Default Data Acquisition Functions¶

Contents

OpenIMU makes data-acquisition simple by reducing the steps required to get high-quality, inertial sensor data. Sensor drivers, filtering, and calibration are handled without the need for additional user input.

The main routine controlling sensor sampling and processing is TaskDataAcquisition. This task calls the routines that acquire sensor measurements, filter the data, and apply calibration. In particular, the task calls the following, which provides functions to acquire sensor data:

inertialAndPositionDataProcessing(dacqRate);


After completion of the sensor processing steps, it then calls the algorithm that operates on sensor readings to create processed output.

Acquiring Sensor Data¶

Inside inertialAndPositionDataProcessing() several getter-functions are provided. These functions obtain sensor data directly from the sensor data-buffers. Function names, described in the following table, were chosen to make the task of each function clear.

Sensor Measurement Getter Functions
Getter Function Description Units
GetAccelData_g() Obtain accelerometer data $$[g]$$
GetAccelData_mPerSecSq() $$[{m / s^2}]$$
GetRateData_radPerSec() Obtain rate-sensor data $$[{r / s}]$$
GetRateData_degPerSec() [°/s]
GetMagData_G() Obtain magnetometer data $$[G]$$
GetBoardTempData() Obtain temperature data [°C]

Note

Most inertial algorithm development will use $$[{m / s^2}]$$, $$[{r / s}]$$, and $$[G]$$. However getters that provide accelerometer and rate-sensor data in $$[g]$$ and [°/s] are also available for the designer who chooses to work in these units.

These getters work by populating the array whose address is provided as an argument to the function. In this example, the functions load the data directly into the data-structure elements gIMU.accel_g, gIMU.rate_degPerSec, gIMU.mag_G, and gIMU.temp_C.

Note

Structure elements (accel_g, rate_degPerSec, etc.) are all defined as doubles in the data structure created in UserMessaging.h. This is done to match the datatype required by the getter functions, described above.

// IMU data structure
typedef struct {
// Timer output counter
uint32_t timerCntr, dTimerCntr;

// Algorithm states
double accel_g[3];
double rate_degPerSec[3];
double mag_G[3];
double temp_C;
} IMUDataStruct;

extern IMUDataStruct gIMU;