GB2490536A

GB2490536A - Environmental condition control system using wireless signal strength

Info

Publication number: GB2490536A
Application number: GB1107530.6A
Authority: GB
Inventors: Siok Kheng Tan; Georgios Kalogridis; Zhong Fan; Costas Efthymiou
Original assignee: Toshiba Research Europe Ltd
Current assignee: Toshiba Europe Ltd
Priority date: 2011-05-05
Filing date: 2011-05-05
Publication date: 2012-11-07
Anticipated expiration: 2031-05-05
Also published as: GB2490536B; GB201107530D0

Abstract

A system for controlling an environmental condition, such as lighting or temperature, in a targeted space, the system comprising at least one sensor device 141 for detecting an environmental condition and providing a corresponding detected signal, a plurality of environmental condition varying devices 150, such as LED lights, for varying the environmental condition of the targeted space, wherein the sensor device and the environmental condition varying devices are equipped with wireless communication means 141a, 150a for communicating with each other. The system further includes a controller 143 configured to determine an estimation of the environmental condition provided by each of the environmental condition varying devices based on a signal strength of a signal sent from each of the environmental condition varying devices to the sensor device, and to compare a detected signal from the sensor device with a predetermined environmental condition value, and to generate a control signal to control at least one of the environmental condition devices based on the estimation. Distance may be determined between the sensor and each light based on the signal strength.

Description

I

ENVIRONMENTAL CONDITION CONTROL METHOD AND APPARATUS

Field

Embodiments described herein relate generally to controlling an environmental condition over a targeted space.

Back round Energy efficiency and management are some of the key green topics across a number of industries. This is due to increased awareness of energy crisis and conservation.

Lighting control is becoming easier to integrate with the development of wireless lighting systems This is due to the ease of installation which allows the wireless lighting system to be easily incorporated in various indoor environments, For example, the control of wireless lighting can be implemented using light sensors at short range using wireless technologies such as ZigBee'.

LED (Light Emitting Diode) light bulbs, which have been the focus of attention as the next generation of light sources, have recently become available in the market in "light bulb" shapes. These LED light bulbs can reduce energy consumption by up to 87% and can last forty times longer than conventional incandescent light bulbs. The combined energy efficiency with high performance makes them an ideal éco-friendly lighting solution for homes and businesses.

Descrjptkn of the drawinq Embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates an arrangement of a lighting system deployed in a targeted area according to a described embodiment; Figure 2 is a block diagram representation of a lighting control system for controlling the lighting system as illustrated in Figure 1; Figure 3 is a flow diagram of a process of determining neighbouring LED lamps according to a described embodiment; Figure 4 is a light sensor neighbour list according to an embodiment; Figure 5 is a LED lamp neighbour list for a light sensor according to an embodiment; Figure 6 is a flow diagram of a process of determining the intensity of each of the LED lamps according to an embodiment; Figure 7 is a flow diagram of a process of preparing a light adjustment process according to an embodiment; and Figure 8 is a flow diagram of a process of light adjustment according to an embodiment of the invention;

DETAILED DESCRIPTION

Specific embodiments will be described in further detail in the following paragraphs on the basis of the attached figures. It will be appreciated that this is by way of example only, and should not be view as presenting any limitation on the scope of protection sought.

According to one embodiment there is provided an apparatus for controlling an environmental condition in a targeted space, the targeted space comprising a plurality of environmental condition varying devices for varying the environmental condition of said targeted space, and at least one sensor device for detecting an environmental condition and providing a corresponding detected signal, the environmental condition varying devices and the sensor device being in communication with the apparatus, wherein the environmental condition varying devices and the sensor device further comprising wireless communication means for communicating with each other, including receiving, at the sensor device, a signal from each of the environmental condition varying devices, the apparatus comprising a controller operable to control said wireless communication means of each of said plurality of environmental condition varying devices to send a wireless signal to said wireless communication means of said sensor device, and upon receiving said wireless signal, the wireless communication means of said sensor device generates an output signal, a receiver for receiving said output signal from said wireless communication means of said sensor device, a signal processor operable to determine signal strength information based on said output signal, and is further operable to determine an estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined signal strength, wherein the receiver is further configured to receive a detected signal from said sensor device, and the signal processor is configured to compare said detected signal with a predetermined environmental condition value, and is further configured to generate a control signal for the controller to control at least one of the plurality of the environmental condition devices based on said estimation of the environmental condition to achieve an environmental condition that is substantially close to the predetermined environmental condition in the targeted space.

The signal processor may be further operable to determine a distance between said sensor device and each of said environmental condition varying devices based on said determined signal strength.

The signal processor may be further operable to determine said estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined distance.

The controller may be configured to identify environmental condition varying devices within a vicinity of said sensor device.

The controller may be further configured to identify sensor devices within a vicinity of said sensor device.

The controller may be further configured to identify said environmental condition varying devices that are within the vicinities of two or more said sensor devices.

The signal processor may be further operable to determine a difference between said detected signal and said predetermined environmental condition value.

The signal processor may be further operable to control at least one of the plurality of said environmental control devices that provides an estimated environmental condition that is substantially close to said difference.

The plurality of environmental condition varying devices may include LED lamps, and said sensor device includes a light sensor.

In another embodiment there is provided an environmental control system for controlling an environmental condition in a targeted space, the environmental control system comprising at least one sensor device for detecting an environmental condition and providing a corresponding detected signal, wherein said sensor device comprises wireless communication means for establishing a communication link with another neighbouring device, a plurality of environmental condition varying devices for varying the environmental condition of the targeted space, wherein each of the plurality of environmental condition varying devices comprises wireless communication means for establishing a communication link with said sensor device, a controller operable to control said wireless communication means of each of said plurality of environmental condition varying devices to send a wireless signal to said wireless communication means of said sensor device, and upon receiving said wireless signal, the wireless communication means of said sensor device generates an output signal, to the controller, the controller is operable to determine signal strength information based on said output signal, the controller is further operable to determine an estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined signal strength, wherein the controller, upon receiving said detected signal from said sensor device, is configured to compare said detected signal with a predetermined environmental condition value, and is further configured to generate a control signal to control at least one of the plurality of the environmental condition devices based on said estimation of the environmental condition to achieve an environmental condition that is substantially close to the predetermined environmental condition in the targeted space.

The controller may be further operable to determine a distance between said sensor device and each of said environmental condition varying devices based on said determined signal strength.

The controller may be further operable to determine said estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined distance.

The controller may be configured to identify said environmental condition varying devices that are within the vicinities of two or more said sensor devices.

The controller may be further configured to determine a difference between said detected signal and said predetermined environmental condition value.

The controller may be further configured to control at least one of the plurality of said environmental control devices that provides an estimated environmental condition that is substantially close to said difference.

According to another embodiment there is provided a method of controlling an environmental condition in a targeted space, the targeted space comprising a plurality of environmental condition varying devices for varying the environmental condition of said targeted space, and at least one sensor device for detecting an environmental condition and providing a corresponding detected signal, the environmental condition varying devices and the sensor device being in communication with the apparatus, wherein the environmental condition varying devices and the sensor device further comprising wireless communication means for communicating with each other, including receiving, at the sensor device, a signal from each of the environmental condition varying devices, the method comprising controlling said wireless communication means of each of said plurality of environmental condition varying devices to send a wireless signal to said wireless communication means of said sensor device, such that upon receiving said wireless signal, the wireless communication means of said sensor device generates an output signal, receiving said output signal from said wireless communication means of said sensor device, determining signal strength information based on said output signal, and determining an estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined signal strength, receiving a detected signal from said sensor device, and comparing said detected signal with a predetermined environmental condition value, and generating a control signal for the controller to control at least one of the plurality of the environmental condition devices based on said estimation of the environmental condition to achieve an environmental condition that is substantially close to the predetermined environmental condition in the targeted space.

The step of determining said estimation of the environmental condition provided by each of the environmental condition varying devices may further include determining a distance between said sensor device and each of said environmental condition varying devices based on said determined signal strength.

In one embodiment, the method may comprise determining said estimation of the environmental condition provided by each of the environmental condition, varying devices based on said determined distance.

In another embodiment, the method may comprise identifying environmental condition varying devices within a vicinity of said sensor device.

In yet another embodiment, the method may comprise identifying sensor devices within a vicinity of said sensor device.

In an embodiment, the method may comprise identifying said environmental condition varying devices that are within the vicinities of two or more said sensor devices.

The method may further comprise determining a difference between said detected signal and said predetermined environmental condition value.

The method may further comprise controlling at least one of the plurality of said environmental control devices that provides an estimated environmental condition that is substantially close to said difference.

One embodiment provides a computer program product comprising computer executable instructions which, when executed by a computer, cause the computer to perform a method as set out above. The computer program product may be embodied in a carrier medium, which may be a storage medium or a signal medium. A storage medium may include optical storage means, or magnetic storage means, or electronic storage means.

The described embodiments can be incorporated into a specific hardware device, a general purpose device configure by suitable software, or a combination of both.

Aspects can be embodied in a software product, either as a complete software implementation, or as an add-on component for modification or enhancement of existing software (such as a plug in). Such a software product could be embodied in a carrier medium, such as a storage medium (e.g. an optical disk or a mass storage memory such as a FLASH memory) or a signal medium (such as a download).

Specific hardware devices suitable for the embodiment could include an application specific device such as an ASIC, an FPGA or a DSP, or other dedicated functional hardware means. The reader will understand that none of the foregoing discussion of embodiment in software or hardware limits future implementation of the invention on yet to be discovered or defined means of execution.

An overview of a deployment of a lighting system is illustrated in Figure 1. Referring to Figure 1, an indoor space 10 (for example a warehouse, an office space, or a house) having wall partitions 14 fitted therein is shown. The indoor space 10 is divided into section A, section B, section C, and section D, and the LED lamps and the light sensors are deployed randomly in the indoor space 10. Section A includes a light sensor I and LED lamps 100, 102. Section B includes light sensors 8, 9 and LED lamps 106, 108, 122, 124, 126. in sections C and D, light sensors 2, 3, 4, 5, 6, 7 are implemented, and LED lamps 104, 110, 112, 114, 116, 118, 120 are deployed.

A lighting control system for controlling the lighting system of Figure 1 will now be described in more detail with respect to Figure 2.

Figure 2 shows schematically components of a lighting control system 12. The lighting control system 12 includes a light sensor 141, LED lamp(s) 150, and a controller 143.

The LED lamps and the light sensors are equipped with wireless communication units (150a and 141a respectively), for example ZigbeeTM standard, and are connected to antennas 150b and 141b respectively.

The controller 143 comprises an input/output (I/O) interface 144, a communication unit 145, a working memory 148, a processor 147, and a mass storage unit 146. For the sake of simplicity, only one of the light sensors (for example, the light sensor 8 as illustrated in Figure 1) deployed in a particular section of the indoor space 10 is described in this example. However, it is noted that the skilled person would understand that more than one light sensor can also be connected to the controller 143 to control LED lamps in other sections of the indoor space 10. In an alternative configuration, the controller 143 may also be integrated with the light sensor 141.

The light sensor 141 is connected to the controller 143 to monitor and/or measure the intensity of light in a section of the indoor space 10. The person skilled in the art will appreciate that any suitable sensors for monitoring or measuring the intensity of light may be employed.

An output of the light sensor 141 is connected to the signal processor 147 via the I/O interface 144 of the controller 143. By this connection, the measured intensity signals can be input to the signal processor 147. The I/O interface 144 also includes an analogue-to-digital converter (ADC) (not shown) which converts the analogue output signals from the light sensor 141 into digital input signals. By means of a general purpose bus 142, external devices (such as the light sensor 141 and the LED lamps 150) through the I/O interface 144 are in communication with the signal processor 147.

Communication unit 145 is connected on the one hand to the general purpose bus 142, and on the other hand to an antenna 149. By means of the communication unit 145 and the antenna 149, the controller 143 is capable of establishing wireless communication with another device (for example, a remote station, the light sensor 141, or the LED lamps 150). Therefore, in an alternative embodiment, the light sensor 141 and the LED lamps 150 can communicate with the controller 143 via a wireless communication link, as opposed to being physically connected to the controller 143.

The signal processor 147 is operable to execute machine code instructions stored in a working memory 148 and/or retrievable from a mass storage unit 146. The signal processor 147 processes the incoming signals according to the method described in the forthcoming paragraphs.

In the described embodiment, the total number of LED lamps is greater than the total number of light sensors such that each of the light sensors controls more than one LED lamp. However, it is noted that this does not prevent the method from being employed in a set up where one light sensor controls one LED light. Wireless signal strength measured by a light sensor provides a good indication of distance between an LED light source and the light sensor. It is noted that a LED light source and a light sensor which are near to each other in a wireless signal space may not necessary be close to each other in a light space. In particular, where there is a partition between them, light is obstructed and therefore the LED light source and the light sensor belong to two different lighting environments under this condition.

During the initialisation process, each of the light sensors will identify their "neighbours". In this example, the neighbours can be in the wireless signal space or the light space. In the wireless signal space, a neighbour is referred to as a node (for example a LED light or a light sensor) which is in radio range with the current node. In the wireless space, a neighbour node can be located at the other side of a partition because wireless signal can travel through walls or multi-path propagation.

Conversely, in the light space, a neighbour is constrained within the same physical space as the node in question, as light cannot pass through a partition.

As shown in Figure 3, all the LED lamps deployed in the targeted space (such as an indoor space described above) are switched on (step 40a). Each of the light sensors measures the overall light intensity respectively (step 40b). This process is to allow the controller 143 to record the maximum overall intensity which is detected by each of the light sensors at a given time. It will be appreciated by the person skilled in the art that this also provides an indication of the maximum level of light brightness that can be achieved over the targeted space. This process can be carried out (1) when the light sensors and the LED lamps are initially deployed in an unknown targeted space, (2) at different times of the day to take into account the different level of ambient light at different times of a day. In a targeted space which is not exposed to ambient light, the maximum overall intensity measured at different times of the day is likely to remain the same.

The following steps are carried out by the controller 143 to detect neighbouring LED lamps of a light sensor.

(1) The controller 143 sends a control signal to the light sensor 141 to broadcast an INViTE message to all the LED lamps that are within a broadcast range of that light sensor (step 40c). As discussed above, the light sensor 141 and the LED lamps 150 are equipped with wireless communication units (141a and 150a respectively) to allow them to communicate with each other. The controller 143 can also send the contra: signal through to the light sensor 141 via a wireless channel using the communication unit 145.

(2) In step 40d, each of the LED lamps 150 that are within the broadcast range of the light sensor 141 sends a REPLY message to the light sensor 141 within a predetermined time period to indicate that it is within the vicinity of the light sensor 141.

(3) Upon receiving the REPLY messages, the light sensor 141 then allocates a time frame for each of the LED lamps 150 (step 40e). The light sensor 141 then sends a INSTRUCT message, in step 40f, to instruct each of the LED lamps 150 to switch off their lights during the respective allocated time frame.

(4) Each of the LED lamps 150 upon receiving the INSTRUCT message switches off and sends an acknowledgement message ACK" to the light sensor 141 to indicate that it has been switched off (steps 40g and 40h).

(5) The light sensor 141 upon receiving the ACK message, measures the overall light intensity of the targeted space to determine the difference in the overall light intensity when a particular LED lamp is off (step 40i).

(6) If there is no difference in the light intensity when a particular LED light is switched off, the controller 143 will record that the particular LED lamp is not a neighbour of the light sensor 141 in that section.

(7) If there is a difference in the measured light intensity when a particular LED lamp is switched off, that LED lamp is recorded as a neighbour of the light sensor 141 in the light space.

(8) It is noted that all the messages include sender's ID and receiver's ID.

Once all the LED lamps have been switched off, the controller 143 generates a list of LED lamp neighbours with respect to the light sensor 141 (step 40j). An example of the LED lamp neighbour (LLN) list is illustrated in Figure 5. Figure 5 illustrates an example of the LED lamp neighbour (LLN) list with respect to light sensor 8. As shown in Figure 5, the LED lamp neighbour list also includes the overall light intensity detected at the light sensor 8 when all the LED lamps are switched on at the initialisation phase. The LED lamp neighbours detected by sensor 8, in this example, are 106, 108, 124, and 122.

In an embodiment, the discovery of neighbouring light sensors for a light sensor can be achieved by intercepting a message sent by a particular light sensor. Any suitable methods of intercepting a message may be employed. For this reason, details of the light sensor will not be described. Figure 4 illustrates a light sensor neighbour (LSN) list. Figure 4 illustrates the light sensor neighbour list for the light sensor 8 whose neighbours includes light sensor 9, 7, and 6.

All the information is collected at the controller 143 with respect to each of the light sensors deployed in the targeted space. Essentially, the light sensors and the LED lamps communicate which each other and the controller 143 in a mesh network configuration. This provides an advantage that no extra infrastructure is required to support the lighting control system and any changes to the network can be supported at any time. It is further noted that a mesh network provides a reliable networking solution as signals can be routed around obstacles. Essentially, the controller 143 holds a record of the LED lamp neighbour (LLN) list and the light sensors neighbour (LSN) list to allow the controller 143 to make decisions as to which of the LED lamps are to be adjusted, when required.

The controller 143 is configured to determine the intensity of light emitted by an LED lamp based on signal strength of a wireless signal transmitted by a wireless communications device of that LED lamp and received by a wireless communications device of the light sensor. For example, this can be achieved by initially providing the controller with information on the transmission (reference) power of the wireless signal of the wireless communications device of each of the LED lamps. The wireless communications device of the LED lamp then transmits a wireless signal to the wireless communications device of the light sensor. The wireless communications device of the light sensor upon receiving the wireless signal passes the received signal to the controller 143 to determine the signal strength of the received signal using the information of the transmission (reference) power of the wireless signal and the actual received power of the wireless signal. The distance between the light sensor and the LED lamp is then estimated based on the determined received signal strength. The intensity of light as a function of distance from the light source can be determined based on an inverse square relationship. This allows the intensity of an LED lamp that can be detected by the light sensor to be determined without measuring the actual intensity of light emitted by that LED lamp. This is advantageous because a new LED lamp can be added at anytime to an existing lighting system, without re-calibrating the lighting system. It is of course noted that other methods of determining the intensity of the LED lamp can also be employed.

It is noted that some of the deployed LED lamps may emit light which can be detected at more than one light sensor. Basically, when a light adjustment decision of an LED lamp is made with respect to a light sensor, it could also affect the overall intensity detected at another neighbouring light sensor. Therefore, it is important to determine which of the LED lamps is solely detected and controlled by one light sensor and which of the LED lamps is detected and controlled by more than one light sensor.

Figure 7 illustrates the process of dividing the LED lamps into two groups, namely sole control LLN (SoC-LLM), and share control LLN (ShC-LLN). In an embodiment, the LED lamps on the SoC-LLN list will be first considered for adjustment when the overall light intensity adjustment is required.

As shown in Figure 7, once the controller 143 has generated the LLN list and the LSN list, the number of neighbouring light sensors associated with a light sensor is determined in the initialisation process (step 64). The initialisation process (step 64) also creates a SoC-LLN list and a ShC-LLN list. Next, the LLN list of the light sensor is compared with the LLN list of another neighbouring light sensor. It is then determined whether there are any common LED lamps in the two LLN lists (step 68). The LED lamps that do not appear on both LLN lists are recorded on the SoC-LLN list (step 70).

Whereas, the LED lamps that appear on both LLN lists are recorded on the ShC-LLN list (step 72). The process continues until the LLN lists of all the neighbouring light sensors have been compared with the LLN list of the light sensor.

Once the SoC-LLN list and the ShC-LLN list are generated, a process as shown in Figure 6 is carried out to determine the distances of each of the light sensors and the neighbouring LED lamps with respect to the light sensor in question. As described in the foregoing paragraphs, the distances can be determined using wireless signal strength information.

The lighting adjustment procedure will now be described in the following paragraphs.

The aim of the lighting adjustment procedure is to determine the combination of LED lamps to be switched on or off in order to achieve a required level of intensity in the targeted space. In an embodiment, the influence of ambient light at different times of the day is taken into consideration.

The lighting adjustment procedure according to an embodiment of the invention will now be described with reference to Figure 8.

As shown in Figure 8, in step 80, the current light overall intensity (CLOI) at a light sensor is determined. This can be achieved by determining the LED lamps which are currently switched on. The result is compared with a predetermined required overall intensity (ROl) level (step 82). if the CLOI measurement is greater than the ROL level, the controller 143 will determine which of the LED lamps are to be switched off (step 84). Accordingly, the determined LED lamps are then switched off in step 84a. If the CLOI is lower than the ROl level, the controller 143 will determine which of the LED lamps are to be switched on (step 86). Accordingly, the controller 143 switches on the determined LED lamps (step 86a).

The overall intensity level at the light sensor is again measured in step 88. In step 90 the CLOI measurement is compared with the ROl level. If the CLOI measurement is greater than the ROI measurement, the "excess intensity" needs to be determined.

This can be simply achieved by calculating the difference between CLOI measurement and the ROL level. If the excess intensity level is below a predetermined threshold, no further action will be taken. if the excess intensity exceeds the predetermined threshold, the controller 143 will identify an LED lamp that provides an intensity level that is closest to the excess intensity. The controller then sends a control signal to switch off the identified LED lamp to reduce the overall intensity level (step 96).

If the CLOI measurement is not greater than the ROl level, the additional intensity required to achieve the required overall intensity level is determined. This can be determined simply by subtracting the CLOI measurement from the ROI level in step 98.

Next, the controller 143 selects the LED lamp that provides an intensity level that closely matches the additional intensity required. The selected LED lamp is then switched on. The procedure continues until the required overall intensity measurement is achieved to provide an optimum level of brightness required in the targeted space.

Although the examples above describe switching (on or off) a selected LED lamp from a LLN list, it would be appreciated by the person skilled in the art that more than one LED lamp can also be selected at any time in order to obtain the required intensity in the targeted space. Furthermore, it will also be understood by the skilled person that, in some applications, fine control of brightness (intensity) of a LED lamp can also be manipulated to achieve the required intensity level.

It will be appreciated by the person skilled in the art that although examples provided herein are directed to lighting systems, the methods and apparatus described can also be applied to any environmental control system. For example, the described method can be applied to control temperature and humidity of a targeted space. This can be achieved, for example, by deploying one or more temperature sensors and fans (or air conditioning systems) in the targeted space.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions, Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

Claims

CLAIMS: 1. An apparatus for controlling an environmental condition in a targeted space, the targeted space comprising a plurality of environmental condition varying devices for varying the environmental condition of said targeted space, and at least one sensor device for detecting an environmental condition and providing a corresponding detected signal, the environmental condition varying devices and the sensor device being in communication with the apparatus, wherein the environmental condition varying devices and the sensor device further comprising wireless communication means for communicating with each other, including receiving, at the sensor device, a signal from each of the environmental condition varying devices, the apparatus comprising: a controller operable to control said wireless communication means of each of said plurality of environmental condition varying devices to send a wireless signal to said wireless communication means of said sensor device, and upon receiving said wireless signal, the wireless communication means of said sensor device generates an output signal; a receiver for receiving said output signal from said wireless communication means of said sensor device; a signal processor operable to determine signal strength information based on said output signal, and is further operable to determine an estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined signal strength; wherein the receiver is further configured to receive a detected signal from said sensor device, and the signal processor is configured to compare said detected signal with a predetermined environmental condition value, and is further configured to generate a control signal for the controller to control at least one of the plurality of the environmental condition devices based on said estimation of the environmental condition to achieve an environmental condition that is substantially close to the predetermined environmental condition in the targeted space.
2. An apparatus according to claim 1, wherein said signal processor is further operable to determine a distance between said sensor device and each of said environmental condition varying devices based on said determined signal strength.
3. An apparatus according to claim 2, wherein said signal processor is further operable to determine said estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined distance.
4. An apparatus according to any one of the preceding claims, wherein said signal processor is further configured to determine a difference between said detected signal and said predetermined environmental condition value.
5. An apparatus according to claim 4, wherein said signal processor is further configured to control at least one of the plurality of said environmental control devices that provides an estimated environmental condition that is substantially close to said difference.
6. An environmental control system for controlling an environmental condition in a targeted space, the environmental control system comprising: at least one sensor device for detecting an environmental condition and providing a corresponding detected signal, wherein said sensor device comprises wireless communication means for establishing a communication link with another neighbouring device; a plurality of environmental condition varying devices for varying the environmental condition of the targeted space, wherein each of the plurality of environmental condition varying devices comprises wireless communication means for establishing a communication link with said sensor device; a controller operable to control said wireless communication means of each of said plurality of environmental condition varying devices to send a wireless signal to said wireless communication means of said sensor device, and upon receiving said wireless signal, the wireless communication means of said sensor device generates an output signal to the controller, the controller is operable to determine signal strength information based on said output signal, the controller is further operable to determine an estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined signal strength; wherein the controller, upon receiving said detected signal from said sensor device, is configured to compare said detected signal with a predetermined environmental condition value, and is further configured to generate a control signal to control at least one of the plurality of the environmental condition devices based on said estimation of the environmental condition to achieve an environmental condition that is substantially close to the predetermined environmental condition in the targeted space.
7. An environmental control system according to claim 6, wherein said controller is further operable to determine a distance between said sensor device and each of said environmental condition varying devices based on said determined signal strength.
8. An environmental control system according to claim 7, wherein said controller is further operable to determine said estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined distance.
9. An environmental control system according to any one of claims 6 to 8, wherein said controller is further configured to determine a difference between said detected signal and said predetermined environmental condition value.
10. An environmental control system according to claim 9, wherein said controller is further configured to control at least one of the plurality of said environmental control devices that provides an estimated environmental condition that is substantially close to said difference.
11. A method of controlling an environmental condition in a targeted space, the targeted space comprising a plurality of environmental condition varying devices for varying the environmental condition of said targeted space, and at least one sensor device for detecting an environmental condition and providing a corresponding detected signal, the environmental condition varying devices and the sensor device being in communication with the apparatus, wherein the environmental condition varying devices and the sensor device further comprising wireless communication means for communicating with each other, including receiving, at the sensor device, a signal from each of the environmental condition varying devices, the method comprising: controlling said wireless communication means of each of said plurality of environmental condition varying devices to send a wireless signal to said wireless communication means of said sensor device, such that upon receiving said wireless signal, the wireless communication means of said sensor device generates an output signal; receiving said output signal from said wireless communication means of said sensor device; determining signal strength information based on said output signal, and determining an estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined signal strength; receiving a detected signal from said sensor device, and comparing said detected signal with a predetermined environmental condition value, and generating a control signal for the controller to control at least one of the plurality of the environmental condition devices based on said estimation of the environmental condition to achieve an environmental condition that is substantially close to the predetermined environmental condition in the targeted space.
12. A method according to claim 11, wherein the step of determining said estimation of the environmental condition provided by each of the environmental condition varying devices further includes determining a distance between said sensor device and each of said environmental condition varying devices based on said determined signal strength.
13. A method according to claim 12, further comprising determining said estimation of the environmental condition provided by each of the environmental condition varying devices based on said determined distance.
14. A method according to any one of claims 11 to 13, further comprising determining a difference between said detected signal and said predetermined environmental condition value.
15. A method according to claim 14, further comprising controlling at least one of the plurality of said environmental control devices that provides an estimated environmental condition that is substantially close to said difference.