Garcia Robot Application Video Demos
The following video demos are available for download:
- Platform components and robot internals.
- Calibrating the CMUCam2 in preparation for running the Linux 2.6.11 version of the application.
- The navigation application in action (running under Linux 2.6.11).
- The navigation application in action (running under Linux 2.4.19).
The videos above demonstrate the behavior of our robot navigation application running under two versions of Linux. Until very recently, and as is shown in the videos above, the version running on 2.4.19 is the more stable, when compared with the 2.6.11 implementation. This is due to timing differences in the way Linux schedules I/O operations, as the application is timing intensive and communication between the host and the sensor/actuator hardware is largely accomplished via the two serial ports located on the Stargate platform.
Since the above videos were created, we have adjusted the application code and tuned parameters, as well as enabled more of the infrared range sensors in order to improve the navigation around the perimeter of similarly colored barriers. Under newer manifestations of the application running on Linux 2.6.11, the robot is now able to traverse and locate objects over much greater distances, as well as more accurately detect objects in its immediate vicinity in order to avoid collisions.
Although we see improved navigation behavior in later versions running under a vanilla Linux kernel, there is still non-determinism in the event dispatch latencies for handling I/O data in the camera capture and motor control threads. This unpredictability leads to erratic motion and failure to switch between states during motor control, possibly causing collisions and sub-optimal navigation paths to occur. Therefore, we plan to extend the system with our User-level Sandboxing mechanism to provide predictable and safe event dispatching.