Takeoff.hpp

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/**
 * @file Takeoff.hpp
 *
 * A class handling all takeoff states and a smooth ramp up of the motors.
 */

#pragma once

#include <lib/hysteresis/hysteresis.h>
#include <drivers/drv_hrt.h>

using namespace time_literals;

enum class TakeoffState {
    disarmed = 0,
    spoolup,
    ready_for_takeoff,
    rampup,
    flight
};

class Takeoff
{
public:
    Takeoff() = default;
    ~Takeoff() = default;

    // initialize parameters
    void setTakeoffRampTime(const float seconds) { _takeoff_ramp_time = seconds; }
    void setSpoolupTime(const float seconds) { _spoolup_time_hysteresis.set_hysteresis_time_from(false, (hrt_abstime)(seconds * (float)1_s)); }

    /**
     * Calculate a vertical velocity to initialize the takeoff ramp
     * that when passed to the velocity controller results in a zero throttle setpoint.
     * @param hover_thrust normalized thrsut value with which the vehicle hovers
     * @param velocity_p_gain proportional gain of the velocity controller to calculate the thrust
     */
    void generateInitialRampValue(const float hover_thrust, const float velocity_p_gain);

    /**
     * Update the state for the takeoff.
     * @param setpoint a vehicle_local_position_setpoint_s structure
     * @return true if setpoint has updated correctly
     */
    void updateTakeoffState(const bool armed, const bool landed, const bool want_takeoff,
                const float takeoff_desired_vz, const bool skip_takeoff, const hrt_abstime &now_us);

    /**
     * Update and return the velocity constraint ramp value during takeoff.
     * By ramping up _takeoff_ramp_vz during the takeoff and using it to constain the maximum climb rate a smooth takeoff behavior is achieved.
     * Returns zero on the ground and takeoff_desired_vz in flight.
     * @param dt time in seconds since the last call/loop iteration
     * @param takeoff_desired_vz end value for the velocity ramp
     * @return true if setpoint has updated correctly
     */
    float updateRamp(const float dt, const float takeoff_desired_vz);

    TakeoffState getTakeoffState() { return _takeoff_state; }

private:
    TakeoffState _takeoff_state = TakeoffState::disarmed;

    float _takeoff_ramp_time = 0.f;
    float _takeoff_ramp_vz_init = 0.f;
    float _takeoff_ramp_vz = 0.f;

    systemlib::Hysteresis _spoolup_time_hysteresis{false}; /**< becomes true MPC_SPOOLUP_TIME seconds after the vehicle was armed */
};