jremington:
In your posted code, the PID algorithm is taking its input via the following line:Input = analogRead(inputPin);Change that to something like (substitute the appropriate variable name):
Input = value_obtained_from_HX711;Be sure to carefully study the PID documentation for the allowable range of PID input values, PID output values, and how to set the Kp, Ki and Kd constants.
Got it, i'll try this asap.
I have read through Brett Beauregard's PID example's, library, and blog post for improving the beginner's PID.
It is hard for me to analyze much of the code as it uses double so many times in ways I do not understand.
I do understand that he provided a way to clamp the output limits by defining outputMax and outputMin.
But is there a way for me to know what input values will be read? Or do I assume 0-1023, and map our live tension range with those values?
#ifndef PID_v1_h
#define PID_v1_h
#define LIBRARY_VERSION 1.2.1
;
class PID
{
public:
//Constants used in some of the functions below
#define AUTOMATIC 1
#define MANUAL 0
#define DIRECT 0
#define REVERSE 1
#define P_ON_M 0
#define P_ON_E 1
//commonly used functions **************************************************************************
PID(double*, double*, double*, // * constructor. links the PID to the Input, Output, and
double, double, double, int, int);// Setpoint. Initial tuning parameters are also set here.
// (overload for specifying proportional mode)
PID(double*, double*, double*, // * constructor. links the PID to the Input, Output, and
double, double, double, int); // Setpoint. Initial tuning parameters are also set here
void SetMode(int Mode); // * sets PID to either Manual (0) or Auto (non-0)
bool Compute(); // * performs the PID calculation. it should be
// called every time loop() cycles. ON/OFF and
// calculation frequency can be set using SetMode
// SetSampleTime respectively
void SetOutputLimits(double, double); // * clamps the output to a specific range. 0-255 by default, but
// it's likely the user will want to change this depending on
// the application
//available but not commonly used functions ********************************************************
void SetTunings(double, double, // * While most users will set the tunings once in the
double); // constructor, this function gives the user the option
// of changing tunings during runtime for Adaptive control
void SetTunings(double, double, // * overload for specifying proportional mode
double, int);
void SetControllerDirection(int); // * Sets the Direction, or "Action" of the controller. DIRECT
// means the output will increase when error is positive. REVERSE
// means the opposite. it's very unlikely that this will be needed
// once it is set in the constructor.
void SetSampleTime(int); // * sets the frequency, in Milliseconds, with which
// the PID calculation is performed. default is 100
//Display functions ****************************************************************
double GetKp(); // These functions query the pid for interal values.
double GetKi(); // they were created mainly for the pid front-end,
double GetKd(); // where it's important to know what is actually
int GetMode(); // inside the PID.
int GetDirection(); //
private:
void Initialize();
double dispKp; // * we'll hold on to the tuning parameters in user-entered
double dispKi; // format for display purposes
double dispKd; //
double kp; // * (P)roportional Tuning Parameter
double ki; // * (I)ntegral Tuning Parameter
double kd; // * (D)erivative Tuning Parameter
int controllerDirection;
int pOn;
double *myInput; // * Pointers to the Input, Output, and Setpoint variables
double *myOutput; // This creates a hard link between the variables and the
double *mySetpoint; // PID, freeing the user from having to constantly tell us
// what these values are. with pointers we'll just know.
unsigned long lastTime;
double outputSum, lastInput;
unsigned long SampleTime;
double outMin, outMax;
bool inAuto, pOnE;
};
#endif