3. System overview and implementations
NeverStop has been designed to integrate into an intelligent
traffic lights management system ensuring that there is minimal
need for additional hardware, as is illustrated in Fig. 1. The system
is comprised of the following components:
EBOX II: the hardware package housing the NeverStop System
Controller and providing connectivity to the traffic lights, the RFID
device and the Central Server. This unit runs a customizedWindows
CE OS image.
Light Control Unit: the controller to interface with the traffic
lights and EBOX II. It may be consisted of one or several PCB(s).
RFID device: the device to send the car flow information to the
EBOX II. It normally contains the following components: tags, readers,
and antennas. We deploy the device both at the entrance and
the exit of the lane.
Central server: the server is in charge of making all the terminal
EBox work in parallel and provides references and historical
data. The central server primarily provides a means of guaranteeing
resilience in the accidental event of an unexpected catastrophic
failure of NeverStop.
Obtained with the above components, the system must adhere
to the following performance requirements:
(1) Frequency of RFID device
The RF tag works on a certain frequency. Taking our system
model into account, we choose ultra high frequency (UHF)
or microwave tag for mobile object identification. Usually, as
microwave RF tag, the effective distance for recognizing information
can reach 3–5 m.
(2) Power control
Both RFID reader and the light control circuit need power supply
modules. As the system is mainly installed in the city, the power
supply is provided with chargers.
(3) Active network connect
The limitation relies on an active network between central
servers and each terminal device. If connection is lost, NeverStop
could lose some functions that depend on the network running
environment. As in the case of multiple intersections, the micro
adjustment of time will be unavailable. Therefore, it is preferred
and desirable to deploy the NeverStop system on a local network
other than on the internet.
3.1. Design objectives
The design ofthe NeverStop system was guided by the following
key design objectives:
(1) Usability: NeverStop is deployed at the intersections to manage
the traffic. For convenience, the administrators do not need
to be aware of the detailed implementation due to that the NeverStop
is automatically configured. Therefore what is required is
just “one-click” initialization. At the same time, administrator can
supervise all the intersections at the server side in case that an
accident happens.
(2)Reliability: as the systemisdesignedto operate withoutuser’s
intervention, itis extremely importantthatthe system runs reliably
and has the ability to handle unexpected situations.
(3) Extensibility: the NeverStop system is designed for efficient
expansion in big data era. To ensure maximum portability and versatility,
it is imperative that the device configuration settings be
remotely obtained. This will enable the NeverStop system to grow
into new markets easily.