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Code Issues Releases Activity

Reduce the memory footprint of the sin lookup table by using sin(x+pi) =

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-sin(x).  Still just needs to move into flash and have some options about
precision when in its own library function.
This commit is contained in:
James Cotton 2012-08-01 12:07:52 -05:00
parent 652647fc87
commit 561cf994b0
2 changed files with 16 additions and 7 deletions
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2
flight/Modules/Autotune/autotune.c
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@ -60,7 +60,7 @@
#include <pios_board_info.h>
// Private constants
#define STACK_SIZE_BYTES 1024
#define STACK_SIZE_BYTES 824
#define TASK_PRIORITY (tskIDLE_PRIORITY+2)
// Private types

21
flight/Modules/Stabilization/stabilization.c
View File

@ -92,7 +92,7 @@ int8_t vbar_gyros_suppress;
bool vbar_piro_comp = false;
// TODO: Move this to flash
static float sin_lookup[360];
static float sin_lookup[180];
// Private functions
static void stabilizationTask(void* parameters);
@ -101,6 +101,15 @@ static float bound(float val, float range);
static void ZeroPids(void);
static void SettingsUpdatedCb(UAVObjEvent * ev);
//! Uses the lookup table to calculate sine (angle is in degrees)
static float sin_l(int angle) {
angle = angle % 360;
if (angle > 180)
return - sin_lookup[angle-180];
else
return sin_lookup[angle];
}
/**
* Module initialization
*/
@ -110,7 +119,7 @@ int32_t StabilizationStart()
// Create object queue
queue = xQueueCreate(MAX_QUEUE_SIZE, sizeof(UAVObjEvent));
for(uint32_t i = 0; i < 360; i++)
for(uint32_t i = 0; i < 180; i++)
sin_lookup[i] = sinf((float)i * 2 * M_PI / 360.0f);
// Listen for updates.
@ -409,8 +418,8 @@ static void stabilizationTask(void* parameters)
uint32_t phase = 360 * dT / relay.Period[i];
if(phase >= 360)
phase = 1;
accum_sin += sin_lookup[phase] * error;
accum_cos += sin_lookup[(phase + 90) % 360] * error;
accum_sin += sin_l(phase) * error;
accum_cos += sin_l(phase + 90) * error;
accumulated ++;
// Make susre we've had enough time since last transition then check for a change in the output
@ -491,8 +500,8 @@ static void stabilizationTask(void* parameters)
uint32_t phase = 360 * dT / relay.Period[i];
if(phase >= 360)
phase = 1;
accum_sin += sin_lookup[phase] * error;
accum_cos += sin_lookup[(phase + 90) % 360] * error;
accum_sin += sin_l(phase) * error;
accum_cos += sin_l(phase + 90) * error;
accumulated ++;
// Make susre we've had enough time since last transition then check for a change in the output