obsidian_backup/补课/多体动力学/16_generalized_forces.ipynb

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  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/latex": [
       "$\\displaystyle l \\dot{q}_{1}\\mathbf{\\hat{a}_x} + l \\dot{q}_{2}\\mathbf{\\hat{b}_x}$"
      ],
      "text/plain": [
       "l⋅q₁̇ a_x + l⋅q₂̇ b_x"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import sympy as sm\n",
    "import sympy.physics.mechanics as me\n",
    "me.init_vprinting(use_latex='mathjax')\n",
    "\n",
    "l = sm.symbols('l')\n",
    "q1, q2, u1, u2 = me.dynamicsymbols('q1, q2, u1, u2')\n",
    "\n",
    "N = me.ReferenceFrame('N')\n",
    "A = me.ReferenceFrame('A')\n",
    "B = me.ReferenceFrame('B')\n",
    "\n",
    "A.orient_axis(N, q1, N.z)\n",
    "B.orient_axis(N, q2, N.z)\n",
    "\n",
    "O = me.Point('O')\n",
    "P1 = me.Point('P1')\n",
    "P2 = me.Point('P2')\n",
    "\n",
    "O.set_vel(N, 0)\n",
    "\n",
    "P1.set_pos(O, -l*A.y)\n",
    "P2.set_pos(P1, -l*B.y)\n",
    "\n",
    "P1.v2pt_theory(O, N, A)\n",
    "P2.v2pt_theory(P1, N, B)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/latex": [
       "$\\displaystyle l \\cos{\\left(q_{1} \\right)} \\dot{q}_{1}\\mathbf{\\hat{n}_x} + l \\sin{\\left(q_{1} \\right)} \\dot{q}_{1}\\mathbf{\\hat{n}_y}$"
      ],
      "text/plain": [
       "l⋅cos(q₁)⋅q₁̇ n_x + l⋅sin(q₁)⋅q₁̇ n_y"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "P1.vel(N).express(N)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 两杆连接"
   ]
  }
 ],
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    "name": "ipython",
    "version": 3
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   "file_extension": ".py",
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