Development of a Wireless Device Control Based Mobile Robot Navigation System

Transcription

1 Development of a Wireless Device Control Based Mobile Robot Navigation System Phey Sia Kwek, Zhan Wei Siew, Chen How Wong, Bih Lii Chua, Kenneth Tze Kin Teo Modelling, Simulation & Computing Laboratory, Material & Mineral Research Unit School of Engineering and Information Technology Universiti Malaysia Sabah Kota Kinabalu, Malaysia msclab@ums.edu.my, ktkteo@ieee.org Abstract Tablets are highly functional and flexible platforms to pair with robotic autonomy and navigation control. The advantage of remotely controlling robots using mobile devices is location independence. New research is merging towards more applications for mobile devices and robotics. Specifically, more emphasis is given to the communication technology that connects mobile devices with robots. In this paper, the design and development of a mobile robot system with tablet is presented in detail. The wireless communications interfaced between the microcontroller, computer and tablet is described. The user is able to navigate the mobile robot to travel through points of interest via a GUI interface on the tablet. Keywords mobile robot; wireless communication; navigation system; GUI (graphical user interface); Android I. INTRODUCTION A mobile robot is a machine mounted on a movable platform. Typically, mobile robots are designed to move to a certain area or environment following the controller instructions. Nowadays, mobile robots are very common in many type of application such as medical, security, military, industrial and even in wireless sensor networks[1]-[4]. Many domestic robots such as vacuum cleaner robots, social robots and even entertainment robots are originate from a simple mobile robot [5]-[7]. The emerging technology of mobile devices and mobile robots has sparked various new applications in the industry [8]. With compact forms, many computing platforms are now armed with many peripheral sensors and communications to enable it to be omnipotent in multitasking. The combination of mobile devices and robots are bringing in novel ideas in a lot of areas. Being able to communicate wirelessly with the robot will bring added convenience and flexibility. Mobile devices such as Android tablets are increasing in popularly [9], [10]. They are hybrid type of a mobile device and laptop. They are getting more powerful, efficient, and easier to use with time. With so many features, it makes them fitting as the platform for the mobile robot development. The tablets provide more portability, longer battery life and more versatility compared laptops. Since many tablets have a data plan through a cell phone carrier. This is convenient while accessing in public place or during travelling. In order to interact between the mobile robot and the tablet device, it is essential to establish a reliable wireless communication link between them. The communication allows the robot to relay state information to a human controller and vice versa. The wireless communication feature of the system is important as it informs the user of what it experiences. The details of this paper are organized as follows. In section II, the overview design of the mobile robot is explained. The development of the mobile robot s prototype is described in section III. In section IV, the implementation is presented. Lastly, the paper is concluded in section V. II. OVERVIEW DESIGN Generally, computer with well-designed software in it can act as centralize control centre in order to send commands to the mobile robot. The general communication link between computer and mobile robot is illustrated Fig. 1. With the emergent technology of the mobile device, tablets can also be used as an attractive and alternative control centre as shown in Fig. 2. Figure 1. Communicate link between mobile robot with PC platform. Tablet-End User Computer- End User Mobile Robot Mobile Robot Figure 2. Communicate link between mobile robot with Tablet platform /12/$ IEEE 95

2 A. Mobile Robots Generally, mobile robots are design to travel in certain environments. They can classify into different categories with different capabilities based on the movable platform. Track robot is type of rolling robot that moves on the track. It is simple and easy to control. However, this kind of robot costs more in building the tracks and not flexible due to limited movement by its tracks. Wheeled robot is the convention type of movement for robots. It can only travel in a smooth plane. Algorithms require to control it is slightly complex compare to track robot. Legged robot is the hardest to control among all. It has robot legs that resemble biological species such as human, animal, and insect. This kind of robot is suitable in walking on uneven environment. However, it requires complex algorithms in order to walk. B. Motor Control Loop Design Motor controller is the foundation for the mechanical of mobile robot system. It can be classified into two major type which is open loop and closed loop controls. Open loop control in mobile robot is simpler among the two types of the controls system. The motor for open loop control system is usually having pre-defined settings. Accurate input commands are important to perform properly. This type of control design usually requires user to control the mobile robot remotely. There is no return feedback after the action. For closed loop control, sensors embedded inside the mobile robot are used to collect feedback from the environment. Based on the feedback, the motor controller selfadjusts accordingly. This type of control system usually require more complex algorithm for controlling. III. PROTOTYPE DEVELOPMENT In this Section, development of a wireless controllable mobile robot navigation system will be discussed. The discussion is split into 3 parts: the line follower robot, user interface software and wireless communication. A. Line Follower Robot Fig. 3 shows the developed board of the line follower robot. It consists of a main microcontroller, infrared sensor array, Direct current (DC) motor controller and wireless communication. Block diagram of the line follower robot is shows in Fig. 4. The diagram shows the basic details of the robot. Figure 4. Block diagram of line follower robot. a) Main Controller Board: There is a lot of microcontroller in market that provided peripheral features such as Timer, PWM modules, UART serial communicate function, and analog to digital converter. The features of microcontroller is useful to manage the importance hardware of this project, therefore microcontroller is chosen to be used as heart of the project to control the whole hardware system. Liquid Crystal Display (LCD) also chosen to be an output display for data information and the display will be connected with microcontroller. Simple I/O control such as pull up resistor with button, reset button, light-emitting diode (LED) indicator, and input sensor can also be controlled by microcontroller when the mobile robot is working. b) Infrared (IR) Sensor Array: Basically, infrared sensors emit infrared light through IR-LED which is called IR Emitter and it reflected by an object in front of the sensor and received by a photo diode which is called an IR Receiver. In case, six IR sensors pair (emitted and receiver) used to detect line colour and it can distinguish black and white colour. The IR emitter and the IR receiver are attached side by side, and they are ensured to point on a reflective surface. Fig. 5 shows the reflective example of IR emitter and IR receiver. IR rays will be absorbed by dark surface, while it is reflected back by white or reflective surface. IR receiver will experience voltage drop if it receives reflected IR rays. By utilizing the voltage drop characteristic of IR receiver, it can act as eyes for the robot. Fig. 6 shows the developed IR sensor array. IR emitter IR receiver IR emitter IR receiver White or reflective surface Black or non-reflective surface Figure 3. Developed board of line follower robot. Figure 5. IR sensor charateristic /12/$ IEEE 96

3 c) DC Motor Driver: In this paper, 360 degree Rotating Servo Motor is chosen to operate and rotate two wheels on right and left hand of robot. Compared with other motors, Servo Motor is lighter, small in size, low cost and lower power supply required (4.5V-6V). Full H-Bridge Driver is most common for DC Motor which is use to control rotate direction of DC motor. H-Bridge is an electronic circuit that enables a voltage to apply across a load in either direction. Fig. 7 shows the basic H-bridge circuit schematic. Fig. 7(a) shows the free run mode which all switches are in open state. Fig. 7(b) shows the DC motor rotate in clockwise direction when switch 1 and switch 4 is close while Fig. 7(c) show the opposite configuration. Further interpretation, the current flowing through a coil creates a magnetic field which collapses when the current is switched off (OUT1, OUT2, OUT3 or OUT4 suddenly turn off). The collapses of the magnetic field of motor induce a brief high voltage and current across the coil, which is very likely to damage IC. The protection diode pairs allow the induced voltage to drive a brief current through the coil and diodes, so the magnetic field dies away quickly rather than instant. The functional truth table of Servo Motor on robot is shown in Table. I. 1.3cm Figure 6. Developed IR sensor array. V cc Motor V cc Motor V cc Motor TABLE I. TRUTH TABLE OF SERVO MOTOR EN1 IN1 IN2 EN2 IN3 IN4 Description Forward Backward Turn Right Turn Left Brake/Stop Brake/Stop B. Robot Control Interface The robot control interface is developed in Visual Basic (VB) and Android application. The developed control interface will be able to provide two-way communications between the mobile robot and end user. a) Computer Based Controller: In a computer based controller, end user can control the mobile robot via Xbee wireless modules between the computer and the robot. Fig. 8 shows the communication block diagram of main controller board. Information in the microcontroller is sent to Xbee module via universal asynchronous receiver transmitter (UART) protocol. Fig. 9 shows the communication block diagram of interface side. Universal serial bus (USB) to UART converter adaptor is used to convert the information receives by Xbee to computer compatible data and vice versa. Fig. 10 shows the developed GUI of robot controller. b) Tablet Based Controller: In tablet based controller, Android application has been developed to communicate with the robot. In this stage, to control the mobile robot from tablet, it needs to manually replace the Xbee module with pins compatible Bluetooth BEE module. The exchange of wireless module provides tablet a Bluetooth connectable device. After established connection between tablet and mobile robot, user can control the robot via UART protocol. There is an alternative way for the tablet to control the robot without replacing the wireless module from the robot. It work by using the computer as relay to convert Xbee information to the computer s built-in Bluetooth module that is connected by tablet as shows in Fig. 11. Fig. 12 shows the example of tablet GUI of robot controller. Shown tablet GUI is the interface of current develop MuRBOT project. DC Motor DC Motor DC Motor Microcontroller Data Out Xbee Module Data In 5 V Power Supply a b c Power Supply Voltage Converter 3.3 V Power Supply Figure 7. H-Bridge circuit Figure 8. Communication block diagram of main controller board /12/$ IEEE 97

4 Computer Serial Bus 5 V USB to UART 5 V Voltage Converter Data Out Data In Xbee Module 3.3 V Figure 9. Communication block diagram of interface side. Figure 10. Computer GUI of robot controller. IV. IMPLEMENTATION Simple tests and experiments are essential to verify the reliability of the mobile robot system. In this work, the verification experiment for testing purpose only uses the computer as the control interface. The mobile robot travels based on the following line environment with Left Hand Rule algorithm. Each turn during travelling, the robot sends all turns of each junction to computer. The simulator receives data via wireless module (transmit and receive mode) and simplified those data as shortest path for mobile robot. The robot movement and direction feedback process is captured from video and illustrated in Fig. 13. In Fig. 13, it shows that the mobile robot could move on unknown line path and transmit data to simulator. The Receive Data & Optimized Path obtained by the system can be simplified as the shortest path as characters arrangement: SLSSR from starting point to end point. After verifying that the mobile robot able to move along the defined path and communicate with the end user correctly, the next testing experiment is conducted for finding the shortest path in the line field. This testing starts from Com Port selection. When the XBee wireless device has plugged into USB port and GUI COM_PORT section will auto detect Com Port ID. The Connect button is provided on the GUI window. On the other hand, ON and OFF button used as activate and deactivate whole GUI window. Based on the static path provided, user could select few destinations for robot with randomly and press GO button to process shortest path planning. Fig. 14(b), the GUI system has arranged the shortest path for robot and robot followed the sequence to moving and reached the desired destination without entering the other points. Fig. 15 shows the line follower robot prototype and Fig. 16 shows the entire controllable mobile robot system. Figure 11. Tablet GUI of robot controller. (a) (b) (c) (d) (e) (f) Figure 12. Tablet GUI of robot controller. Figure 13. The robot travelling on path and data tranmission process /12/$ IEEE 98

5 (a) Selected Com Port and connect it with 9600 baud rate. Figure 15. Line follower robot prototype. Figure 16. Controllable mobile robot system. (c) Shortest path auto-arrange and robot communication with GUI. (d) Robot travelling to next destination. V. CONCLUSION In conclusion, the mobile robot platform is designed and developed with the Android based device. By using any Android based device, the control function of the mobile robot can be accessed by connecting it via Bluetooth. It provides more reliability and feasibility in controlling the mobile robot since many people already use Android based device in their daily lives. On top of the current works, more advanced features and tasks will be integrated for future development. Implementing artificial intelligence algorithms can provide decision-making capability to the mobile robot. Advanced controller algorithms could also improve the mobile navigation system with higher accuracy and speed. ACKNOWLEDGMENT The authors would like to acknowledge the financial assistance of the Universiti Malaysia Sabah Research Grant Scheme, grant no. SLB0014-TK-1/2011, and Universiti Malaysia Sabah Postgraduate Scholarship Scheme. Figure 14. Robot travelling on static line map with shortest path and with GUI communication. REFERENCES [1] N.A.A. Latiff, N.M.A. Latiff, R.B. Ahmad, "Prolonging lifetime of wireless sensor networks with mobile base station using particle swarm optimization," 4th International Conference on Modeling, Simulation and Applied Optimization, pp. 1-6, 2011, doi: /icmsao /12/$ IEEE 99

6 [2] Z.W. Siew, A. Kiring, H.T. Yew, P. Neelakantan and K.T.K. Teo, Energy efficient clustering algorithm in wireless sensor networks using Fuzzy Logic control, Proc IEEE Colloquium on Humanities, Science and Engineering Research, pp , 2011, doi: /chuser [3] Z.W. Siew, C.H. Wong, C.S. Chin, A. Kiring, K.T.K. Teo, Cluster heads distribution of wireless sensor networks via adaptive Particle Swarm Optimization, Proc. 4th International Conference on Computational Intelligence, Communication Systems and Networks, pp , 2012, doi: /CICSyN [4] C.H. Wong, Z.W. Siew, M.K. Tan, R.K.Y. Chin, K.T.K. Teo, Optimization of distributed and collaborative beamforming in wireless sensor networks, Proc. 4th International Conference on Computational Intelligence, Communication Systems and Networks, pp , 2012, doi: /CICSyN [5] E. Park, K.J. Kim, and A.P.D Pobil, Energy efficient complete coverage path planning for vacuum cleaning robots, Lecture Notes in Electrical Engineering, Future Information Technology Application, and Service, Vol. 164, pp , 2012, doi: / _3. [6] J. Allen, J.E. Young, D. Sakamoto, and T. Igarashi, "Style by demonstration for interactive robot motion," Proc. Conference of the Designing Interactive Systems,pp , 2012, doi: / [7] J.S. Gutmann, K. Culp, M.E. Munuch, and P. Pirjanian, "The social impact of a systematic floor cleaner," IEEE Workshop on Advanced Robotics and its Social Impacts, pp , doi: /arso [8] H.M. Do, C.J. Mouser, and W. Sheng, "Building a telepresence robot based on an open source robot operating system and Android," unpublished. [9] A.A. Ozok, D. Benson, J. Chakraborty, and A.F. Norcio, "A comparative study between tablet and laptop PCs: user satisfaction and preferences," International Journal of Human-Computer Interaction, Vol. 24, Iss. 3, pp , 2008, doi: / [10] W. Liang, S. Yu, and T. Long, "A study of the tablet computer's application in K-12 schools in China," International Conference on Advanced Intelligence and Awareness Internet, pp , 2011, doi: /cp /12/$ IEEE 100