Wiki

[Connor]

Reserved for Driver Control

Driver Control Tutorial [Arcade] (VEXCode)

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

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 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 desired is reached, change turnError = turnDifference - d…

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. Team 5225 Introduction to Position Tracking Document But at a less extreme level, for people just looking to take a step up from move.relative you may like the base control…

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. @Drew2158U Motion profiling is unnecessary, you don’t need motion profiling to arc. @TNT_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 control …

[technik3k]

Reserved for Debugging Output discussion

TBD

[technik3k]

Displaying Images on V5

Animated GIF Demo (VEXcode)

Hers’s another demo that can be built with VEXcode. It’s not very well developed and uses a couple of C API’s that we don’t usually expose that were added to vexos 1.0.5. I’ll also explain a couple of more advanced aspects of the setup in another post later, specifically how to allow VEXcode access to more dynamic memory than is available with the default project build scripts. output looks like this. [gifdemo] and uses this animated gif. [world] You can display more than one gif by creat…

Drawing Image on V5 Screen

Sorry I neglected to state I was using VexCode C++. I have looked at some things on the forum and came up with this code #include "vex.h" using namespace vex; // A global instance of vex::brain used for printing to the V5 brain screen vex::brain Brain; int main() { Brain.Screen.drawImageFromFile("cube.png",20,20); while(1) { // Allow other tasks to run this_thread::sleep_for(10); } } Unfortunately this will not draw the image.

Having troubles displaying gifs

Did you include “vex.h” and “gifclass.h” at the beginning of your program? See attached example in this topic: Animated GIF Demo (VEXcode) vex::Gif class is not a part of the default VEXcode API: https://api.vexcode.cloud/v5/html/annotated.html PNG and BMP images can be drawn with drawImageFromFile(): https://api.vexcode.cloud/v5/html/classvex_1_1brain_1_1lcd.html#ac1a069baa3212a8c697d70c8fa8e5187 See example here: Drawing Image on V5 Screen

Display image on V5 using vex code

A Guide to Changing Program Icons

A guide to icons on the V5 When you upload a program to the V5, you may notice that the icon for it corresponds with what program you used to code it in. But you’ve probably wondered at some point how to change the icon, right? Well here’s a guide on how to do so, wether you code in PROS or VexCode (but it still requires PROS either way). How it works But first, let’s get into how it works. VexOS looks for the icon you specify in the .ini file uploaded to the brain when uploading your program …

[technik3k]

Accessing Multiple Files on SDCard

SD Card Help

Here’s a simple example showing how to use the VCS SD card save and load file API. This saves some information into a file called “test.h” on the SD card and then reads it back again. #include "robot-config.h" // storage for some information to save uint8_t myTestData[ 100 ]; uint8_t myReadBuffer[ 1000 ]; int main() { // set the test data to something detectable for(int i=0;i<100;i++) { myTestData* = i * 2; } // write test data to SD Card int nWritten…

SD Card Help

Here, this is what it should be #include "robot-config.h" // storage for some information to save uint8_t myTestData[ 100 ]; uint8_t myReadBuffer[ 1000 ]; int main() { // set the test data to something detectable for(int i=0;i<100;i++) { myTestData[i] = i * 2; } // write test data to SD Card int nWritten = Brain.SDcard.savefile( "test.h", myTestData, sizeof(myTestData) ); // did that work ? if( nWritten > 0) { // display on screen how …

SD Card errors

the sdcard functions all require a buffer pointer, not values like you are passing. If you really want to write binary data, it might be something like this. int x = 23; Brain.SDcard.appendfile("file", (uint8_t *)&x, sizeof(int) ); to write the values as text, you need to convert to a string. int x = 23; char buffer[32]; sprintf(buffer, "%d", x ); Brain.SDcard.appendfile("file", (uint8_t *)buffer, strlen(buffer) ); make sure the file exists if you want to use appen…

Error reading from sdcard - #4 by jpearman

Differences in the SD Card commands bug - #3 by jpearman

What SD cards are supported for the V5 Brain? - #7 by jpearman

[technik3k]

Autonomous Mode Selectors

WalshBots Autonomous Feature Selector

James Pearman posted an example of autonomous selection using the V5 Robot Brain. It allows up to eight different routines to be selected before start of a match. We have extended this to allow the buttons to select features to be enabled or not, for example shoot preload or not. It also allows to select the starting tile and alliance. Attached is an example program and brief description. Thanks James for being an awesome teacher to all! If there are bugs, please let me know. Be sure to cr…

VEXcode Button Generator

Hey everyone, I’ve been playing around with a program that builds rectangular buttons onto the V5 screen and I think it has turned out pretty nice. I initially made it to make it quicker to build our autonomous selectors, but the more the program expanded the clearer it was that it could help make a lot of projects simpler and faster (though not necessarily for use in VRC). As a result, I’m releasing the code for anyone who wants to use it. disclaimer: Right off the bat, know this program has…

Pre-Made VEX V5 PROS Auton Selector

Check out this VEX V5 Auton Selector made using LVGL. Check it out here. [67626102-d9e1d080-f814-11e9-84cd-63a44e6a35af] Lemme know what you think.

Auton Selector

Here is a basic example I of an autonomous selector in Vexcode… int autonToRun = 0; class Button { public: int x, y, width, height; std::string text; vex::color buttonColor, textColor; Button(int x, int y, int width, int height, std::string text, vex::color buttonColor, vex::color textColor) : x(x), y(y), width(width), height(height), text(text), buttonColor(buttonColor), textColor(textColor){} void render() { Brain.Screen.drawRectangle(x, y, width, he…

LVGL Auton Selector with Okapi chassis and Pathfinder Auton Example

For those interested, I’ve updated the Okapi/Pathfinder example to use PROS 3.2.1 and OkapiLib 4.0.3. The auton selector is still the slightly modified 5090Z version. Prior versions are available if you look under the “tags” option on GitHub. Many of the answers I provide are tested here so you’ll see how to limit voltage for motors, toggle speed, joystick text and rumble, auto switch to a different tab, and multiple profile controllers. This update was prompted by questions I see on how to …

[Connor]

Position Tracking/Odometry

Position Tracking/Odometry Tutorial

Hello! I will be allocating this thread to odometry, as requested by many. Because I do not have a robot with me, I have utilized Roblox Studio to help me figure out and test the code (then translating it from lua to C++). I am pretty new to odometry, but I am able to figure out the gist by teaching myself and trial/error (as what @Cody said, doing is the best teacher ). So if/when I have the time, I will be posting tutorial videos on position tracking and odometry. If you need any help l…

[Connor]

#includes in C++

#include files in VEXcode

How would I go about using #include to include other header or source files in my VEXcode project? When I make a new source file and include in it vex.h (so it can access my motor ports) and then try to include that file in main.cpp it gives me errors like "you are redefining “Controller 1” and stuff like that. I am trying to put all of my autonomous routines in separate files. If I was to put an autonomous routine in a separate file should it be a .h or a .cpp file and what directory should …