Brookstone Rover AC13
The Brookstone® Rover is sold exclusively (for $99,-) in the United States and can be controlled by ipod, iphone, or other Apple device. It has a camera at front, a microphone, and an IR led which can be used to “see in the dark”. It runs on 6 AA batteries which is directly the only “minus” of the robot. Different from for example the iRobot Create®, recharging the thing can only be done manually. If you want to stalk your cats if you are on holidays, you will have to turn on the robot before you leave and it will have run out of power before it’s time to check if your neighbour did do his job. But, for now, it’s a perfect toy!
Last month, we got one from under the christmas tree, and hence, a challenge is born! How to control this interesting robot from an android device. First we use nmap to see which ports are open. The result: one TCP port open at 80, and two UDP ports at 67 and 10000. We connect to port 80 and see that there is a HTTP page served which requires username and password. After hitting ESC for three times, it shows a misspelled “Device Embeded Web UI Version” phrase, just as Foscam IP cameras do! Probably the same developers have programmed the firmware for the Rover! Time to disassemble the robot to check if this is true.
Yes! Remarkably enough there is a similar chip which reads spansion s29gl032n90tfi040 (Flash) as in the Foscam line of IP cameras. The board looks almost the same as the one at the computersolutions.cn blog. Checking the CGI API document from Foscam reveals that the Rover responds to document cgi scripts such as “decoder_control.cgi”, “camera_control.cgi”, “wifi_scan”, “get_params” and “set_params”.
We connect an iphone to the robot via the default ad-hoc network started up by the rover. And we connect a mini laptop to it at the same time, now running “sudo tcpdump -XXvvvs0 -i wlan0 port 80” reveals the network traffic. And we just see that the iphone logs into the browser by issuing an HTTP GET request “http://192.168.1.100/check_user.cgi?user=AC13&pwd=AC13”. That was easy, we already know the username and password: AC13. Now, to quickly check if there are (unencrypted) images going through the network we run
"sudo driftnet -i wlan0"
and yes, it displays the sequence of images transmitted by the robot. So far, so good!
The developers do not seem to use the cgi scripts at all. Just as on the Foscam IP cameras, there is a binary protocol used to command the camera to start streaming. It starts with “MO_O” or “MO_V” and then there is a sequence of bytes which represents a command. After careful examining this binary stream we extracted the commands going from the iphone towards the robot. A python script that gets you one image is published on the androidcommunity forum. There were nasty details such as the necessity to close the socket and open the socket at the same port after authentication.
To actually be able to remotely control the robot we need to do more. Google provided a nice SDK to build your own apps, integrated with Eclipse, debugging by connecting your phone via USB. Almost everything works out of the box. We need to transform our python code to Java to use it on Android. We wanted not only to be able to stream images, but also to control the robot by moving the cell phone. The result can be found in the Android market, as the RoverOpen app. Contrary to most apps, this one is completely open source. The code can be found at the server of our mother company, Almende Redmine. Feel free to contribute to the code to make this app better! Enjoy!
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