efi_pid.h

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/**
 * @file efi_pid.h
 *
 * everyone including ChibiOS-Contrib has a version of 'pid.h' so we use unique file name to avoid drama
 *
 *
 * @date Sep 16, 2014
 * @author Andrey Belomutskiy, (c) 2012-2020
 */
 
#pragma once
 
#include "pid_state_generated.h"
#include "output_channels_generated.h"
 
// See PidCic below
#define PID_AVG_BUF_SIZE_SHIFT 5
#define PID_AVG_BUF_SIZE (1<<PID_AVG_BUF_SIZE_SHIFT) // 32*sizeof(float)
 
#define NOT_TIME_BASED_PID 1
 
// minimal period 5m meaning maximum control frequency 200Hz
#define PID_MINIMAL_PERIOD_MS 5
 
#define GET_PERIOD_LIMITED(pid_s_ptr) maxI(PID_MINIMAL_PERIOD_MS, ((pid_s_ptr)->periodMs))
 
#define MS2SEC(x) (x * 0.001)
 
struct pid_s;
 
/**
 * default basic implementation also known as PidParallelController
 */
class Pid : public pid_state_s {
public:
    Pid();
    explicit Pid(pid_s *parameters);
    void initPidClass(pid_s *parameters);
    bool isSame(const pid_s *parameters) const;
 
    /**
     * This version of the method takes dTime from pid_s
     *
     * @param Controller input / process output
     * @returns Output from the PID controller / the input to the process
     */
    float getOutput(float target, float input);
    virtual float getOutput(float target, float input, float dTime);
    // doesn't limit the result (used in incremental CIC PID, see below)
    float getUnclampedOutput(float target, float input, float dTime);
    void updateFactors(float pFactor, float iFactor, float dFactor);
    virtual void reset();
    float getP() const;
    float getI() const;
    float getD() const;
    float getOffset() const;
    float getMinValue() const;
    float getIntegration(void) const;
    float getPrevError(void) const;
    void setErrorAmplification(float coef);
#if EFI_TUNER_STUDIO
    void postState(pid_status_s& pidStatus) const;
#endif /* EFI_TUNER_STUDIO */
    void showPidStatus(const char* msg) const;
    void sleep();
    int resetCounter;
    // todo: move this to pid_s one day
    float iTermMin = -1000000.0;
    float iTermMax =  1000000.0;
protected:
    pid_s *parameters = nullptr;
    virtual void updateITerm(float value);
};
 
 
/**
 * A PID implementation with a modified cascaded integrator-comb (CIC) filtering.
 * Used for incremental auto-IAC control. See autoIdle() in idle_thread.cpp
 * See pid_cic.md.
 *
 * https://rusefi.com/forum/viewtopic.php?f=9&t=1315
 */
class PidCic : public Pid {
 
public:
    PidCic();
    explicit PidCic(pid_s *pid);
 
    void reset(void) override;
    using Pid::getOutput;
    float getOutput(float target, float input, float dTime) override;
    
private:
    // Circular running-average buffer for I-term, used by CIC-like filter
    float iTermBuf[PID_AVG_BUF_SIZE];
    // Needed by averaging (smoothing) of iTerm sums
    float iTermInvNum;
    // Total PID iterations (>240 days max. for 10ms update period)
    int totalItermCnt;
 
private:
    void updateITerm(float value) override;
};
 
/**
 * A PID with derivative filtering (backward differences) and integrator anti-windup.
 * See: Wittenmark B., Astrom K., Arzen K. IFAC Professional Brief. Computer Control: An Overview. 
 * Two additional parameters used: derivativeFilterLoss and antiwindupFreq
 * (If both are 0, then this controller is identical to PidParallelController)
 *
 * TODO: should PidIndustrial replace all usages of Pid/PidParallelController?
 */
class PidIndustrial : public Pid {
public:
    PidIndustrial();
    explicit PidIndustrial(pid_s *pid);
 
    using Pid::getOutput;
    float getOutput(float target, float input, float dTime) override;
 
public:
    // todo: move this to pid_s one day
    float antiwindupFreq = 0.0f;            // = 1/ResetTime
    float derivativeFilterLoss = 0.0f;  // = 1/Gain
 
private:
    float limitOutput(float v) const;
};