For the full article please see the July/August 2008 issue of Robot Magazine which is now available.
In this new version of Romey I expanded Romey’s sensory capabilities and dramatically change the mission from that of a “free range” robot to a web-based telepresence robotic system.
Romey is built on the A4WD1 Rover from Lynxmotion and is equipped with a Ping ultrasonic sensor and three Sharp GP2D12 IR distance sensors. Romey uses the Basic ATOM Pro 28-M for its main controller installed on a Lynxmotion Mini Atom Bot Board. Power for the Bot Board and related electronics is supplied by a 7.2 volt 2800mAh battery. Control for the four motors is performed by a Sabertooth 2X10 Dual Channel motor controller. Power for the motors is supplied by a 12 volt 1600mAh battery mounted inside the chassis.
There was one weakness in Romey’s sensor coverage that needed to be addressed. There are two small gaps between the center and left and center and right GP2D12s IR sensors. The Infrared Proximity Detector (IRPD) from Lynxmotion works to fill these gaps. The IRPD has two cables that plug directly into the Bot Board. There is a sensitivity adjustment and status LEDs used to set the detection distance. For Romey this was about six inches. The IRPD is mounted just under the center GP2D12 on the chassis’s front panel. In the software, the Avoid behavior was modified to use the additional IRPD information.
To support the telepresence mission Romey required two major upgrades. The first was to replace the existing wireless color video camera with a Panasonic BL-C30A Network Camera. The BL-C30A is a self contained web cam that connects to your network using 802.11b or 802.11g wireless technology (Wi-Fi). The camera is mounted to the Lynxmotion Base Rotate Kit. Because the camera has its own pan and scan ability and it is mounted on the Base Rotate Kit it’s now possible to scan nearly 360 degrees around. Like the original video camera the BL-C30A requires 12 volts DC for power so the existing battery was reused to power it.
The second part of the upgrade is to add a Parallax 912 MHz RF transceiver module. The transceiver is used to receive movement commands from the special Romey Web Server. The transceiver has a range of up to 800 feet, employs 16-bit CRC error checking and has a built-in FIFO buffer. The unit is mounted on Romey’s top deck using Velcro and connects to the Bot Board using a custom cable.
The Romey Web Server makes web-based telepresence possible. Because we are using an off the shelf network camera, the seeing part of telepresence (video) is relatively straight forward. The camera has a built-in web server that sends its video data through your wireless router using 802.11b/g Wi-Fi and then out to the web browser. The real work is in sending commands back that are used control Romey’s movements. Since I wanted to use a web browser to do this I built a small web server of my own that receives commands from the web browser and then translates them into commands that get sent to Romey via the 912 MHz link.
The hardware for the Romey Web Server is simple. At the heart of the server is the Parallax PINK (Parallax Internet Netburner Kit). The PINK is a self contained web server which enables a microcontroller to communicate over a network or the Internet. The Basic ATOM Pro is used for the microcontroller. All the components are mounted in an 8 x 6 plastic enclosure.
To use the web interface you request the nb_Romey.htm page in the browser with the appropriate domain name or IP address. This is the main page for an HTML frame set. A frame set is a special page that brings together other pages into a single browser window. For Romey we are bringing together two pages: the control panel and the web page for the Network Camera. This gives the appearance and convenience of having a single integrated user interface.
Detailed schematics, HTML pages and all the source code can be downloaded from the links on the right or from http://www.botmag.com/issue11.