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  /**
   * @file ecl_yaw_controller.cpp
   * Implementation of a simple orthogonal coordinated turn yaw PID controller.
   *
   * Authors and acknowledgements in header.
   */
  
  #include "ecl_yaw_controller.h"
  #include <stdint.h>
  #include <float.h>
  #include <geo/geo.h>
  #include <ecl/ecl.h>
  #include <mathlib/mathlib.h>
  #include <systemlib/err.h>
  
  ECL_YawController::ECL_YawController() :
  	ECL_Controller("yaw"),
  	_coordinated_min_speed(1.0f)
  {
  }
  
  ECL_YawController::~ECL_YawController()
  {
  }
  
  float ECL_YawController::control_attitude(const struct ECL_ControlData &ctl_data)
  {
  	/* Do not calculate control signal with bad inputs */
  	if (!(isfinite(ctl_data.roll) &&
  				isfinite(ctl_data.pitch) &&
  				isfinite(ctl_data.speed_body_u) &&
  				isfinite(ctl_data.speed_body_v) &&
  				isfinite(ctl_data.speed_body_w) &&
  				isfinite(ctl_data.roll_rate_setpoint) &&
  				isfinite(ctl_data.pitch_rate_setpoint))) {
  		perf_count(_nonfinite_input_perf);
  		return _rate_setpoint;
  	}
  
  //	static int counter = 0;
  	/* Calculate desired yaw rate from coordinated turn constraint / (no side forces) */
  	_rate_setpoint = 0.0f;
  	if (sqrtf(ctl_data.speed_body_u * ctl_data.speed_body_u + ctl_data.speed_body_v * ctl_data.speed_body_v +
  				ctl_data.speed_body_w * ctl_data.speed_body_w) > _coordinated_min_speed) {
  		float denumerator = (ctl_data.speed_body_u * cosf(ctl_data.roll) * cosf(ctl_data.pitch) +
  				ctl_data.speed_body_w * sinf(ctl_data.pitch));
  
  		if(fabsf(denumerator) > FLT_EPSILON) {
  			_rate_setpoint = (ctl_data.speed_body_w * ctl_data.roll_rate_setpoint +
  					9.81f * sinf(ctl_data.roll) * cosf(ctl_data.pitch) +
  					ctl_data.speed_body_u * ctl_data.pitch_rate_setpoint * sinf(ctl_data.roll)) /
  				denumerator;
  
  //			warnx("yaw: speed_body_u %.f speed_body_w %1.f roll %.1f pitch %.1f denumerator %.1f _rate_setpoint %.1f", speed_body_u, speed_body_w, denumerator, _rate_setpoint);
  		}
  
  //		if(counter % 20 == 0) {
  //			warnx("denumerator: %.4f, speed_body_u: %.4f, speed_body_w: %.4f, cosf(roll): %.4f, cosf(pitch): %.4f, sinf(pitch): %.4f", (double)denumerator, (double)speed_body_u, (double)speed_body_w, (double)cosf(roll), (double)cosf(pitch), (double)sinf(pitch));
  //		}
  	}
  
  	/* limit the rate */ //XXX: move to body angluar rates
  	if (_max_rate > 0.01f) {
  	_rate_setpoint = (_rate_setpoint > _max_rate) ? _max_rate : _rate_setpoint;
  	_rate_setpoint = (_rate_setpoint < -_max_rate) ? -_max_rate : _rate_setpoint;
  	}
  
  
  //	counter++;
  
  	if(!isfinite(_rate_setpoint)){
  		warnx("yaw rate sepoint not finite");
  		_rate_setpoint = 0.0f;
  	}
  
  	return _rate_setpoint;
  }
  
  float ECL_YawController::control_bodyrate(const struct ECL_ControlData &ctl_data)
  {
  	/* Do not calculate control signal with bad inputs */
  	if (!(isfinite(ctl_data.roll) && isfinite(ctl_data.pitch) && isfinite(ctl_data.pitch_rate) &&
  				isfinite(ctl_data.yaw_rate) && isfinite(ctl_data.pitch_rate_setpoint) &&
  				isfinite(ctl_data.airspeed_min) && isfinite(ctl_data.airspeed_max) &&
  				isfinite(ctl_data.scaler))) {
  		perf_count(_nonfinite_input_perf);
  		return math::constrain(_last_output, -1.0f, 1.0f);
  	}
  
  	/* get the usual dt estimate */
  	uint64_t dt_micros = ecl_elapsed_time(&_last_run);
  	_last_run = ecl_absolute_time();
  	float dt = (float)dt_micros * 1e-6f;
  
  	/* lock integral for long intervals */
  	bool lock_integrator = ctl_data.lock_integrator;
  	if (dt_micros > 500000)
  		lock_integrator = true;
  
  	/* input conditioning */
  	float airspeed = ctl_data.airspeed;
  	if (!isfinite(airspeed)) {
  	/* airspeed is NaN, +- INF or not available, pick center of band */
  	airspeed = 0.5f * (ctl_data.airspeed_min + ctl_data.airspeed_max);
  	} else if (airspeed < ctl_data.airspeed_min) {
  	airspeed = ctl_data.airspeed_min;
  	}
  
  
  	/* Transform setpoint to body angular rates (jacobian) */
  	_bodyrate_setpoint = -sinf(ctl_data.roll) * ctl_data.pitch_rate_setpoint +
  		cosf(ctl_data.roll)*cosf(ctl_data.pitch) * _rate_setpoint;
  
  	/* Transform estimation to body angular rates (jacobian) */
  	float yaw_bodyrate = -sinf(ctl_data.roll) * ctl_data.pitch_rate +
  		cosf(ctl_data.roll)*cosf(ctl_data.pitch) * ctl_data.yaw_rate;
  
  	/* Calculate body angular rate error */
  	_rate_error = _bodyrate_setpoint - yaw_bodyrate; //body angular rate error
  
  	if (!lock_integrator && _k_i > 0.0f && airspeed > 0.5f * ctl_data.airspeed_min) {
  
  	float id = _rate_error * dt;
  
  	/*
  	 * anti-windup: do not allow integrator to increase if actuator is at limit
  	 */
  	if (_last_output < -1.0f) {
  		/* only allow motion to center: increase value */
  		id = math::max(id, 0.0f);
  	} else if (_last_output > 1.0f) {
  		/* only allow motion to center: decrease value */
  		id = math::min(id, 0.0f);
  	}
  
  	_integrator += id;
  	}
  
  	/* integrator limit */
  	//xxx: until start detection is available: integral part in control signal is limited here
  	float integrator_constrained = math::constrain(_integrator * _k_i, -_integrator_max, _integrator_max);
  
  	/* Apply PI rate controller and store non-limited output */
  	_last_output = (_bodyrate_setpoint * _k_ff + _rate_error * _k_p + integrator_constrained) * ctl_data.scaler * ctl_data.scaler;  //scaler is proportional to 1/airspeed
  	//warnx("yaw:_last_output: %.4f, _integrator: %.4f, _integrator_max: %.4f, airspeed %.4f, _k_i %.4f, _k_p: %.4f", (double)_last_output, (double)_integrator, (double)_integrator_max, (double)airspeed, (double)_k_i, (double)_k_p);
  
  
  	return math::constrain(_last_output, -1.0f, 1.0f);
  }
  