vtol_att_control_main.cpp

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/**
 * @file VTOL_att_control_main.cpp
 * Implementation of an attitude controller for VTOL airframes. This module receives data
 * from both the fixed wing- and the multicopter attitude controllers and processes it.
 * It computes the correct actuator controls depending on which mode the vehicle is in (hover,forward-
 * flight or transition). It also publishes the resulting controls on the actuator controls topics.
 *
 * @author Roman Bapst 		<bapstr@ethz.ch>
 * @author Lorenz Meier 	<lm@inf.ethz.ch>
 * @author Thomas Gubler	<thomasgubler@gmail.com>
 * @author David Vorsin		<davidvorsin@gmail.com>
 * @author Sander Smeets	<sander@droneslab.com>
 * @author Andreas Antener 	<andreas@uaventure.com>
 *
 */
#include "vtol_att_control_main.h"
#include <systemlib/mavlink_log.h>
#include <uORB/PublicationQueued.hpp>

using namespace matrix;

VtolAttitudeControl::VtolAttitudeControl() :
	WorkItem(MODULE_NAME, px4::wq_configurations::rate_ctrl),
	_loop_perf(perf_alloc(PC_ELAPSED, "vtol_att_control: cycle"))
{
	_vtol_vehicle_status.vtol_in_rw_mode = true;	/* start vtol in rotary wing mode*/

	_params.idle_pwm_mc = PWM_DEFAULT_MIN;
	_params.vtol_motor_id = 0;

	_params_handles.idle_pwm_mc = param_find("VT_IDLE_PWM_MC");
	_params_handles.vtol_motor_id = param_find("VT_MOT_ID");
	_params_handles.vtol_fw_permanent_stab = param_find("VT_FW_PERM_STAB");
	_params_handles.vtol_type = param_find("VT_TYPE");
	_params_handles.elevons_mc_lock = param_find("VT_ELEV_MC_LOCK");
	_params_handles.fw_min_alt = param_find("VT_FW_MIN_ALT");
	_params_handles.fw_alt_err = param_find("VT_FW_ALT_ERR");
	_params_handles.fw_qc_max_pitch = param_find("VT_FW_QC_P");
	_params_handles.fw_qc_max_roll = param_find("VT_FW_QC_R");
	_params_handles.front_trans_time_openloop = param_find("VT_F_TR_OL_TM");
	_params_handles.front_trans_time_min = param_find("VT_TRANS_MIN_TM");

	_params_handles.front_trans_duration = param_find("VT_F_TRANS_DUR");
	_params_handles.back_trans_duration = param_find("VT_B_TRANS_DUR");
	_params_handles.transition_airspeed = param_find("VT_ARSP_TRANS");
	_params_handles.front_trans_throttle = param_find("VT_F_TRANS_THR");
	_params_handles.back_trans_throttle = param_find("VT_B_TRANS_THR");
	_params_handles.airspeed_blend = param_find("VT_ARSP_BLEND");
	_params_handles.airspeed_mode = param_find("FW_ARSP_MODE");
	_params_handles.front_trans_timeout = param_find("VT_TRANS_TIMEOUT");
	_params_handles.mpc_xy_cruise = param_find("MPC_XY_CRUISE");
	_params_handles.fw_motors_off = param_find("VT_FW_MOT_OFFID");
	_params_handles.diff_thrust = param_find("VT_FW_DIFTHR_EN");
	_params_handles.diff_thrust_scale = param_find("VT_FW_DIFTHR_SC");
	_params_handles.dec_to_pitch_ff = param_find("VT_B_DEC_FF");
	_params_handles.dec_to_pitch_i = param_find("VT_B_DEC_I");
	_params_handles.back_trans_dec_sp = param_find("VT_B_DEC_MSS");


	_params_handles.down_pitch_max = param_find("VT_DWN_PITCH_MAX");
	_params_handles.forward_thrust_scale = param_find("VT_FWD_THRUST_SC");

	/* fetch initial parameter values */
	parameters_update();

	if (static_cast<vtol_type>(_params.vtol_type) == vtol_type::TAILSITTER) {
		_vtol_type = new Tailsitter(this);

	} else if (static_cast<vtol_type>(_params.vtol_type) == vtol_type::TILTROTOR) {
		_vtol_type = new Tiltrotor(this);

	} else if (static_cast<vtol_type>(_params.vtol_type) == vtol_type::STANDARD) {
		_vtol_type = new Standard(this);

	} else {
		exit_and_cleanup();
	}
}

VtolAttitudeControl::~VtolAttitudeControl()
{
	perf_free(_loop_perf);
}

bool
VtolAttitudeControl::init()
{
	if (!_actuator_inputs_mc.registerCallback()) {
		PX4_ERR("MC actuator controls callback registration failed!");
		return false;
	}

	if (!_actuator_inputs_fw.registerCallback()) {
		PX4_ERR("FW actuator controls callback registration failed!");
		return false;
	}

	return true;
}

/**
* Check for command updates.
*/
void
VtolAttitudeControl::vehicle_cmd_poll()
{
	if (_vehicle_cmd_sub.updated()) {
		_vehicle_cmd_sub.copy(&_vehicle_cmd);
		handle_command();
	}
}

/**
* Check received command
*/
void
VtolAttitudeControl::handle_command()
{
	// update transition command if necessary
	if (_vehicle_cmd.command == vehicle_command_s::VEHICLE_CMD_DO_VTOL_TRANSITION) {
		_transition_command = int(_vehicle_cmd.param1 + 0.5f);

		// Report that we have received the command no matter what we actually do with it.
		// This might not be optimal but is better than no response at all.

		if (_vehicle_cmd.from_external) {
			vehicle_command_ack_s command_ack{};
			command_ack.timestamp = hrt_absolute_time();
			command_ack.command = _vehicle_cmd.command;
			command_ack.result = (uint8_t)vehicle_command_ack_s::VEHICLE_RESULT_ACCEPTED;
			command_ack.target_system = _vehicle_cmd.source_system;
			command_ack.target_component = _vehicle_cmd.source_component;

			uORB::PublicationQueued<vehicle_command_ack_s> command_ack_pub{ORB_ID(vehicle_command_ack)};
			command_ack_pub.publish(command_ack);
		}
	}
}

/*
 * Returns true if fixed-wing mode is requested.
 * Changed either via switch or via command.
 */
bool
VtolAttitudeControl::is_fixed_wing_requested()
{
	bool to_fw = false;

	if (_manual_control_sp.transition_switch != manual_control_setpoint_s::SWITCH_POS_NONE &&
	    _v_control_mode.flag_control_manual_enabled) {
		to_fw = (_manual_control_sp.transition_switch == manual_control_setpoint_s::SWITCH_POS_ON);

	} else {
		// listen to transition commands if not in manual or mode switch is not mapped
		to_fw = (_transition_command == vtol_vehicle_status_s::VEHICLE_VTOL_STATE_FW);
	}

	// handle abort request
	if (_abort_front_transition) {
		if (to_fw) {
			to_fw = false;

		} else {
			// the state changed to mc mode, reset the abort request
			_abort_front_transition = false;
			_vtol_vehicle_status.vtol_transition_failsafe = false;
		}
	}

	return to_fw;
}

void
VtolAttitudeControl::abort_front_transition(const char *reason)
{
	if (!_abort_front_transition) {
		mavlink_log_critical(&_mavlink_log_pub, "Abort: %s", reason);
		_abort_front_transition = true;
		_vtol_vehicle_status.vtol_transition_failsafe = true;
	}
}

int
VtolAttitudeControl::parameters_update()
{
	float v;
	int32_t l;
	/* idle pwm for mc mode */
	param_get(_params_handles.idle_pwm_mc, &_params.idle_pwm_mc);

	/* vtol motor count */
	param_get(_params_handles.vtol_motor_id, &_params.vtol_motor_id);

	/* vtol fw permanent stabilization */
	param_get(_params_handles.vtol_fw_permanent_stab, &l);
	_vtol_vehicle_status.fw_permanent_stab = (l == 1);

	param_get(_params_handles.vtol_type, &l);
	_params.vtol_type = l;

	/* vtol lock elevons in multicopter */
	param_get(_params_handles.elevons_mc_lock, &l);
	_params.elevons_mc_lock = (l == 1);

	/* minimum relative altitude for FW mode (QuadChute) */
	param_get(_params_handles.fw_min_alt, &v);
	_params.fw_min_alt = v;

	/* maximum negative altitude error for FW mode (Adaptive QuadChute) */
	param_get(_params_handles.fw_alt_err, &v);
	_params.fw_alt_err = v;

	/* maximum pitch angle (QuadChute) */
	param_get(_params_handles.fw_qc_max_pitch, &l);
	_params.fw_qc_max_pitch = l;

	/* maximum roll angle (QuadChute) */
	param_get(_params_handles.fw_qc_max_roll, &l);
	_params.fw_qc_max_roll = l;

	param_get(_params_handles.front_trans_time_openloop, &_params.front_trans_time_openloop);

	param_get(_params_handles.front_trans_time_min, &_params.front_trans_time_min);

	/*
	 * Minimum transition time can be maximum 90 percent of the open loop transition time,
	 * anything else makes no sense and can potentially lead to numerical problems.
	 */
	_params.front_trans_time_min = math::min(_params.front_trans_time_openloop * 0.9f,
				       _params.front_trans_time_min);


	param_get(_params_handles.front_trans_duration, &_params.front_trans_duration);
	param_get(_params_handles.back_trans_duration, &_params.back_trans_duration);
	param_get(_params_handles.transition_airspeed, &_params.transition_airspeed);
	param_get(_params_handles.front_trans_throttle, &_params.front_trans_throttle);
	param_get(_params_handles.back_trans_throttle, &_params.back_trans_throttle);
	param_get(_params_handles.airspeed_blend, &_params.airspeed_blend);
	param_get(_params_handles.airspeed_mode, &l);
	_params.airspeed_disabled = l != 0;
	param_get(_params_handles.front_trans_timeout, &_params.front_trans_timeout);
	param_get(_params_handles.mpc_xy_cruise, &_params.mpc_xy_cruise);
	param_get(_params_handles.fw_motors_off, &_params.fw_motors_off);
	param_get(_params_handles.diff_thrust, &_params.diff_thrust);

	param_get(_params_handles.diff_thrust_scale, &v);
	_params.diff_thrust_scale = math::constrain(v, -1.0f, 1.0f);

	/* maximum down pitch allowed */
	param_get(_params_handles.down_pitch_max, &v);
	_params.down_pitch_max = math::radians(v);

	/* scale for fixed wing thrust used for forward acceleration in multirotor mode */
	param_get(_params_handles.forward_thrust_scale, &_params.forward_thrust_scale);

	// make sure parameters are feasible, require at least 1 m/s difference between transition and blend airspeed
	_params.airspeed_blend = math::min(_params.airspeed_blend, _params.transition_airspeed - 1.0f);

	param_get(_params_handles.back_trans_dec_sp, &v);
	// increase the target deceleration setpoint provided to the controller by 20%
	// to make overshooting the transition waypoint less likely in the presence of tracking errors
	_params.back_trans_dec_sp = 1.2f * v;

	param_get(_params_handles.dec_to_pitch_ff, &_params.dec_to_pitch_ff);
	param_get(_params_handles.dec_to_pitch_i, &_params.dec_to_pitch_i);

	// update the parameters of the instances of base VtolType
	if (_vtol_type != nullptr) {
		_vtol_type->parameters_update();
	}

	return OK;
}

void
VtolAttitudeControl::Run()
{
	if (should_exit()) {
		_actuator_inputs_fw.unregisterCallback();
		_actuator_inputs_mc.unregisterCallback();
		exit_and_cleanup();
		return;
	}

	if (!_initialized) {
		parameters_update();  // initialize parameter cache

		if (_vtol_type->init()) {
			_initialized = true;

		} else {
			exit_and_cleanup();
			return;
		}
	}

	perf_begin(_loop_perf);

	const bool updated_fw_in = _actuator_inputs_fw.update(&_actuators_fw_in);
	const bool updated_mc_in = _actuator_inputs_mc.update(&_actuators_mc_in);

	// run on actuator publications corresponding to VTOL mode
	bool should_run = false;

	switch (_vtol_type->get_mode()) {
	case mode::TRANSITION_TO_FW:
	case mode::TRANSITION_TO_MC:
		should_run = updated_fw_in || updated_mc_in;
		break;

	case mode::ROTARY_WING:
		should_run = updated_mc_in;
		break;

	case mode::FIXED_WING:
		should_run = updated_fw_in;
		break;
	}

	if (should_run) {
		// check for parameter updates
		if (_parameter_update_sub.updated()) {
			// clear update
			parameter_update_s pupdate;
			_parameter_update_sub.copy(&pupdate);

			// update parameters from storage
			parameters_update();
		}

		_v_control_mode_sub.update(&_v_control_mode);
		_manual_control_sp_sub.update(&_manual_control_sp);
		_v_att_sub.update(&_v_att);
		_local_pos_sub.update(&_local_pos);
		_local_pos_sp_sub.update(&_local_pos_sp);
		_pos_sp_triplet_sub.update(&_pos_sp_triplet);
		_airspeed_validated_sub.update(&_airspeed_validated);
		_tecs_status_sub.update(&_tecs_status);
		_land_detected_sub.update(&_land_detected);
		vehicle_cmd_poll();

		// check if mc and fw sp were updated
		bool mc_att_sp_updated = _mc_virtual_att_sp_sub.update(&_mc_virtual_att_sp);
		bool fw_att_sp_updated = _fw_virtual_att_sp_sub.update(&_fw_virtual_att_sp);

		// update the vtol state machine which decides which mode we are in
		_vtol_type->update_vtol_state();

		// reset transition command if not auto control
		if (_v_control_mode.flag_control_manual_enabled) {
			if (_vtol_type->get_mode() == mode::ROTARY_WING) {
				_transition_command = vtol_vehicle_status_s::VEHICLE_VTOL_STATE_MC;

			} else if (_vtol_type->get_mode() == mode::FIXED_WING) {
				_transition_command = vtol_vehicle_status_s::VEHICLE_VTOL_STATE_FW;

			} else if (_vtol_type->get_mode() == mode::TRANSITION_TO_MC) {
				/* We want to make sure that a mode change (manual>auto) during the back transition
				 * doesn't result in an unsafe state. This prevents the instant fall back to
				 * fixed-wing on the switch from manual to auto */
				_transition_command = vtol_vehicle_status_s::VEHICLE_VTOL_STATE_MC;
			}
		}



		// check in which mode we are in and call mode specific functions
		switch (_vtol_type->get_mode()) {
		case mode::TRANSITION_TO_FW:
		case mode::TRANSITION_TO_MC:
			// vehicle is doing a transition
			_vtol_vehicle_status.vtol_in_trans_mode = true;
			_vtol_vehicle_status.vtol_in_rw_mode = true; // making mc attitude controller work during transition
			_vtol_vehicle_status.in_transition_to_fw = (_vtol_type->get_mode() == mode::TRANSITION_TO_FW);

			_fw_virtual_att_sp_sub.update(&_fw_virtual_att_sp);

			if (mc_att_sp_updated || fw_att_sp_updated) {
				_vtol_type->update_transition_state();
				_v_att_sp_pub.publish(_v_att_sp);
			}

			break;

		case mode::ROTARY_WING:
			// vehicle is in rotary wing mode
			_vtol_vehicle_status.vtol_in_rw_mode = true;
			_vtol_vehicle_status.vtol_in_trans_mode = false;
			_vtol_vehicle_status.in_transition_to_fw = false;

			_vtol_type->update_mc_state();
			_v_att_sp_pub.publish(_v_att_sp);

			break;

		case mode::FIXED_WING:
			// vehicle is in fw mode
			_vtol_vehicle_status.vtol_in_rw_mode = false;
			_vtol_vehicle_status.vtol_in_trans_mode = false;
			_vtol_vehicle_status.in_transition_to_fw = false;

			if (fw_att_sp_updated) {
				_vtol_type->update_fw_state();
				_v_att_sp_pub.publish(_v_att_sp);
			}

			break;
		}

		_vtol_type->fill_actuator_outputs();
		_actuators_0_pub.publish(_actuators_out_0);
		_actuators_1_pub.publish(_actuators_out_1);

		// Advertise/Publish vtol vehicle status
		_vtol_vehicle_status.timestamp = hrt_absolute_time();
		_vtol_vehicle_status_pub.publish(_vtol_vehicle_status);
	}

	perf_end(_loop_perf);
}

int
VtolAttitudeControl::task_spawn(int argc, char *argv[])
{
	VtolAttitudeControl *instance = new VtolAttitudeControl();

	if (instance) {
		_object.store(instance);
		_task_id = task_id_is_work_queue;

		if (instance->init()) {
			return PX4_OK;
		}

	} else {
		PX4_ERR("alloc failed");
	}

	delete instance;
	_object.store(nullptr);
	_task_id = -1;

	return PX4_ERROR;
}

int
VtolAttitudeControl::custom_command(int argc, char *argv[])
{
	return print_usage("unknown command");
}

int
VtolAttitudeControl::print_usage(const char *reason)
{
	if (reason) {
		PX4_WARN("%s\n", reason);
	}

	PRINT_MODULE_DESCRIPTION(
		R"DESCR_STR(
### Description
fw_att_control is the fixed wing attitude controller.
)DESCR_STR");

	PRINT_MODULE_USAGE_COMMAND("start");
	PRINT_MODULE_USAGE_NAME("vtol_att_control", "controller");
	PRINT_MODULE_USAGE_DEFAULT_COMMANDS();

	return 0;
}

int vtol_att_control_main(int argc, char *argv[])
{
	return VtolAttitudeControl::main(argc, argv);
}