Add Why Run To Position Mode Is Not A Good Idea

src/contributors.md

@@ -9,3 +9,5 @@
 - j5155 [(github)](https://github.com/j5155) [(discord)](https://discord.com/users/496774369054425109)
 - Arush [(github)](https://github.com/ArushYadlapati) [(discord)](https://discord.com/users/764258716463529986)
 - ZachWaffle [(github)](https://github.com/zachwaffle4) [(discord)](https://discord.com/users/522513851942436867)
+- NN [(github)](https://github.com/NipunNagendra) [(discord)](https://discord.com/users/667550773181415425)
+

src/pidf_controllers/why_run_to_position_mode_is_not_a_good_idea.md

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+# Why Run To Position Is Not A Good Idea
+When using a PID(F) controller to move a motor to a certain position, it is often tempting
+to use the `RUN_TO_POSITION` mode, especially since it appears in many examples.
+This motor run mode is built into the FTC SDK and is designed to move a motor to a certain encoder position autonomously.
+
+However, this mode is not ideal for a few reasons (ordered from most to least significant):
+## Locked at 20 HZ
+
+The `RUN_TO_POSITION` mode is locked at 20 HZ,
+meaning that the motor will only update its position every 50 milliseconds.
+
+**Why this is a problem:**
+
+Imagine a scenario where you are trying to move a motor to a certain position.
+If the motor is moving too fast, it will overshoot the target position and then have to correct itself.
+However, if the motor is only updating its position 20 times per second, it will not be able to correct itself quickly enough,
+leading to overshoots and even oscillations.
+
+Here's a [demo](https://www.youtube.com/watch?v=fusr9eTceEo&t=133s) of this effect.
+
+### Why going Custom PID(F) is better:
+With a custom PID(F) controller, you can update the motor's position every loop. Since most FTC loops run at higher than 20hz,
+a custom solution will update the motor's position more frequently solving the problems mentioned.
+
+## Syntax Requirement and Crash Errors
+The `RUN_TO_POSITION` mode requires that you set the target position before you start the motor.
+```java
+motor.setTargetPosition(1000);
+motor.setMode(DcMotor.RunMode.RUN_TO_POSITION);
+motor.setPower(1);
+```
+
+First, this syntax is required to be followed exactly. This means that if you want to switch between manual and automatic control,
+you will have to change the motor mode every time you switch. Programming any FSM or even any complex auto becomes quite difficult.
+
+While this seems like a minor inconvenience, if done in the wrong order, it **crashes the entire bot without outputting any useful error messages**.
+This can be a significant issue not only when debugging but also in games if it's precisely not controlled.
+
+## Customizability and Tuning
+Although the 'RUN_TO_POSITION' mode allows for some basic PID tuning, most teams don't do it and just use the default values.
+This can lead to scenarios where the motor improperly responds to disturbances or even fails to reach the target position.
+
+Moreover, the RTP mode is a simple PID controller, meaning that it doesn't have the advanced features that a custom PID(F) controller has.
+
+For example, for systems like arms and slides, you may want to add feedforward gains to counteract gravity or friction. RTP will not allow you to do that.
+
+- https://www.ctrlaltftc.com/feedforward-control
+- https://www.youtube.com/watch?v=E6H6Nqe6qJo
+# Sooo, how do I solve it?
+PID(F) controllers seem scary, but they really aren't. All they do is try to get a motor to a certain position and hold it there.
+Here's a [guide](https://www.ctrlaltftc.com/pidf_controllers/integrating_a_custom_PIDF_controller) on not only how to implement one but the logic.
+
+And of course, if you don't wanna do that or code your own, there are libraries like [FTCLib](https://ftclib.org/) and [Homeostasis](https://www.ctrlaltftc.com/homeostasis-by-thermal-equilibrium/what-is-homeostasis) that have PID(F) controllers that are just plug-n-play (with tuning of course).
+
+If you're using Roadrunner, you can use this [recipe](https://cookbook.dairy.foundation/roadrunner_056/how_to_integrate_a_PIDF_controller_with_roadrunner/how_to_integrate_a_PIDF_controller_with_roadrunner.html#pidf-controller-and-gains)
+
+Happy coding! 🎉
+
+*Last Updated: 2024-11-02*