LynxMotion Robotic Arm Remote Access Implementation
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1. by updating the connection label element 2 1 System specific Implementation Details Arch Linux has been selected as the OS of choice for this particular instance ofthe XRA as it offers a bare bones installation of Linux and comes with no graphical desktop environment Arch uses a powerful system management daemon called systemd 8 that makes it easy to create persistent background services systemd has been leveraged in order to make both the Robotic Arm Device Port and video streamer into system services that start automatically at boot time System services are created by writing service files in the usr lib systemd system directory Listings 4 and 5 content the contents of the radp service and video streamer service Listing 4 radp service Unit Description Robotic Arm Device Port Requires nginx service Before nginx service Service Type simple PIDFile var run xra pid Restart always StandardError syslog SyslogIdentifier RADP User root WorkingDirectory root ExecStart usr bin node root xor_radp js Install WantedBy multi user servic Listing 5 video streamer service Unit Description MJPEG Stream on port 8080 Service Type simple PIDFile var run mjpg_streamer pid ExecStart usr bin mjpg_streamer i input_uvc so r 320x240 f 10 m Install WantedBy multi user target The following command will enable these services2. slider slide function event ui radp emit cmd servoNum 2 angle ui value 180 100 S wrist slider slide function event ui radp emit cmd servoNum 3 angle ui value 180 100 S claw slider slide function event ui radp emit cmd servoNum 4 angle ui value 180 100 radp on status function msg status text msg I radp on fdbk function msg S rotation slider value 100 msg servo0 180 S shoulder slider value 100 msg servol 40 140 S elbow slider value 100 msg servo2 15 165 S wrist slider value 100 msg servo3 180 S claw slider value msg servo4 H H lt script gt lt snip gt The code in Listing 3 contains the JavaScript code behind the control panel This code is rather concise as JavaScript provides rich APIs for creating event driven applications and jQuery has been used as a simple way to reference and manipulate page elements to create a dynamic web page The first line of this script tries to establish a socket connection with the RADP after the page has loaded The RADP port number has been specified by appending 8000 to the server IP or URL The next line of code sets up a function to be called when the socket is successfully established This on connect event will notify the user that they have successfully connected
3. Exclusive Online Robotics Robotic Arm Implementation and Testing James Carroll Tyler Thomas Draft 1 June 2 2014 CEN 4935 Senior Software Engineering Project Instructor Dr Janusz Zalewski Computer Science amp Software Engineering Programs Florida Gulf Coast University Ft Myers FL 33965 1 Introduction This XOR Robotic Arm XRA is a web application for telerobotic control of a robotic arm over the Internet The specific requirements and design description for the XRA are contained in 1 and 2 This document covers the details of the implementation and testing of the XRA software The XRA implementation has been done with a strict policy of platform independence so that both developers and users of the XRA can use practically any operating system any platform This is a major divergence from the previous projects 3 4 5 6 7 which all utilized Microsoft s development tools and Windows Embedded CE In addition to eliminating any restrictions on platform the XRA is also free from any proprietary interests making it easier to use replicate and extend The rest of the paper will cover the materials used for the XRA the code that makes it work and the testing procedures used to ensure every requirement has been met 1 1 Bill of Materials ALSA robotic arm SSC 32 Serial Servomotor Controller USB to Serial adapter TI Beagleboard xM Logitech C920 USB Webcam S Table 1 Bill of Materials N
4. d from xra html lt snip gt lt script gt S function var radp io connect http onlinerobotics net 8000 var countdownTimeoutID 1 var countdownDateTime new Date 0 0 0 0 5 radp on connect function s Update status labels S connection status text Connected Start the countdown timer var secondsString countdownDateTime getSeconds toString if secondsString lt 10 secondsString 0 secondsString S countdown text countdownDateTime getMinutes secondsString remaining countdownTimeoutID setInterval function countdownDateTime setSeconds countdownDateTime getSeconds 1 var secondsString countdownDateTime getSeconds toString if secondsString lt 10 secondsString 0 secondsString S countdown text countdownDateTime getMinutes secondsString remaining 1000 countdown timer interval I radp on disconnect function clearTimeout countdownTimeoutID S countdown text S connection status text Disconnected S connection status css color red rotation slider slide function event ui radp emit cmd servoNum 0 angle ui value 180 100 shoulder slider slide function event ui radp emit cmd servoNum l angle ui value 180 100 elbow
5. e that the device port was already bound to one RAC inspection by a second user as to whether requirements relating to display and socket connection were made 3 2 Test Results a from the XRA server 3 2 1 2 The control panel should contain a live video stream of the robotic arm Passed A video stream of the arm is displayed at the top of the control panel 3 2 2 1 The RAC should connect to the RADP as soon as it is loaded Passed In order to conform to requirement 3 2 3 2 if another client is connected to the RADP the current client fails to connect In all other cases it connects right away 3 2 2 2 The RAC shall contain five slider elements for controlling the arm s five joints Passed Each slider element also has a label at each end indicating which physical orientations correspond to each slider extreme Each of the sliders in requirement 3 2 2 2 shall be used to adjust the angle of one of the arm s joints by transmitting the desired angle value The data sent with a command emission contains both information relating to which servo is being controlled and to which angle it will be set 3 2 2 4 Upon connecting to the RADP the RAC sliders shall update to reflect the positions of the arm s joints Passed In the interest of protecting the hardware the arm is set to a predetermined position entirely vertical upon a disconnect to minimize joint stress Upon connection the RAC sliders are set to ref
6. lect this position 3 2 2 5 Commands sent from the RAC shall conform to the XSMF Every message sent to the RADP has a target identifier and value field for joint angle 3 2 3 1 The RADP shall listen for connecting RACs on a specific port The RADP listens on port 8000 10 3 2 3 2 The RADP shall only accept one RAC connection at a time Passed When the RADP is in use additional connections are rejected and prompted with the message The XRA is currently in use Please try again later 3 2 3 3 The RADP shall convert XOR Commands received from a RAC into device specific Si a for the robotic arm controller Passed This is done in xor This is done in xor_radp js in the on command callback function Js in the on command callback function 3 2 3 4 The RADP shall send any status changes to the connected RAC using XOR fase Feedback in XSMF Passed Status changes are sent with a target identifier of status with a value containing the status update message 3 2 3 5 The RADP should notify any rejected RACs using XOR Feedback containing a reason for the rejection Passed When a connection is rejected a status message is displayed on the control panel below the video feed Any tools used for developing the XRA should be free and open source Arch Linux Node js and its packages are all free and open source 3 4 2 Any communication between the RAC and RADP should conform to
7. ltiple clients e Add more widgets to the control panel like network stats uptime a client queue etc e Implement a login feature so that only credentialed user can connect to the RADP e Design a hardware controller that interprets the arm movements of the operator in order to control the arm e Establish an online community so that others can host their own telerobotic devices at OnlineRobotics net e Extend the software to be able to control other types of robotics systems With the prevalence of Internet driven technology anybody should be able to have their own online telerobotic systems As long as the XOR project remains free and open the may one day be a reality 13 5 References 1 J Carroll and T Thomas Exclusive Online Robotics Robotic Arm Software Requirements Specification http itech fgcu edu 24 Apr 2009 2 J Carroll and T Thomas Exclusive Online Robotics Robotic Arm Software Design Description http itech fgcu edu 28 Apr 2009 3 Daboin Carlos Robotic Arm Connectivity User Manual Project http itech fgcu edu 13 Aug 2009 4 LaForge Robert ALSA Robotic Arm Project Web Based Control with Spatial Awareness and Intuitive Manipulation http itech fgcu edu N d 5 Saldivar Adrian and Kyle Rosier Remote Software Updater for eBox 2300 and Windows CE6 http itech fgcu edu 4 April 2012 6 Fernandez Arnold and Victor Fernandez Robotic Arm Remote Control Maintenance User Manual http i
8. n file will open up a socket that listens for connecting controllers and initializes communication with the SSC 32 device The first 13 lines of this program in Listing 1 do just this Listing 1 Snipped from xra_device_port js var radpSocket var SerialPort require socket io listen 8000 require serialport SerialPort Serial port connection to the SSC 32 var ssc port new SerialPort dev ttyUSBO baudrate 115200 To run the xor_radp js program Node js is invoked and passed the file name root apollo node xor_radp js The radpSocket listens on port 8000 because port 80 is already bound to by the HTTP server In order to serve the Socket io files to the client a TCP proxy pass through is needed so that requests for socket io on port 80 are passed on to port 8000 This is done in Nginx by adding the lines red in Listing 2 to the nginx conf file This file is typically located at etc nginx nginx conf Listing 2 Snipped from nginx conf http server location socket io proxy_pass http localhost 8000 proxy http version 1 1 proxy_set_header Upgrade Shttp_upgrade proxy_set_header Connection upgrade The last component to describe is the control panel The control panel is a web page that is served to the user upon directing their browser to the IP address or URL of the server The full listing for the control panel web page is in the Appendix Listing 3 Snippe
9. ote that the major expenses the AL5A and the Beagleboard xM were selected because of their availability at the authors institution There are however much more affordable options for low power robotic arms and development boards like the OWI 535 and the Raspberry Pi Of course using a different robotic arm would most likely require a few changes to the server side code It is also possible to just run the server side programs on any old PC which would eliminate the need to purchase another system Lastly the Logitech C920 was selected because of its hardware compression in both the MJPEG and H 264 formats however there are much less expensive USB webcams with hardware compression What this all means is that it is very possible to recreate this project with under 100 in hardware costs Of course the software is all 100 free 1 2 Tools and Software Server side software e Node js with the following packages installed o Socket io o SerialPort e Nginx e MJPG Streamer for online MJPEG streaming e SSH daemon typically enabled by default for remote access Client side software e Modern web browser o e g Chromium or Firefox e SSH client o e g built in ssh utility Linux Mac OS PuTTY e SFTP client o e g WinSCP Filezilla Cyberduck e Text Editor o e g Sublime Text Notepad Vim Emacs 2 Implementation The best starting point for understanding how the XRA operates under the hood is in the xor_radp js file Ru
10. so that they start automatically at boot time root apollo systemctl enable radp service root apollo systemctl enable video streamer servic 3 Testing 3 1 Test Plan The testing procedures outlined in this section will ensure that the software that has been delivered meets the requirements set forth in the SRS 1 Each of these requirements will have a specific testing procedure that will test the compliance of the software While other systems may require more complex testing methods such as batch scripts the XRA project can mainly be tested by visual inspection or manual interaction Other testing which has been applied was used to gauge the ease of use This subsection outlines how each of the requirements will be tested and the following subsection will display which tests have been passed and which have failed and why The great majority of requirements have been put in place to promote user ease It is with that motivation that several volunteer testers were chosen with varying degrees of technological literacy Upon any troubling interaction by a user the portion of the XRA software under question was closer analyzed and improved upon until no usability problems were found Other than the requirements which are obviously satisfied upon use of the client side RACP by a single user some requirements called for the access of the robotic arm over more than one machine In the cas
11. tech fgcu edu 18 April 2013 7 Baquero Abraham Robotic Arm Remote Control http itech fgcu edu 8 Nov 2013 8 Wiki systemd https wiki archlinux org index php systemd 27 May 2014 9 Surg Ann Transcontinental Robot Assisted Remote Telesurgery Feasibility and Potential Applications http www ncbi nlm nih gov pmc articles PMC 1422462 Apr 2002 10 United States Department of Justice Vanguard Robot Assessment https www ncjrs gov pdffiles 1 nij 204637 pdf 4 July 2004 11 Something Interesting Digital Sid Office Robot http sidigital co sid 12 Goldberg Ken The Telegarden http www ieor berkeley edu goldberg garden Ars 13 Joyent Inc Node js http nodejs org 14 Appendix All of the source code for the XRA project is hosted online at http git io xra 15
12. the XSMF Passed Every message sent to or from the RADP is emit ed with a target identifier followed by target values Ban 5 Ban 1 The XRA shall favor platform independent software Passed The control panel works on Windows Mac OS Linux and mobile platforms The XRA source code can be modified via SFTP and any text editor 3 5 2 1 The XRA should be accessible at all times except when taken down for maintenance 11 12 4 Conclusion The goal of this project was to create a telerobotics web application for controlling a robotic arm Simply put this goal has been accomplished Furthermore there is no need to take this statement at face value the project is hosted at OnlineRobotics net for everyone to see In summary the following goals have been accomplished for this project e Create a cross platform web application accessible from anywhere in the world with an Internet connection e Use exclusively open source tools so that anyone may view use and extend the XRA source code without paying a dime e Leverage techniques and technology to create highly maintainable and reliable software At the time of this writing the XRA is in a very early stage There are practically limitless extensions modifications and applications for this software To name a few e Implement a queue so that additional clients can wait for their turn to control the arm e Have multiple arms that can be controlled by mu
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