right control kernel should keep the information of every component in the architecture. When we add a new component into our system, we must send register information to the resource access right control kernel first. After this action, this new component is a member of this system and its information will be broadcast to other related components. This mechanism makes the address information of all components transparent. Although every component has all needed information about the other components, it is clear that it can not communicate with other components without address information. To make the system work properly, the resource access right control kernel has responsibility to route information among components in this architecture. Figure 2.4 shows an example of sending a control message from a function agent to their destination EAs. Turn on the lamps hold by the living room space agent Turn on Living Room Space Agent Direct control Lamp Lamps control Messages Resource Access Right Control Kernel Message Turn on the lamps hold by living room and bedroom space agents Message Bedroom Space Agent Turn on Direct control Lamp Turn on the lamps hold by the bedroom space agent Figure 2.4 An example of lamp control In this example, we have one function agent and two space agents. The lamps control function agent exactly knows that there are two space agents in the system but does not know where they are. Once it needs to control the lamps belonging to these space agents, it will send the control message to the resource access right control kernel first. The kernel will route the control message to the proper machine according to the register information of these space agents, and these space agents will receive messages from the kernel and control the lamps directly. Guarantee control priority and avoid control conflict As mentioned in the pervious subsections, both function agents and personal preference agents can be multiple in the proposed architecture, so conflict problems may arise within these two kinds of agents. A similar solution is to resort to a priority mechanism to prevent it. In addition to being the communication center for all the components in the architecture, the kernel is capable of coordinating resources out of the entire HA system. However, it is important that the control right of resources should not be uncertain. To this end, we will ask all components in the architecture should obey the following steps when they want to allocate some resources: Step 1. Send resource allocation requests to the kernel Step 2. Send control messages Step 3. Send resource release messages to the kernel Every function agent and personal preference agent has one priority value and these priority values will be compared in step 1 by the resource access right control kernel if necessary. Generally speaking, once a resource is allocated to some agent, we can not allocate it anymore until step 3 is finished, but there is one exception. If the newly arrived allocation request has higher priority, the current control right of this resource will be preempted Environment Variable Server This component is the mechanism that allows the integrated control architecture to take advantages of Internet. Because Internet is a modern technology that influences life dramatically, the system should be much more powerful and will provide greater life quality improvement if we integrate Internet into our architecture. This component has the following responsibilities Maintain environment variables Environment variables are variables that can be referred to by both the components within the control architecture and the sites in the Internet, which can be considered as parameters of the entire architecture. The function agents and personal preference agents should refer to these parameters to make control decisions. The current control strategy will be affected by these environment variables. The environment variable server must protect these variables against the invalid access from the Internet and maintain the database. data from the Internet automatically In the integrated home control architecture we proposed, the environment variable server can be

5 considered as the information provider of the outside world. The decision mechanism in the architecture may require the current data of the real world to make some decisions. Because of this requirement, we proposed that the environment variable server should have ability to collect information from the Internet automatically. Accept query and update request of environment variable from the Internet or the home network Because the environment variables are the bridge between the HA system and the outside world, it must handle the query and update request of environment variable from the Internet or the home network. 3 Experiment 3.1 Experiment Environment In our experiment, we construct the purposed architecture in the Intelligent Robotics Laboratory in NTU. The complete HA system includes software and hardware, and it allows people to control both real and virtual EAs. The conceptual structure is shown in Figure 3.1. Integraged Home Control Architecture DDE ( Dynamic Data Exchange) LonWorks Network Real Appliacnes Intouch Virtual Appliacnes Figure 3.1 Architecture of implementation Now, we list all the hardware devices and software components used in our experiment in the following. Integrated home control architecture All the components implemented in the architecture include the space agents, the resource access right control kernel, the personal preference agents and the environment variable server. Besides these components, two function agents are also implemented to execute power saving strategy and to remotely control EAs, respectively. From previous explanation about function agents in section 2, we know that adding and deleting function agents will change the control capability in our HA system. In the setup of our experiment, totally five personal computers are used, and each one executes one software component in the architecture. Dynamic data exchange Dynamic data exchange (DDE) is a mechanism provided by Microsoft Windows. It provides a convenient way to exchange data between different programs. Because we want to control both real and virtual EAs, we use DDE as the interface technique between our software components and the EAs. We have two DDE servers. One is Echelon LNS DDE server[5] which is developed by Echelon and we can exchange data between our programs and the LonWorks network through this server. The other one is developed by ourselves to be a bridge between our programs and the Intouch[11]. LonWorks network We have established a LonWorks network in our laboratory with two LonWorks control nodes, both of which act as the controller of physical EAs. Real electronic appliances We installed several real EAs to demonstrate the capability of our HA system. Temperature sensor: The temperature sensor can sense the temperature in the environment. sensor: The brightness sensor can sense the brightness in the environment. Smoke sensor: This smoke sensor can sense whether there exists smoke in this space. Person Infrared Radio Sensor: This sensor can detect the existence of humans around the space. Switch: The lighting switch can turn on and turn off the lights. Camera: The camera can take pictures while receiving request to monitor the surrounding space. Intouch Intouch is a graphical human-machine interface (HMI) for industrial automation, process control and supervisory monitoring. It has ability to exchange data by DDE, and we take advantage of this feature to produce a virtual home environment. Virtual electronic appliance We created a virtual home environment by using Intouch, and there are some virtual EAs in it. The virtual home environment is shown in Figure 3.2. Figure 3.2 Virtual home 3.2 System Setup In this HA system, we have two space agents, two

6 function agents, one resource access right control kernel, one personal preference agent and one environment variable server. Because we use DDE as the interface technique between our software components and EAs, we control both real and virtual EAs at the same time. As has been described in section 2, we know that the function agents installed in the system provide the pre-defined functionality to the HA system. In our experiment, we have function agents with power saving and remote control functionality, respectively. Because of these function agents, we can make our real and virtual EAs change their status according to the current home environment automatically. The physical layout of our system is shown in Figure 3.3. Environment Variable Server Ethernet Power Saving & Remote Control Personal Preference Agent References [1] Li-Chen Fu; Teng-Jei Shih, Holonic supervisory control and data acquisition kernel for 21st century intelligent building system, Robotics and Automation, Proceedings. ICRA '00. IEEE International Conference on, Volume: 3, 2000 Page(s): [2]Nunes, R.J.C.; Delgado, J.C.M., An internet application for home automation, Electrotechnical Conference, MELECON th Mediterranean, Volume: 1, 2000, Page(s): [3]Want, R.; Borriello, G., Survey on information appliances, IEEE Computer Graphics and Applications, Volume: 20 3, May-June 2000, Page(s): [4]Jini Network Technology, [5]Echelon Corporation, PDA Wireless Remote Control Intouch Virtual Home Environment Space Agent A Resource Access Right Control Kernel Space Agent B LonWorks Network Control Node Smoke sensor Temperature sensor Camera Control Node sensor Person Infrared Radio Sensor Figure 3.3 Physical layout of our experiment 4 Conclusion There are some important factors in the HA system, including EAs, control strategies, and personal preference. These factors will be different in each home environment. Thus, we have to find a solution so that we can adjust these factors easily. In order to solve this problem, we proposed five components in our integrated home control architecture to allow the automation system to be easily re-configured according to various special requirements. We also construct a tight relation between the HA system and the Internet. In the future, the HA system will become smarter because of the ability of collecting information from the Internet. In our experiment, all the components in our architecture are implemented. We also created a real home environment and a virtual one to be controlled by our HA system. The process of developing a powerful HA system will encounter a lot of problems. In this paper, we considered the possible problems and tried to find an efficient way to resolve these problems in the software level. We will continuously research how to construct a more powerful HA both in the hardware and software aspects. Undoubtedly, living in an intelligent home environment is the trend in the 21st century. [6]Haakenstad, L.K., The open protocol standard for computerized building systems: BACnet, Control Applications, Proceedings of the 1999 IEEE International Conference on, Volume: 2, 1999, Page(s): [7]Steven T. Bushby, BACnet: a Standard Communication Infrastructure for Intelligent Buildings, Journal of Automation in Construction, 1997, Vol 6, [8]J. M. Bradshaw, editor, Software Agents. AAAI/MIT Press, Menlo Park, CA, ISBN [9]Wonderware Corp., [10]XML.com, [11]Java Remote Method Invocation (RMI), [12]Overview of CORBA.,