25 January 2010

Robot Components

Time to explain the components of the robot a bit more. The diagram provides an overview.

The main platform is the iRobot Create. It is an autonmous robot by itself but provides control through a serial port connection using a protocol called the Open Interface (OI). The OI can read the sensors and control the actuators of the Create.

The Fit PC Slim is a compact, low power PC with 3 USB ports and a Wifi, plus the usual PC components. It is powered from the Create through a voltage regulator on the Interface Board (IB). The IB also carries the USB interfaces for the serial port and I2C.

I2C is a standard 2 wire bus for controlling actuators and accessing sensor input. I'm not totally sure what is going to be on the bus. I expect a compass module, at least, to provide orientation. I have sonar and IR distance sensors working on I2C but am not sure which to use. These would be backup for detecting obstacles via vision processing. A main goal is for the robot to move around without bumping into obstacles. I also have a digital I/O board that could be used to provide LED indicators of what the robot is doing.

The reasons for the Wifi on the Slim is to download software and allow monitoring from the desktop or laptop, especially in the field.

RoboRealm (RR)is a software package whose main purpose is vision processing. It also has a lot of robot control capability, including a plug-in for the Create. I decided not to use that plug-in after some issues figuring out exactly how it worked. That may have been a mistake. My other concern was the latency of getting sensor information with it getting collected by RR and then collected from RR by the control program. RR will be used to handle the camera and vision processing.