What follows are some of the strengths and weaknesses of
various combat robot designs that should be considered by builders and
designers.
Ram Bot
Drum Bot Clamp
Bot Crusher
Bot Hammer
Bot
Lifter
Bot Saw
Bot Push
Bot Spear
Bot Horizontal
Spinner Bot
Thwack
Bot (Spin Type) Thwack Bot (Overhead
Type) Vertical
Spinner Bot
Wedge
Bot
Ram Bots
Features: 4 wheel drive
Large wheels with high traction
Strong drive system
Strong frame
High degree of shock resistance
No active weapon
Invertible
Plenty of ground clearance
Strengths: Strong against spinning weapons, saws, drums and Spinning Bots
Design: The primary considerations
for a Ram Bot are rugged construction, power and traction. Select drive motors, batteries and controllers and construct the base and frame around them. Select a wheel size and gear ratio to provide rapid acceleration and a top speed of no more than 25 kph. Your Ram Bot should be able to push at least twice its own weight. Remember that your bot must be able to accelerate and overcome your
opponents weight and drive power. You will need large high-traction wheels to provide
sufficient traction. Go-kart and wheelbarrow wheels are good choices. Fill them with foam to improve their durability. Four or six wheel drive is better than two wheel drive for a Ram Bot. Four wheels are needed to ensure the entire weight of the bot is
transferred to the tire tread for maximum traction. Design your bot with the wheels as close to the front and rear of the bot as possible to reduce the hazards encountered when fighting wedges or lifting robots. Make sure that your wheel spacing front to back is greater than the wheel spacing side to side or your bot will be difficult to drive. Build your bot with plenty of ground clearance so as to reduce the risk of
becoming hung up on wedges, lifting arms or debris. Design your bot such that one end can be lifted of the ground and the two remaining wheels still touch the ground. A rule of thumb is to use wheels with a diameter that is 1/4th the
length of your bot. Ram bots must to be able to take serious hits. The bot should have a strong frame, electronics and other vital components should be isolated from vibration and shock. Try to use gear head motors so that your drive system does not rely on chassis alignment.
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Drum Bot
Feature: Wide spinning drum with teeth
Drum usually mounted on the horizontal at the front
Drum usually rotates upwards to lift opponents on contact
Can be designed to be invertible
Strengths: Although the drum usually requires less time to spin up, it also carries less inertia and thus inflicts less damage than the Vertical Spinner Bot. This type of bot has a lower center of gravity and is more stable than the Vertical Spinner, the Drum Bot can also be designed to be
invertible. Because of the smaller spinning mass, the Drum Bot is more maneuverable
as there is less gyroscopic force to contend with. The wider weapon requires less lining up when attacking the
opponent.
Design: If the spinning drum is kept small, this bot can easily be designed to be operated in the inverted position. By keeping the drum smaller than the drive wheels and by using a
reversible weapon motor the weapon can operate effectively when inverted or right side up. Because the weapon tends to lift
opponents, the bot can operate well by ramming and pushing opponents around the arena. Use well mounted pillow blocks on both sides of the drum. As with all spinning weapons, a strong support structure for the weapon is
necessary. Power the drum with a drive chain or timing belt connected to a drive motor mounted within the body. Some Drum Bots also make use of a wedge to assist feeding
opponents into the drum and to prevent them from going under the drum. Design the drum to spin up quickly, three to four seconds at most. Drums work best with an
aggressive driver, thus bots that must set up an attack, such as Thwack Bots and Lifters can be readily
beaten by a good Drum Bot. However a well armored Wedge, Ram, or Push Bot can be a difficult
opponent.
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Clamp Bots
Features: Actuated lifting arms with a second actuated arm for clamping.
Capable of picking up and holding opponents.
Strenths: Good choice against slower moving and less
maneuverable opponents.
Design: The clamping system must be able to open
sufficiently to hold the largest opponents likely encountered. The end of the clamp must be sufficiently strong and apply enough force to carry the weight of the
opponent. Pneumatics are a good choice for Clamp Bots as pneumatics can operate quickly reducing the risk of an
opponent escaping before the clamp closes. Electric actuators will also work and are capable of delivering higher clamping
strength but operate as a slower speed. Attention must be given to mechanism leverages when building a Clamp Bot. As in Lifter Bots, placing most of the bots weight towards the rear of the bot reduces the risk of tipping. Successful Clamp Bots are capable of high speed which allows them to catch their
opponents. Hammer Bots should be approached from the side when operating a Clamp Bot, so the the Hammer Bot does not gain the leverage to hit repeatedly in the same spot. Spinning weapons can damage and render useless a clamp mechanism if it is not rugged. Spinner Bots can be difficult unless the Clamp Bot rams the Spinner until it stops spinning. Clamp Bots can work effectively against Rams, Wedges and Thwack Bots.
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Crusher Bot
Features: Large pincers or claws
Usually hydraulically powered
Very powerful crushing capabilities
Strengths: A well constructed Crusher Bot is one of the few combat robots that has the potential to cause severe internal damage to an
opponent. A Crusher Bot has the advantage that once the weapon has grasped the opponent
and has begun crushing, the opponent may find it virtually impossible to escape. The Crusher Bot is then able to take the
opponent combat robot to a corner or obstacle and take repeated bites.
Design: Because of the strength requirements of the crushing mechanism or claw, the Crush Bot has little weight left over for the drive system and armor. As a result, the Crush Bot will find that fast,
maneuverable opponents challenging to grab and crush. Slower Rams, Push Bots and Hammer Bots can be easy prey, where as a Spinners and Thwack Bots can be difficult opponents. The builder must focus on a pincer or claw design that is strong enough to handle its own crushing pressure. A claw design should taper to form a spike or point that focuses the force on a small area to penetrate the opponent. The claw design should also be able to handle the forces encountered when closing on a sloped surface. Pincers or claws must open wide enough to be able to close onto a sizable bot. A small claw will only be able to damage small
protrusions and extensions. A claw that does not open wide enough may not be able to dig in when attempting to bite a sloped surface. The claws should open
sufficiently wide and be deep enough to reach around one third of an opponents bot to
achieve serious damage potential. Pincers that close to slowly allow the opposing competitor opportunity to escape. A two stage hydraulic system will allow the claws to close quickly then by switching to the high pressure mode to
achieve the power for crushing.
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Flipper Bots
Features: Uses large bore pneumatics
Actuated arm powered by high pressure air (HPA) or CO2.
Capable of tossing opponents
Frequently make use of a reservoir tank to deliver the volumes of gas required.
Strengths: Strong against
opponents that have weaker chassis or inadequate shock mountings for electronics.
Design: This type of bot requires a very strong chassis and drive system to withstand the extreme forces encountered each time the system is fired or activated. Particular care must be taken when constructing this type of robot as high pressure gasses are extremely dangerous. This type of combat robot
relies on the opponent being damaged when they strike the ground after being thrown into the air. This type of bot can also be expensive to build and unreliable. Spring powered mechanisms that use gear motors and latches to re-cock the mechanism are heavier than
pneumatics as well as more complex to design and build. The added weight of CO2 or HPA tanks and components, and the added weight for structural
strength may mean less armor or a weaker drive system.
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Hammer bot
Features: Hammer or axe weapon
Weapon can strike repeatedly and rapidly
Usually four wheels for stability
Weapon can frequently be used as a self righting mechanism
Usually pneumatically actuated
Strength: While spinners take time to spin up, the hammer or axe weapon must be able to get up to speed in a single swing. The advantage gained is the ability to strike repeatedly and with accuracy in a short time. Even if captured by a Clamp Bot or Lifter Bot, the weapon can still be effective.
Design: A weapon that operates over 180 degrees of rotation permits the weapon to
achieve full speed before striking an opponent. This can be achieved using a pneumatically driven rack and pinion that drives the hammer handle or arm.
Another method is to use a chain wrapped around a sprocket attached to the hammer handle. By pulling on the chain with a pneumatic cylinder a very rapid fire rate can be achieved. Use large bore tubing and valves to increase the flow rate of compressed gasses will assist in
achieving a fast hammer weapon. A low pressure reservoir will also improve the weapons speed and firing rate. Rapidly firing the hammer weapon will freeze up the
pressure system and pressure tank. Some builders use an electric motor to operate the axe or hammer weapon. The advantage is the ease of designing a reliable system that operates through 180 degrees of rotation. Take care to optimize the motor's gear ratio to
achieve maximum speed. A hammer is most effective against opponents with weak top armor of a fragile frame, otherwise the the operator should try to strike as many hits as possible. The Hammer Bots is most effective against Wedges, Rams, Thwack Bots and Saw Bots. The hammer weapon is difficult to disable and if well designed can get lots of god hits in. Hammer Bots will have a difficult time against Spinner Bots and Flipper Bots.
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Lifter Bots
Features: Rugged, slow moving lifting mechanism
Lifting mechanism using simple mechanics
Long travel mechanism can be used for self righting
Mechanisms can be stopped or reversed in mid travel
Strengths: Lifter Bots are strong against bots that rely on traction such as wedges and rams. Bots with overhanging edges are particularly vulnerable to Lifter Bots. Thwack Bots are difficult for lifters as their wild spinning, open wheeled
invertible design make it difficult for a Lifter Bot to get the opponents wheels off of the ground.
Design: Lifter Bots may use pneumatics to operate the lifting mechanism however gear motor and electric linear actuators are more common. The advantage of being capable to stop the lifting mechanism in mid travel allows the bot to lift
opponents and then drag them around the arena, opposed to simply flipping them. Lifters should be constructed with attention to the principles of leverage. If the arm extends to far beyond the front of the chassis the Lifter Bot risks tipping forward. Building your bot with as much of the weight towards the rear reduces the risk of tipping when lifting an
opponent. Successful lifting arms are designed to be able to lift the entire weight of the
opponent, however designers will also need to consider the forces their bot will be exposed to when carrying the added weight of their
opponent. Consider placing wheels flanking the tip of the lifting mechanism to take advantage of the added traction when lifting. An exposed lifting mechanism risks damage from spinning weapons thus rendering it non functional.
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Saw Bot
Features: Abrasive or toothed disk
Powerful weapon motor
Frequently used with other bot designs (IE: Wedge Bot with a saw weapon)
Design: Although easy to design and build, the saw weapon tends to lack effectiveness. It is difficult and time
consuming to cut through an opponent, and tougher yet when your opponent is struggling to escape. The most effective blades tend to be emergency rescue blades. These blades are thick, heavy blades, with an abrasive coating to cut rapidly through almost any material. These blades can be expensive and only available through specialty dealers. These blades also require a very powerful motor to be used effectively. Other types of blades tend to prove ineffective. Abrasive blades for metals are useless against plastics and wood, where as blades intended for plastics and woods are ineffective against metals. The most effective Saw Bots store energy in large saws and act more as spinners than saws. An upwardly spinning blade will tend to lift the
opponent, and increases the risk of the blade binding or bending. A downward spinning blade reduces binding and helps to hold the opponent in place, but increases the risk of the Saw Bot flipping itself. Saw Bots are more effective against bots constructed with thin metal or polycarbonate (Lexan) armor. Although the Saw Bot tends to be a less effective design in disabling an
opponent, they do leave lots of scratches, shallow cuts, and throw off lots of sparks that impress judges and spectators, which can give you a win in a close match.
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Push Bots
Features: High traction
Lower speed for pushing power
High ground clearance
Four or six wheel drive
Rugged design
Heavy Armour
Invertible
Strength: Strong against spinning weapons, saws, drums, and Spinning Bots
Push Bots tend not to win by directly knocking out their opponent but rather by pushing their
opponent into arena hazards.
Design: Should be designed with a rugged frame and more heavily armored than a Ram Bot. Electronics should be isolated from shock and vibration. Like the Ram Bot, large wheels to provide a maximum amount of traction is needed to push
opponents around the arena and into hazards. However, because Push Bots tend to be slower, heavy armor is advised to protect against the increased
likelihood of being hit by an opponent. Design your Push Bot with wheels close to the front and rear of the bot such that lifting one end leave 2 wheels still in contact with the ground.
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Spear Bot
Features:
Long thin piercing rod
Usually pneumatically powered
Frequently six wheeled
Frequently combined with a wedge design
Strengths: Matches involving opponents with thin armor or that require accuracy to be effective such as Clamp, Lifter and Crusher Bots, will tend to require agility and driving skill as bots attempt to position themselves for maximum effect. An effective spear that can penetrate deeply through side armor can damage vital internal components.
Design:
Most effective spears are designed to strike an opponent near the end of the spears travel. High
velocity is more important than weapon mass, as it is the speed of the spear or spike that allows the weapon to
penetrate the opponents armor. Care must be taken that the spear is not to weak less it become bent when striking an
opponent. Spear Bots need traction to be able to avoid pushing themselves away from the
opponent when firing the weapon. The problem with spear weapons is that the can become stuck when penetrating an
opponents armor. The spear is then at risk of becoming bent as an opponent struggles to get free. To counter this problem, design the spear to be slightly tapered over its length. Blunting the end of the spear will increase impact damage rather than pierce the armor. A diamond or knife shaped point is more effective at penetrating armor than a bullet or conical shaped tip. Wedges and Ram Bots tend to be well
armored and difficult for a spear weapon to penetrate.
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Spinner Bot
Features: Heavy spinning disk, blade or bar
Uses a flywheel to store energy
Dome or cone shaped shell
Strengths: Although Spinner Bots do not store as much energy as disk or wheel shaped spinning weapons, they are impossible for an
opponent to attack without being struck by the Spinner Bot's weapon.
Design: The faster a Spinner Bot can "spin up" the better. A Spinner Bot that requires 8 - 10 seconds to spin up may never have the
opportunity to be effective in an attack. You should target a spin up time of 3 or 4 seconds when designing the bot. The support shaft, bearings and support structure for the spinning mechanism should be as rugged as possible as these components will need to withstand the forces of impacts. Wheels should be small and should fit under the spinning weapon. The extensions that impact the
opponent should be as constructed of a very hard, sharp material. The Spinner Bot can be a very destructive force in the arena but this comes at a cost, as the Spinner Bot encounters as much force as its
opponent on impact. Some fully enclosed spinners employ rollers mounted to the frame to help the shell spin smoothly even if the shell becomes dented or bent. An out of balance shell can cause a spinner to self destruct. It can be very difficult for an
operator to determine which way is forward in a rapidly spinning bot. To deal with this issue some builders include a tail from the underside of the bot, others have used a non-spinning flag that extends up through the center of the main shaft. Gyroscopic effect of the spinning shell will make the bot
veer away from a straight line. A four wheel bot will add more stability and reduce the driving issues caused by gyroscopic effect. Other builders use R/C helicopter rate gyroscopes in the electronics to compensate for this effect. The greatest enemy for the Spinner Bot is a solidly built Ram Bot or Wedge Bot. Spinner Bots do best against Clamp Bots, Lifter Bots and bots with exposed parts that can be bent or broken off. A Spinner Bot should try to defeat its
opponent in as few hits as possible as in some cases a Spinner Bot can be its own worst enemy.
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Thwack Bot (Spin type)
Features: Two wheel drive
Long arm with hammer, axe or spike weapon
Capable of spinning in place with high speed
Uses drive motors to provide attack power.
Invertible
Strengths: Difficult opponents for wedges, rams, clamps and lifters.
Design: A narrow bot with narrow wheels are what allow thwack bots to achieve high spin rates. Weight on the weapon or on idler wheels results in lower spin rates due to friction. Wheels must be close together for this design to
achieve high spin rates, but this will result in slower spin up times. Because of the higher wheel RPM and the narrow spacing this type of bot can be difficult to drive. The weakness inherent to Thwack Bots is that they are unable to move around while spinning. Navigation systems that allow a thwack bot to move about while spinning have been attempted but with little success. Thus a Thwack Bot must rely on its
opponents either attacking while they spin in place or the Thwack Bot must develop enough force in less than one rotation to do damage to the
opponent. Powerful spinning weapons can be difficult for a Thwack Bot as the long weapon arm can be struck thus stopping the Thwack Bots spinning.
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Thwack Bot (Overhead type)
Features: Two wheel drive
Long arm with hammer, axe or spike weapon
Long arm flips over when bot reverses direction suddenly
Wide 2 wheel base with entire body between the wheels.
Uses drive motors to provide attack power.
Invertible
Strengths: Difficult opponents for wedges, rams, clamps and lifters.
Design: Motor torque is the key to an Overhead Thwack Bot. Suddenly reversing direction allows the motor's torque to toss the long weapon arm over the top and down upon the opponent. Attacks are
achieved by charging an opponent then suddenly throwing the bot into reverse. Poor balance, closely mounted wheels and uneven traction can cause the weapon to be inaccurate. Widely mounted wheels will improve accuracy of attacks. Optimizing wheel size, gearing and motor torque, can be difficult. Weapon should be light and center of mass must be close to the wheel axis to allow this type of bot to flip over.
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Vertical Spinner
Features: Large vertical spinning disk disk or blade
Strengths: The large spinning front mounted weapon almost always has the exposed portion of the weapon spinning in an upwards direction. When this upward spinning weapon strikes an
opponent the force of the impact frequently inflicts damage and flips the opponent. The advantage over a
horizontal spinning weapon is that the force from the impact tends to the Vertical Spinner Bot against the floor and not sideways across the floor. The trade off is that a vertical spinner is exposed on the sides and rear, as well the Vertical Spinner Bot must carefully line up on the
opponent to be effective.
Design: The large disk raises the bots center of gravity such that a wide body to support it is
necessary. The wide body increases its vulnerability to attacks from the sides and somewhat reduces the bots
maneuverability. A strong support structure is required to absorb the forces encountered when striking an
opponent. Vertical Spinner Bots have also been known to self destruct due to a bent or out of balance spinning weapon. The sides and rear of the bot should be well armored as this is its vulnerability. Low Wedges and
maneuverable Ram Bots can be a challenge for a Vertical Spinner to defeat. The bot should be designed with a wide wheel base to resist being flipped over by gyroscopic forces when turning. This type of bot is also difficult to drive and quickly turn as it leans hard when turning, however this can be controlled somewhat by using R/C helicopter gyroscopes to control the bot. These bots are effective against slower moving
opponents that cannot disable the spinner quickly. Slow moving Lifter, Clamp or Ram Bot can be an easy victim. Matches with horizontal spinners can go either way, however the fight is usually very violent and brief.
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Wedge Bots (Classic or Cheese Wedge and Parallelogram Wedge)
Features: Two wheel drive
Highly rugged design
Invertible and non-invertible designs
Frequently uses shock mounted armor
Strengths: Rugged design makes this a worthy
opponent against spinning weapons, Spin Bots and Ram Bots.
Design: The wedge designs tend to make these bots vulnerable to attack from below
and other wedges, lifters and floor mounted hazards. Using rubber mounts to attach the shell to the frame protects the drive train, chassis and electronics from damage. Damage to the shell should not affect the drive system. Some designs use sufficiently large wheels to allow the Wedge Bot to be driven inverted.
The Parallelogram Wedge Bot is usually a four wheel drive. This design makes use of a wedge on the front and an inverted wedge on the back. When inverted this design allows the rear wedge to be used, as it then becomes the front of the
bot. Although wedge designs seldom inflict damage, a well armored wedge is a good tactic against spinners. Wedges defeat
opponents by driving under their opponents and lifting the opponent's wheels off of the ground. With the
opponent now without sufficient traction, the wedge can drive the opponent into arena hazards. With a good hit, a wedge will flip a spinner over.
An effective wedge relies on a drive system that gives 20 - 25 kph and a well engineered scoop front. A two wheel design will give faster turn rates where as a four wheel wedge will tend to be more stable and easier to operate. The front edge of the wedge should be thin and capable of bearing impacts with
opponents, hazards and obstacles. The front edge of the wedge should not be constructed of sheet metal as many wedges have been disabled when the front of the metal was bent down, lifting the front end off of the ground. Wedge Bots tend to be vulnerable to faster, lower, and more powerful Wedge Bots, as well as Lifter Bots and Clamp Bots.
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