978-1-4799-0059-6/13/$31.00 ©2014 IEEE

ZigBee Wireless Communication for Monitoring Renewable Street Light System

Thinaharan Ramachandran United Embedded Technology

No 22A-2A, Jalan Temenggung 7/9, Seksyen 9, Bandar Mahkota Cheras, 43200, Cheras

Selangor, Malaysia rthinaharan@gmail.com

Low Tang Jung

Computer & Information Sciences Department Universiti Teknologi PETRONAS

Bandar Seri Iskandar, 31750 Tronoh, Perak, lowtanjung@petronas.com.my

Vasaki Ponnusamy, Faculty of Integrative Sciences and Technology

Quest International University Perak Jalan Raja Permaisuri Bainun, 30250 Ipoh

vasaki.ponnusamy@gmail.com,

Anang Hudaya

Faculty of Information Science and Technology (FIST), Multimedia University,

Jalan Ayer Keroh Lama, 75450 anang.amin@mmu.edu.my

Abstract— The advancement of technology brings advantages to human race to certain extent. Unfortunately, some of the technological inventions not only brings advantages, but also disadvantages. One of the disadvantages is the pollution of environment. Therefore, to prevent the pollution from getting worse, environmental-friendly aspect is suggested to be included in new inventions nowadays. Thanks to the invention of solar panel, solar energy is able to become a renewable energy source that can be applied to various applications. Considering the increase of electricity consumption every year in Malaysia, solar powered street lighting system is proposed in order to reduce the burning of fossil fuels to generate electricity, hence reducing air pollution. The street lighting system will consist of automated switching mechanism to further reduce the electricity consumption of street lights. The system will also be able to provide energy measurement to determine the efficiency of street lights. Some security features provided by selected wireless communication protocol will also be implemented to secure the system.

Keywords—ZigBee, energy harvesting, street light system, renewable energy

I. INTRODUCTION It has been few decades since the existence of street light in urban areas. The first modern street light was implemented in Austrian Empire in 1853 [1]. The Austrian street lights were powered by the use of kerosene. However, carbon arc lights were introduced to replace kerosene street lights due to the risk of using kerosene. As in 1880, defective kerosene street lights caused nearly two of every five fires in New York City [2]. Carbon arc light composes two carbon-made electrodes and alternating current is used to ensure consumption of both electrodes is in equal rates. It was the first widely-used type of electric street lighting. The title of ‘First City of Light’ was

given to Tamworth, New South Wales in Australia due to the first location to implement the arc lights as the city’s street lights in 1888 [3]. Although the emergence of arc light as street light prevents the use of kerosene, it has its disadvantages. Most notably is the rapid consumption of carbon rods that causes heavily use of human resource as technicians have to replace the carbon rods after a short period of time, making it not user-friendly. The invention of incandescent light bulb replaced the use of arc light as street lighting. By heating the filament wire to a very high temperature with electric current passing through it, incandescent light bulb produces light without using carbon electrodes. This solved the rapid electrode consumption of arc light. However due to efficiency issue (converting less than 5% of energy used into visible light compared to other types of lighting), incandescent light bulb is forced to undergo another development for the use of street lighting system. Today, high pressure sodium (HPS) lights are commonly used in street lighting system [4]. Compared to incandescent light, HPS light provides the greatest amount of photopic vision with the least amount of electricity consumption, solving the efficiency issue and hence making it a more reliable technology than the previous. Wireless communication has become widely used technology nowadays. Examples of wireless service are telemetry control and traffic control systems, infrared and ultrasonic remote control devices, Global Positioning System (GPS), cordless computer peripherals and more [5]. These applications have clearly showed that wireless technology aids us to solve many problems and achieve more convenient lifestyle. Therefore, it is suggested that our street light to be integrated with wireless technology so as to improve management and maintenance. Some researchers have [6-7] already thought of this idea and have developed street lighting

system using GPRS transmission, power line carrier transmission or GSM. However, according to the document RFC 5548 (2009) – Routing Requirements for Urban Low-Power and Lossy Networks, where ‘Sensing and actuating nodes placed outdoors in urban environments so as to improve people’s living conditions as well as to monitor compliance with increasingly strict environmental laws. These field nodes are expected to measure and report a wide gamut of data (for example, the data required by applications that perform smart-metering or that monitor meteorological, pollution, and allergy conditions). Majority of these nodes are expected to communicate wirelessly over a variety of links such as IEEE 802.15.4, low-power IEEE 802.11, or IEEE 802.15.1 (Bluetooth), which given the limited radio range. And these large number of nodes require the use of suitable routing protocols’ [8], it is suggested that Zigbee (IEEE 802.15.4), WIFI (IEEE 802.11), and Bluetooth (IEEE 802.15.1) are more suitable wireless communication technology to be used in urban area compared to GPRS transmission or GSM.

In this research project as shown in Fig.1, ZigBee technology will be implemented in the solar based smart street light design with remote service management system. Besides that, the project also involves the design of smart street lighting system. The design of the smart street light system comprises of three major aspects which is the implementation of smart street light control system, the use of an environment friendly energy resource and to provide a surveillance security system. The microcontroller connects and controls sensors, voltage and current measurement. The controller will control the camera and the motion detection for monitoring environment in a residential area against theft, crime or malicious attacks. The overall idea of this project proposal is to implement street lighting system with sustainability, consistency and reliability.

Fig. 1. Data Communication of The System using ZigBee Module

II. PROBLEM STATEMENT Street lighting system in Malaysia is still designed based on previous reliability standards and does not get benefit of latest technological developments. Although HPS light is the most commonly used lighting for street light, it is still a not so appropriate solution for night lighting when scotopic/photopic light calculations are used. White light sources have been shown to double driver peripheral vision and increase driver brake reaction time at least 25% [9]. Therefore, use of technology for the sources of light needs to be considered. Moreover Malaysia’s electricity generating capacity increased by 20% between 2000 and 2009, and is projected to increase

further by almost 3% per year [10]. The more electricity is needed, the more fossil fuels need to be burned to obtain electricity. Burning of fossil fuels such as oil, coal, gas creates by-products such as CO2, SO2 which will cause air pollution when released into the air. Therefore, a renewable energy must be considered to prevent air pollution and to help sustain the increase of electricity demand in Malaysia.

A. Objectives • To implement solar panel as the primary source energy to

recharge street light DC battery. • To conduct efficiency monitoring of street light based on

energy measurement from the solar and battery. • To implement a security system using the motion detector

and camera to report for unforeseen situation in the surrounding area like theft and intrusion.

• To initiate a remote method invocation registry service for each street light to ease the process of notifying the status of each street light that is connected in the network structure.

B. Related Works Immanuel Schweizer, Nils Fleischhacker, Dirk Bradler, Max Muhlhauser and Thorsten Strufe [11] proposed an approach called Solar-aware Distributed Flow (SDF) to maximize the sampling rate in solar wireless sensor networks. SDF allows each node to predict the harvested energy and compute a sustainable flow and control its local neighborhood. Hence, feasibility can be achieved in solar sensor networks as SDF approach is able to overcome energy constraints, which is a hard bound on sensor networks. The notion of the energy consumption rate is also introduced to allow perceptual operation. SDF achieved over 80% of the theoretical optimum based on extensive simulation. Cesare Alippi and Christian Galperti [12] proposed Maximum Power Point Tracker (MPPT) circuit that is specifically designed for wireless sensor network. MPPT is a power transferring circuit that conveys solar energy into rechargeable batteries for the network. Therefore, wireless sensor network that deploys MPPT no longer rely on battery (which is a finite resource) as energy supply. An ad hoc adaptive algorithm is introduced to maximize energy transfer from the solar cell to the batteries, thus keeping the MPPT electronics in optimal working point and achieve high efficiency. The implementation is particularly effective even in critical weather conditions. As MPPT is designed for low power operations, experimental results showed that high energy transfer rate is generated when the cell is in shadow or the weather is cloudy, where existing solutions for wireless sensor network nodes do not produce energy in such situations. Thiemo Voigt, Adam Dunkels, Juan Alonso, Hartmut Ritter, and Jochen Schiller [13] proposed to utilize solar power in wireless sensor networks and extend LEACH (a well-known cluster-based protocol) for networks to become solar-aware. The aim of this protocol is to extend the life-time of the sensor network by preferably choosing solar-powered nodes to

perform the energy intensive task if being a cluster head. Simple heuristics that has shown good results in test cases is used to choose cluster head. The simulations showed that making LEACH solar-aware increases the lifetime of a sensor network in typical scenarios. A handover scheme that allows changes of cluster heads during steady-state phase of the LEACH protocol was also presented and evaluated for solar-aware version of the centralized LEACH protocol. Chaitanya Amin, AshutoshNerkar, Paridhi Holani, and Rahul Kaul [14] proposed GSM based autonomous street illumination system for efficient power management. GSM is used as the communication medium between the concentrator controller and control center. Microcontroller C8051F350 is installed on each street light to control various sensors and GSM SIM300 module is installed for wireless communication. The main challenge of hardware is to produce low cost and tiny sensor nodes. Power theft control was also proposed to be added into the system. Deepak Kapgate [15] proposed a wireless streetlight control system with Jennic Wireless Microcontroller JN-5139 which is an IEEE802.15.4 based wireless microcontroller as communication between street lights and monitoring software. The duration of the operation of street lights is taken into concern. The project also aimed to increase frequency band for network nodes to get maximum possible data rate. Result showed that the duration of street lights operation can be monitored through implementing light dependent sensors. The life of lamps is extended due to efficient control of duration of operation. Higher data rate of transmission is also achieved using JN-5139 microcontroller which has higher frequency band up to 2.4 GHz compared to ISM frequency band which has only some tens of MHz. De Dominics [16] proposed an intelligent street lighting and monitoring which maximizes energy saving and minimizes light pollution as well as taking account of the environment and safety standards needed in all traffic condition. Energy saving is achieved making light source into minimum illumination. Settings can be adjusted to suit various environmental conditions. Light level can be predefined according to requirement provided. Reza Mohammaddoust, Abolfazl Toroghi Haghighat, Mohamad Javad Motahari Sharif and Niccolo Capanni [17] proposed a dynamically lighted roadway in which lighting can be adjusted to any three levels (0.2cd/m2, 1cd/m2, and 2.0cd/m2) depending on the amount of traffic, time of day, and weather conditions. 900MHz is used as frequency band of the system wireless communication. This results in lower data communication rate. The evaluation of DYNO (Dynamic Public Lighting) concluded that low level (0.2cd/m2) can be applied under low traffic volume and favorable weather conditions.

III. IMPLEMENTATION

Fig. 2. Overall Controller Architecture of Smart Street Light System

Fig.2 illustrates the architecture of a control system in

the smart street light system. The control system architecture has an 8 bits microcontroller unit, rechargeable battery, circuit for recharging battery, lamp post and solar panel. The motion sensor works simultaneously with the camera module. The camera will start capturing the event when there is a trigger from the motion sensor. The purpose of the motion sensor is to send out trigger when there is suspicion subject noticed around the area of the street light. Obviously the placement of the motion sensor is very crucial because placing it in a lower, middle and higher position may not function to trigger as required, therefore experiments will be conducted to evaluate the position of motion sensor in a street light to justify an exact accuracy of trigger. The microcontroller required at least 5VDC to operate and Arduino microcontroller has built in regulator to regulate 12VDC input voltage from an adaptor. The light sensor (LDR) captures the light intensity of the environment and turns on or off the LED lamp post. The LDR will only send a high state to the microcontroller to turn the relay circuit to turn on the LED lamp after 7.05pm. LDR sensor functions against resistance and light intensity.

An experiment to find the average nominal resistance will trigger relay circuit to turn on the LED lamp at 7.05pm, during cloudy climate or when other causes of the climatic changes. Since SPST type of relay is used in this architecture, therefore the same relay will switch off the LED lamp in the day time after 7.00am or when the sufficient brightness reduces the prescribed nominal resistance. A hall current sensor measures the current supplied to the LED lamp. If there is high surge current measured in the LED lamp post the controller will determine that there is malfunction of the LED lamp and send the record to the remote coordinator unit. A voltage divider circuit that is connected to the microcontroller from the storage battery and solar panel measures the

differences of voltage from the reference voltage in order to determine the capacity of the storage battery and the performance of the solar panel. The XBee is an IEEE802.15.4 ZigBee unit that has the similar outlook of a XBee wireless RF module. The XBee is the unit for sending in and out the data from the microcontroller RAM to the coordinator for measuring the overall performance of the individual street light. Logs file which is created from the firmware code consists of health check profile of a street light. The rechargeable circuit is for charging the rechargeable storage battery. The microcontroller has the feature of 10 bit ADC sampling rate. The hall sensor, light sensor and voltage dividers use the 10 bit ADC sampling rate to determine the current value, nominal resistance and the performance voltage reading from the battery and the solar panel.

Fig. 3 Physical Outlook of Smart Street Light Design

Fig.3 illustrates the installation suggestion of the

smart street lamp. The solar panel fixed to the street lamp supplies DC voltage to the storage battery to recharge. Since the rechargeable battery is heat resistance, therefore placing the battery on the panel bracket that connects the solar panel does not affect the battery durability. All wires in the street light are concealed in the poly iron rod to avoid damage to the wires from weather condition like rain, mist or hot and wind. The super bright LED is sufficient for achieving the brightness. Weather proof casing will be used for the controller, motion detector and the camera module to avoid damages happen to the hardware components and parts from the unpredicted weather condition. .

Fig. 4. Client Server Connection

Fig.4 illustrates the client server connection to monitor the health status of each lamp post in a residential area. A Remote Method Invocation (RMI) register register’s all the unique street lights that is connected in the network structure. Each street light is declared with a separate server with a unique name of the street light. The internet gateway with the wireless access passes the health information of each street light to the client from the remote method invocation in a JAVA platform. The client will be able to access each server and monitor each street light’s health status in a residential area.

The service maintenance report of the smart street light system is simulated in JAVA platform. To implement Client-Server environment with RMI registry service, the following steps are taken as shown in Fig.5. RMI is a distributed system technology that is usually implemented in large distributed network system for conveniently receiving information by invocation from a virtual machine to the object methods that run on other virtual machines. This is the best method to handle the individual street light that is connected in a large distributed network. For instance, many street lights are available in residential areas or business centers in urban cities therefore via RMI the object methods are invoked to check the street light health status for further action. The following are the processes of establishing RMI:

First an interface must be constructed with the description of the method for allowing client to invoke the methods remotely. Secondly the interface for server is constructed for registering the service with the RMI registry and also for implementing security to the JVM. The security is to avoid malicious surprises from the accessibility of remote classes. The third step is to implement the RMI client to call the registry to obtain reference to the remote object. To execute RMI, the RMI registry and servers are turn on and then followed by the client.

In summary, the major process to implement RMI is to list the object methods and develop the method’s requirements. The server requires RMI registry port accessibility, which is port 1099. Prior invocation from the RMI registry to the object methods, the individual server street light will release the information that is required for maintenance that the servers must be kept alive all the time.

Once the client connects to RMI registry, a lookup table is accessed and scanned to locate the required server for the client to obtain information on the street light health check. Error prompt is set in the program to have feedback of errors in the establishment of RMI in a Client-Server mechanism.

Fig. 5. Implementation of RMI for Smart Street Light

The following are the results obtained from the Netbean JAVA platform that simulates the concepts of RMI in a Client-Server environment. Dummy data are created and stored in a folder of the same path the project file is created for this simulation project.

Table 1 : Dummy Data to Resemble as from the Controller Unit Data Server 1 Server 2 Server 3

Street Light

Code

Lamppost 001 Lamppost 002 Lamppost

003

Solar Panel

Voltage

12.5V 12.45V 11.45V

Battery Voltage 14.2V 13.8V 13.2V

Camera Mode 1 (HIGH) 1 (HIGH) 0 (LOW)

LDR Voltage 2.56V 1.25V 1.2V

Lamp Current 0.25A 1.3A 1.25A

Motion Sensor

Status

1 (HIGH) 1 (HIGH) 0 (LOW)

The above dummy data is created to resemble actual result that will be collected in log file from a smart street light that is connected in the distributed network. For each dedicated server a smart street light unique code is given. The hardware measures the solar panel voltage to determine the ability of the solar panel that is charging the rechargeable battery. The battery voltage is measured to determine the sustainability of the battery. The status of camera and motion detector is notified in an integer representation. Logic 1 is notifying that the camera is capturing image because there is similar trigger of logic 1 from the motion sensor to alarm an intruder been detected nearby the smart street light. Both the motion detector and camera has the logic state because the camera will only capture image once there is motion detection. A zero integer determines that the area is safe and no intrusion happened. The LDR voltage is further processed to determine the light intensity around the area. For instance the 2.56V determines that the light intensity surrounding the lamppost 001 is brighter than the position of lamppost 002 and 003. The lamp current is measured to determine the endurance of LED lamp. If the lamp current reading is higher than 1.35A then the street light should have malfunctioning LED lights.

Fig. 6. Received Record from Server 1 of the Smart Street Light

Figure.7 Received Record from Server 2 of the Smart Street Light

Fig .8 Received Record from Server 3 of the Smart Street Light

Fig. 6 to Fig. 8 shows that 3 different smart street lights are used with 3 different servers. Each server is turned on successfully and ready for the client to access via RMI registry. It shows that the client has successfully established the connection with the RMI’s registry unit and obtained the stored output result of each smart street light’s health check information.

IV. CONCLUSION AND FUTURE WORKS The proposal here is to design a smart street light system (SSL) which uses solar power supply to operate the controller, the communication module and to charge storage battery during day time. The charged battery will be used to operate at night. Therefore the system is independent from electric power source. An automation control is required to establish the functions of this system. The software at remote server is used for logging the light intensity obtained from the lamppost via the ZigBee module. The bidirectional communication established between the remote server and the lamppost enables the maintenance effectiveness of the smart street light. The RMI will ease the maintenance process of the smart street light over remote monitoring. The system can be improved with employing an image processing method to extract image for evaluation purposes.

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