RobotWar Gun and Radar Behavior by Richard Fowell This is the second article in a series. Familiarity with the previous article, "Speeding up Your Robot", is occasionally assumed. In this installment, we examine what we have learned about gun and radar behavior from our test robots. The program adds about 13 units to the fuse range set by you, which tends to cause near-miss shots to explode long. The shells seem to travel at a speed of about 5000, which is 100 units per turn. Thus they take about 3.5 turns to cross the board from corner to opposite corner, or 2.5 turns from side to side. It appears that if you command a range of less than about 13, the gun heats up but doe not fire. As far as the shells are concerned, robots seem to be about 12 units wide, and about 15.5 units high. Curious. Interesting, too. This implies that BOTTOM would do better as LEFT or RIGHT. (This would also help prevent the collisions BOTTOM gets into while descending, since it seems that robots never start at the same Y position, although they frequently have nearly identical X positions.) The range that the radar reports when it spots a robot appears to be precisely the distance between the centers of the robots, and is the same whether one looks at the center of a robot or at its edge. For example, if one robot was at (X,Y) = (2.33,20), and it saw a robot at (X,Y)=(50,90), the value stored in RADAR would be -1*SQRT((50-2.33)**2 + (90-20)**2), or -84.69. The thing that determines whether or not you actually see a robot is whether or not a straight line drawn from the center of your robot along the RADAR direction will intersect an orthogonal, square cross centered on the other robot, with both the vertical and the horizontal arms 24 units wide. This is unexpected and has profound implications. For example, it explains why one may see a stationary robot and shoot where one saw it, yet | miss. It also explains the amazing hit rate of +--+--+ the NORDEN class against stationary robots: |XX|XX| <---- robot viewed diagonally, the radar image is almost --+--+--+-- <- image precisely the same as the actual robot -- what |XX|XX| you see is what you hit. Note as well that this +--+--+ means that robots seem smaller when viewed at an | angle rather than orthogonally. Measured orthogonally, robots are 24 units across -- Figure 1. Radar image diagonally, they are 24 * cosine( 45 degrees ), compared to or 16.97 units across. physical robot.