One way to win a Robot Combat match is to incapacitate your opponent. People use many strategies and techniques in their bots to accomplish this. Some weapons focus on maximizing the damage they can inflict on their opponent, while other weapons are designed to control or invert their opponents so they can't drive. Many people have commented that strategies around weapon types are a bit like playing rock-paper-scissors: Designs that are effective against one type of opponent are less effective against others.
These weapons lift the opponent and cause them to lose control of motion. Since the overall goal of a match is to incompacitate your opponent, lifting an opponent off of its wheels can be an effective way to win a match. Lifters can be especially effective when the arena has a pit or an 'out' area where a lifter can place its opponent.
A wedge is a sloped surface that might lift an opponent off the ground, even slightly. Many bots have wedges in their design, even if it appears to be only incidental to the bot's operation.
While they are simple passive weapons, wedges are very useful when the bot has a skilled driver.
- Breaking contact between the opponent's wheels and the ground
- Lifting an opponent until their weapon is unable to reach you, or no longer effective
- Lifting an opponent to keep it from attacking your active weapon, assuming your weapon has greater reach than theirs
- Lifting an opponent to feed it into your active weapon
- Armored defense; deflection against attacking weapons
- Crushing opponents against walls
- Pushing opponents into hazards
- Lifting opponents out of bounds or into a pit
- Fixed wedges are attached to the body of the bot, or are part of the body. Many insect-weight bots have only two wheels, and a wedge or scoop holds up the front or back of the bot. A fixed wedge slightly above the arena floor can be effective, but may be ineffective against a lower wedge. Wedges that rest on the floor can become jammed due to floor scratches, uneven floors, and damage to the bot, and can be stuck under walls or barriers.
- Hinged or ground-scraping wedges slide on the floor and may be more likely to get under an opponent, and they pivot to discourage jamming on uneven floors.
Small wedges that are used to get under opponents are known as wedgelets. These can often save weight compared to a larger wedge, but can be difficult to make strong enough to survive an opponent's weapon. The 'Wolverine Claws' by BotKits.com are a very effective example. Recently, there has been a bit of an 'arms race' with wedglets becoming longer and longer in an effort to get under an opponent before they can get under you. Currently there aren't any rules on wedglet size or length but some events are considering them. Wedgelets offer little in the way of armored defense except against low attacks, but they have the benefit of being individually replaced without the cost of renewing a full-sized wedge.
Wedge design notes
- Generally the bot with the lower wedge is at an advantage, but imperfections in arena floors and walls can make it very difficult to drive if your wedge scrapes the arena floor.
- When going against cutting weapons and spinners, give your bot a heavier wedge that is able to withstand the abuse.
A lifter is designed to slide under another bot and pick it up. Lifters can be made in any shape or size that will give an advantage over an opponent.
- Single vs. forks
- Lift with spinner
- Disorientation and disruption of the opponent
- Causing fall damage to opponents
- Breaking off pieces of opponents
- Disabling opponents if they land upside down, if they cannot self-right or operate inverted
- Potentially lifting and carrying an opponent toward a pit or other hazard
Flippers and Launchers
A flipper is a lifter that is strong enough to rapidly flip an opponent upside-down and/or far away. This may be done with a simple servo on small bot.
A flipper that is so fast and powerful that it can throw an opponent directly toward the ceiling of the arena is sometimes called a Launcher. These are made with complicated mechanisms that release stored energy from spring-powered, pneumatic, or hydraulic devices.
Lifter design notes
- On small bots, a lifter can be precisely positioned with a servo. Since the end of the lifter is often close to the ground, adjust your transmitter or receiver to a convenient "down" position.
- Lifters should not use plastic-gear servos, as the gears tend to break during heavy use.
- Remember that your opponent's bot weighs the same as your own in most cases. Proper balance (center of gravity) is required for your bot to be the one that stays on the ground!
Spinning weapons can inflict damage on opponents with a hard, fast impact from a rotating element.
A vertically spinning weapon usually mounted across the front of a robot. Normally hitting an opponent with any part of the drum will inflict damage. They take various forms:
- Solid drum with machined teeth
- Solid drum with added teeth, bolt heads, etc.
- Shaft with spinning discs
- Machined bar stock, often hollow to save weight, sometimes with added teeth or bolts
These are sometimes named "beater bars" after the spinning cylinder inside the front of an upright vacuum cleaner, but instead of beating and brushing carpets, they strike opposing bots.
- Disorientation and disruption of the opponent
- Inflicts serious damage with an effective hit
- May fling opponents into walls or hazards; fall damage
- Super easy to use - aim and kill
- Gyroscopic effect means that one side of the robot will tend to lift into the air, especially in turns.
- Frequently damaged in fights due to high impacts
- The side facing opponents should strike upwards.
- Drum spinners may be directly driven using a motor at one end (or even fitted inside the drum), but many are belt-driven instead.
- Brushless motors are often used for maximum acceleration and effect.
- Drum spinners require strong, heavily reinforced mounting points at both ends. In most cases a metal frame is required.
- Both ends should have easily replaceable bearings. Bearings on the motor shaft or body often need to be reinforced as well.
- The drum must be perfectly balanced to avoid severe vibration and loss of control.
- High-mounted horizontals are great for damaging top-mounted weapons and may be positioned to reach over wedges to strike the body of opponents.
- Low-mounted horizontals (undercutters) can destroy wheels, tires, guards and frames on many bots. However, they could be deflected by hardened wedges.
- Gyroscopic effects
- Easier than a vert to target opponent with a big spinning horizontal element
- Turning / yaw of the robot is not a problem
- After a big hit, the reaction force can throw the aggressor robot across an arena into hazards or even destroy it
- If the robot becomes tipped (e.g. on an opponent's wedge) it can gyro in a very uncontrollable manner
- Saw arms
- Gyro effects
Overhead spinning weapons
Actively articulated weapons which incorporate a spinning element; technically more complex but can be effective and fun.
- Overhead saw / hammer saw - does damage by abrading the top of the opponent where armour may be weak or exposed components
- Overhead vertical spinner - kinetic energy overhead weapon - e.g. Battlebots heavyweight Sawblaze
- Overhead drill
Full body weapons
Large portions of your bot, or even the entire bot, can be put into motion as a spinning weapon. These are tricky to build; it is crucial that the bot be perfectly balanced, with its weight evenly distributed, so that it doesn't lose control or tear itself apart.
The armor / body of a shell spinner rotates around robot's internal components. When done correctly this weapon can provide 360-degrees of offence and defence which makes it an appealing option. There can be challenges with stability if the shell isn't properly balanced. Also shell spinners can not operate inverted; they will often have a curved bar coming out of the top to aid in self-righting.
This type of bot has a round, steerable core surrounded by a spinning ring. It is similar to a shell-spinner in appearance but the spinner doesn't rotate on a central shaft. This approach does have the advantage of making it easier to drive the weapon with multiple motors but the integrity of the ring can be difficult to maintain upon impacts which often results in shell spinners stopping their spinning.
The entire bot spins rapidly, but using computer-assisted controls, it can still be steered. See Melty Brain.
Any of the above bots, but incorporating a hammer, or an arm with spikes, extending from the side of the bot. It is driven into position and then commanded to spin in place to create a circular zone in which other bots may be damaged. Since Thwackbots just spin in place, they typically require an opponent to drive into them. It is possible for thwackbots to drive towards an opponent perform a skid-and-spin manuver to hit them but these attacks typically have less power. Thwack bots don't qualify for events that require active weapons but if they include Meltybrain drive they will often qualify.
Full body flail
A variant of the thwackbot that incorporates one or more flails (like a mace, or a chain) which can be whipped around to cause damage. These are more difficult to operate, since the weight distribution of the weapon is not fixed.
Full body drum
Hammers inflict destructive shock waves, dents, and puncture damage on opponents.
Seize control of opponents and puncture or throw them for damage.
Ramming weapons are intended to be driven toward opponents to cause damage.
- Steering opponents
Ramming design notes
- These weapons are only effective in bots with high acceleration, high speed, high traction, and very skilled drivers.
There are other weapon types that are uncommon and/or not permitted in most event rules due to reasons of safety, liability, or arena durability.
Flame weapons can set fire to vulnerable pieces of opponents' bots, and can potentially cause over-temperature shutdown or damage to electronics. They are among the most spectacular weapons, even when ineffective due to defensive armor.
Where permitted, flame weapons must follow strict build guidelines concerning fuels, pressurization and pressure containers, suitable valves and materials, duration of use, and many more details. If you are seriously thinking of using them, work closely with the event organizers and place yourself under the mentorship of a builder experienced in flame weapons.