PID-Controller

Simple implementation for multiple floating-point PID Controllers. More...

Files
file	pid.h
	PID Library Header.
file	pid.c
	PID Library Implementation.

Data Structures
struct	PIDState
	Data Structure for a single PID Controller. More...

Macros
#define	ROLL   0
	Roll index for pidTarget, pidOutput and pidStates. More...
#define	PITCH   1
	Pitch index for pidTarget, pidOutput and pidStates. More...

Functions
void	pidInit (void)
	Initialize Roll and Pitch PID. More...
void	pidTask (void)
	Step the Roll and Pitch PID Controllers. More...
void	pidSet (PIDState *pid, double kp, double ki, double kd, double min, double max, double iMin, double iMax)
	Set the parameters of a PID controller. More...
double	pidExecute (double should, double is, PIDState *state)
	Execute a single PID Control Step. More...

Variables
double	pidTarget [2]
	Roll and Pitch target angles. More...
double	pidOutput [2]
	Roll and Pitch PID Output. More...
PIDState	pidStates [2]
	Roll and Pitch PID States. More...
PIDState	pidStates [2]
	Roll and Pitch PID States. More...
double	pidTarget [2]
	Roll and Pitch target angles. More...
double	pidOutput [2]
	Roll and Pitch PID Output. More...

Detailed Description

Simple implementation for multiple floating-point PID Controllers.

Macro Definition Documentation

#define PITCH   1

Pitch index for pidTarget, pidOutput and pidStates.

Examples:

uartFlight.c.

Definition at line 61 of file pid.h.

Referenced by pidTask(), and setMotorSpeeds().

#define ROLL   0

Roll index for pidTarget, pidOutput and pidStates.

Examples:

uartFlight.c.

Definition at line 60 of file pid.h.

Referenced by pidTask(), and setMotorSpeeds().

Function Documentation

double pidExecute	(	double	should,
		double	is,
		PIDState *	state
	)

Execute a single PID Control Step.

Parameters

should	Target value
is	Measured value
state	PID State

Returns

PID Output

Definition at line 54 of file pid.c.

References getSystemTime(), PIDState::intMax, PIDState::intMin, PIDState::kd, PIDState::ki, PIDState::kp, PIDState::last, PIDState::lastError, PIDState::outMax, PIDState::outMin, and PIDState::sumError.

Referenced by pidTask().

                                                             {
    time_t now = getSystemTime();
    double timeChange = (double)(now - state->last);
    double error = should - is;
    double newErrorSum = state->sumError + (error * timeChange);
    if ((newErrorSum >= state->intMin) && (newErrorSum <= state->intMax))
        state->sumError = newErrorSum; // Prevent Integral Windup
    double dError = (error - state->lastError) / timeChange;
    double output = (state->kp * error) + (state->ki * state->sumError) + (state->kd * dError);
    state->lastError = error;
    state->last = now;
    if (output > state->outMax) {
        output = state->outMax;
    }
    if (output < state->outMin) {
        output = state->outMin;
    }
    return output;
}

void pidInit

(

void

)

Initialize Roll and Pitch PID.

Stores the PID States in pidStates. Also resets pidTarget to zero.

Examples:

uartFlight.c.

Definition at line 74 of file pid.c.

References PID_D, PID_I, PID_INTMAX, PID_INTMIN, PID_OUTMAX, PID_OUTMIN, PID_P, pidSet(), and pidTarget.

                   {
    for (uint8_t i = 0; i < 2; i++) {
        pidSet(&pidStates[i], PID_P, PID_I, PID_D, PID_OUTMIN, PID_OUTMAX, PID_INTMIN, PID_INTMAX);
        pidTarget[i] = 0.0;
    }
}

void pidSet	(	PIDState *	pid,
		double	kp,
		double	ki,
		double	kd,
		double	min,
		double	max,
		double	iMin,
		double	iMax
	)

Set the parameters of a PID controller.

The state variables will be reset to zero.

Parameters

pid	PIDState to be changed.
kp	New Proportional constant.
ki	New Integral constant.
kd	New Derivative constant.
min	New minimum Output.
max	New maximum Output.
iMin	New minimal Integral Sum.
iMax	New maximal Integral Sum.

Examples:

uartFlight.c.

Definition at line 81 of file pid.c.

References PIDState::intMax, PIDState::intMin, PIDState::kd, PIDState::ki, PIDState::kp, PIDState::last, PIDState::lastError, PIDState::outMax, PIDState::outMin, and PIDState::sumError.

Referenced by pidInit().

                                                                                                              {
    pid->kp = kp;
    pid->ki = ki;
    pid->kd = kd;
    pid->outMin = min;
    pid->outMax = max;
    pid->intMin = iMin;
    pid->intMax = iMax;
    pid->lastError = 0;
    pid->sumError = 0;
    pid->last = 0;
}

void pidTask

(

void

)

Step the Roll and Pitch PID Controllers.

Placing their output in pidOutput and reading the input from pidTarget and the global orientation Angles.

Examples:

uartFlight.c.

Definition at line 94 of file pid.c.

References orientation, pidExecute(), pidOutput, pidTarget, Angles::pitch, PITCH, Angles::roll, and ROLL.

                   {
    pidOutput[ROLL] = pidExecute(pidTarget[ROLL], orientation.roll, &pidStates[ROLL]);
    pidOutput[PITCH] = pidExecute(pidTarget[PITCH], orientation.pitch, &pidStates[PITCH]);
}

Variable Documentation

double pidOutput[2]

Roll and Pitch PID Output.

Definition at line 52 of file pid.c.

Referenced by pidTask(), and setTask().

double pidOutput[2]

Roll and Pitch PID Output.

Examples:

uartFlight.c.

Definition at line 52 of file pid.c.

Referenced by pidTask(), and setTask().

PIDState pidStates[2]

Roll and Pitch PID States.

Definition at line 50 of file pid.c.

PIDState pidStates[2]

Roll and Pitch PID States.

Examples:

uartFlight.c.

Definition at line 50 of file pid.c.

double pidTarget[2]

Roll and Pitch target angles.

Definition at line 51 of file pid.c.

Referenced by pidInit(), and pidTask().

double pidTarget[2]

Roll and Pitch target angles.

Examples:

uartFlight.c.

Definition at line 51 of file pid.c.

Referenced by pidInit(), and pidTask().