GETTING THOSE HOWLS OF APPROVAL

We all love to hear shouts of excitement from the audience and we thrill to the crowd's applause. To get this kind of response you need to toss your opponent around or take some chunks out of it. Unless your battle box is spectacular in some other way, you will need some kind of weapon to visibly damage your opponent.

Only the basics are needed to create an effective wedge-bot. Note the motors, speed controllers, and batteries inside Devil’s Plunger.		Here is a prime example of why wedge-bots are so effective. Look at the heavy damage that the front end of Devil’s Plunger sustained in only ONE competitive match. At a tournament, your robot will have to be able to take this kind of damage repeatedly in multiple matches for two or three days at a time!

	Drum spinners are among the most reliable of the spinner designs. Here, Falcon's drum takes some chunks out of Devil's Plunger's titanium wedge.
	WINNING WITH SPINNING If you do build a full body spinner, here are the tricks that will ensure your success: Spin as much mass as FAST as possible. Spinning speed is more important than mass past a certain rpm. Your spinning mass must get to fighting speed in two seconds, and destructive speed in four seconds. Use a drivetrain that resists spinning, for example, treads or 4WD. Use an electronic airplane gyro to stabilize yaw. Make the base and spindle support supremely stiff and strong. It is more efficient in terms of weight and power to have one motor pulling 200 amps than two motors pulling 100 amps. Put your weight in the batteries, not the motors. Keep spinning; with a spinner you must spin to win!

Unfortunately most of the local competitions around the country do not have arena hazards (arena weapons). You need a weapon to get that audience raving. What kind of robot and weapon is right for you?

THWACKBOTS

Thwackbots are nearly as easy to build as a box, but can have a little more offensive potential. Essentially a thwackbot is a battle box with a hammer or axe attached to it. The robot can drive around like the basic box, and some can spin in place to get the hammer up to speed for an attack.

The only real problem with this type of attack is controlling the thwackbot and its hammer while the entire robot is spinning in place! All the opponent has to do is avoid coming within reach of the spinning robot. Experienced roboteers will just sit there, outside the thwack's reach, and simply wait for it to stop spinning.

Some thwackbot builders have attempted a specialized driving technique—spinning the entire robot while it moves in a straight line.

One early proponent of this idea dubbed this maneuver 'Melty-Brain' and the term has stuck. So far there have been only a few builders that have been able to get their robots to move in a straight line while the entire bot spins on its own axis, and none have done it particularly effectively.

Icewave uses a 120cc 2-stroke Partner engine to spin a four-foot, hardened tool-steel bar about three inches above the ground.
The bar weighs over 50 pounds while the whole robot only weighs 120 pounds.

OVER-HEAD HAMMER BOTS

Another crowd favorite is the vertical hammer bot (a robot that swings a hammer and tries to bash an opponent or poke holes in the top of an opponent). Not many people have been able to make a bot hit hard enough with a hammer (or axe, or pick, or anything) to do much damage to the relatively lightly armored top of an opponent, so if you can perfect this technique you will probably have a winner.

SPINNERS RULE

The full body spinner, Shrederator, rips, tears, and dare I say “shreds” into the titanium skin of Hexadecimator, a pneumatic flipper bot.

Next we have my personal favorite design, the spinners. Even Carmen Electra agreed with me in a post-fight interview that "Spinners Rule." Spinner bots that are easiest to make include the bar and disk spinners. A bar spinner is similar to a disk spinner in the way that it hits and in the way the robot reacts when delivering a punch, but it weighs less. You can spin a bar or disk vertically or horizontally and each method has advantages and disadvantages. For a vertical spinner, nearly all the roboteers will spin the attacking side from the ground up so that when the weapon hits the opponent it throws the opponent into the air.

But vertical spinners do have the liability of gyroscopic precession. When these types of bots try to turn while spinning a fairly heavy mass they have a tendency to lift up on one side or the other. The tilt can come at very inopportune times and rob the bot of its driving power (by lifting a drive wheel) or reduce the bot's turning rate.

You can also spin a disk or bar horizontally. This eliminates the gyroscopic lift of the drive wheels and actually helps with overall stability. Of course when the horizontal spinner hits the opponent, usually both robots go flying in opposite directions.

DRUMS AND THRESHER SPINNERS

Another kind of spinner similar to the vertical bar/disk spinner is a drum spinner (a spinning cylinder shaped like a rolling pin or a barrel; thresher types may have chains or protruding rods). A drum will give a bigger hit than a blade or bar because it typically weighs more. It also can have the advantage of a lower profile that allows strikes closer to the opponent's base. This design still suffers from the gyroscopic precession prevalent in vertical spinners.

If you are lucky enough to fight in an arena with built-in weapons
then the match is all about control. In this match Karcas gets Verbal Abuse
under the arena sledgehammers (known as The Pulverizers) for a few
well-placed whacks.

FULL BODY SPINNERS

My favorite type of spinner is a configuration that has the entire external body rotating. It is the most effective for many reasons. Combat robotics is all about efficiency. Some build with exotic components and high-tech, high-dollar items. Many builders spend their weight budget armoring their bot and then add a weapon, or vice-versa. I think it is a really good idea if the armor is the weapon. By completely surrounding the robot with high strength material that is also used as the weapon, you have solved two problems at once. There are other spinners that whirl some weight around, but none spin the same ratio of weight (compared to total robot weight) as a full body spinner. Moreover, none are as well armored as this type.

LIFTERS, FLIPPERS AND CHUCKERS

The next step that most builders make after the wedge-box is to make a lifter bot. The lifter bot is a robot that simply lifts its wedge to get the other robot off its driving wheels. If you add more power to the lifter, it becomes a flipper: You will be able to flip your opponent over. Now take a flipper and add even more power. This ultimate lifter bot is called a bot chucker because it will chuck the opponent many feet into the air. If the hit doesn't kill the airborne bot, the landing usually does.

ROBOT DESIGN SOURCES

There are many books available to review these basic designs in more detail. Take a look at Chris Hannold's "Combat Robots Complete" and "Combat Robot Weapons," or Grant Imahara's "Kickin' Bot." There are many web sites to peruse for design ideas like RobotCombat.com or TeamDelta.com, and once you get on those sites you will find hundreds of links to other sites. You can also get online help most of the time as many builders hang out in the Robot Fighting League's forum: http://forums.delphiforums.com/THERFL/start.

CONCLUSION

Choosing your robot's configuration will come naturally as you review your personality, your engineering skills, and your building ability. Robots with complicated weapons are exciting but hard to keep running throughout a long grueling event. It's worth the effort though, as nothing can replace the thrill you feel when the crowd is roaring for you. Hey, the design that you are inspired to pursue could turn out to be quite a crowd pleaser, but you won't know until you build it. So get out there and just do it!

LINKS

Battlebots, www.battlebots.com.
RobotCombat, www.robotcombat.com
Robot Fighting League, www.botleague.com

For more information, please see the source guide in the magazine.

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