diff options
Diffstat (limited to 'src/modules/commander/calibration_routines.cpp')
| -rw-r--r-- | src/modules/commander/calibration_routines.cpp | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/modules/commander/calibration_routines.cpp b/src/modules/commander/calibration_routines.cpp new file mode 100644 index 000000000..be38ea104 --- /dev/null +++ b/src/modules/commander/calibration_routines.cpp @@ -0,0 +1,220 @@ +/**************************************************************************** + * + * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Author: Lorenz Meier <lm@inf.ethz.ch> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name PX4 nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/** + * @file calibration_routines.cpp + * Calibration routines implementations. + * + * @author Lorenz Meier <lm@inf.ethz.ch> + */ + +#include <math.h> + +#include "calibration_routines.h" + + +int sphere_fit_least_squares(const float x[], const float y[], const float z[], + unsigned int size, unsigned int max_iterations, float delta, float *sphere_x, float *sphere_y, float *sphere_z, float *sphere_radius) +{ + + float x_sumplain = 0.0f; + float x_sumsq = 0.0f; + float x_sumcube = 0.0f; + + float y_sumplain = 0.0f; + float y_sumsq = 0.0f; + float y_sumcube = 0.0f; + + float z_sumplain = 0.0f; + float z_sumsq = 0.0f; + float z_sumcube = 0.0f; + + float xy_sum = 0.0f; + float xz_sum = 0.0f; + float yz_sum = 0.0f; + + float x2y_sum = 0.0f; + float x2z_sum = 0.0f; + float y2x_sum = 0.0f; + float y2z_sum = 0.0f; + float z2x_sum = 0.0f; + float z2y_sum = 0.0f; + + for (unsigned int i = 0; i < size; i++) { + + float x2 = x[i] * x[i]; + float y2 = y[i] * y[i]; + float z2 = z[i] * z[i]; + + x_sumplain += x[i]; + x_sumsq += x2; + x_sumcube += x2 * x[i]; + + y_sumplain += y[i]; + y_sumsq += y2; + y_sumcube += y2 * y[i]; + + z_sumplain += z[i]; + z_sumsq += z2; + z_sumcube += z2 * z[i]; + + xy_sum += x[i] * y[i]; + xz_sum += x[i] * z[i]; + yz_sum += y[i] * z[i]; + + x2y_sum += x2 * y[i]; + x2z_sum += x2 * z[i]; + + y2x_sum += y2 * x[i]; + y2z_sum += y2 * z[i]; + + z2x_sum += z2 * x[i]; + z2y_sum += z2 * y[i]; + } + + // + //Least Squares Fit a sphere A,B,C with radius squared Rsq to 3D data + // + // P is a structure that has been computed with the data earlier. + // P.npoints is the number of elements; the length of X,Y,Z are identical. + // P's members are logically named. + // + // X[n] is the x component of point n + // Y[n] is the y component of point n + // Z[n] is the z component of point n + // + // A is the x coordiante of the sphere + // B is the y coordiante of the sphere + // C is the z coordiante of the sphere + // Rsq is the radius squared of the sphere. + // + //This method should converge; maybe 5-100 iterations or more. + // + float x_sum = x_sumplain / size; //sum( X[n] ) + float x_sum2 = x_sumsq / size; //sum( X[n]^2 ) + float x_sum3 = x_sumcube / size; //sum( X[n]^3 ) + float y_sum = y_sumplain / size; //sum( Y[n] ) + float y_sum2 = y_sumsq / size; //sum( Y[n]^2 ) + float y_sum3 = y_sumcube / size; //sum( Y[n]^3 ) + float z_sum = z_sumplain / size; //sum( Z[n] ) + float z_sum2 = z_sumsq / size; //sum( Z[n]^2 ) + float z_sum3 = z_sumcube / size; //sum( Z[n]^3 ) + + float XY = xy_sum / size; //sum( X[n] * Y[n] ) + float XZ = xz_sum / size; //sum( X[n] * Z[n] ) + float YZ = yz_sum / size; //sum( Y[n] * Z[n] ) + float X2Y = x2y_sum / size; //sum( X[n]^2 * Y[n] ) + float X2Z = x2z_sum / size; //sum( X[n]^2 * Z[n] ) + float Y2X = y2x_sum / size; //sum( Y[n]^2 * X[n] ) + float Y2Z = y2z_sum / size; //sum( Y[n]^2 * Z[n] ) + float Z2X = z2x_sum / size; //sum( Z[n]^2 * X[n] ) + float Z2Y = z2y_sum / size; //sum( Z[n]^2 * Y[n] ) + + //Reduction of multiplications + float F0 = x_sum2 + y_sum2 + z_sum2; + float F1 = 0.5f * F0; + float F2 = -8.0f * (x_sum3 + Y2X + Z2X); + float F3 = -8.0f * (X2Y + y_sum3 + Z2Y); + float F4 = -8.0f * (X2Z + Y2Z + z_sum3); + + //Set initial conditions: + float A = x_sum; + float B = y_sum; + float C = z_sum; + + //First iteration computation: + float A2 = A * A; + float B2 = B * B; + float C2 = C * C; + float QS = A2 + B2 + C2; + float QB = -2.0f * (A * x_sum + B * y_sum + C * z_sum); + + //Set initial conditions: + float Rsq = F0 + QB + QS; + + //First iteration computation: + float Q0 = 0.5f * (QS - Rsq); + float Q1 = F1 + Q0; + float Q2 = 8.0f * (QS - Rsq + QB + F0); + float aA, aB, aC, nA, nB, nC, dA, dB, dC; + + //Iterate N times, ignore stop condition. + int n = 0; + + while (n < max_iterations) { + n++; + + //Compute denominator: + aA = Q2 + 16.0f * (A2 - 2.0f * A * x_sum + x_sum2); + aB = Q2 + 16.0f * (B2 - 2.0f * B * y_sum + y_sum2); + aC = Q2 + 16.0f * (C2 - 2.0f * C * z_sum + z_sum2); + aA = (aA == 0.0f) ? 1.0f : aA; + aB = (aB == 0.0f) ? 1.0f : aB; + aC = (aC == 0.0f) ? 1.0f : aC; + + //Compute next iteration + nA = A - ((F2 + 16.0f * (B * XY + C * XZ + x_sum * (-A2 - Q0) + A * (x_sum2 + Q1 - C * z_sum - B * y_sum))) / aA); + nB = B - ((F3 + 16.0f * (A * XY + C * YZ + y_sum * (-B2 - Q0) + B * (y_sum2 + Q1 - A * x_sum - C * z_sum))) / aB); + nC = C - ((F4 + 16.0f * (A * XZ + B * YZ + z_sum * (-C2 - Q0) + C * (z_sum2 + Q1 - A * x_sum - B * y_sum))) / aC); + + //Check for stop condition + dA = (nA - A); + dB = (nB - B); + dC = (nC - C); + + if ((dA * dA + dB * dB + dC * dC) <= delta) { break; } + + //Compute next iteration's values + A = nA; + B = nB; + C = nC; + A2 = A * A; + B2 = B * B; + C2 = C * C; + QS = A2 + B2 + C2; + QB = -2.0f * (A * x_sum + B * y_sum + C * z_sum); + Rsq = F0 + QB + QS; + Q0 = 0.5f * (QS - Rsq); + Q1 = F1 + Q0; + Q2 = 8.0f * (QS - Rsq + QB + F0); + } + + *sphere_x = A; + *sphere_y = B; + *sphere_z = C; + *sphere_radius = sqrtf(Rsq); + + return 0; +} + |