Robot Basics

Overview

Welcome to Battlebots! The environment of Battlebots will be fairly fast-paced. We only meet once a week for the first semester, which in the first few meetings will be spent on the ground work for what is probably the most engaging and important phase ... designing your robot. The purpose of this guide is to educate the reader, our new battlebots members, on some key factors relating to designs of robots and analyzing the pros and cons. Often, new members try to design the perfect bot. However, designing the perfect robot is not possible. Everything has a disadvantage, a weakness that can be exploited. But that does not make it a bad design. It could be an effective one. However, it is important to consider all aspects of different types before determining what you will implement.

Types of Robots

The first step of designing your robot is to decide what type you want to build. There have been several different designs throughout the history of battlebots and competitions. However, this guide will cover some of the generic designs that show up consistently each year in competition. It is important to keep in mind that each type of robot has their own advantages. However, it goes without saying that they also have their disadvantages and difficulties.

Drum Spinners

Drum bots have a rotating cylindrical-shaped weapon (medium to large sized) usually attached with barbs or teeth attached to the cylindrical weapon to tear apart and flip opponent's bot. Drum bots are a good bot type for beginners and are quite common for new 3lb members to use as their first type.

Advantages

Drums, as mentioned, are a great bot for beginners. Their weapon is simple, yet quite reliable and destructive upon certain hits. Drum's weapons are generally sturdy because they are usually made from a block of metal, which means that it will be difficult for it to break. They allow your bot to be stable when you are attacking an opponent bot, dealing several quick and continuous attacks. If correctly designed, drums are capable of launching or flipping the opponent bots in the air. If your opponent's bot is not invertible and they get flipped, it is more than likely that they wont be able to continue and you will emerge victorious in that match. Speaking of invertibility, drums can be designed to be invertible which gives you an advantage when you get flipped.

Disadvantages

Because the nature of the weapon, Drum spinner bots generally have a very small strike zone. The heavy mass in the front of the bot rotating at high RPM will making driving your bot fairly difficult. Sometimes, with powerful weapons at high RPM, the gyroscopic forces acting on the bot could cause lift to occur on one side of the bot when turning. Similar to Horizontal/Vertical Bar Spinners, upon your weapon's contact on an opponent bot, the recoil from the impact could potentially cause damage to your own bot, sometimes making it immobile. If not properly designed or built, as with any heavy hitting weapon type, the weapon could be ripped apart. The weapon is generally sturdy, however, after direct attacks from opponent bot or extended contact, it is likely for your weapon to be damaged and will be less effective.

Summary (Drum Spinners)
Advantages	Disadvantages
Sturdy weapon	Small strike zone
Powerful weapon capable of flipping opponent bot	Gyroscopic effects cause control and turning issues
Could be designed invertible	Potential self-inflicting damage
High damage output	Weapon could get ripped off / damaged

Horizontal Spinners

Briefly, there are two common variations to spinners: bar spinners and disk spinners. Bar spinners are similar to disk spinners, except, as stated in the name, the weapons of bar spinners are shaped like a bar. The robot's weapon motor is a factor that determines the effectiveness of the weapon of spinners. The structure of the weapon system is similar to that of a drum spinner, where the weapon's spin up is controlled by the weapon motor, commonly connected by a pulley system. Horizontal Bar spinners are commonly known for their destructive power. Weapons of this types enable both offensive, as well as defensive, advantage (explained in "Advantages").

Advantages

The body of the bar spinners are generally similar. However, the uniqueness of the bot comes with the weapon design. This weapon types offers very versatile weapons, meaning that there can be many variations to it. Bar either be single-edged or multi-edged where the hitting edge could be (one or more combinations of) a blunted edge, sharp-bladed edges, or spiked edges, and so on. The more edges of contact you have, the damage will lose effectiveness. For example, a single-edged weapon, upon weapon's contact, will not have interference until its next contact. This allows more spin up, which maximizes damage per hit. However, with multi-edged weapon, the more edges there are, the weapon will have difficulty with spinning the weapon because it has more than one edge that will make contact, which will slow the weapon speed upon each contact. However, this is not necessarily a bad thing because multi-edges will hit more frequently, doing decreasing damage upon each hit. Regardless of the design, bar spinners have a large strike zone, much greater than drum spinners, and if made properly, the weapon can be highly destructive. Similar to the drum spinners, horizontal bar spinners can be designed to be invertible, which will make it more difficult for the opponent to try and defeat you. The gyroscopic forces at high to to full speed of a horizontal bar spinner, depending on size and power of the weapon, can help stabilize your robot and stop it self from being flipped over.

Disadvantages

Because of the design of the weapon and its front placement, robot must be designed to where the front (where the weapon system is held) is elongated from the main body of the robot. This is because you need to have it designed so that the the robot does not get hit by its own weapon. Generally, regardless of the design, the weapon is powerful and it does a lot of damage. However, this is could also be disadvantageous. Generally, a lot of the weight for this robot type is focused on the weapon. Its also important to keep in mind that the structure of the robot itself needs to be strong. Upon a hit, your robot, more than likely will experience recoil. If your robot is not structurally strong over all, parts of your bot, including your electronics, could be adversely affected. Not only can recoil potentially harm your robot, it could also affect your driving ability. Upon contact it could redirect your robot in a different direction. In some cases, it could cause your robot to go airborne and/or be flipped over, but it is every easy to design your robot to be invertible. Gyroscopic effects caused by the spinning of the heavy weapon can cause an issues with driving abilities. The robot will want to turn in the opposite direction from the direction that your weapon is spinning. However, driving ability stabilizes as the weapon spins at high to full speed. Like the drum spinner, the weapon is attached using a pulley system that connects it to the weapon motor using a belt. Impacts could damage your belt, which could cause weapon failure. If your weapon or weapon system fails in some way, or if your belt spinning your weapon fails in some way, your bot will no longer have a functioning weapon. Usually, this is the only weapon your robot is equipped with, so there is no secondary weapon. If you end up with an inactive weapon, it is more than likely that you will lose that match.

Mobility and Defense

Wedges

As you may recall, wedges are one of the most common implemented designs. Remember, wedges do not have actual weapons. Because it does not have a weapon, which normally would take up majority of the robot's weight, it allows for a stronger structural design of the robot or for the use of better (or more) drive motors for better mobility, maybe a combination of both.

The big picture of wedges is to temporarily (or, in some cases, permanently) disable the opponents mobility. In other words, your "weapon" is the wedge that tries to get under the opponent's robot. Once this is done, they will lose traction, thus their mobility. In some cases, the opponent's bot will be flipped. At that point, you have control of that match. If your opponent's bot is not invertible or has no self-right mechanism, it is more than likely that you won that match. In order to get under the robot, the easiest way to achieve this is to design your wedge, varying the bot's height and size of the wheels, such that it is as close to the ground as possible. It goes with out saying, this tactic of getting under the opponent requires a strong drive system, which is made possible by the weight saved by not having a weapon.

A wedge bot will find racking up points to win to be difficult. It is possible to include spikes, on either the wedge or its body as a defense mechanism (while also potentially dealing very limited offensive damage). The potential tradeoff, depending on the how you implement this addition to the design, is that it may or may not be possible to make your robot be invertible.

The concept seems pretty simple and straightforward, however it turns out to be pretty effective type when put to use. They have a type advantage against most other bot types. In other words, as long as your wedge can get under an opponent bot, you have some advantage. Pretty much the only counter type to a wedge bot are types such as undercutters, lifters, other wedges; basically anything that is closer to the ground than your type. In some instances, vertical spinners could pose a threat as well.