Diff: IMUfilter.h
- Revision:
- 0:4e7171d6f97e
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/IMUfilter.h Fri Jun 01 08:16:53 2012 +0000
@@ -0,0 +1,143 @@
+/**
+ * @author Aaron Berk
+ *
+ * @section LICENSE
+ *
+ * Copyright (c) 2010 ARM Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @section DESCRIPTION
+ *
+ * IMU orientation filter developed by Sebastian Madgwick.
+ *
+ * Find more details about his paper here:
+ *
+ * http://code.google.com/p/imumargalgorithm30042010sohm/
+ */
+
+#ifndef IMU_FILTER_H
+#define IMU_FILTER_H
+
+/**
+ * Includes
+ */
+#include "mbed.h"
+
+/**
+ * Defines
+ */
+#define PI 3.1415926536
+
+/**
+ * IMU orientation filter.
+ */
+class IMUfilter {
+
+public:
+
+ /**
+ * Constructor.
+ *
+ * Initializes filter variables.
+ *
+ * @param rate The rate at which the filter should be updated.
+ * @param gyroscopeMeasurementError The error of the gyroscope in degrees
+ * per second. This used to calculate a tuning constant for the filter.
+ * Try changing this value if there are jittery readings, or they change
+ * too much or too fast when rotating the IMU.
+ */
+ IMUfilter(double rate, double gyroscopeMeasurementError);
+
+ /**
+ * Update the filter variables.
+ *
+ * @param w_x X-axis gyroscope reading in rad/s.
+ * @param w_y Y-axis gyroscope reading in rad/s.
+ * @param w_z Z-axis gyroscope reading in rad/s.
+ * @param a_x X-axis accelerometer reading in m/s/s.
+ * @param a_y Y-axis accelerometer reading in m/s/s.
+ * @param a_z Z-axis accelerometer reading in m/s/s.
+ */
+ void updateFilter(double w_x, double w_y, double w_z,
+ double a_x, double a_y, double a_z);
+
+ /**
+ * Compute the Euler angles based on the current filter data.
+ */
+ void computeEuler(void);
+
+ /**
+ * Get the current roll.
+ *
+ * @return The current roll angle in radians.
+ */
+ double getRoll(void);
+
+ /**
+ * Get the current pitch.
+ *
+ * @return The current pitch angle in radians.
+ */
+ double getPitch(void);
+
+ /**
+ * Get the current yaw.
+ *
+ * @return The current yaw angle in radians.
+ */
+ double getYaw(void);
+
+ /**
+ * Reset the filter.
+ */
+ void reset(void);
+
+private:
+
+ int firstUpdate;
+
+ //Quaternion orientation of earth frame relative to auxiliary frame.
+ double AEq_1;
+ double AEq_2;
+ double AEq_3;
+ double AEq_4;
+
+ //Estimated orientation quaternion elements with initial conditions.
+ double SEq_1;
+ double SEq_2;
+ double SEq_3;
+ double SEq_4;
+
+ //Sampling period
+ double deltat;
+
+ //Gyroscope measurement error (in degrees per second).
+ double gyroMeasError;
+
+ //Compute beta (filter tuning constant..
+ double beta;
+
+ double phi;
+ double theta;
+ double psi;
+
+};
+
+#endif /* IMU_FILTER_H */