From f60d657f728ec8fda5dc76bfbc8484303ea67e78 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Mon, 21 Jan 2013 21:51:32 +1100
Subject: [PATCH] AP_InertialSensor: added timer for accumulating samples for
PX4
this makes the driver much more tolerant of sketch timing errors
---
.../AP_InertialSensor_PX4.cpp | 19 ++++++++++++-------
.../AP_InertialSensor/AP_InertialSensor_PX4.h | 5 +++--
2 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_PX4.cpp b/libraries/AP_InertialSensor/AP_InertialSensor_PX4.cpp
index 85aa665063..c97a4ec69c 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_PX4.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_PX4.cpp
@@ -19,7 +19,8 @@ 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;
+uint64_t AP_InertialSensor_PX4::_last_accel_timestamp;
+uint64_t AP_InertialSensor_PX4::_last_gyro_timestamp;
int AP_InertialSensor_PX4::_accel_fd;
int AP_InertialSensor_PX4::_gyro_fd;
@@ -80,10 +81,10 @@ bool AP_InertialSensor_PX4::update(void)
hal.scheduler->suspend_timer_procs();
- // base the time on the number of gyro samples, as that is what is
+ // base the time on the gyro timestamp, 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;
+ _delta_time = (_last_gyro_timestamp - _last_update_usec) * 1.0e-6f;
+ _last_update_usec = _last_gyro_timestamp;
_accel = _accel_sum / _accel_sum_count;
_accel_sum.zero();
@@ -145,16 +146,20 @@ void AP_InertialSensor_PX4::_accumulate(void)
}
_in_accumulate = true;
- if (::read(_accel_fd, &accel_report, sizeof(accel_report)) == sizeof(accel_report)) {
+ if (::read(_accel_fd, &accel_report, sizeof(accel_report)) == sizeof(accel_report) &&
+ accel_report.timestamp != _last_accel_timestamp) {
_accel_sum += Vector3f(accel_report.x, accel_report.y, accel_report.z);
_accel_sum_count++;
+ _last_accel_timestamp = accel_report.timestamp;
}
- if (::read(_gyro_fd, &gyro_report, sizeof(gyro_report)) == sizeof(gyro_report)) {
+ if (::read(_gyro_fd, &gyro_report, sizeof(gyro_report)) == sizeof(gyro_report) &&
+ gyro_report.timestamp != _last_gyro_timestamp) {
_gyro_sum += Vector3f(gyro_report.x, gyro_report.y, gyro_report.z);
_gyro_sum_count++;
- _last_timestamp = gyro_report.timestamp;
+ _last_gyro_timestamp = gyro_report.timestamp;
}
+
_in_accumulate = false;
}
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h b/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
index dcc71e23c9..a164eb1c78 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
@@ -32,14 +32,15 @@ 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;
+ uint64_t _last_update_usec;
float _delta_time;
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;
+ static uint64_t _last_accel_timestamp;
+ static uint64_t _last_gyro_timestamp;
uint8_t _sample_divider;
// accelerometer and gyro driver handles