The relation between intelligent system components

To deals with ISs, we need to know the related between the selected components that comprise a control system and do not communicate with each other (hardwired and software) which are the four aspects under investigation in terms of the nature of IS in buildings. Hardwired can provide satisfactory and economical control of small buildings. It is the modern programmable controller contains a microprocessor and performs local control of a plant or subsystem and exchanges information with the rest of the building management system. Software take place at three levels: the management level for supervisors, automation level for controllers, and field level for sensors and actuators (Doukas et al., 2007; Suberamian 2009).

This section illustrates ISs, including the hardware components, which are more important for this research than the software ones.

 Valves

The aim is to provide a final controlled output which is nearly linear with valve position, to assist in providing satisfactory control. Control valves for hydraulic circuits should be chosen to give adequate authority and a characterisation appropriate for the output device.

 Dampers

Dampers are used to control air flow in ducts in a manner analogous to the use of valves in hydraulic circuits. The damper chosen for a particular situation must satisfy both the physical requirements of the application and also provide suitable control characteristics.

 Motors

Motors are major users of electricity, and can provide energy efficiency. The motor aims to reduce the voltage supplied from an autotransformer.

 Pumps and fans

The specification of pumps and fans is outside the responsibility of the controls engineer. A single pump may not be able to satisfy the full design flow and yet provide economical operation at part loads.

 Control panels and motor control centres

This component gives protection for the equipment and operating staff and allows convenient connection of hardwired interlocks by control equipment, so that it can be mounted in an enclosed cabinet. Thus, the cabinet will contain such equipment as relays, contactors, isolators, fuses, starters and motor speed controllers.

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 The intelligent outstations

The intelligent controller is the workhorse of most control systems. It provides local control of subsystems while communicating over a network with the building management system (BMS). Known variously as a field processing unit, distributed processing unit, freely programmable controller or simply as a controller, it combines a standalone control capability with the ability to communicate over a network with the head end supervisor (CIBSE, 2002).

The most important aspect is the relation between the components in IBs in general. According to the IB (CIBSE, 2000, p. 4-17), communication of these components could be wired or wireless.

A network implies that a number of devices are connected with each other via a communications system. A communications network is characterised by two essential parts:

 A physical medium, which is used to transport the signals, e.g. wire and

 A protocol, which is the set of common language rules for the communication signals. This provides local control of subsystems while communicating over a network with the building management system. The intelligent outstation, or universal controller, is at the heart of the contemporary building management system (BMS). Known variously as a field processing unit, distributed processing unit, freely programmable controller or simply as a controller, it integrates standalone controllability with the capacity to interact over a network. Modern building management systems are controlled by means of software operations.

The complexity of a large system places demands on the user interface design.

The supervision should be arranged so that access is possible at several controlled levels, from simple supervision to fault location and reconfiguration.

One of the important aspects in current research is the user, and there are two levels of operation which will be explored next.

90 4.3.5 The operation of intelligent systems

There were two types of operation of IS which is the last aspects under investigation in terms of the nature of IS in buildings. These are:

1) Sensors

A sensor measures a physical amount and transforms it into a signal that is read by an observer or instrument. The sensor has to be placed so that it can provide information representing the amount measured, giving access for maintenance and calibration. Sensors might be inside or outside, but they are required for effective operation (CIBSE, 2002, p.3). Different forms of sensor technology have confirmed the capacity to deal with the difficulties of human activities in IB. which can be classified into the following groups:

 Direct environmental sensing

This form of sensing gives an important insight into real behaviour and situations, although it has practical and complex costs and can also generate privacy issues (Caine, 2005). This sensor includes: (1) simple binary sensors to detect those activities which indicate the occupant’s presence and positions in the building; (2) Video cameras and audio equipment which identify and follow the user, and generate detailed information on human monitoring and computer interpretation; (3) Radio frequency identification, which is used to identify the occupants. Authors such as Suzuki and Doi (2001, p.246) mention other sensors in the smart home environment, to help to reveal activities and the need for automatic services. For example, there are sensors which are linked with activities, such as working in a place, eating, and others. However, privacy is the most common issue linked to the use of sensor technology especially for specific buildings. Direct environment systems may give more detail regarding the actual situation and the occupants may not prioritise their privacy if it supports a genuine need.

 Mobile environmental sensing

These sensors include: (1) Wearable devices or implantable devices and Microsystems⁴ linked to a service centre by both wired and wireless networks, with the objective of obtaining concurrent biomedical signals (Chana et al., 2009, p.92);

and (2) robots, which interface with the outside via speech, visual displays, facial expressions and physical motions, to track people, make predictions about their

4Can be swallowed, such as microcapsule devices, which are now available (Cook and Song, 2009).

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behaviour, and respond in an appropriate way. Robots are designed to help people and range from the simplest to the most technologically sophisticated by facilitating household maintenance and observing those in need of ongoing care or for mail collection and delivery, and window cleaning in building (Ochoa and Capeluto,2006, p. 1130). The goal of this type of sensor is to help with, and enhance, the life quality for daily activities which might be used with people who live alone, especially the elderly.

 Infrastructure mediated systems

Infrastructure mediated systems need the implementation of single or multiple sensors besides the extant infrastructure of the building. For example, the degree of pressure alteration across all the sensors can be used to identify unique variations in airflow in the physical space due to human movements, such as when a person walks through a door, or when a door opens or closes (Patel et al. 2008, p. 15). A power line noise detector can be connected to a normal wall socket to detect a number of electrical events in the building, to detect the electrical noise on building power lines caused by the sudden turning on of electrical devices and the noise caused by particular devices being operated. Hydro Sense, a custom-made pressure sensor, may be connected to any accessible point in a building’s extant water infrastructure, to recognise individual fixtures at which water is in use, and to provide an estimate both of how much water is being used and water usage, with error rates which can be compared to water supplied by meters (Ding et al., 2011, p.132). It seems that this type of sensor helps the occupants to control building performance, such as water, ventilation and others functions.

2) Actuator

An actuator is a motor which moves or controls a system that reacts to the output signal from a controller and affords the mechanical action to control the device, such as a valve or damper (Li and Yu 2011, p.2090). Actuators may be classified into:

 Simple but distributed

In 2009, Cook and Song explained a simple actuator which has inspired them in smart environments, for example light switches, or complex systems, which can sometimes be hidden, for example remote controls for TV and Hi-Fi systems.

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 Complex but focused

Kuhnela et al. (2011, p. 693) highlighted another actuator which is difficult but focused, which is the cell phone. Users now use their phones for more than messaging, and are accustomed to the many interaction options provided by touch screens and motion sensors. Although so many features are covered by the phone, enhancing the mobility of life, at home there are still many separate applications with individual interfaces.

To interact with smart environments and an IS, the user might need actuators, and these two types of actuator could be applied in IB according to the lifestyle.