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1. Introduction

The Sentinel is a project that has been developed by teams from two different classes at Columbia University's School of Engineering and Applied Science:

    W4735 Visual Interfaces, taught by Prof. John R. Kender, Spring Semester 2001

    E3940 Microprocessor Laboratory, taught by Prof. Andrew Campbell, Spring Semester 2001

Figure 1.1
For management reasons the project has been neatly divided between the two groups:

    W4735: This part of the Sentinel essentially takes as input the output of a simple analog camera through the Java Media Framework. The series of images are analyzed for road information in the form of a line that is differently colored from the rest of the road. The software then reduces the image data, interprets the data and makes a decision in the form of "drive forward", "turn right", "turn left", or "detected forking road". This simple decision is then sent through the network layer to a laptop, which is in turn connected via the parallel port to the Z-80 processor. The W4735 team's work ends at the point where the laptop receives the next direction for the tank.

    E3940: This part of the Sentinel takes as input the output of W4735's portion of the project (see previous point). In case the decision is to step forward, turn right, or turn left, the decision is simply turned into an electrical signal on a remote control that steers the tank. Should the decision be a "forking road", further signals from the W4735 team are ignored, while the tank attempts to pick up infrared signals from either side of the forking road by means of appropriate sensors. Depending on where the signal originates, the Z-80 processor makes a decision to turn into that part of the road. After the tank has been re-positioned, further commands are again read from W4735's output.