diff --git a/notebooks/MPC_racecar_tracking.ipynb b/notebooks/MPC_racecar_tracking.ipynb index f65bd93..cbce5c7 100644 --- a/notebooks/MPC_racecar_tracking.ipynb +++ b/notebooks/MPC_racecar_tracking.ipynb @@ -1273,7 +1273,7 @@ "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", - "version": "3.8.5" + "version": "3.7.6" } }, "nbformat": 4, diff --git a/notebooks/equations.ipynb b/notebooks/equations.ipynb index 40d4d3d..865bbcb 100644 --- a/notebooks/equations.ipynb +++ b/notebooks/equations.ipynb @@ -671,7 +671,7 @@ "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", - "version": "3.8.5" + "version": "3.7.6" } }, "nbformat": 4, diff --git a/notebooks/numericalJacobian.ipynb b/notebooks/numericalJacobian.ipynb new file mode 100644 index 0000000..ea68822 --- /dev/null +++ b/notebooks/numericalJacobian.ipynb @@ -0,0 +1,127 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# Compute the jacobian numerically\n", + "\n", + "link: --> http://www.maths.lth.se/na/courses/FMN081/FMN081-06/lecture7.pdf\n", + "\n", + "Often the Jacobian is not **analytically** available and it has to be computed numerically.\n", + "It can be computed column wise by finite differences:\n", + "\n" + ] + }, + { + "cell_type": "code", + "execution_count": 12, + "metadata": {}, + "outputs": [], + "source": [ + "import numpy as np\n", + "\n", + "def f(x,u):\n", + " \"\"\"\n", + " :param x:\n", + " :param u:\n", + " \"\"\"\n", + " xx = x[0]\n", + " xy = x[1]\n", + " v = x[2]\n", + " theta =x[3]\n", + " \n", + " a = u[0]\n", + " delta = u[1]\n", + " \n", + " L=0.3\n", + " \n", + " #vector of ackerman equations\n", + " return np.array([\n", + " [np.cos(theta)*v],\n", + " [np.sin(theta)*v],\n", + " [a],\n", + " [v*np.arctan(delta)/L]\n", + " ])\n", + "\n", + "def J(f,x,u,epsilon=1e-6):\n", + " \"\"\"\n", + " :param f:\n", + " :param x:\n", + " :param u:\n", + " \"\"\"\n", + " \n", + " \n", + " x_minus = x-epsilon\n", + " u_minus = u-epsilon\n", + " \n", + " x_plus = x+epsilon\n", + " u_plus = u+epsilon\n", + " \n", + " # compute finite differences\n", + " f_plus = f(x_plus, u_plus)\n", + " f_minus = f(x_minus, u_minus)\n", + " \n", + " jac = (f_plus - f_minus)/2*epsilon\n", + " \n", + " return jac\n", + " " + ] + }, + { + "cell_type": "code", + "execution_count": 13, + "metadata": {}, + "outputs": [ + { + "data": { + "text/plain": [ + "array([[1.e-12],\n", + " [0.e+00],\n", + " [1.e-12],\n", + " [0.e+00]])" + ] + }, + "execution_count": 13, + "metadata": {}, + "output_type": "execute_result" + } + ], + "source": [ + "#starting condition\n", + "x=np.array([0,0,0,0])\n", + "u=np.array([1,0])\n", + "\n", + "J(f,x,u)" + ] + }, + { + "cell_type": "code", + "execution_count": null, + "metadata": {}, + "outputs": [], + "source": [] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python 3", + "language": "python", + "name": "python3" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 3 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython3", + "version": "3.7.6" + } + }, + "nbformat": 4, + "nbformat_minor": 4 +}