It is very important to select the proper drivetrain for your robot. You need to consider specifics of the game. Your driving style and experience, as well as requirements for lateral movement, power, and speed among other factors are integral to selection of a drivetrain.
Tank drive is most common type of drive seen, as well as the simplest. A Tank drive consists of two rows of wheels parallel to each other on either side of the robot. There are many different subsets, including 4-wheel, 6-wheel, and whether the use of traction wheels included as any of the sets of the wheels.
H-Drives are built as Tank drives are, except there are wheel(s) mounted perpendicular to the drive which allow for lateral movement. All wheels must be omni wheels for the drive to be able to function.
Holonomic drive, also called an X-Drive, consists of wheels mounted at angles from each other. It is good for lateral movement, and increases speed and power of turns. However, linear drive speed and power are decreased due to the nature of how wheels run toward each other to move linearly. All wheels must be omni wheels in order for this drive to function.
Mecanum drive uses 4 mechanum wheels to move linearly forward, backward, left, and right. Mechanum drives are much harder for another robot to push around, however are usually slower than a H-drive.
Nylocks are heavier, but have much greater grip. They likely will not significantly loosen even after extensive use. Additionally, not tightening them (and allowing the screw to spin freely) is perfect for rotating joints.
Keps are lighter and are the quickest to use. Their teeth help maintain its position when tightened, but not as much as nylocks and cannot be rotated once tightened. Perfect for prototyping or securing less vital structure.
Plain nuts are the lightest and are used mostly on parts with places for the nuts designed onto them, such as the clamping shaft collar or V2 rack gears.
basic gear ratios
Builders can trade motor speed for motor torque (and vice versa) by using a system of gears to change the speed of the output shaft.
gears have a set number of teeth, and when gears mesh, the output gear rotates however many teeth the input rotated, not the number of rotations the shaft went through. Builders can use this to their advantage so that the output gear rotates faster, but with less torque (larger gear -> smaller gear), or slower but with increased torque (smaller gear -> larger gear).
If gear sizes become too extreme, more advanced builders may use compound gearing to exponentially modify their gear ratios. This is done by having the output shaft from previous gearing become the input shaft for more gearing with different gear sizes.
no cantilevered drive wheels
As a general rule, for anything on a shaft other than shaft collars and washers, the shaft should be secured to structure on both sides of whatever it is supporting.
Not doing this results in the shaft having a lot of wiggle room, as typically seen when wheels are exposed on the outside of a robot.
At tournaments, there are various ways of scouting that can be done to improve your chances of doing well. They are as follows:
• Match scouting: Before each qualification match, it is extremely important that you go and talk to your alliance partner, to coordinate autonomous programs, match strategies, and any other miscellaneous aspects to the upcoming match. This will also tie in with the second way if scouting.
• General tournament scouting: Throughout s tournament, it is helpful to take notes on each team/robot in attendance. Whether it be a quick robot summary, or detailed notes on the successes and weak points of each mechanism, doing so will allow you to be better prepared for your matches. This ties in to the 1st way of scouting, as you should be taking down notes on your alliance partners and opponents after every match.
When it comes time for alliance selection, having notes and scouting data is extremely helpful when deciding on who to pick for the elimination bracket. They will also help you to find any “hidden gems” that might be a better pick than some of the higher ranked robots. Scouting will also prepare you if a team decides to use the “scorched earth” strategy (go down the line of teams and ask each one until one accepts) to mess up any potential powerhouse alliances.