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Diffstat (limited to 'ctrl/kinematics.vala')
| -rw-r--r-- | ctrl/kinematics.vala | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/ctrl/kinematics.vala b/ctrl/kinematics.vala new file mode 100644 index 0000000..0e90a8f --- /dev/null +++ b/ctrl/kinematics.vala @@ -0,0 +1,148 @@ +/* Copyright 2012, Sebastian Reichel <sre@ring0.de> + * Copyright 2012, Ted Carancho + * + * Ported from AeroQuad + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +public class Kinematics { + /* quaternion elements representing the estimated orientation */ + double q0; + double q1; + double q2; + double q3; + + /* scaled integral error */ + double exInt = 0.0; + double eyInt = 0.0; + double ezInt = 0.0; + + /* proportional gain governs rate of convergence to accelerometer */ + double kpAcc = 0.2; + + /* integral gain governs rate of convergence of gyroscope biases */ + double kiAcc = 0.0005; + + /* proportional gain governs rate of convergence to magnetometer */ + double kpMag = 2.0; + /* integral gain governs rate of convergence of gyroscope biases */ + double kiMag = 0.005; + + /* half the sample period*/ + double halfT = 0.0; + + public double[] kinematicsAngle = new double[3]; + public double[] correctedRateVector = new double[3]; + public double[] gyroAngle = new double[2]; + + public Kinematics(double hdgX, double hdgY) { + for (var axis = AXIS.X; axis <= AXIS.Z; axis+=1) + kinematicsAngle[axis] = 0; + for (var axis = AXIS.X; axis <= AXIS.Y; axis+=1) + gyroAngle[axis] = 0; + + double hdg = Math.atan2(hdgY, hdgX); + q0 = Math.cos(hdg/2); + q1 = 0; + q2 = 0; + q3 = Math.sin(hdg/2); + } + + public void update(double gx, double gy, double gz, double ax, double ay, double az, double mx, double my, double mz, double time) { + double norm; + double hx, hy, hz, bx, bz; + double vx, vy, vz, wx, wy, wz; + double exAcc, eyAcc, ezAcc; + double exMag, eyMag, ezMag; + double q0i, q1i, q2i, q3i; + + halfT = time/2; + + /* normalise the accelerometer measurements */ + norm = Math.sqrt(ax*ax + ay*ay + az*az); + ax = ax / norm; + ay = ay / norm; + az = az / norm; + + /* normalise the magnometer measurements */ + norm = Math.sqrt(mx*mx + my*my + mz*mz); + mx = mx / norm; + my = my / norm; + mz = mz / norm; + + /* compute reference direction of flux */ + hx = mx * 2 * (0.5 - q2 * q2 - q3 * q3) + my * 2 * (q1 * q2 - q0 * q3) + mz * 2 * (q1 * q3 + q0 * q2); + hy = mx * 2 * (q1 * q2 + q0 * q3) + my * 2 * (0.5 - q1 * q1 - q3 * q3) + mz * 2 * (q2 * q3 - q0 * q1); + hz = mx * 2 * (q1 * q3 - q0 * q2) + my * 2 * (q2 * q3 + q0 * q1) + mz * 2 * (0.5 - q1 * q1 - q2 * q2); + + bx = Math.sqrt((hx*hx) + (hy*hy)); + bz = hz; + + /* estimate direction of gravity and flux (v and w) */ + vx = 2 *(q1 * q3 - q0 * q2); + vy = 2 *(q0 * q1 + q2 * q3); + vz = q0 * q0 - q1 * q1 - q2 * q2 + q3 * q3; + + wx = bx * 2*(0.5 - q2 * q2 - q3 * q3) + bz * 2 * (q1 * q3 - q0 * q2); + wy = bx * 2*(q1 * q2 - q0 * q3) + bz * 2 * (q0 * q1 + q2 * q3); + wz = bx * 2*(q0 * q2 + q1 * q3) + bz * 2 * (0.5 - q1 * q1 - q2 * q2); + + /* error is sum of cross product between reference direction of fields and direction measured by sensors */ + exAcc = (vy*az - vz*ay); + eyAcc = (vz*ax - vx*az); + ezAcc = (vx*ay - vy*ax); + + exMag = (my*wz - mz*wy); + eyMag = (mz*wx - mx*wz); + ezMag = (mx*wy - my*wx); + + /* integral error scaled integral gain */ + exInt = exInt + exAcc*kiAcc + exMag*kiMag; + eyInt = eyInt + eyAcc*kiAcc + eyMag*kiMag; + ezInt = ezInt + ezAcc*kiAcc + ezMag*kiMag; + + /* adjusted gyroscope measurements */ + correctedRateVector[AXIS.X] = gx = gx + exAcc*kpAcc + exMag*kpMag + exInt; + correctedRateVector[AXIS.Y] = gy = gy + eyAcc*kpAcc + eyMag*kpMag + eyInt; + correctedRateVector[AXIS.Z] = gz = gz + ezAcc*kpAcc + ezMag*kpMag + ezInt; + + /* integrate quaternion rate and normalise */ + q0i = (-q1*gx - q2*gy - q3*gz) * halfT; + q1i = ( q0*gx + q2*gz - q3*gy) * halfT; + q2i = ( q0*gy - q1*gz + q3*gx) * halfT; + q3i = ( q0*gz + q1*gy - q2*gx) * halfT; + q0 += q0i; + q1 += q1i; + q2 += q2i; + q3 += q3i; + + /* normalise quaternion */ + norm = Math.sqrt(q0*q0 + q1*q1 + q2*q2 + q3*q3); + q0 = q0 / norm; + q1 = q1 / norm; + q2 = q2 / norm; + q3 = q3 / norm; + + /* save the adjusted gyroscope measurements */ + correctedRateVector[AXIS.X] = gx; + correctedRateVector[AXIS.Y] = gy; + correctedRateVector[AXIS.Z] = gz; + + /* calculate euler angles */ + kinematicsAngle[AXIS.X] = Math.atan2(2 * (q0*q1 + q2*q3), 1 - 2 *(q1*q1 + q2*q2)); + kinematicsAngle[AXIS.Y] = Math.asin(2 * (q0*q2 - q1*q3)); + kinematicsAngle[AXIS.Z] = Math.atan2(2 * (q0*q3 + q1*q2), 1 - 2 *(q2*q2 + q3*q3)); + } +} |