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Final Year Project Presentation. The Design and Implementation of an Intelligent, Wireless Robot By Mark Heneghan. Why a Robot??. Reasons as to why I choose to do my Final Year Project in the field of robotics: Have been intrigued by robotics always.
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Final Year Project Presentation The Design and Implementation of an Intelligent, Wireless Robot By Mark Heneghan
Why a Robot?? Reasons as to why I choose to do my Final Year Project in the field of robotics: • Have been intrigued by robotics always. • Have a major interest in automotive electronics and a robotics project allowed me to gain some experience with current research areas. • A robotics project is useful to the Department, as it could be demonstrated to visitors and create an interest in the course, due to its exciting nature.
Project Aims A project spec was drawn up by consulting with my appointed Project Supervisor, Mr. Fergal O’Malley. Here are the basic requirements set out for the project: • Design and build a battery powered robot. • Microprocessor operated. • Wirelessly controlled via Wifi Internet Connection with webpage control interface. • To implement extra functionality using sensors i.e. Line Following and Obstacle Detection. • Mobile phone control. • Live Camera Feed.
Research The Gumstix Connex 400 mother board was chosen as the “brains” behind the robot. Reasons: • 400 MHz Intel PXA255 core processor, allowing quick execution of programs. • Allows Wifi connectivity using the Wifistix expansion board. • Several GPIO for sensors accessed using Breakout GS expansion board. • Pre-installed web server which allows control of the robot via a webpage. • An embedded version of Linux is installed on the processor, allowing easy use once a good knowledge of the OS is gained.
Research • A simple robot kit, the TankBot, was decided on as the robot chassis. It contains 2 pre-modified servo motors, controlled using Pulse Width Modulation. • In order to program the robot, C was to be used initially. However C would have been very complex and time consuming. Therefore the higher level language; Python, was chosen as the language to be used. • Python allows programming of the registers which control the GPIO, to be carried out easily. This is done by importing the ‘pxaregs’ kernel module, which was pre-installed on the motherboard by the Department. A few simple commands is all that is required to manipulate the required registers only, cutting down on the amount of code to be written by approximately a factor of 10 in comparison to C.
Research • Power was initially to be supplied to the robot using 2 power supplies; a 5V (later 6V) for the Gumstix system and a 6V for motors and other hardware. • However during testing I decided to add a 3rd supply, 6V, to supply the demand of all external circuitry • Networking with the robot was made easy by the Wifistix which is basically a network card and is configured to connect to any desired Wireless LAN using the embedded Linux OS.
Research • Line Following and Obstacle Detection were researched and sensors were chosen to implement these functions. • The Sharp GP2D12 Distance Detector was used for Obstacle Detection • Maplin photo-reflectors were used for Line Following.
Research • Also research was carried out for extra desired add-ons such as Mobile Phone control and Live Camera Streaming. • Mobile Phone control could be achieved using a WAP browser or a J2ME application • The most accessible way to gain live Camera feed from the robot was to use an IP camera, one of which is being used in a fellow student’s project and may also easily be incorporated into my project control webpage.
Design Implementation • Gaining experience with using Linux and Gumstix was a time consuming part of the project. Once basic knowledge of Linux was achieved using the Gumstix was not that difficult. • Initially a USB connection was used to access the Gumstix, using USBNet. • Through USB, Wifi settings were configured to connect to the “NUIGALWAY” wireless network. • However most programming and testing was carried out using a USB connection.
Design Implementation • When the Tankbot was constructed, some mechanical adjustments were required. • Motors were tested to find required voltage levels and PWM signals to control them. • Motors needed to be isolated from the Gumstix, in order to protect the hardware. Opto-couplers were used for this purpose. • The registers were programmed to configure the 2 PWM outputs on the Gumstix, in order to implement basic control. GPIO16 and GPIO17 are the respective GPIO outputs for PWM0 and PWM1.
Design Implementation Using Python, programs were written to allow full control of the robot i.e. Forward, Reverse, Left, Right and Stop.
Design Implementation • Setting up the web-server was relatively simple. A simple web page was designed and stored in the /var/www folder of the Gumstix, which is the home folder of the Boa web-server. • This site contains links, which execute programs to allow full control of the robot using a web browser. • CGI programming is used to execute a program from the web. To convert the existing python files to CGI, a basic ‘content-type’ determination is placed in the code, which tells the browser how to handle any text printed in the program. When the program is executed, the browser outputs any text printed in the CGI files as HTML.
Design Implementation • In implementing Obstacle Detection, an ADC was used in order to convert the output of the Distance Detector into a digital number, which may be read by the Gumstix. • The 3 most significant bits are read from the 8-bit output ADC. This is to allow the desired sensitivity of the Sensor. • Using a python program the 3 outputs are constantly polled and ANDed together. If the output is ‘high’ then an obstacle is within 10 – 15 cm. The robot is programmed to reverse a certain distance and then turn right and continue with forward motion.
Design Implementation • In implementing line following, a circuit was constructed consisting of 3 photo-reflectors. Each sensor has an output which is read by the Gumstix. • The 3 outputs are polled using a python program. A sensor outputs a ‘high’ when over black and a ‘low’ when over white. • The program interprets the GPIO and makes a decision as to the motion of the robot.
Design Implementation • In creating CGI files to execute line following and obstacle detection, problems were encountered with python as regards internal memory allocation. • Shell programming was used to solve the problem. • Shell programming, executes Linux shell commands in the form of a program, and allow your Linux OS to carry out a set of instructions all at once.
Power Consumption • A major design issue with the robot is the power consumption of the Gumstix system. • It is powered by a 6V supply, which is obtained using a 7806 6V Regulator with 2 x PP3 (9V) batteries. • With all 3 boards connected the system consumes about 1.2W at 6V. • The batteries tend to drain very fast. This is also due to the power consumed by the Regulator itself. • Max use time of 2 PP3 Energizer Ultra batteries is approximately 2 hours, which proved costly when testing the robot.
Results • Currently the Project has produced a reliable robot which may be fully controlled using any web browser. • It may also operate in Obstacle Detect mode and Line Following mode, also executable from the web. • The robot may also be controlled using a WAP browser on a mobile phone. This may be only simulated using Openwave Phone Simulator, due to the IP address of the Wifistix not being available outside the NUIGALWAY network. This is Computer Services’ policy. • It is possible to stream live video, using a fellow classmates project, which incorporates live streaming from an IP camera based in the Lab. • Unfortunately control using a J2ME application was not achieved.
Results • The Gumstix system, was a good choice in hardware for this project, although it is not without its faults. • One fault is that it does not securely connect together, and all boards are vulnerable to being separated easily and hence causing them to short and blow. • However it is a very powerful piece of hardware, which has ease of use once minimal experience is gained.
Conclusion • Overall the project was very beneficial to my Degree, as I gained experience in areas which are generally not part of the curriculum. • Also I hope that this project may enhance my chances of working in the field of automotive electronics, due having gained knowledge in some fields which are currently being used or researched. • I also think that this project may be a good sample project which can be demonstrated to visitors, which may increase interest in Electronic Engineering.
Thank You • Thanks to my supervisor, Mr. Fergal O’Malley for his guidance throughout the project. • Thanks to Mr. Liam Kilmartin for assessing my progress in this project. • Also thanks to the Martin, Myles and Shaun and also to Frank Callaly for their assistance with any issues encountered during the project.
