Wiki

As was already said in the introduction, the purpose of this topic is not to duplicate vast amounts of knowledge already available on the Vex Forum and external sites, but to make it easy to find that information.

We welcome and value all contributions and currently any forum users with TL1 trust level could edit Wiki posts.

However, to maintain high quality of the Wiki, everybody has to adhere to the Wiki Guidelines, that are detailed below.

Please, DO NOT CREATE NEW POSTS in this topic, unless you have a prior approval from the Wiki maintainers team (TBD).

Current open discussion about this wiki could be found in this thread: VEX Forum Wiki

This Style and contribution Guidelines are work in progress and we are going to define and put them here in the near future…

In general, the preference is to stay brief and, whenever possible, use a link to an existing topic, instead of copying its content into the Wiki.

Strategy

We could start by listing things “we wish we knew at the beginning” and then sort them into beginner / intermediate / advanced categories.

Beginner category is something that needs to be communicated right away.
Intermediate is something that could wait until later in the season or second season.
And advanced is something (like odometry/tracking) that would be great to get to, but is not required by most of the teams.

If we use pyramid diagram, then we could start from the top with the most basic and most important knowledge, then expand it into intermediate level, with more information that relies on more prior experience, and so forth …
block-pyramid

technik3k · October 2, 2019, 6:43am

Building the robot - what constitutes the robot - basics

VRC Legal definition of the robot (according to the Game Manual <R1>)

One Robot per Team. Only one (1) Robot will be allowed to compete per Team in the VEX Robotics Competition. Though it is expected that Teams will make changes to their Robot at the competition, a Team is limited to only one (1) Robot. As such, a VEX Robot, for the purposes of the VEX Robotics Competition, has the following subsystems:

Subsystem 1: Mobile robotic base including wheels, tracks, legs, or any other mechanism that allows the robot to navigate the majority of the flat playing field surface. For a stationary Robot, the robotic base without wheels would be considered Subsystem 1.

Subsystem 2: Power and control system that includes a legal VEX battery, a legal VEX control system, and associated motors for the mobile robotic base.

Subsystem 3: Additional mechanisms (and associated motors) that allow manipulation of game objects or navigation of field obstacles.

Given the above definitions, a minimum Robot for use in any VEX Robotics Competition event (including Skills Challenges) must consist of 1 and 2 above.

TBD

Example

https://www.youtube.com/watch?v=3yedhYdeiLM

Details

Brain, Battery, VexNet, and most importantly license plates: 7580A 2015 Robot Reveal.

Just kidding

https://help.vex.com/category/369-engineering

technik3k · October 2, 2019, 6:55am

Overview of common chassis types

How could we help a new team to choose a chassis for the robot?

https://help.vex.com/article/372-how-to-select-a-drivetrain

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.

Drivetrain Type	Pros	Cons
1. All omni tank drive	- easy to build	- can be easily pushed to the side
	- 2 or 4 motors
	- can be chained front-back
2. H-Drive	- all advantages of tank drive	- needs extra motor
		- tricky to distribute weight
3. X-Drive	- resists pushing	- harder to build
4. Mecanum	TBD	- requires 4 motors

Omni wheel vs Mecanum

technik3k · October 2, 2019, 6:59am

Overview of frequently used Lift Types

2-bar
4-bar, 6-bar (n-bar)
DR4B
Cascade
Chain-bar
…

technik3k · October 2, 2019, 7:02am

Overview of frequently used intakes

Claw
Side rollers
Top roller
Forklift
Passive (pneumatics)

technik3k · October 2, 2019, 7:25am

Best Building practices (general)

bearings
screw joints
Types of nuts
- 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.
spacers, standoffs mounting
use all omni drive base with 4 motors

DR4B Tutorial by 333A

VEX Build Quality Tutorial/Instruction video:

technik3k · October 2, 2019, 7:52am

Programming environments, links to help and tutorials

https://www.learncpp.com
https://www.tutorialspoint.com/cprogramming/index.htm

V5:

Cortex:

TBD: Supported languages, platforms, blocks vs text, which one to choose…

API Reference:

Tutorials

LVGL:

https://team81k.github.io/ProsLVGLTutorial/

For pre-V5 (Cortex) hardware:

https://www.robotc.net/wikiarchive/Tutorials/Getting_Started/Getting_Started_with_the_VEX_CORTEX

technik3k · October 2, 2019, 8:05am

Programming: Getting Started with VEXcode

https://help.vex.com/category/130-getting-started

Motor config
Sensor config
Competition template

VEXcode, motor groups and drivetrain example
VEXcode for experts

vexforum.com/t/autonomous-help-with-vexcode/71698/2

https://help.vex.com/article/110-vex-example-program-with-controller-c-arcade-drive

http://www.cplusplus.com/doc/tutorial/

technik3k · October 2, 2019, 8:10am

Programming: Common Beginner Mistakes and FAQs

TBD

Note:

make process closed with exit code : 2 means ‘code could not compile, your code probably has errors’. When creating a thread for help, please attach the whole log with your code.

https://help.vex.com/article/120-how-to-use-blocking-vs-non-blocking-code

Force Compile of Files

technik3k · October 2, 2019, 8:11am

V5 Architecture and Troubleshooting

V5 architecture diagram (may need to move to advanced topics): The PROS of PROS

V5 Troubleshooting:

Invalid Asset Table/Battery Medic: V5 Brain “Invalid Asset Table Version”
Red Controller Screen: V5 Controller shows red screen and computer/brain icon
Controller Vibrating: V5 Controller keeps vibrating
V5 Brain won't connect to computer
https://help.vex.com/article/143-how-to-use-the-battery-medic-to-diagnose-the-internal-state-of-the-battery
https://help.vex.com/article/142-how-to-interpret-error-messages-with-the-v5-battery

Tips/warnings for v5?

V5 mini USB Port / use magnetic cable
V5 Motor inserts / be careful
V5 ports and static

Make sure you have installed the latest VexOS firmware which could be found here:

Make sure that radio type is to VEXnet and not Bluetooth:

run your program. press the button on the V5 brain to toggle between the user program screen and the vexos screen.

technik3k · October 2, 2019, 8:15am

Engineering Design Process

https://www.google.com/search?q=engineering+design+process
TBD

technik3k · October 2, 2019, 8:26am

Engineering Notebook Resources

(Screen for redundant / duplicate topics)

Design Award Tips? - #2 by tabor473
Starting the Engineering Notebook
2915A Engineering Notebook 2016
Notebook Tips
Engineering Notebook Tips Selection and Strategy
How should I start off my notebook? (Summer without teammates)
what are Some Tips to add to the Notebook?
Engineering Notebook Expectations At Worlds
Example of an award winning notebook?
What is the best piece of advice you could give for an engineering notebook to be successful?
Notebook setup/layout

engineering notebook 1575A 2015-2016.pdf (45.0 MB)

With permission from Keilan, Alumni of 590B:
Instance of a World-Winning Engineering Notebook From VEX Worlds 2019

This notebook helped give 590B Design Award at:
2019 VEX Robotics World Championship - VEX Robotics Competition High School Division

technik3k · October 2, 2019, 8:33am

CAD software: links, tutorials, tips

VEX w/ Fusion 360 Tutorials

https://www.autodesk.com/education/competitions-and-events/vex/recommended-software

technik3k · October 2, 2019, 8:36am

Preparing for the competition day

References (redundant?):

https://www.roboticseducation.org/resources-library/
101 Things I Wish I'd Known Before My First VEX Tournament
Advice for first competition?

https://www.vexwiki.org/robotics_competitions/101_things
https://www.roboticseducation.org/documents/2013/06/101-things.pdf/

technik3k · October 2, 2019, 8:44am

Tips on how competition works

To be expanded:

Qualifications
Scouting:
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.

Alliance selection
BO1
Skills
Judging
Who qualifies

technik3k · October 2, 2019, 8:48am

Beyond the competition

What else is there in VRC beyond going to competitions?

What every Parent needs to know about VEX Robotics Competition

External websites and user communities

Frequently used acronyms

VEX Forum Wiki Rules and Style Guidelines