pid.h

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/****************************************************************************
 *
 *   Copyright (C) 2008-2013 PX4 Development Team. All rights reserved.
 *   Author: Laurens Mackay <mackayl@student.ethz.ch>
 *           Tobias Naegeli <naegelit@student.ethz.ch>
 *           Martin Rutschmann <rutmarti@student.ethz.ch>
 *           Anton Babushkin <anton.babushkin@me.com>
 *           Julian Oes <joes@student.ethz.ch>
 *
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/**
 * @file pid.h
 *
 * Definition of generic PID controller.
 *
 * @author Laurens Mackay <mackayl@student.ethz.ch>
 * @author Tobias Naegeli <naegelit@student.ethz.ch>
 * @author Martin Rutschmann <rutmarti@student.ethz.ch>
 * @author Anton Babushkin <anton.babushkin@me.com>
 * @author Julian Oes <joes@student.ethz.ch>
 */

#ifndef PID_H_
#define PID_H_

#include <stdint.h>

__BEGIN_DECLS

typedef enum PID_MODE {
    /* Use PID_MODE_DERIVATIV_NONE for a PI controller (vs PID) */
    PID_MODE_DERIVATIV_NONE = 0,
    /* PID_MODE_DERIVATIV_CALC calculates discrete derivative from previous error,
     * val_dot in pid_calculate() will be ignored */
    PID_MODE_DERIVATIV_CALC,
    /* PID_MODE_DERIVATIV_CALC_NO_SP calculates discrete derivative from previous value,
     * setpoint derivative will be ignored, val_dot in pid_calculate() will be ignored */
    PID_MODE_DERIVATIV_CALC_NO_SP,
    /* Use PID_MODE_DERIVATIV_SET if you have the derivative already (Gyros, Kalman) */
    PID_MODE_DERIVATIV_SET
} pid_mode_t;

typedef struct {
    pid_mode_t mode;
    float dt_min;
    float kp;
    float ki;
    float kd;
    float integral;
    float integral_limit;
    float output_limit;
    float error_previous;
    float last_output;
} PID_t;

__EXPORT void pid_init(PID_t *pid, pid_mode_t mode, float dt_min);
__EXPORT int pid_set_parameters(PID_t *pid, float kp, float ki, float kd, float integral_limit, float output_limit);
__EXPORT float pid_calculate(PID_t *pid, float sp, float val, float val_dot, float dt);
__EXPORT void pid_reset_integral(PID_t *pid);

__END_DECLS

#endif /* PID_H_ */