Wiki

[technik3k]

Reserved for V5 Vision sensor wiki entry

@jpearman

have a look at these knowledge base articles.

https://help.vex.com/category/205-vision-sensor

There are two different ways to configure the sensor depending on whether you want to use the robot config panel or just create vision header files.

@jmckenna

STEM Lab that discusses how to use the Vision Sensor with VEXcode V5 Blocks. You can find it here: https://education.vex.com/parent-wrapper.php?id=vision-sensor-v5

There is also an example project in both VEXcode V5 Blocks & text that features the Vision Sensor.

https://api.vexcode.cloud/v5/html/classvex_1_1vision.html

Vision Sensor

@R47

The imaging sensor itself has a resolution of 640x400, but the vision sensor processes the data, and the data returned has a resolution of 316x212.

V5: Aim a VEX V5 Vision Sensor at a Target

This is a demonstration of how to write code using the V5 Vision Sensor to find a vision target object, and then orient your robot to “face” directly towards the target. You will need to configure the vision sensor before trying the program. We include a link to how to configure the Vision Sensor here. Sample Projects Blockly Python C++ https://i.imgur.com/FWkRdwH.png

Vision sensor setup

There still seems to be some issues setting up the vision sensor. Although we do know that VCS 1.0/vision sensor utility has a few bugs in this area, it is still pretty simple, I’m not sure why the theories about needing to freeze the image are running around. Anyway, here’s a quick demo showing how easy it is. https://youtu.be/kB0r0-aLYIw The configuration that is hidden inside robot-config.h looks like this and is what is used in your program to setup the vision sensor when it runs. vex::…

Vision Sensor targeting

I had a play around today with the vision sensor on one of my old demo robots. The goal was just to test some simple targeting code that could be used as a basis for a more complex program. The robot setup looks like this. [P1050576] I obviously have a large target, but the concept would be the same no matter what size although the code would need to filter out more noise (meaning removing small intermittent objects) with something less well defined. I have the vision sensor mounted sideway…

Vision sensor FOV measurements

I’ve been asked a few times about the vision sensor field of view. I wrote in this thread that is was 67 deg, that was based on quick measurements with a target pretty close to the sensor, that number is close but not correct. @Windows10010 posted earlier today here that they thought it was 30 deg, that seemed way too narrow from what I remembered. I used to do this type of measurement often as I worked in the film industry for a camera manufacturer. It’s pretty easy to do, harder with this …

VEX Library

Some debugging tricks:

@jpearman

If you look at the V5 dashboard when you are running your code, do you see the detected objects ?

When your code is not running, you can test the vision sensor with our preset values for red, green, blue and yellow, but these settings are not related to anything in your program, they are just for testing if it is working.

Meaning of Vision Sensor parameters?
Vision Sensor config - objectCount inconsistent - #7 by jpearman
V5 Vision Sensor "The Camera detected must be unlocked" - #19 by jpearman
Vision Sensor Wifi - #9 by jpearman
Vision Sensor Having Issues Seeing Objects - #7 by jpearman
V5 Vision Sensor Color Code Coordinate Tracking

Vision Sensor Math:

Vision Sensor

EDIT: DODGY AND/OR INCORRECT MATH CASE WITH GROUND OBJECT I am not that confident in my math, but here is what I came up with. SETUP Your sensor is mounted on a tower. Your sensor is always a certain distance from the ground, if your robot stays level. https://i.imgur.com/B9wMAI0.png The sensor can see objects, and it gives them X and Y coordinates. (x is between 0 and 640, y is between 0 and 400.) I am not sure if the coordinates will work exactly as shown, but it will be close enough. ht…

Object Tracking:

V5 Vision Sensor Object Tracking

We’ve been experimenting with the V5 vision sensor to better understand how it works and what its limitations are. Theo, our programmer, has so far been able to make it track and follow a ball using just a P loop for now. We used an old NBN ball because our game objects hadn’t arrived yet. https://www.youtube.com/watch?v=58oS6WNp49I

[technik3k]

Reserved for V5 Inertial Sensor wiki entry
https://kb.vex.com/hc/en-us/articles/360037382272-Inertial-Sensor-Sensors-for-VEX-V5

[technik3k]

Reserved for V5 Optical Sensor

Vex Knowlege base article

[technik3k]

Reserved for V5 Distance Sensor
Vex Knowlege base article

[technik3k]

Reserved for V5 3-Wire Expander

(I’m not so sure this needs it own entry but I will put it for now - Floub)

3-Wire Expander

Using the V5 3-Wire Expander

[technik3k]

Reserved for V5 Rotation Sensor

VEX "Coming Soon" Page

We have a winner. It’s an absolute magnetic encoder, can spin infinitely in either direction, and can accept a pass through HS shaft.

VEX "Coming Soon" Page

Neither. It uses a different technology. It remembers position only within the 0-360 deg range, but can also work like an encoder and provide a continuous position and velocity. Ninjaed by Art…

[technik3k]

Reserved for V5 controller information, tips, and tricks

https://help.vex.com/article/16-how-to-update-your-v5-wireless-controller-firmware

https://help.vex.com/article/11-pairing-wireless-controller-to-the-brain

https://help.vex.com/article/36-how-to-calibrate-the-v5-controller

https://help.vex.com/article/15-how-to-reset-your-controller

Scuff controller add on for V5:

V5 Scuff Controller Add-on | Online Challenges

@holbrook

Since so many people have been asking in this thread recently, here’s a .zip containing all the parts in STL format:

v5_scuff_controller.zip (2.7 MB)

Controller mod for USB-C:

(Unofficial) V5 Controller Ergonomic Upgrade Kit, 8 Paddle Scuf, USB-C, Belt-clip Holster, etc

I’m having trouble fixing some problems that came up with the original Inventor files after I went through them again to make the final report for the Online Challenge so I’m not able to release those files yet, but I do have the .obj files from when I 3D Printed the prototype. It might not be the best experience yet as it’s only V1 (for example, the bottom paddles are a bit awkward, and the clamshells need a ton of support), but if you really want them you can download it here: https://drive…

Issues: (check if this is still the behavior)

@jpearman

We can only send a new line of text to the controller every 50mS due to the relatively low bandwidth channel we have between brain and controller. If a call is made to controller.screen.print before 50mS has elapsed from the previous call, we call task::sleep on that thread until the 50mS requirement has been met.

@theol0403

With PROS, you have to delay between each command by 50ms. If you don’t, the commands you send will not be forwarded to the controller, which only updates every 50ms.

I believe VEXCode automatically inserts those delays in the controller commands for you.

Controls (move to programming section later):
Best joystick controls for drive train?
Tank or Arcade???

Controller troubleshooting dashboard:
V5 controller don't respond to the programming - #11 by jpearman

[technik3k]

Reserved for V5 custom cables how-to

VEX Library

@Barin

Actually it’s explicitly declared legal in the game manual now, rule :

Custom V5 Smart Cables are allowed. Teams must use official V5 Smart Cable Stock but may use commodity 4P4C connectors and 4P4C crimping tools. Teams who create custom cables acknowledge that incorrect wiring may have undesired results.

@Barin

As someone who has been crimping Category cable since well before V5 was released, only recently did I finally have the chance to try crimping V5 cables.

What I can say beyond a shadow of a doubt is that VEX’s crimping tool, with a plastic die, is utter garbage. I had several failed crimps, causing the Brain to simply not recognize connected motors. When I did a sanity check with a crimping tool I used for actual Category cabling (with a metal die, just like every crimping tool worth anything), every single crimp worked (and yes, I used the exact same technique).

So, for all I know, the incidence of issues with custom-crimped cables but not factory-crimped cables could somehow be related to the crimping tool. Your mileage may vary, but I can confidently recommend even this $10 crimping tool over VEX’s. You can even get a whole crimping kit, complete with cable tester , for less than the price of VEX’s crimping tool (I can confirm the crimping tool in this exact kit worked perfectly on V5 cable).

TL;DR Try using a real crimping tool in the future. Testing your cables with a cable tester before use is a good idea too.

More V5 smart cable details

@OscarMNOVA12

4P4C refers to the connector, also known as RJ9,10, 22.

The cables themselves are custom specified for the load of V5 devices. A standard 4 wire flat cable with 26 awg with may work, but it won’t be ideal. And it’s ok for testing purposes but know you’re accepting responsibility for all the risks it entails.

It’s not legal for competition.

@jpearman

Aside from the rules stating that V5 smart cables must be used for competition. Not all cables are created equal, here is a comparison, I don’t have specs for either the VEX cable or the random silver 4 conductor phone cable I had, but there’s a significant difference.

@lacsap

Does anyone know what gauge wire is used in the v5 smart cables? It appears to be 24 awg from @jpearman 's picture, but I’d like to be sure…

To be clear, you may not make your own cables for competition. VEX Cable stock is labeled with V5 logo, so it can spotted during inspection.

[technik3k]

Reserved for V5 in-depth system architecture overview

https://www.vexrobotics.com/v5-architecture.html

@jpearman

This is high level system architecture.

VEXCode get Run Time function? - #3 by jpearman

@jpearman

raw message rate for the inertial sensor is 50Hz. Three wire port (ADI) is 100Hz. Motor is 200Hz, but data is still only available to user code at 100Hz as explained by @hotel.
I’m very skeptical about the double integration being able to reproduce accurate results, but will be happy if someone can prove me wrong.

Defining three wire devices in text - #11 by jpearman

Move to separate RS485 entry later:

Smart Ports Power Wire

This is mainly aimed for @jpearman. Is there any way to provide power to a DC device through a smart port by taking a smart cable and splicing up one end? I’m trying to find a way to power LED lights from smart ports so that I don’t have to waste a legacy port.

VEXcode V5 Text Preview

You can already use VEXcode (and VCS) to interface to custom electronics using a smart port as a generic serial RS485 port. There’s only a C API at the moment, and little documentation, we will probably add a C++ API before next season. Contact me for more details and I can provide some sample code.

Move to programming / multitasking section later:

Help with Task Programming

The VCS/VEXcode scheduler is very similar to the ROBOTC scheduler. There are some differences due to the fact that ROBOTC was running as a virtual machine and had more control over when exactly the task switching could occur, however, the concepts are very similar. startTask( myTask ) becomes vex::task taskId( myTask ) wait1Msec(10) becomes task::sleep(10) AbortTimeSlice() becomes task::yield() and so on. (and I fixed the broken links in the original topic)

Trying to multitask in Vex Coding Studios for User Control

Here is some example code. It’s from VEXcode but should work in VCS as well. It uses additional tasks for drive and controlling a motor with one button. #include "vex.h" using namespace vex; // A global instance of vex::brain used for printing to the V5 brain screen vex::brain Brain; // A global instance of vex::competition vex::competition Competition; // define your global instances of motors and other devices here vex::motor leftMotor( vex::PORT1 ); vex::motor rightMotor( vex::P…

Move to programming communication section later:

VEXcode V5 Text Preview - #65 by jpearman
Wireless Uploading and Terminal Usage to V5 Brain - #12 by jpearman (multiple posts about V5 communication)

Possible problem due to order of initialization of 3-wire port Brain.ThreeWirePort instances:

Memory Permission Error - #2 by jpearman

[technik3k]

Reserved for V5 in-depth system troubleshooting topic 1

Motor commands and dynamic power limiting information:

How does the decreased current affect the robot when using more than 8 motors

vexos 1.0.9 uses a different algorithm than versions 1.0.8 and earlier. 8 or less motors are still capped at 2.5A. 9 or more are capped as follow, remember this is current at the motor not current from the battery, 9 2.39A 10 2.29A 11 2.20A 12 2.12A 13 2.04A 14 1.98A 15 1.91A 16 1.85A 17 1.80A 18 1.74A 19 1.69A 20 1.65A However, those values are only valid if user code has not set current limit lower on one or more motors. If that has happened we take the user specified lower motor curren…

How does the decreased current affect the robot when using more than 8 motors

so most of the time teams are not sending a voltage to the motor but rather a requested velocity. Even when the motor is told to stop, it may be using a significant amount of power depending on the brake mode of the motor. The current limiting happens inside each motor, even when we limit continuous current to 2.5A, the transient current can be much more than that and the motor needs to respond quickly to these changes. Individual motors don’t have knowledge of what all the other motors are …

V5 motor configuration upon reconnect

It’s a feature (bug really) of PROS. vexos keeps the configuration for flags like reverse if the motor is not present when user code starts or is unplugged, however, PROS doesn’t send it though on startup if it thinks there is no motor, VEXcode however does. The things we keep backup values for are brake mode encoderUnits gearset reversed currentLimit voltageLimit One reason for keeping these values is safety, I didn’t want a motor running at full power when user code had aske…

V5 motor configuration upon reconnect

That’s correct, the reverse flag is handled by vexos and not sent to the motor, it’s much easier to handle things like updating the current motor position when user code changes the reverse flag while the motor is running (why you would want to do that I don’t know, but some of these design decisions were taken more than 4 years ago and based on robotc functionality). yea, PROS always validates the the correct type of device is on a given port before calling into vexos

[technik3k]

Reserved for V5 in-depth system troubleshooting topic 2

Important information about event callbacks implementation and its limitations:

@jpearman

event registration should only be done once, move these outside of the while loop.

@jpearman

Does old callback get erased when I set new callback function?

No, callbacks for an event should only be registered once, registering an additional callback will cause both to fire, registering a null pointer will not free resources.

@jpearman

It does consume additional resource, event handlers should only be registered once, if you register either the same or an additional callback the event will call both handlers.

On V5 each event handler is a thread blocked on a semaphore, when the event fires, vexos released the semaphore allowing the thread to run, the thread calls the user registered callback.

There is currently no way to unregister an individual event handler.

On IQ, which uses the same core functionality in VEXcode, we don’t have enough memory to dedicate a thread to each event so we have to use a thread pool instead, this limits the number of events that can simultaneously fire and be serviced.

@jpearman

yea, I set the limit at 100 events. Some are registered when you create, for example, an instance of a competition object. If you have some tasks, that limit is reduced, limit for tasks is 128, but as an event also runs as a task it uses resources for both.

Callbacks - #26 by jpearman

[technik3k]

Reserved for V5 in-depth system troubleshooting topic 3

[Connor]

Reserved for general programming tutorials

Installation Tutorial (VEXCode)

C++ VEXCode V5 Text Tutorials - Installing VEXCode

Interface Walkthrough (VEXCode)

C++ VEXCode V5 Text Tutorials - The Interface, Robot Configuration, Competition Template

Variables and Functions (VEXCode)

C++ VEXCode V5 Text Tutorials - Variables, if, else if, else, and while Statements

Programming Arm and Claw (VEXCode)

C++ VEXCode V5 Text Tutorials - Basic Programming Clawbot Arm and Claw

VEXCode knowledge-base article:

VEX Library

[Connor]

Reserved for Driver Control

Driver Control Tutorial [Arcade] (VEXCode)

C++ VEXCode V5 Text Tutorials - Programming the Clawbot Drivetrain THE RIGHT WAY

Slew Rate

Slew Rate with P controller

Slew rate is a programming technique to prevent motors from being overworked by gradually changing to different motor targets, instead of directly setting them. For example: Without a slew rate controller, you might set motors like so: motor[3] = 0; motor[3] = 127; This can be harmful to the motor controllers, so you can ease their strain by doing something like this: motor[3] = 0; motor[3] = 10; motor[3] = 20; … motor[3] = 127; Note that no one actually does slew rate like that, it’…

C++ Methods? Tasks? Slew Rate

In terms of how I might approach this using C++, I would probably subclass motor to add additional variables needed to handle slew control. namespace vex { class slew_motor : public vex::motor { friend class smart_motors; private: short motor_cmd; short motor_req; short motor_slew; public: slew_motor( int index ) : motor( index ) { motor_slew = 10; motor_cmd = 0; motor_req = 0; }; ~slew_motor…

[Connor]

Reserved for Macros

1814D Delta IV Macros/Automation Explanation

Two mode Button Toggle Example (ROBOTC, but easily convertable to VEXCode and PROS)

How do you make a push button work as a toggle switch using PLTW natural language?

bool enable = false, btnState = false; while(1){ enable = sensorValue[touch] && !btnState ? !enable : enable; btnState = sensorValue[touch]; if(enable){ //do } else { //do another thing } wait1Msec(10); }

[technik3k]

Reserved for Joystick control scaling, deadband

Exponential Tray Programming

Does anyone have any sort of guide to programming motors to either speed up or slow down exponentially using RMS C++? Specifically using a potentiometer. We would like to try and implement something like this for our tray.

Arcade and X-Arcade Drive using full range of joystick without clipping

Well I found out how to add tables so I figured I’d put the Arcade drive equation here with the tables showing some values for different joystick positions. The X-Arcade tables are interactive so they are still in HTML form found at the github link above. If using joy and/or motor ranges that are not -127 to 127 then the 127 in the equations changes to the joy value and the output value must be scaled to the motor range. Arcade Drive Equations Extrapolated from Arcade function These equation…

Custom Curving Thread and Example (VEXCode)

VEXCode Joystick Curving

Hello, today I will be discussing Joystick Curving in VEXCode, inspired by Pilons 5225A. Example Code for VEX Clawbot: turningCurve = 5; turningRed = false; forwardCurve = 10; forwardRed = false; //graph of red and blue lines from 5225A here //https://www.desmos.com/calculator/sdcgzah5ya int curveJoystick(bool red, int input, double t){ int val = 0; if(red){ val = (std::exp(-t/10)+std::exp((std::abs(input)-100)/10)*(1-std::exp(-t/10))) * input; }else{ //blue val = std::exp(…

[technik3k]

Reserved for Callbacks (and Tasks) discussion

VEXcode for experts

you can. I’ve never really talked or explained events much. We use them internally for things like button presses using function on other classes, but you can create you own events and choose when to use them. For programmers coming from blocks, this should be quite familiar, although many of the places they are used in blocks should really be using function calls instead. if you have a function like this. void eventHandlerA() { static int event_count = 0; Brain.Screen.printAt( 10, …

How do I use the controller button pressed command

yea, this is used when polling the button, it returns a boolean indicating if the button is currently pressed or not. Controller1.ButtonA.pressing() These are used when you want your code to be event based. Controller.ButtonA.pressed( callback_pressed ); Controller.ButtonA.released( callback_released ); A callback used an an event is running in its own thread, that means you can block using time consuming code or a while loop if you really want to, for example, this code using namespace…

[technik3k]

Reserved for PID Control

PID Tutorial and Examples (VEXCode)

VEXCode PID Tutorial

I will be allocating this thread to answering any questions in regards to the tutorial https://www.youtube.com/watch?v=_Itn-0d340g&feature=youtu.be Fair Warning: I am unsure if I have the positive and negative motor values correct, as this is all done on the top of my head. So If the robot is continuing to go even after the lateral position is reached, change error = averagePosition - desiredValue; to error = desiredValue - averagePosition; If the robot continues to go even after the turning…

If you are planning on using PID on arms, add Gravity Compensation or else the PID will not work properly:

Weight Negation (Gravity Compensation) Tutorial

Hello everyone! As I am working on my robot, I have to think about how to program my robot in such a manner where the robot is almost capable to hold its own position without the need of additional elements. Basically speaking, PID is built in such a manner where it doesn’t take consideration of weight, but it is essential in going from point A to point B with the extra ability to react against external forces. So, what we need to do is create a simple convenient algorithm to negate weight to b…

PID Example (ROBOTC)

What is a PID controller?

The p part is proportional, or what we nickname “error”. error = desiredValue - currentValue. This is a position, or delta x So if you get the derivative of error (which error is a position, or delta x), you will get speed (error - previousError). So, you can use the this to help correct if the robot is moving too fast or too slow due to external sources like additional unknown friction or battery crapping out. How the derivative is applied in code is by error(current error at the moment) - p…

PID for Autonomous in Vex Coding Studio

[technik3k]

Reserved for Simple Driving PIDs

Very Simple Very Accurate Chassis Control Code Release

Most everyone struggles with accurate base control in auton. At the highest level, 5225 developed a 3 tracking wheel solution that allowed them to set the world record in programming skills last year, and a handful of teams including 8059 and 139 have replicated their “odometry” based on a document they released last year. https://www.vexforum.com/t/team-5225-introduction-to-position-tracking-document/49640 But at a less extreme level, for people just looking to take a step up from move.relat…

Drive Straight PID Loop

I think this worked. This was for encoder backs, so you will need to change nMoterEncoder] to SensorValue() for OSE’s. // function to run drive motors for specified distance in units defined by WHEEL_DIAM then stop the drive motors // +dist = forward, -dist = reverse. void driveDistance(int dist) { nMotorEncoder[drive_LF] = 0; // reset the ime values to 0 nMotorEncoder[drive_RF] = 0; driveLastError = 0; // update driveLastError driveTarget = fabs(dist/(WHEEL_DIAM*PI) * ENCODER_TICKS); // …

Exiting a PID loop

I was very happy to see that almost every important aspect of the robust PID algorithm was already covered by many people. The most important thing to know for PID exit condition, is whether it is intended for user control or autonomous. In case of the user control - PID shouldn’t have its own while loop, but the main while(true) loop that has all the code for checking user inputs would call PID function once in 10-20 mS and let it determine necessary motor power. Variables like accumulated in…

7842F 2018-19 Robot Showcase - Flywheel Control, Odometry, Engineering Journals & More

Hello everyone! I’m Theo from 7842F, and I’m the programmer for our team. I’ve been meaning to make this post ever since worlds, but I haven’t had the time to do so. I now finally have some time before my school starts (I still have 1 week of summer ) to show the VEX community our robot and all the different designs we have implemented to make it. Even though the Turning Point season is way over, the things I will show in this post still applies to this year and VEX in general. Who Are…

Combining turn and linear movement PIDs

I’m assuming the poster is asking about combining PIDs to get an arc with a tank drive. If they are asking about turning while driving w/ holonomic drive, I can make a new post. @DrewWHOOP Motion profiling is unnecessary, you don’t need motion profiling to arc. @Micah_7157X Yes, there are a few ways to do what you want (which I’m assuming is doing some sort of arc): simply add the outputs of a distance and angle PID you can control the arc length and final heading, but can’t really contro…

[technik3k]

Reserved for Debugging Output discussion

TBD