After two weeks of introduction to Robocode, it was time to create a competitive robot. Even looking at sample robots and collaborating with fellow classmates, it was hard to find a place to start. What type of movement, targeting, or firing strategies will be effective against other robots? For starters, it began with developing a single robot that can counter as many of the following eight sample robots: Walls, RamFire, SpinBot, Crazy, Fire, Corners, Tracker, and SittingDuck.
After much toil, I implemented this strategy:
StrafeNShoot
(Source code)
Movement: Essentially uses the 4 corners movement as a method of getting around the map. Starts to go to the upper left, and then lower right, upper right, lower left, and back to upper left; going in a perpetual cycle throughout the match.
Targeting: As it moves to each corner, the robot tries to keep the gun pointed either at the center of the battlefield, or at the enemy.
Firing: As soon as it sees another robot, it will reposition the gun and fire with a power of 2. I used power of 2 because throughout trial runs, the points gained outweighed the energy used. However, when it gets shot at or collides with another robot, it will immediately realign the gun and shoot with a power of 3. Since the robot is moving most of the time, it was difficult for other robots to hit, so it was feasible to use maximum power.
Trial Runs:
Consistently Defeated: RamFire, Crazy, Fire, Corners, Tracker, SittingDuck
I noticed that with my strategy I had an advantage over stationary/tracking type robots. Because my robot moves at drastic lengths from one side of the battlefield to the other, stationary type robots will continually keep firing and missing; expending their energy and ultimately disabling themselves.
Tracking type robots have a hard time repositioning themselves. By the time they reposition and start moving to my location, I’ve already moved onto a different heading and the tracker is just trying to keep up. Meanwhile I’m firing as I’m moving to each corner.
Although Crazy is neither a tracker nor a stationary robot, its random movements work to its disadvantage, often times it runs into my bullets, and since it only shoots when it sees a target without any type of tracking, my robot will have moved on by the time it fires.
The Troublesome Two: Walls and SpinBot
Examining all the sample robots, it was hard to come up with a solid movement strategy. Robots such as Crazy, SpinBot, and Walls, make it hard to create a standard pattern of attack, even tracking their movements makes it difficult. When it comes to these two robots, my win/lose ratio is about split 50/50.
For Walls, the initial placement of the robots seems to play a significant role. When the robots are initially placed, sometimes my movements are exactly in-line with Walls so every time Walls fires, my robot will get hit and the converse is the same. Sometimes Walls’ movement is in-line with mine, so every time I fire, Walls will get hit.
For SpinBot, because it keeps moving in a circle, it can seemingly dodge all of my shots. Sometimes I’ll run out of energy just trying to shoot at it, or at rare occasions I’ll collide with it and I’ll fire at maximum power to take the win. Also, at times SpinBot will use up all of its energy just trying to shoot and I’ll take the win when it becomes disabled.
Here are my final results, 100 matches for each of the 8 robots:
Walls: score percent: 53; 47 wins; 53 losses
RamFire: score percent: 57; 77 wins; 23 losses
SpinBot: score percent: 53; 53 wins; 47 losses
Crazy: score percent: 68; 65 wins; 35 losses
Fire: score percent: 84; 97 wins; 3 losses
Corners: score percent: 83; 100 wins; 0 losses
Tracker: score percent: 82; 98 wins; 2 losses
SittingDuck: score percent: 100; 100 wins; 0 losses
Lessons Learned
During the creation process, I came across many contradictions. What worked to defeat one did not work against another. For predictable movements, it seemed that a blunt strategy like RamFire would be a sure win. But for robots with completely random movements, the only way to combat it was to move randomly as well.
Creating a single robot that could defeat all eight of the sample robots would be no easy feat, and by doing so would increase success in real competitive battle. However, the only way to test it out is to put it in actual battle. Talking with a few classmates, I found that I could easily defeat a specific sample robot while theirs could not, and vice versa.
When I was designing my robot, I was only thinking of survivability. Meaning, I thought that if I outlasted my opponent I would win. However, survivability is only one part of your total score. Even if a robot is defeated, it can still out rank your opponent, so even a blunt robot like RamFire can still out rank you because it will gain a lot of ram points. I will keep these things in mind when I make upgrades to StrafeNShoot.
No comments:
Post a Comment