static void getVector(float controlVector[4], vario_type type)
{
FlightModeSettingsPositionHoldOffsetData offset;
FlightModeSettingsPositionHoldOffsetGet(&offset);
// scale controlVector[3] (thrust) by vertical/horizontal to have vertical plane less sensitive
controlVector[3] *= offset.Vertical / offset.Horizontal;
float length = sqrtf(controlVector[0] * controlVector[0] + controlVector[1] * controlVector[1] + controlVector[3] * controlVector[3]);
if (length <= 1e-9f) {
length = 1.0f; // should never happen as getVector is not called if control within deadband
}
{
float direction[3] = {
controlVector[1] / length, // pitch is north
controlVector[0] / length, // roll is east
controlVector[3] / length // thrust is down
};
controlVector[0] = direction[0];
controlVector[1] = direction[1];
controlVector[2] = direction[2];
}
controlVector[3] = length * offset.Horizontal;
// rotate north and east - rotation angle based on type
float angle;
switch (type) {
case NSEW:
angle = 0.0f;
// NSEW no rotation takes place
break;
case FPV:
// local rotation, using current yaw
AttitudeStateYawGet(&angle);
break;
case LOS:
// determine location based on vector from takeoff to current location
{
PositionStateData positionState;
PositionStateGet(&positionState);
TakeOffLocationData takeoffLocation;
TakeOffLocationGet(&takeoffLocation);
angle = RAD2DEG(atan2f(positionState.East - takeoffLocation.East, positionState.North - takeoffLocation.North));
}
break;
}
// rotate horizontally by angle
{
float rotated[2] = {
controlVector[0] * cos_lookup_deg(angle) - controlVector[1] * sin_lookup_deg(angle),
controlVector[0] * sin_lookup_deg(angle) + controlVector[1] * cos_lookup_deg(angle)
};
controlVector[0] = rotated[0];
controlVector[1] = rotated[1];
}
}
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 plan_setup_AutoCruise()
{
PositionStateData positionState;
PositionStateGet(&positionState);
PathDesiredData pathDesired;
PathDesiredGet(&pathDesired);
FlightModeSettingsPositionHoldOffsetData offset;
FlightModeSettingsPositionHoldOffsetGet(&offset);
float startingVelocity;
FlightModeSettingsPositionHoldStartingVelocityGet(&startingVelocity);
// initialization is flight in direction of the nose.
// the velocity is not relevant, as it will be reset by the run function even during first call
float angle;
AttitudeStateYawGet(&angle);
float vector[2] = {
cos_lookup_deg(angle),
sin_lookup_deg(angle)
};
hold_position[0] = positionState.North;
hold_position[1] = positionState.East;
hold_position[2] = positionState.Down;
pathDesired.End.North = hold_position[0] + vector[0];
pathDesired.End.East = hold_position[1] + vector[1];
pathDesired.End.Down = hold_position[2];
// start position has the same offset as in position hold
pathDesired.Start.North = pathDesired.End.North + offset.Horizontal; // in FlyEndPoint the direction of this vector does not matter
pathDesired.Start.East = pathDesired.End.East;
pathDesired.Start.Down = pathDesired.End.Down;
pathDesired.StartingVelocity = startingVelocity;
pathDesired.EndingVelocity = 0.0f;
pathDesired.Mode = PATHDESIRED_MODE_FLYENDPOINT;
PathDesiredSet(&pathDesired);
// re-iniztializing deltatime is valid and also good practice here since
// getAverageSeconds() has not been called/updated in a long time if we were in a different flightmode.
PIOS_DELTATIME_Init(&actimeval, UPDATE_EXPECTED, UPDATE_MIN, UPDATE_MAX, UPDATE_ALPHA);
}
/**
* Use the lookup table to return sine(angle) where angle is in radians
* @param[in] angle Angle in radians
* @returns cos(angle)
*/
float cos_lookup_rad(float angle)
{
int degrees = angle * RAD2DEG;
return cos_lookup_deg(degrees);
}
/**
* Apply a step function for the stabilization controller and monitor the
* result
*
* Used to Replace the rate PID with a relay to measure the critical properties of this axis
* i.e. period and gain
*/
int stabilization_relay_rate(float error, float *output, int axis, bool reinit)
{
RelayTuningData relay;
RelayTuningGet(&relay);
static portTickType lastHighTime;
static portTickType lastLowTime;
static float accum_sin, accum_cos;
static uint32_t accumulated = 0;
const uint16_t DEGLITCH_TIME = 20; // ms
const float AMPLITUDE_ALPHA = 0.95f;
const float PERIOD_ALPHA = 0.95f;
portTickType thisTime = xTaskGetTickCount();
static bool rateRelayRunning[MAX_AXES];
// This indicates the current estimate of the smoothed error. So when it is high
// we are waiting for it to go low.
static bool high = false;
// On first run initialize estimates to something reasonable
if (reinit) {
rateRelayRunning[axis] = false;
cast_struct_to_array(relay.Period, relay.Period.Roll)[axis] = 200;
cast_struct_to_array(relay.Gain, relay.Gain.Roll)[axis] = 0;
accum_sin = 0;
accum_cos = 0;
accumulated = 0;
// These should get reinitialized anyway
high = true;
lastHighTime = thisTime;
lastLowTime = thisTime;
RelayTuningSet(&relay);
}
RelayTuningSettingsData relaySettings;
RelayTuningSettingsGet(&relaySettings);
// Compute output, simple threshold on error
*output = high ? relaySettings.Amplitude : -relaySettings.Amplitude;
/**** The code below here is to estimate the properties of the oscillation ****/
// Make sure the period can't go below limit
if (cast_struct_to_array(relay.Period, relay.Period.Roll)[axis] < DEGLITCH_TIME) {
cast_struct_to_array(relay.Period, relay.Period.Roll)[axis] = DEGLITCH_TIME;
}
// Project the error onto a sine and cosine of the same frequency
// to accumulate the average amplitude
int32_t dT = thisTime - lastHighTime;
float phase = ((float)360 * (float)dT) / cast_struct_to_array(relay.Period, relay.Period.Roll)[axis];
if (phase >= 360) {
phase = 0;
}
accum_sin += sin_lookup_deg(phase) * error;
accum_cos += cos_lookup_deg(phase) * error;
accumulated++;
// Make sure we've had enough time since last transition then check for a change in the output
bool time_hysteresis = (high ? (thisTime - lastHighTime) : (thisTime - lastLowTime)) > DEGLITCH_TIME;
if (!high && time_hysteresis && error > relaySettings.HysteresisThresh) {
/* POSITIVE CROSSING DETECTED */
float this_amplitude = 2 * sqrtf(accum_sin * accum_sin + accum_cos * accum_cos) / accumulated;
float this_gain = this_amplitude / relaySettings.Amplitude;
accumulated = 0;
accum_sin = 0;
accum_cos = 0;
if (rateRelayRunning[axis] == false) {
rateRelayRunning[axis] = true;
cast_struct_to_array(relay.Period, relay.Period.Roll)[axis] = 200;
cast_struct_to_array(relay.Gain, relay.Gain.Roll)[axis] = 0;
} else {
// Low pass filter each amplitude and period
cast_struct_to_array(relay.Gain, relay.Gain.Roll)[axis] =
cast_struct_to_array(relay.Gain, relay.Gain.Roll)[axis] *
AMPLITUDE_ALPHA + this_gain * (1 - AMPLITUDE_ALPHA);
cast_struct_to_array(relay.Period, relay.Period.Roll)[axis] =
cast_struct_to_array(relay.Period, relay.Period.Roll)[axis] *
PERIOD_ALPHA + dT * (1 - PERIOD_ALPHA);
}
lastHighTime = thisTime;
high = true;
RelayTuningSet(&relay);
} else if (high && time_hysteresis && error < -relaySettings.HysteresisThresh) {
/* FALLING CROSSING DETECTED */
lastLowTime = thisTime;
high = false;
}
return 0;
}
/**
* Compute desired attitude from the desired velocity for fixed wing craft
*/
uint8_t FixedWingFlyController::updateFixedDesiredAttitude()
{
uint8_t result = 1;
const float dT = fixedWingSettings->UpdatePeriod / 1000.0f;
VelocityDesiredData velocityDesired;
VelocityStateData velocityState;
StabilizationDesiredData stabDesired;
AttitudeStateData attitudeState;
FixedWingPathFollowerStatusData fixedWingPathFollowerStatus;
AirspeedStateData airspeedState;
SystemSettingsData systemSettings;
float groundspeedProjection;
float indicatedAirspeedState;
float indicatedAirspeedDesired;
float airspeedError;
float pitchCommand;
float descentspeedDesired;
float descentspeedError;
float powerCommand;
float airspeedVector[2];
float fluidMovement[2];
float courseComponent[2];
float courseError;
float courseCommand;
FixedWingPathFollowerStatusGet(&fixedWingPathFollowerStatus);
VelocityStateGet(&velocityState);
StabilizationDesiredGet(&stabDesired);
VelocityDesiredGet(&velocityDesired);
AttitudeStateGet(&attitudeState);
AirspeedStateGet(&airspeedState);
SystemSettingsGet(&systemSettings);
/**
* Compute speed error and course
*/
// missing sensors for airspeed-direction we have to assume within
// reasonable error that measured airspeed is actually the airspeed
// component in forward pointing direction
// airspeedVector is normalized
airspeedVector[0] = cos_lookup_deg(attitudeState.Yaw);
airspeedVector[1] = sin_lookup_deg(attitudeState.Yaw);
// current ground speed projected in forward direction
groundspeedProjection = velocityState.North * airspeedVector[0] + velocityState.East * airspeedVector[1];
// note that airspeedStateBias is ( calibratedAirspeed - groundspeedProjection ) at the time of measurement,
// but thanks to accelerometers, groundspeedProjection reacts faster to changes in direction
// than airspeed and gps sensors alone
indicatedAirspeedState = groundspeedProjection + indicatedAirspeedStateBias;
// fluidMovement is a vector describing the aproximate movement vector of
// the surrounding fluid in 2d space (aka wind vector)
fluidMovement[0] = velocityState.North - (indicatedAirspeedState * airspeedVector[0]);
fluidMovement[1] = velocityState.East - (indicatedAirspeedState * airspeedVector[1]);
// calculate the movement vector we need to fly to reach velocityDesired -
// taking fluidMovement into account
courseComponent[0] = velocityDesired.North - fluidMovement[0];
courseComponent[1] = velocityDesired.East - fluidMovement[1];
indicatedAirspeedDesired = boundf(sqrtf(courseComponent[0] * courseComponent[0] + courseComponent[1] * courseComponent[1]),
fixedWingSettings->HorizontalVelMin,
fixedWingSettings->HorizontalVelMax);
// if we could fly at arbitrary speeds, we'd just have to move towards the
// courseComponent vector as previously calculated and we'd be fine
// unfortunately however we are bound by min and max air speed limits, so
// we need to recalculate the correct course to meet at least the
// velocityDesired vector direction at our current speed
// this overwrites courseComponent
bool valid = correctCourse(courseComponent, (float *)&velocityDesired.North, fluidMovement, indicatedAirspeedDesired);
// Error condition: wind speed too high, we can't go where we want anymore
fixedWingPathFollowerStatus.Errors.Wind = 0;
if ((!valid) &&
fixedWingSettings->Safetymargins.Wind > 0.5f) { // alarm switched on
fixedWingPathFollowerStatus.Errors.Wind = 1;
result = 0;
}
// Airspeed error
airspeedError = indicatedAirspeedDesired - indicatedAirspeedState;
// Vertical speed error
descentspeedDesired = boundf(
velocityDesired.Down,
-fixedWingSettings->VerticalVelMax,
fixedWingSettings->VerticalVelMax);
descentspeedError = descentspeedDesired - velocityState.Down;
// Error condition: plane too slow or too fast
fixedWingPathFollowerStatus.Errors.Highspeed = 0;
fixedWingPathFollowerStatus.Errors.Lowspeed = 0;
if (indicatedAirspeedState > systemSettings.AirSpeedMax * fixedWingSettings->Safetymargins.Overspeed) {
fixedWingPathFollowerStatus.Errors.Overspeed = 1;
result = 0;
}
if (indicatedAirspeedState > fixedWingSettings->HorizontalVelMax * fixedWingSettings->Safetymargins.Highspeed) {
fixedWingPathFollowerStatus.Errors.Highspeed = 1;
result = 0;
}
if (indicatedAirspeedState < fixedWingSettings->HorizontalVelMin * fixedWingSettings->Safetymargins.Lowspeed) {
fixedWingPathFollowerStatus.Errors.Lowspeed = 1;
result = 0;
}
if (indicatedAirspeedState < systemSettings.AirSpeedMin * fixedWingSettings->Safetymargins.Stallspeed) {
fixedWingPathFollowerStatus.Errors.Stallspeed = 1;
result = 0;
}
/**
* Compute desired thrust command
*/
// Compute the cross feed from vertical speed to pitch, with saturation
float speedErrorToPowerCommandComponent = boundf(
(airspeedError / fixedWingSettings->HorizontalVelMin) * fixedWingSettings->AirspeedToPowerCrossFeed.Kp,
-fixedWingSettings->AirspeedToPowerCrossFeed.Max,
fixedWingSettings->AirspeedToPowerCrossFeed.Max
);
// Compute final thrust response
powerCommand = pid_apply(&PIDpower, -descentspeedError, dT) +
speedErrorToPowerCommandComponent;
// Output internal state to telemetry
fixedWingPathFollowerStatus.Error.Power = descentspeedError;
fixedWingPathFollowerStatus.ErrorInt.Power = PIDpower.iAccumulator;
fixedWingPathFollowerStatus.Command.Power = powerCommand;
// set thrust
stabDesired.Thrust = boundf(fixedWingSettings->ThrustLimit.Neutral + powerCommand,
fixedWingSettings->ThrustLimit.Min,
fixedWingSettings->ThrustLimit.Max);
// Error condition: plane cannot hold altitude at current speed.
fixedWingPathFollowerStatus.Errors.Lowpower = 0;
if (fixedWingSettings->ThrustLimit.Neutral + powerCommand >= fixedWingSettings->ThrustLimit.Max && // thrust at maximum
velocityState.Down > 0.0f && // we ARE going down
descentspeedDesired < 0.0f && // we WANT to go up
airspeedError > 0.0f && // we are too slow already
fixedWingSettings->Safetymargins.Lowpower > 0.5f) { // alarm switched on
fixedWingPathFollowerStatus.Errors.Lowpower = 1;
result = 0;
}
// Error condition: plane keeps climbing despite minimum thrust (opposite of above)
fixedWingPathFollowerStatus.Errors.Highpower = 0;
if (fixedWingSettings->ThrustLimit.Neutral + powerCommand <= fixedWingSettings->ThrustLimit.Min && // thrust at minimum
velocityState.Down < 0.0f && // we ARE going up
descentspeedDesired > 0.0f && // we WANT to go down
airspeedError < 0.0f && // we are too fast already
fixedWingSettings->Safetymargins.Highpower > 0.5f) { // alarm switched on
fixedWingPathFollowerStatus.Errors.Highpower = 1;
result = 0;
}
/**
* Compute desired pitch command
*/
// Compute the cross feed from vertical speed to pitch, with saturation
float verticalSpeedToPitchCommandComponent = boundf(-descentspeedError * fixedWingSettings->VerticalToPitchCrossFeed.Kp,
-fixedWingSettings->VerticalToPitchCrossFeed.Max,
fixedWingSettings->VerticalToPitchCrossFeed.Max
);
// Compute the pitch command as err*Kp + errInt*Ki + X_feed.
pitchCommand = -pid_apply(&PIDspeed, airspeedError, dT) + verticalSpeedToPitchCommandComponent;
fixedWingPathFollowerStatus.Error.Speed = airspeedError;
fixedWingPathFollowerStatus.ErrorInt.Speed = PIDspeed.iAccumulator;
fixedWingPathFollowerStatus.Command.Speed = pitchCommand;
stabDesired.Pitch = boundf(fixedWingSettings->PitchLimit.Neutral + pitchCommand,
fixedWingSettings->PitchLimit.Min,
fixedWingSettings->PitchLimit.Max);
// Error condition: high speed dive
fixedWingPathFollowerStatus.Errors.Pitchcontrol = 0;
if (fixedWingSettings->PitchLimit.Neutral + pitchCommand >= fixedWingSettings->PitchLimit.Max && // pitch demand is full up
velocityState.Down > 0.0f && // we ARE going down
descentspeedDesired < 0.0f && // we WANT to go up
airspeedError < 0.0f && // we are too fast already
fixedWingSettings->Safetymargins.Pitchcontrol > 0.5f) { // alarm switched on
fixedWingPathFollowerStatus.Errors.Pitchcontrol = 1;
result = 0;
}
/**
* Compute desired roll command
*/
courseError = RAD2DEG(atan2f(courseComponent[1], courseComponent[0])) - attitudeState.Yaw;
if (courseError < -180.0f) {
courseError += 360.0f;
}
if (courseError > 180.0f) {
courseError -= 360.0f;
}
// overlap calculation. Theres a dead zone behind the craft where the
// counter-yawing of some craft while rolling could render a desired right
// turn into a desired left turn. Making the turn direction based on
// current roll angle keeps the plane committed to a direction once chosen
if (courseError < -180.0f + (fixedWingSettings->ReverseCourseOverlap * 0.5f)
&& attitudeState.Roll > 0.0f) {
courseError += 360.0f;
}
if (courseError > 180.0f - (fixedWingSettings->ReverseCourseOverlap * 0.5f)
&& attitudeState.Roll < 0.0f) {
courseError -= 360.0f;
}
courseCommand = pid_apply(&PIDcourse, courseError, dT);
fixedWingPathFollowerStatus.Error.Course = courseError;
fixedWingPathFollowerStatus.ErrorInt.Course = PIDcourse.iAccumulator;
fixedWingPathFollowerStatus.Command.Course = courseCommand;
stabDesired.Roll = boundf(fixedWingSettings->RollLimit.Neutral +
courseCommand,
fixedWingSettings->RollLimit.Min,
fixedWingSettings->RollLimit.Max);
// TODO: find a check to determine loss of directional control. Likely needs some check of derivative
/**
* Compute desired yaw command
*/
// TODO implement raw control mode for yaw and base on Accels.Y
stabDesired.Yaw = 0.0f;
stabDesired.StabilizationMode.Roll = STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE;
stabDesired.StabilizationMode.Pitch = STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE;
stabDesired.StabilizationMode.Yaw = STABILIZATIONDESIRED_STABILIZATIONMODE_MANUAL;
stabDesired.StabilizationMode.Thrust = STABILIZATIONDESIRED_STABILIZATIONMODE_MANUAL;
StabilizationDesiredSet(&stabDesired);
FixedWingPathFollowerStatusSet(&fixedWingPathFollowerStatus);
return result;
}
// with both solutions for C
// this might be reached in headwind stronger than maximum allowed
// airspeed.
return false;
}
}
void FixedWingFlyController::AirspeedStateUpdatedCb(__attribute__((unused)) UAVObjEvent *ev)
{
AirspeedStateData airspeedState;
VelocityStateData velocityState;
AirspeedStateGet(&airspeedState);
VelocityStateGet(&velocityState);
float airspeedVector[2];
float yaw;
AttitudeStateYawGet(&yaw);
airspeedVector[0] = cos_lookup_deg(yaw);
airspeedVector[1] = sin_lookup_deg(yaw);
// vector projection of groundspeed on airspeed vector to handle both forward and backwards movement
float groundspeedProjection = velocityState.North * airspeedVector[0] + velocityState.East * airspeedVector[1];
indicatedAirspeedStateBias = airspeedState.CalibratedAirspeed - groundspeedProjection;
// note - we do fly by Indicated Airspeed (== calibrated airspeed) however
// since airspeed is updated less often than groundspeed, we use sudden
// changes to groundspeed to offset the airspeed by the same measurement.
// This has a side effect that in the absence of any airspeed updates, the
// pathfollower will fly using groundspeed.
}
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
}