"Water Cube" LED landscape lighting and control system

The National Aquatics Centre is one of the main venues for the 2008 Beijing Olympic Games, where swimming, diving, synchronized swimming and water polo competitions will be held. National Swimming Center is located at the southern end of the Olympic Park, east of the National Stadium, building area of 80000m217000, is by far the world's largest swimming pool. After building landscape lighting demonstration program, the National Swimming Center by RGB LED, the fixed outer cushion structural steel frame, lateral projection light cloth, the "Water Cube" surface brightness, color and pattern to meet the requirements, the formation of certain scenes and models. This "cavity transparent" lighting and LED lighting this application has created a precedent.

The way of illumination, the way of cloth and the choice of light source

The National Swimming Center uses ETFE air pillow to form the outer envelope. The air pillow is composed of 3-4 layer ETFE film fixed on the metal frame, filled with air between each of the two ETFE layer, and a layer of ETFE gas pillow membrane near the middle of the cavity, according to the requirements of building thermal plated with silver spots, plating area were 10%, 20%, 30%, 50%, 65%, total air pillow 24 kinds of specifications. Inside and outside the air pillow is the steel frame. Because of this envelope decided "not for the" Water Cube "building landscape lighting way light", because there is no good reflector; are not suitable for the general lighting in light ", because light to light the 6 layer film, the optical loss is too large; are not suitable for contour lighting the" Water Cube ", because the air pillow facade has radian, but very smooth, not suitable for external lighting. We adopt the method of light transmission in the cavity. After fixing the outer frame of the air cushion, the cloth is arranged on the side of the metal frame, and the side surface is projected. In order to save energy, environmental protection and facilitate the formation of more lighting scenarios, we chose the LED light source.

Brightness index and power index

(1) brightness index

The brightness on building facades, the International Commission on illumination CIE regulations: City downtown area is 12cd/ m2, the general area of 6cd/ m2; Beijing city regulations on building the Olympic Park District facade lighting brightness is not higher than 6cd/ m2. According to the above provisions, we determined the National Swimming Center building landscape lighting four facade brightness is not higher than 6cd/ m2, the roof is not higher than 3cd/ m2.

(2) estimation of transmittance of ETFE film and air pillow

Due to the lowest LED blue light effect, and the human eye is not sensitive to blue light, so the calculation based on blue light. The X-ray rate of ETFE air cushion can be regarded as the product of the X-ray rate of three layer ETFE film. About 0.6.

(3) estimation of coefficient U

Assuming that the coefficient U is between 0.2-0.3.

(4) per watt LED- luminous flux to blue light, for example, the unit power (per watt) 10-15Lm. (6) ETFE air cushion per square meter surface power is about 6-15W, take 6W. After the test, for a large area of the ETFE air cushion facade brightness control at 2-4 cd/ M2 is appropriate.

Control system

Control system is the core component of landscape lighting system. Through comparison, we put forward the following design scheme: using IPv6 based real-time Ethernet networking solutions. With FPGA as the hardware carrier, all functions of the control node are realized on a single chip.

(1) using IPv6 real time Ethernet

Ethernet is the most widely used and most mature computer network. Ethernet based on TCP/IP is a standard open network, which has been the mainstream of the development of computer network technology. With rich software and hardware resources, low price. High communication rate. At present, the Ethernet communication speed is much faster than the fieldbus, Ethernet can meet the higher bandwidth requirements. Great potential for sustainable development. Due to the wide application of Ethernet, it attracts a lot of investment in technology. The IPv6 uses 128 bit address length, provide almost unlimited address, the introduction of IPv6 lighting control network, so that each source has an independent IP address, this will make the lighting control network function becomes particularly strong, in the transmission rate, network scale, remote control, system maintenance and other aspects are obtained to improve the quality of. When traditional Ethernet is used in control, the most important thing is to ensure the real-time problem. The traditional Ethernet uses the CSMA/CD medium access control mechanism, which has the problem of uncertain queuing delay and uncertain communication response. Under the premise of sacrificing some complex functions, the Ethernet protocol is modified and reduced to a certain extent, so that the Ethernet has real time.

(2) the FPGA field programmable logic chip

As the basic composition and the main hardware carrier, network nodes should have the following characteristics and functions:

The autonomy system: each node over the network to connect the nodes independent to complete their tasks, and the node capacity can be expanded, the supporting software configuration can be loaded at any time, is a high reliability subsystem independent operation. Coordination: through the real-time and reliable control of the local network to achieve the transmission of data sharing, between the nodes from the overall function and optimization of the process of full coordination. Linear and real-time: through a large number of I/O interface, real-time control and detection of the control object, at the same time, network routing, configuration loop online modification, local fault online maintenance. Reliability: the use of fault-tolerant design from the structure, so that in the case of failure of any node,