International Journal of Electronics and Computer Science Engineering 1148 Available Online at www.ijecse.org ISSN- 2277-1956 Automatic Docking System with Recharging and Battery Replacement for Surveillance Robot M.Meena 1, P.Thilagavathi 2 1 PG Scholar, Department of ECE, K.S.R. College of Engg., Tiruchengode, Tamil Nadu, 637215, India. meena.er22@gmail.com 2 Associate Professor, Department of ECE, K.S.R. College of Engg., Tiruchengode, Tamil Nadu, 637215, India. thilagaramaniece@gmail.com Abstract- Most of the applications like industrial automation, home automation, hospitals, space exploration, military, etc, the surveillance robot are widely used. For that, continuous functioning of surveillance robot is necessary. In this paper, the development of automatic docking system with recharging and battery replacement process for surveillance robot is proposed. The robot can return to the docking station for recharging operations when the battery is low. The charging duration of the battery mounted in the robot is an important issue. To overcome this problem, battery replacement is a perfect solution. The battery is automatically exchanged within 30 seconds. So the robot needs not to be turned off for long duration of time while replacing the battery. Key Words: Surveillance Robot, Battery Exchanging, Docking Station 1. Introduction Surveillance robots are conventionally guarded in buildings, supermarkets, factories, etc. To execute their assignments the robots are travel along the patrol path in these environments. The time duration capability is a critical function for robots and it is relied on the power supply. Normally high capacity batteries are large sized and decrease the mobility of robots. It is not a good solution to solve the battery recharging problem. To increase the long term activity of robots the docking station is to be used. In recent years the size and the cost of mobile robots have decreased significantly, they are finding to increase the uses in home applications. The development and characterization of a surveillance robot with automatic docking and recharging capabilities for home security was proposed. This system is composed of a surveillance robot and a docking station [5]. Monitoring devices are usually mounted on fixed locations such as doors, windows and walls in home security systems. Using multiple ultrasonic sensor modules, the home security surveillance system has been developed [6]. Most of researchers in the world are now engaged in designing the surveillance robots for home security system. The patrol robot system for home security with interaction functionalities has been presented in [3]. A low cost GSM/GPRS based wireless home security system includes the liquid crystal display and the capacitive sensor keyboard. In this the wireless transceiver module receives the security information from the sensor nodes and sends the information to the controller [10]. Automatic video based human motion analyzer for consumer surveillance system has 3 D construction scheme for scene understanding. So that the actions of persons can be analyzed in different views. This system analyses the sequence in four levels, they are preprocessing level, object based level, and event based level, visualization level [7]. A hybrid sensor network system for home monitoring applications has sensor board, motor board and mote. The robot base is added to the node structure [4]. The name registration and recognition system consist of three different states a standby state, a recognition state and registration state and also voice activity detection algorithm is used. This system is to realize a call and home service for home robots using a voice interface [8]. The robot system integrates the variety of sensors to gather information and detect the abnormal events including fire alarm and lethal gas leakage. The self patrol mode is used in development of a patrol robot for home security with network assisted interactions [1]. Multilevel and multisensor based intelligent recharging system for mobile
AUTOMATIC DOCKING SYSTEM WITH RECHARGING AND BATTERY REPLACEMENT FOR SURVEILLANCE ROBOT 1149 robots consist of four connection points. Two connection points are to provide dc 36Vfor the driver system and the other two are provide 12V for the industrial personal computer (IPC) and the other hardware devices [9]. Adaptations of the A* algorithm for the computation of fastest paths in deterministic discrete-time dynamic networks contains origin node and the destination node. This algorithm is to compute at fastest (minimum travel time) path from one origin node to one destination node for multiple departure time at the origin node, in dynamic networks [2]. 2. System Design According to the user request and task properties the surveillance robot can work in three modes: They are 1) Patrolling mode. 2) First responder mode. 3) Remote control mode. In that patrolling mode, the surveillance robots are moved around the predefined routes. Any security related information is obtained, it will be sent to the server for further analysis. The surveillance robot is programmed to work in cooperation with other fixed monitoring devices, in that first responder mode. When one of those devices reports a security event to the surveillance robot, it will navigate to the target region to perform onsite operations. In the remote control mode, the surveillance robot will be controlled by the remote user. The docking interface of the robot consists of two charging electrodes on the front side. The charging electrodes are installed on the elastic supports so that docking process can be effectively buffered. 2.1. Surveillance Robot The hardware components of the surveillance robot are shown in FIG 1. It consists of two DC motors, Microcontroller, two IR sensors, servomotor, and USB camera, etc., mainly the two dc motors are used to rotate the wheels of the robot. The servo motor is used for tilting the camera for a wide view. The robot communicates with docking station through the ZigBee module. The surveillance robot depends on the two IR sensors to perform obstacle avoidance. The core board is the central control of the surveillance robot. The core board contains microcontroller and switch controller. The analog to digital convertor (ADC) is in built of the microcontroller. This ADC is used to detect the real time status of on board battery. In normal working status, when detecting that the on board battery voltage is lower than the preset voltage, the microcontroller will command the robot to return the docking station for exchanging the battery and turn back to start to work again. The encoder is used to calculate the distance between the robot and the docking station. In this project PIC16F877A is used. PIC16F877A contains of High-performance RISC CPU, 10-bit multi-channel Analog-to- Digital converter.
IJECSE,Volume1,Number 3 M. Meena and P. Thilagavathi Circuit Diagram 2.1.1(a) Robot section
AUTOMATIC DOCKING SYSTEM WITH RECHARGING AND BATTERY REPLACEMENT FOR SURVEILLANCE ROBOT 1151 Block diagram 2.1(b). Robot section Fig 1: Hardware Components of Surveillance Robot 2.2. (a) Docking Station The hardware components of the docking station are shown in FIG 2. It includes charging module, communication module and IR sensors, etc, Fig 2: Hardware Components of Docking Station Each side of the docking station has an IR sensor to detect the obstacles, according to the outputs of the IR sensors and encoder, the related position between the robot and the docking station can be determined. Therefore the robot will connect to the docking station automatically. During the docking process, the IR sensor on the robot will temporarily disconnected to avoid interfering with the IR sensors on the docking station. 2.3. Power Supply Normally the power supply of the robot is the on-board battery. The battery capability affects the working duration of the robot. Normally high capacity batteries provide long time duration but relatively decrease the mobility of
IJECSE,Volume1,Number 3 M. Meena and P. Thilagavathi robot. And also it wastes the energy due to their heavier weight. The selection of battery is an important factor for designing the robot docking module. Four specifics of commercial rechargeable batteries are listed in Table 1. BATTERY TYPE NiCd NiMH Gravimetric Energy Density (Wh/kg) 45-80 Internal Resistance (includes peripheral circuits) in mw 100 to 200 1 6V Liion 60-120 200 to 300 1 6V Lead Acid 30-50 <100 1 12V 200 Cycle Life (to 80% of initial capacity) 1500 2 300 to 500 2,3 to 300 2 Fast Charge Time Load Current - peak - best result Operating Temperature (discharge only) 1h typical 20C 1C -40 to 110-160 150 to 250 1 7.2V 500 to 1000 3 2-4h 8-16h 2-4h 5C 0.5C or lower -20 to 5C 7 0.2C -20 to >2C 1C or lower -20 to Table 1 Comparison of Different Kinds of Battery Cycle life is defined as the number of complete charge-discharge cycles which battery can perform before its capacity falls below 80% of its initial rated capacity. According to these important parameters Li-ion battery is chosen for the surveillance robot with following features, such as higher energy density, higher capacity, lighter weight, over 500 cycles and no pollution. Using this Li-ion battery may reduce the frequency of exchanging the battery relatively. Li-ion battery may explode when overcharged above 4.5V. In order to prevent the Li-ion battery overcharging and provides the information of the battery to robot. Through analog to digital convertor, robot can detect the battery level and decide whether the surveillance robot needs to exchange the battery. 3. Design Mechanism A message has been sent out when the voltage of the Li-ion battery which is mounted on the surveillance robot is below the threshold. After receiving this message, the surveillance robot moves to the docking station automatically. The surveillance robot enters to the docking station in reverse because the battery is mounted back of that robot. Movable carrier is designed to align the docking station with the surveillance robot. The movable carrier consists of two grabbing arms, an oscillating bar, a battery frame and two charging units. There are two electrodes set at the back of the surveillance robot and to connect the electrodes of the docking station. To keep the power on status of the robot, the electrodes are connected to the docking station during the battery exchanging process. The electrodes are designed to double checking whether the entering object is a surveillance robot. The grabbing arms are hook-shaped. It is assembled under the movable carrier extends and catches the surveillance robot into the docking station. Two pins are installed at the bottom of the surveillance robot, because to
AUTOMATIC DOCKING SYSTEM WITH RECHARGING AND BATTERY REPLACEMENT FOR SURVEILLANCE ROBOT 1153 make the grabbing arms successfully catching that robot. Thus, the grabbing arms can stably grab the surveillance robot after the grabbing arms hooking the pin. The battery frame moves the exhausted battery to the empty charging unit to charge the battery, and it simultaneously moves the full charged battery into the surveillance robot from the other charging unit. Then the full-charged battery is put into the surveillance robot by the push pulling devices. 4. Battery Exchanging and the Robot Docking Process Analog to digital convertor is used to compare the voltage level of the robot. When the voltage level is below the threshold level, the robot will move to the docking station automatically and IR Sensor tracks the route of the docking station. Fig 3 shows the design flow of robot docking and the battery exchanging process. Fig 3: Flow Chart When the robot reaches the docking station, the IR sensor detects it; finally the docking process is carried out. Each time the robot reaches the docking area; it first has to adjust its direction to be parallel with the docking station.
IJECSE,Volume1,Number 3 M. Meena and P. Thilagavathi There are two stages to check whether the robot enters to the docking station. One is the IR sensor and other is the electrode unit on the oscillating bar. When the robot enters the docking station, it tracks the IR rays. Another signal is triggered by the electrodes as the surveillance robot successfully connects the oscillating bar. The grabbing arms start to pick the surveillance robot as both signals are triggered. If the signal is triggered by the oscillating bar, it is possible that the entering angle between the robot and the docking station is too large. It brings out the robot cannot exactly connect the electrodes at this moment, a signal is sent to confirm whether the system announce the entering robot to the docking station. After that the robot readjusts the entering angle to enter the docking station repeatedly. When the garbing arms start catches the robot, the movable carriers moves and rotates to align the entering robot. A sensor is used to confirm whether the aligning action is accomplished or not. The electrode units can provide the power to the robot and avoid the damage during the battery exchanging process. The battery frame moves the exhausted battery to the empty charging unit and moves the full charged battery to put in to the robot. Finally, the grabbing arms loose the robot and to perform its task continuously. 5. Result In this the robot docking station with charging and battery replacement was introduced. The robot can move back to the docking station when the battery is too low. The robot can work 4.5 hours with 12V Li-ion battery which is required 3.5 hours for the fast full charging. In other words, the robot only works 14 hours about and it spends 10 hours on waiting for exchanging station in a day without the battery replacement. With this design, it only takes 30 seconds to accomplish the automatic battery exchanging process. References [1] C. Chang, K. Chen, H. Lin, C. Wang and J. Jean, Development of a patrol robot for home security with network assisted interactions, in SICE Annual Conference 2007, Kagawa University, Japan, 2007, pp. 924-928. [2] C. Ismail and S. Lan, Adaptations of the A* algorithm for the computation of fastest paths in deterministic discretetime dynamic networks, IEEE Transactions Intelligent Transportation Systems, Vol. 3, No. 1, pp. 60-74, 2002. [3] G. Song, K. Yin, Y. Zhou and X. Cheng, A Surveillance Robot with Hopping Capabilities for Home Security, IEEE Transactions Consumer Electron, Vol. 55, No. 4,pp. 2034-2039, 2009. [4] G. Song, Z. Wei, W. Zhang and A. Song, A hybrid sensor network system for home monitoring applications, IEEE Transactions Consumer Electronics, Vol. 53, No. 4, pp. 1434-1439, 2007. [5] Guangming Song, Hui Wang, Jun Zhang, and Tianhua Meng, Automatic Docking System for Recharging Home Surveillance Robots, IEEE Transactions on Consumer Electronics, Vol. 57, No. 2, pp. 428-435 May 2011. [6] Ren C. Luo and Kuo L. Su, Multilevel multisensor-based intelligent recharging system for mobile robot, IEEE Transactions Industrial Electronics, Vol. 55, No. 1, pp. 270-279, 2008. [7] W. Lao, J. Han and Peter H.N. de With, Automatic video-based human motion analyzer for consumer surveillance system, IEEE Trans Consumer Electronics, Vol. 55, No. 2, pp. 591-598, 2009. [8] Yoo Oh, Jae Yoon, Ji Park, Mina Kim and Hong Kim, A name recognition based call-and-come service for home robots, IEEE Transactions Consumer Electronics, Vol. 54, No. 2, pp. 247-253, 2008. [9] Y. W. Bai, L. S. Shen and Z. H. Li, Design and implementation of an embedded home surveillance system by use of multiple ultrasonic sensors, IEEE Transactions Consumer Electronics, Vol. 56, No. 1, pp. 119-124, 2010. [10] Y. Zhao and Z. Ye, A low cost GSM_GPRS based wireless home security system, IEEE Transactions Consumer Electronics, Vol. 54, No. 2, pp. 567-572, 2008