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AP_InertialSensor: user a timer to drive data collection on PX4

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this reduces the chance of missing a sample if the main sketch is a
bit slow
This commit is contained in:
Andrew Tridgell 2013-01-21 19:44:01 +11:00
parent b9b3ef91a1
commit 3d0cb755d2
2 changed files with 60 additions and 26 deletions
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62
libraries/AP_InertialSensor/AP_InertialSensor_PX4.cpp
View File

@ -14,6 +14,15 @@ const extern AP_HAL::HAL& hal;
#include <drivers/drv_accel.h>
#include <drivers/drv_gyro.h>
Vector3f AP_InertialSensor_PX4::_accel_sum;
uint32_t AP_InertialSensor_PX4::_accel_sum_count;
Vector3f AP_InertialSensor_PX4::_gyro_sum;
uint32_t AP_InertialSensor_PX4::_gyro_sum_count;
volatile bool AP_InertialSensor_PX4::_in_accumulate;
uint64_t AP_InertialSensor_PX4::_last_timestamp;
int AP_InertialSensor_PX4::_accel_fd;
int AP_InertialSensor_PX4::_gyro_fd;
uint16_t AP_InertialSensor_PX4::_init_sensor( Sample_rate sample_rate )
{
switch (sample_rate) {
@ -54,6 +63,9 @@ uint16_t AP_InertialSensor_PX4::_init_sensor( Sample_rate sample_rate )
ioctl(_accel_fd, SENSORIOCSQUEUEDEPTH, 10);
ioctl(_gyro_fd, SENSORIOCSQUEUEDEPTH, 10);
// register a 1kHz timer to read from PX4 sensor drivers
hal.scheduler->register_timer_process(_ins_timer);
return AP_PRODUCT_ID_PX4;
}
@ -64,33 +76,35 @@ bool AP_InertialSensor_PX4::update(void)
while (num_samples_available() == 0) {
hal.scheduler->delay(1);
}
uint32_t now = hal.scheduler->micros();
// the current mpu6000 PX4 driver does not buffer samples, so
// using the sample count times 5ms would produce a bad delta time
// if we missed one. For now we need to use the clock to get the
// delta time
_delta_time = (now - _last_update_usec) * 1.0e-6f;
_last_update_usec = now;
Vector3f accel_scale = _accel_scale.get();
hal.scheduler->suspend_timer_procs();
// base the time on the number of gyro samples, as that is what is
// multiplied by time to integrate in DCM
_delta_time = _gyro_sum_count / 200.0;
_last_update_usec = (uint32_t)_last_timestamp;
_accel = _accel_sum / _accel_sum_count;
_accel_sum.zero();
_accel_sum_count = 0;
_gyro = _gyro_sum / _gyro_sum_count;
_gyro_sum.zero();
_gyro_sum_count = 0;
hal.scheduler->resume_timer_procs();
// add offsets and rotation
_accel.rotate(_board_orientation);
_accel.x *= accel_scale.x;
_accel.y *= accel_scale.y;
_accel.z *= accel_scale.z;
_accel -= _accel_offset;
_gyro = _gyro_sum / _gyro_sum_count;
_gyro.rotate(_board_orientation);
_gyro -= _gyro_offset;
_accel_sum.zero();
_accel_sum_count = 0;
_gyro_sum.zero();
_gyro_sum_count = 0;
return true;
}
@ -121,11 +135,16 @@ float AP_InertialSensor_PX4::get_gyro_drift_rate(void)
return ToRad(0.5/60);
}
uint16_t AP_InertialSensor_PX4::num_samples_available(void)
void AP_InertialSensor_PX4::_accumulate(void)
{
struct accel_report accel_report;
struct gyro_report gyro_report;
if (_in_accumulate) {
return;
}
_in_accumulate = true;
if (::read(_accel_fd, &accel_report, sizeof(accel_report)) == sizeof(accel_report)) {
_accel_sum += Vector3f(accel_report.x, accel_report.y, accel_report.z);
_accel_sum_count++;
@ -134,8 +153,19 @@ uint16_t AP_InertialSensor_PX4::num_samples_available(void)
if (::read(_gyro_fd, &gyro_report, sizeof(gyro_report)) == sizeof(gyro_report)) {
_gyro_sum += Vector3f(gyro_report.x, gyro_report.y, gyro_report.z);
_gyro_sum_count++;
_last_timestamp = gyro_report.timestamp;
}
_in_accumulate = false;
}
void AP_InertialSensor_PX4::_ins_timer(uint32_t now)
{
_accumulate();
}
uint16_t AP_InertialSensor_PX4::num_samples_available(void)
{
_accumulate();
return min(_accel_sum_count, _gyro_sum_count) / _sample_divider;
}

16
libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
View File

@ -30,17 +30,21 @@ public:
private:
uint16_t _init_sensor( Sample_rate sample_rate );
static void _ins_timer(uint32_t now);
static void _accumulate(void);
uint32_t _last_update_usec;
float _delta_time;
Vector3f _accel_sum;
uint32_t _accel_sum_count;
Vector3f _gyro_sum;
uint32_t _gyro_sum_count;
static Vector3f _accel_sum;
static uint32_t _accel_sum_count;
static Vector3f _gyro_sum;
static uint32_t _gyro_sum_count;
static volatile bool _in_accumulate;
static uint64_t _last_timestamp;
uint8_t _sample_divider;
// accelerometer and gyro driver handles
int _accel_fd;
int _gyro_fd;
static int _accel_fd;
static int _gyro_fd;
};
#endif
#endif // __AP_INERTIAL_SENSOR_PX4_H__