rooty/LibrePilot
1
0
Fork 0
mirror of https://bitbucket.org/librepilot/librepilot.git synced 2025-01-29 14:52:12 +01:00
Code Issues Releases Activity

Tweak the integral calculation so it is scaled in ms internally. This avoids a

Browse Source 
loss of precision on the accumulation.
This commit is contained in:
James Cotton 2011-06-22 18:51:25 -05:00
parent 373689207a
commit a09642675c
1 changed files with 42 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

84
flight/Modules/Stabilization/stabilization.c
View File

@ -94,21 +94,21 @@ static void SettingsUpdatedCb(UAVObjEvent * ev);
int32_t StabilizationInitialize()
{
// Initialize variables
// Create object queue
queue = xQueueCreate(MAX_QUEUE_SIZE, sizeof(UAVObjEvent));
// Listen for updates.
// AttitudeActualConnectQueue(queue);
AttitudeRawConnectQueue(queue);
StabilizationSettingsConnectCallback(SettingsUpdatedCb);
SettingsUpdatedCb(StabilizationSettingsHandle());
// Start main task
xTaskCreate(stabilizationTask, (signed char*)"Stabilization", STACK_SIZE_BYTES/4, NULL, TASK_PRIORITY, &taskHandle);
TaskMonitorAdd(TASKINFO_RUNNING_STABILIZATION, taskHandle);
PIOS_WDG_RegisterFlag(PIOS_WDG_STABILIZATION);
return 0;
}
@ -120,8 +120,8 @@ static void stabilizationTask(void* parameters)
portTickType lastSysTime;
portTickType thisSysTime;
UAVObjEvent ev;
ActuatorDesiredData actuatorDesired;
StabilizationDesiredData stabDesired;
RateDesiredData rateDesired;
@ -129,28 +129,28 @@ static void stabilizationTask(void* parameters)
AttitudeRawData attitudeRaw;
SystemSettingsData systemSettings;
FlightStatusData flightStatus;
SettingsUpdatedCb((UAVObjEvent *) NULL);
// Main task loop
lastSysTime = xTaskGetTickCount();
ZeroPids();
while(1) {
PIOS_WDG_UpdateFlag(PIOS_WDG_STABILIZATION);
// Wait until the AttitudeRaw object is updated, if a timeout then go to failsafe
if ( xQueueReceive(queue, &ev, FAILSAFE_TIMEOUT_MS / portTICK_RATE_MS) != pdTRUE )
{
AlarmsSet(SYSTEMALARMS_ALARM_STABILIZATION,SYSTEMALARMS_ALARM_WARNING);
continue;
}
}
// Check how long since last update
thisSysTime = xTaskGetTickCount();
if(thisSysTime > lastSysTime) // reuse dt in case of wraparound
dT = (thisSysTime - lastSysTime) / portTICK_RATE_MS / 1000.0f;
lastSysTime = thisSysTime;
FlightStatusGet(&flightStatus);
StabilizationDesiredGet(&stabDesired);
AttitudeActualGet(&attitudeActual);
@ -164,11 +164,11 @@ static void stabilizationTask(void* parameters)
float q_desired[4];
float q_error[4];
float local_error[3];
// Essentially zero errors for anything in rate or none
if(stabDesired.StabilizationMode[STABILIZATIONDESIRED_STABILIZATIONMODE_ROLL] == STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE)
rpy_desired[0] = stabDesired.Roll;
else
rpy_desired[0] = stabDesired.Roll;
else
rpy_desired[0] = attitudeActual.Roll;
if(stabDesired.StabilizationMode[STABILIZATIONDESIRED_STABILIZATIONMODE_PITCH] == STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE)
@ -180,13 +180,13 @@ static void stabilizationTask(void* parameters)
rpy_desired[2] = stabDesired.Yaw;
else
rpy_desired[2] = attitudeActual.Yaw;
RPY2Quaternion(rpy_desired, q_desired);
quat_inverse(q_desired);
quat_mult(q_desired, &attitudeActual.q1, q_error);
quat_inverse(q_error);
Quaternion2RPY(q_error, local_error);
#else
// Simpler algorithm for CC, less memory
float local_error[3] = {stabDesired.Roll - attitudeActual.Roll,
@ -194,16 +194,16 @@ static void stabilizationTask(void* parameters)
stabDesired.Yaw - attitudeActual.Yaw};
local_error[2] = fmod(local_error[2] + 180, 360) - 180;
#endif
for(uint8_t i = 0; i < MAX_AXES; i++) {
gyro_filtered[i] = gyro_filtered[i] * gyro_alpha + attitudeRaw.gyros[i] * (1 - gyro_alpha);
}
float *attitudeDesiredAxis = &stabDesired.Roll;
float *actuatorDesiredAxis = &actuatorDesired.Roll;
float *rateDesiredAxis = &rateDesired.Roll;
//Calculate desired rate
for(int8_t ct=0; ct< MAX_AXES; ct++)
{
@ -212,13 +212,13 @@ static void stabilizationTask(void* parameters)
case STABILIZATIONDESIRED_STABILIZATIONMODE_RATE:
rateDesiredAxis[ct] = attitudeDesiredAxis[ct];
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE:
rateDesiredAxis[ct] = ApplyPid(&pids[PID_ROLL + ct], local_error[ct]);
break;
}
}
uint8_t shouldUpdate = 1;
RateDesiredSet(&rateDesired);
ActuatorDesiredGet(&actuatorDesired);
@ -234,7 +234,7 @@ static void stabilizationTask(void* parameters)
{
rateDesiredAxis[ct] = -settings.MaximumRate[ct];
}
}
switch(stabDesired.StabilizationMode[ct])
{
@ -262,16 +262,16 @@ static void stabilizationTask(void* parameters)
break;
}
break;
}
}
// Save dT
actuatorDesired.UpdateTime = dT * 1000;
if(PARSE_FLIGHT_MODE(flightStatus.FlightMode) == FLIGHTMODE_MANUAL)
shouldUpdate = 0;
if(shouldUpdate)
{
actuatorDesired.Throttle = stabDesired.Throttle;
@ -279,16 +279,16 @@ static void stabilizationTask(void* parameters)
actuatorDesired.NumLongUpdates++;
ActuatorDesiredSet(&actuatorDesired);
}
if(flightStatus.Armed != FLIGHTSTATUS_ARMED_ARMED ||
!shouldUpdate || (stabDesired.Throttle < 0))
{
ZeroPids();
}
// Clear alarms
AlarmsClear(SYSTEMALARMS_ALARM_STABILIZATION);
AlarmsClear(SYSTEMALARMS_ALARM_STABILIZATION);
}
}
@ -296,15 +296,15 @@ float ApplyPid(pid_type * pid, const float err)
{
float diff = (err - pid->lastErr);
pid->lastErr = err;
pid->iAccumulator += err * pid->i * dT;
if(fabs(pid->iAccumulator) > pid->iLim) {
if(pid->iAccumulator >0) {
pid->iAccumulator = pid->iLim;
} else {
pid->iAccumulator = -pid->iLim;
}
// Scale up accumulator by 1000 while computing to avoid losing precision
pid->iAccumulator += err * (pid->i * dT * 1000);
if(pid->iAccumulator > (pid->iLim * 1000)) {
pid->iAccumulator = pid->iLim * 1000;
} else if (pid->iAccumulator < -(pid->iLim * 1000)) {
pid->iAccumulator = -pid->iLim * 1000;
}
return ((err * pid->p) + pid->iAccumulator + (diff * pid->d / dT));
return ((err * pid->p) + pid->iAccumulator / 1000 + (diff * pid->d / dT));
}
@ -335,7 +335,7 @@ static void SettingsUpdatedCb(UAVObjEvent * ev)
{
memset(pids,0,sizeof (pid_type) * PID_MAX);
StabilizationSettingsGet(&settings);
float * data = settings.RollRatePI;
for(int8_t pid=0; pid < PID_MAX; pid++)
{
@ -346,7 +346,7 @@ static void SettingsUpdatedCb(UAVObjEvent * ev)
// The dT has some jitter iteration to iteration that we don't want to
// make thie result unpredictable. Still, it's nicer to specify the constant
// based on a time (in ms) rather than a fixed multiplier. The error between
// based on a time (in ms) rather than a fixed multiplier. The error between
// update rates on OP (~300 Hz) and CC (~475 Hz) is negligible for this
// calculation
const float fakeDt = 0.0025;