Volume 118 No. 20 2018, 4337-4342 ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu ijpam.eu Hardware Implementation of an Explorer Bot Using XBEE & GSM Technology M. V. Sai Srinivas, K. Yeswanth, E. Vijay, B. Bhanu prakash, Gayathri Narayanan Dept. of Electronics and Communications Engineering, Amrita Vishwa Vidyapeetham, Amritapuri, India venkatasaisrinivas1@gmail.com, gayathrin@am.amrita.edu Abstract In this work, we implement a robot for exploration purposes using Xbee and GSM Technology. The robot is operated by Arduino microcontroller and the motion of the robot is controlled by XBee Modules. We use Ultra Sonic Sensor (obstacle detection sensor) which is based on electro-mechanical energy transformation to measure the distance from the sensor to the target. The metal detector sensor, which works on the principle of mutual inductance helps to detect explosives, which increases the efficiency of the Robot. All the opponent positions will be captured by a night vision wireless camera, equipped with built-in Audio and Video feature. At the transmitting end by using a laptop, commands are sent to the receiver s end to control the motion of the robot. At the receiver end, four motors are interfaced for movement. In case of the failure of XBee modules, we control the motion of the robot by using GSM Module with a bit delay. We also receive the messages of the sensors readings of obstacles to the transmitter end. Keywords Explorer Bot, Arduino microcontroller, GSM, Xbee. 1 - Introduction Life of human beings is very precious but lots of people are losing their lives every minute in the world, especially in war attacks as well as due to natural disasters. In several of these mishaps, saving human lives is a highly challenging task due to the difficulty in accessing the mishap prone areas. This problem can be solved in a smart way by introducing robots. Robots are intelligently developed such that it can perform tasks that human beings can. In this work, we have designed and developed the hardware prototype of an explorer robot which can suitably substitute for human beings where physical human intervention is a challenging task. The following sections outline the System Model and gives a glimpse into the results. 2 System Design Arduino Arduino microcontroller is a highly integrated chip that contains all the components comprising a controller. It includes CPU, RAM, some form of ROM, I/O Ports and timers [2]. Every component in the robot like the Xbee module, Sensors, GSM module etc., are interconnected with the Arduino. It works with the input voltage of 7 to 12 V. The whole program to control the bot is written in Arduino IDE(Integrated Development Environment). XBee Module The motion of the robot is controlled by XBee module. It works with a supply voltage of 2.8-3.4 V. Xbee uses IEEE 802.15.4 protocol at a frequency of ISM (Industrial Scientific and Medical) band of 2.4 GHz which is the new standard for low cost, highly efficient and low power transmission and is better than IEEE 802.11 protocol [3].It is a reliable protocol and gives timely packet 4337
transmission while maintaining its stability [4] [5].We use two Xbee Modules of series2 - one as the transmitter and other as the receiver. Fig 3: Transmission Reception between Xbee modules Sensors (a) UltraSonic Sensor Fig 1: Flowchart of the Motion of the Bot Ultra Sonic Sensor is popular, cheap and reliable technique of sensing distances of objects for localization [1].It is a technique that uses sound propagation to navigate, communicate or detect objects [1]. The object range is calculated by Range, R = ct/2 where c is the speed of sound and T is the time taken by the beam. Interface Fig 2: Camera and Xbee transmitter Here the wireless communication occurs between two XBee devices. For communication between two Xbee modules, we need to pair the two modules by giving PAN ID and 16-bit address in XCTU software. So the transmitter will able to communicate with the receiver i.e., if we send a message from the transmitter as shown in Fig 2 the same will be received by the receiver placed in the robot as shown in Fig 3. Xbee is one of the ZigBee devices which are used as the latest technology in wireless communication instead of Bluetooth modules because XBee covers a range of 300 feet. Our robot consists of four ultrasonic sensors which covers all the four sides of the bot. If any obstacle comes in between the path it gives information about the obstacle and gives the distance between the path and obstacle in centimeters as shown in Fig 4. The information is sent to the mobile. Fig 4: Alert received in the mobile 4338
explosive items like landmines etc., which works on the principle of electromagnetism. If any metal is detected a small beep sound is given as an alarm for the user. GSM-Module X: Real time Y: Duration to receive signal Fig 5 : Graph between real time and duration Fig 5 gives the duration undergone with respect to the real time. If the object is placed in between 2cm and 40cm the time taken will be around 2500ms. If no object is placed then the duration is around 15000ms. In this prototype, we use GSM 900A module, which plays a vital role in the working of the robot. This module should be equipped with a SIM card, so that it can transmit and receive data wirelessly. The receiver and transmitter pins of the GSM are connected in the inverse manner to the pins of Arduino receiver and transmitter respectively, by which process, data communication is established with the Arduino Board. It can communicate by AT commands (AT + CMGF=1; to convert module to text sending-mode) Operations performed by GSM Module: If Xbee connection is lost i.e., the robot has gone beyond the exceeded range then the GSM-wireless technology comes into play as shown in Fig 1. We can operate robot by assigning directions with the mobile phone by sending messages to the GSM Module. This would imply that the range of the robot is extended to maximum limit, where the mobile network persists. In addition to receiving the messages from the controller of the robot, the GSM module itself is capable of sending messages to the controller of the robot(i.e., the sensor values from the ultra sonic sensors like the distance and the direction of the obstacle from the robot) Fig 6: Duration vs. Distance graph Fig 6 shows the relationship between the distance and the duration of ultrasonic sensor and the object. From the graph we deduce that if the distance increases time increases. (b) Metal Detector The other sensor used in this robot is a metal detector. It is placed in the robot to detect Fig 7: Snapshot of live streaming data from the bot. 4339
Wireless Camera A wireless night vision camera is placed on the top of the robot and the receiver is attached to the laptop as shown in Fig 2 so that we can get live streaming in the laptop as shown in Fig 7. It consumes low power and has built-in microphone and transmits audio along with the video. Servo motors Servo motor is a servo mechanism. It is closed loop servo mechanism that uses position feedback to control its motion and final position [6]. We have used servo motors for rotating wireless camera and ultrasonic sensors to cover 180 degrees. DC motors and Motor drivers In this robot, we have used DC motors of 60 RPM which is connected to 12 V motor driver and it is controlled by the Arduino. We used two blades connected to DC Motors as defending feature for cutting small bushes, plants etc., coming in the middle of the path. accordingly,when the specified data is received by the Arduino(For example,when character `w` is transmitted from the transmitter,robot is setup to move in forward motion).if else the connection between the Xbee s are terminated or lost,gsm- Controlling the motion of the robot comes into existence.now the specified characters of the motion are sent over the mobile to GSM.Latter Arduino is directed by the GSM module.the Ultrasonic Sensors attached to the robot has the ability to emit sound waves which then travel through air and reflects through the object which is then received by the receiver.the total travelling time is then recorded,by using simple math formula we can find the actual distance between the sensor and the object.both direction and the distance of the obstacle are sent to the assigned mobile number through GSM module.the Audio and the Video of the surroundings of the robot are broadcasted simultaneously with the help of night vision camera. A metal detector contains a coil of wire known as the transmitter coil.when electricity flows through the coil, a magnetic field is created all around it.the metal detector has a second coil called receiver coil which gets active, when a metal is detected and notifies the controller of the bot by a beep sound.thus the controller of the robot becomes alert and deviates from that direction.primary disturbances in the path of the robot are cleared with the help of the blades attached at the front of the robot. The complete hardware prototype was built and tested by assembling all the components as shown below in Fig 9.. Fig 8.Circuit Diagram of bot. Hardware Implementation-Overview All the Individual Components are connected to Arduino as per the circuit diagram.primarily the data is sent from the Xbee transmitter (Fig 2),the transmitted data is received by the Xbee receiver.the Arduino is pre-programmed and works Fig 9: Hardware Prototype of the Explorer Bot 4340
Conclusion The project is a robotic vehicle using Xbee modules with XCTU application for wireless operation. The robot has a metal detector, ultrasonic sensor along with a camera which can transmit real-time video with night vision capabilities. GSM module is responsible for continuous alerts through SMS. GSM also helps in remote operation for robotic movement. The robot will become autonomous when the signal is lost from Xbee and GSM900A. Two blades are placed in front of the robot which is used for clearing the path. This prototype can be used for exploration purposes in order to substitute for human intervention. [6] H.P. Moravec, A. Elfes, High resolution maps from wide anle sonar, presented at the IEEE conference Robotics and Automation,1985. References [1] Rechie Ranaisa Dam, Determining 2D shape of object using Ultrasonic Sensor.Published in Electrical Engineering and Information CommunicatioTechnology (ICEEICT),2016, at Dhaka. [2] J.E Piercy, American National Standard: Method for calculation of the absorption of sound by the atmosphere,.ansisi-26-1978(acoust. Soc.Am.,1978). [3] Mohammed Umer Shahzad, Wireless Control Robot Using Xbee Module With Multiple Sensors Acknowledgement on HMI.Published in Recent Advances in Electrical Engineering (RAEE),2017 International Symposium on 24-26 Oct.2017. [4] Pangun Park, Di Marco, Modeling and Optimization of the IEEE 802.15.4 Protocol for Reliable and Timely communications.ieee Transactions on Parallel and Distributed Systems,Vol. 24,pp. 550-564,May 2009. [5] Bo Wu, Hai Lin Stability analysis for wireless networked control system in unslotted IEEE 802.15.4 protocol 11 th IEEE International Conference on Control & Automation (ICCA),June 2014,pp. 1084-1089 4341
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