integrator.h

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/**
 * @file integrator.h
 *
 * A resettable integrator
 *
 * @author Lorenz Meier <lorenz@px4.io>
 * @author Julian Oes <julian@oes.ch>
 */

#pragma once

#include <mathlib/mathlib.h>
#include <matrix/math.hpp>

class Integrator
{
public:
    Integrator(uint32_t auto_reset_interval = 4000 /* 250 Hz */, bool coning_compensation = false);
    ~Integrator() = default;

    // no copy, assignment, move, move assignment
    Integrator(const Integrator &) = delete;
    Integrator &operator=(const Integrator &) = delete;
    Integrator(Integrator &&) = delete;
    Integrator &operator=(Integrator &&) = delete;

    /**
     * Put an item into the integral.
     *
     * @param timestamp Timestamp of the current value.
     * @param val       Item to put.
     * @param integral  Current integral in case the integrator did reset, else the value will not be modified
     * @param integral_dt   Get the dt in us of the current integration (only if reset).
     * @return      true if putting the item triggered an integral reset and the integral should be
     *          published.
     */
    bool put(const uint64_t &timestamp, const matrix::Vector3f &val, matrix::Vector3f &integral, uint32_t &integral_dt);

    /**
     * Put an item into the integral but provide an interval instead of a timestamp.
     *
     * @param interval_us   Interval in us since last integration.
     * @param val       Item to put.
     * @param integral  Current integral in case the integrator did reset, else the value will not be modified
     * @param integral_dt   Get the dt in us of the current integration (only if reset). Note that this
     *          values might not be accurate vs. hrt_absolute_time because it is just the sum of the
     *          supplied intervals.
     * @return      true if putting the item triggered an integral reset and the integral should be
     *          published.
     */
    bool put_with_interval(unsigned interval_us, matrix::Vector3f &val, matrix::Vector3f &integral, uint32_t &integral_dt);

    /**
     * Get the current integral and reset the integrator if needed.
     *
     * @param reset         Reset the integral to zero.
     * @param integral_dt   Get the dt in us of the current integration (only if reset).
     * @return      the integral since the last read-reset
     */
    matrix::Vector3f    get(bool reset, uint32_t &integral_dt);


    /**
     * Get the current integral and reset the integrator if needed. Additionally give the
     * integral over the samples differentiated by the integration time (mean filtered values).
     *
     * @param reset         Reset the integral to zero.
     * @param integral_dt   Get the dt in us of the current integration (only if reset).
     * @param filtered_val  The integral differentiated by the integration time.
     * @return      the integral since the last read-reset
     */
    matrix::Vector3f    get_and_filtered(bool reset, uint32_t &integral_dt, matrix::Vector3f &filtered_val);


    /**
     * Set auto reset interval during runtime. This won't reset the integrator.
     *
     * @param auto_reset_interval           New reset time interval for the integrator (+- 10%).
     */
    void set_autoreset_interval(uint32_t auto_reset_interval) { _auto_reset_interval = 0.90f * auto_reset_interval; }

private:
    uint32_t _auto_reset_interval{0};           /**< the interval after which the content will be published
                                 and the integrator reset, 0 if no auto-reset */

    uint64_t _last_integration_time{0};     /**< timestamp of the last integration step */
    uint64_t _last_reset_time{0};           /**< last auto-announcement of integral value */

    matrix::Vector3f _alpha{0.0f, 0.0f, 0.0f};          /**< integrated value before coning corrections are applied */
    matrix::Vector3f _last_alpha{0.0f, 0.0f, 0.0f};         /**< previous value of _alpha */
    matrix::Vector3f _beta{0.0f, 0.0f, 0.0f};               /**< accumulated coning corrections */
    matrix::Vector3f _last_val{0.0f, 0.0f, 0.0f};   /**< previous input */
    matrix::Vector3f _last_delta_alpha{0.0f, 0.0f, 0.0f};       /**< integral from previous previous sampling interval */

    bool _coning_comp_on{false};                /**< true to turn on coning corrections */

    /* Do a reset.
     *
     * @param integral_dt   Get the dt in us of the current integration.
     */
    void _reset(uint32_t &integral_dt);
};