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e017f93f16
Also added some references/smart pointers to a couple places that seemed convenient to the user. I haven't updated the constructors for RobotDrive() related examples, pending the results of gerrit change https://usfirst.collab.net/gerrit/#/c/960/ A few things that we are noticing: --It might be nice if ReturnPIDInput() didn't have to be const; when people try to override it, they have to remember to put the const in and if they don't, then the compiler error isn't the most obvious (especially since this is a change). This would also apply to PIDGet() in the PIDSource interface. --SendableChooser still takes raw pointers. This could lead to an issue I had to debug briefly where you accidentally call GetSelected() on autoChooser and put the resulting raw pointer into a unique_ptr, which destroys the pointer when it goes out of scope. Specifically, I was testing the PacGoat example and I ended up with a situation where if auto mode was run once, it was fine, but if it was run twice, the selected command would have been destroyed by the unique_ptr. I believe that this just requires updating SendableChosser to take shared_ptr. --When the samples are compiled with -pedantic, it points out that START_ROBOT_CLASS macro expansion results in a redundant semicolon. Change-Id: Ib4c025a61263d0d2780d4253faa31713e15333a5
81 lines
2.7 KiB
C++
81 lines
2.7 KiB
C++
#include "WPILib.h"
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/**
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* This is a sample program to demonstrate how to use a soft potentiometer and a PID
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* Controller to reach and maintain position setpoints on an elevator mechanism.
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*
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* WARNING: While it may look like a good choice to use for your code if you're inexperienced,
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* don't. Unless you know what you are doing, complex code will be much more difficult under
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* this system. Use IterativeRobot or Command-Based instead if you're new.
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*/
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class Robot: public SampleRobot {
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const int potChannel = 1; //analog input pin
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const int motorChannel = 7; //PWM channel
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const int joystickChannel = 0; //usb number in DriverStation
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const int buttonNumber = 4; //button on joystick
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const double setPoints[3] = { 1.0, 2.6, 4.3 }; //bottom, middle, and top elevator setpoints
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//proportional, integral, and derivative speed constants; motor inverted
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//DANGER: when tuning PID constants, high/inappropriate values for pGain, iGain,
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//and dGain may cause dangerous, uncontrollable, or undesired behavior!
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const double pGain = -5.0, iGain = -0.02, dGain = -2.0; //these may need to be positive for a non-inverted motor
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AnalogInput potentiometer;
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Victor elevatorMotor;
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Joystick joystick;
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PIDController pidController;
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public:
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Robot() :
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//make objects for potentiometer, the elevator motor controller, and the joystick
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potentiometer(potChannel), elevatorMotor(motorChannel), joystick(joystickChannel),
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//potentiometer (AnalogInput) and elevatorMotor (Victor) can be used as a
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//PIDSource and PIDOutput respectively.
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//The PIDController has to take a pointer to the PIDSource and PIDOutput, so
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//you must call &potentiometer and &elevatorMotor to get their pointers.
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pidController(pGain, iGain, dGain, &potentiometer, &elevatorMotor) {}
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/**
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* Runs during autonomous.
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*/
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void Autonomous() {
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}
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/**
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* Uses a PIDController and an array of setpoints to switch and maintain elevator positions.
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* The elevator setpoint is selected by a joystick button.
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*/
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void OperatorControl() {
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pidController.SetInputRange(0, 5); //0 to 5V
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pidController.SetSetpoint(setPoints[0]); //set to first setpoint
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int index = 0;
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bool currentValue;
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bool previousValue = false;
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while (IsOperatorControl() && IsEnabled()) {
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pidController.Enable(); //begin PID control
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//when the button is pressed once, the selected elevator setpoint is incremented
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currentValue = joystick.GetRawButton(buttonNumber);
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if (currentValue && !previousValue) {
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pidController.SetSetpoint(setPoints[index]);
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index = (index + 1) % (sizeof(setPoints)/8); //index of elevator setpoint wraps around
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}
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previousValue = currentValue;
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}
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}
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/**
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* Runs during test mode.
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*/
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void Test() {
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}
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};
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START_ROBOT_CLASS(Robot)
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