/** ****************************************************************************** * @addtogroup OpenPilotModules OpenPilot Modules * @{ * @addtogroup StabilizationModule Stabilization Module * @brief cruisecontrol mode * @note This file implements the logic for a cruisecontrol * @{ * * @file cruisecontrol.h * @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2014. * @brief Attitude stabilization module. * * @see The GNU Public License (GPL) Version 3 * *****************************************************************************/ /* * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include #include #include #include static float cruisecontrol_factor = 1.0f; static inline float CruiseControlLimitThrust(float thrust) { // limit to user specified absolute max thrust return boundf(thrust, stabSettings.cruiseControl.min_thrust, stabSettings.cruiseControl.max_thrust); } // assumes 1.0 <= factor <= 100.0 // a factor of less than 1.0 could make it return a value less than stabSettings.cruiseControl.min_thrust // CP helis need to have min_thrust=-1 // // multicopters need to have min_thrust=0.05 or so // values below that will not be subject to max / min limiting // that means thrust can be less than min // that means multicopter motors stop spinning at low stick static inline float CruiseControlFactorToThrust(float factor, float thrust) { // don't touch thrust if it's less than min_thrust // without that test, quadcopter props will spin up // to min thrust even at zero throttle stick // if Cruise Control is enabled on this flight switch position if (thrust > stabSettings.cruiseControl.min_thrust) { return CruiseControlLimitThrust(thrust * factor); } return thrust; } static float CruiseControlAngleToFactor(float angle) { float factor; // avoid singularity if (angle > 89.999f && angle < 90.001f) { factor = stabSettings.settings.CruiseControlMaxPowerFactor; } else { // the simple bank angle boost calculation that Cruise Control revolves around factor = 1.0f / fabsf(cos_lookup_deg(angle)); // factor in the power trim, no effect at 1.0, linear effect increases with factor factor = (factor - 1.0f) * stabSettings.cruiseControl.power_trim + 1.0f; // limit to user specified max power multiplier if (factor > stabSettings.settings.CruiseControlMaxPowerFactor) { factor = stabSettings.settings.CruiseControlMaxPowerFactor; } } return factor; } void cruisecontrol_compute_factor(AttitudeStateData *attitude, float thrustDemand) { static float previous_angle; static uint32_t previous_time = 0; static bool previous_time_valid = false; // For multiple, speedy flips this mainly strives to address the // fact that (due to thrust delay) thrust didn't average straight // down, but at an angle. For less speedy flips it acts like it // used to. It can be turned off by setting power delay to 0. // It takes significant time for the motors of a multi-copter to // spin up. It takes significant time for the collective servo of // a CP heli to move from one end to the other. Both of those are // modeled here as linear, i.e. twice as much change takes twice // as long. Given a correctly configured maximum delay time this // code calculates how far in advance to start the control // transition so that half way through the physical transition it // is just crossing the transition angle. // Example: Rotation rate = 360. Full stroke delay = 0.2 // Transition angle 90 degrees. Start the transition 0.1 second // before 90 degrees (36 degrees at 360 deg/sec) and it will be // complete 0.1 seconds after 90 degrees. // Note that this code only handles the transition to/from inverted // thrust. It doesn't handle the case where thrust is changed a // lot in a small angle range when that range is close to 90 degrees. // It doesn't handle the small constant "system delay" caused by the // delay between reading sensors and actuators beginning to respond. // It also assumes that the pilot is holding the throttle constant; // when the pilot does change the throttle, the compensation is // simply recalculated. // This implementation of future thrust isn't perfect. That would // probably require an iterative procedure for solving a // transcendental equation of the form linear(x) = 1/cos(x). It's // shortcomings generally don't hurt anything and work better than // without it. It is designed to work perfectly if the pilot is // using full thrust during flips and it is only activated if 70% or // greater thrust is used. uint32_t time = PIOS_DELAY_GetuS(); // Get roll and pitch angles, calculate combined angle, and begin // the general algorithm. // Example: 45 degrees roll plus 45 degrees pitch = 60 degrees // Do it every 8th iteration to save CPU. if (time != previous_time || previous_time_valid == false) { float angle, angle_unmodified; // spherical right triangle // 0.0 <= angle <= 180.0 angle_unmodified = angle = RAD2DEG(acosf(cos_lookup_deg(attitude->Roll) * cos_lookup_deg(attitude->Pitch))); // Calculate rate as a combined (roll and pitch) bank angle // change; in degrees per second. Rate is calculated over the // most recent 8 loops through stabilization. We could have // asked the gyros. This is probably cheaper. if (previous_time_valid) { float rate; // rate can be negative. rate = (angle - previous_angle) / ((float)(time - previous_time) / 1000000.0f); // Define "within range" to be those transitions that should // be executing now. Recall that each impulse transition is // spread out over a range of time / angle. // There is only one transition and the high power level for // it is either: // 1/fabsf(cos(angle)) * current thrust // or max power factor * current thrust // or full thrust // You can cross the transition with angle either increasing // or decreasing (rate positive or negative). // Thrust is never boosted for negative values of // thrustDemand (negative stick values) // // When the aircraft is upright, thrust is always boosted // . for positive values of thrustDemand // When the aircraft is inverted, thrust is sometimes // . boosted or reversed (or combinations thereof) or zeroed // . for positive values of thrustDemand // It depends on the inverted power settings. // Of course, you can set MaxPowerFactor to 1.0 to // . effectively disable boost. if (thrustDemand > 0.0f) { // to enable the future thrust calculations, make sure // there is a large enough transition that the result // will be roughly on vs. off; without that, it can // exaggerate the length of time the inverted to upright // transition holds full throttle and reduce the length // of time for full throttle when going upright to inverted. if (thrustDemand > 0.7f) { float thrust; thrust = CruiseControlFactorToThrust(CruiseControlAngleToFactor((float)stabSettings.settings.CruiseControlMaxAngle), thrustDemand); // determine if we are in range of the transition // given the thrust at max_angle and thrustDemand // (typically close to 1.0), change variable 'thrust' to // be the proportion of the largest thrust change possible // that occurs when going into inverted mode. // Example: 'thrust' is 0.8 A quad has min_thrust set // to 0.05 The difference is 0.75. The largest possible // difference with this setup is 0.9 - 0.05 = 0.85, so // the proportion is 0.75/0.85 // That is nearly a full throttle stroke. // the 'thrust' variable is non-negative here switch (stabSettings.settings.CruiseControlInvertedPowerOutput) { case STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDPOWEROUTPUT_ZERO: // normal multi-copter case, stroke is max to zero // technically max to constant min_thrust // can be used by CP thrust = (thrust - CruiseControlLimitThrust(0.0f)) / stabSettings.cruiseControl.thrust_difference; break; case STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDPOWEROUTPUT_NORMAL: // reversed but not boosted // : CP heli case, stroke is max to -stick // : thrust = (thrust - CruiseControlLimitThrust(-thrustDemand)) / stabSettings.cruiseControl.thrust_difference; // else it is both unreversed and unboosted // : simply turn off boost, stroke is max to +stick // : thrust = (thrust - CruiseControlLimitThrust(thrustDemand)) / stabSettings.cruiseControl.thrust_difference; thrust = (thrust - CruiseControlLimitThrust( (stabSettings.settings.CruiseControlInvertedThrustReversing == STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDTHRUSTREVERSING_REVERSED) ? -thrustDemand : thrustDemand)) / stabSettings.cruiseControl.thrust_difference; break; case STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDPOWEROUTPUT_BOOSTED: // if boosted and reversed if (stabSettings.settings.CruiseControlInvertedThrustReversing == STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDTHRUSTREVERSING_REVERSED) { // CP heli case, stroke is max to min thrust = (thrust - CruiseControlFactorToThrust(-CruiseControlAngleToFactor((float)stabSettings.settings.CruiseControlMaxAngle), thrustDemand)) / stabSettings.cruiseControl.thrust_difference; } // else it is boosted and unreversed so the throttle doesn't change else { // CP heli case, no transition, so stroke is zero thrust = 0.0f; } break; } // 'thrust' is now the proportion of max stroke // multiply this proportion of max stroke, // times the max stroke time, to get this stroke time // we only want half of this time before the transition // (and half after the transition) thrust *= stabSettings.cruiseControl.half_power_delay; // 'thrust' is now the length of time for this stroke // multiply that times angular rate to get the lead angle thrust *= fabsf(rate); // if the transition is within range we use it, // else we just use the current calculated thrust if ((float)stabSettings.settings.CruiseControlMaxAngle - thrust <= angle && angle <= (float)stabSettings.settings.CruiseControlMaxAngle + thrust) { // default to a little above max angle angle = (float)stabSettings.settings.CruiseControlMaxAngle + 0.01f; // if roll direction is downward // then thrust value is taken from below max angle // by the code that knows about the transition angle if (rate < 0.0f) { angle -= 0.02f; } } } // if thrust > 0.7; else just use the angle we already calculated cruisecontrol_factor = CruiseControlAngleToFactor(angle); } else { // if thrust > 0 set factor from angle; else cruisecontrol_factor = 1.0f; } if (angle >= (float)stabSettings.settings.CruiseControlMaxAngle) { switch (stabSettings.settings.CruiseControlInvertedPowerOutput) { case STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDPOWEROUTPUT_ZERO: cruisecontrol_factor = 0.0f; break; case STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDPOWEROUTPUT_NORMAL: cruisecontrol_factor = 1.0f; break; case STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDPOWEROUTPUT_BOOSTED: // no change, leave factor >= 1.0 alone break; } if (stabSettings.settings.CruiseControlInvertedThrustReversing == STABILIZATIONSETTINGS_CRUISECONTROLINVERTEDTHRUSTREVERSING_REVERSED) { cruisecontrol_factor = -cruisecontrol_factor; } } } // if previous_time_valid i.e. we've got a rate; else leave (angle and) factor alone previous_time = time; previous_time_valid = true; previous_angle = angle_unmodified; } // every 8th time } float cruisecontrol_apply_factor(float raw) { if (stabSettings.settings.CruiseControlMaxPowerFactor > 0.0001f) { raw = CruiseControlFactorToThrust(cruisecontrol_factor, raw); } return raw; }