@@ -571,12 +571,19 @@
    },
    "outputs": [],
    "source": [
-    "# TODO: write a deriative function.\n",
+    "# TODO: write a deriative function to pass to odeint.\n",
     "#  Note that the input state will have x and the derivative of x in it\n",
     "#   You will return the derivative of x and the derivative of the derivative of x\n",
     "#   Note that the derivative never changes - you only have to calculate the second derivative\n"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -600,7 +607,8 @@
     "# TODO write a function that takes in the starting conditions (x and the derivative of x), along with the parameters\n",
     "#  you need to calculate the derivative (zeta, k, and m)\n",
     "# Call integrate and return the result of that function, along with the t values\n",
-    "#   You might also want the step for the t and the total amount of time to integrate over as parameters"
+    "#   You might also want the step for the t and the total amount of time to integrate over as parameters\n",
+    "# This function should return "
    ]
   },
   {
 
@@ -203,7 +203,7 @@
    },
    "outputs": [],
    "source": [
-    "# Don't change this one\n",
+    "# Don't change this cell - this is the code/set of angles we grade from\n",
     "angles_check = [np.pi/2, -np.pi/4, -3.0 * np.pi/4, [np.pi/3.0, np.pi/4.0, -np.pi/4.0]]\n",
     "set_angles_of_arm_geometry(arm_geometry, angles_check)\n",
     "matrices = get_matrices_all_links(arm_geometry)\n",
 
@@ -42,11 +42,7 @@
    "source": [
     "# The usual imports\n",
     "import numpy as np\n",
-    "import matplotlib.pyplot as plt\n",
-    "\n",
-    "# These are the routines used in the lecture activity - we'll re-use them here\n",
-    "import matrix_routines as mt\n",
-    "from object_routines import read_object, plot_object_in_world_coord_system"
+    "import matplotlib.pyplot as plt"
    ]
   },
   {
 
@@ -310,7 +310,8 @@ def get_gripper_location(arm_with_angles):
     # TODO:
     # Step 1: Get the matrices
     # Step 2: Use the last matrix plus the rotation of the wrist to build a matrix for the gripper
-    # Step 3: Multiply the last matrix by [d, 0] to get the location in world coordinates
+    # Step 3: Multiply the last matrix by the point [grasp_dist, 0] to get the location in world coordinates.
+    #   Don't forget the 1 when building the matrix for the point
     # Format for returning a tuple
     return (0, 0)
Original file line number	Diff line number	Diff line change
`@@ -42,11 +42,7 @@`
`42`	`42`	`"source": [`
`43`	`43`	`"# The usual imports\n",`
`44`	`44`	`"import numpy as np\n",`
`45`		`- "import matplotlib.pyplot as plt\n",`
`46`		`- "\n",`
`47`		`- "# These are the routines used in the lecture activity - we'll re-use them here\n",`
`48`		`- "import matrix_routines as mt\n",`
`49`		`- "from object_routines import read_object, plot_object_in_world_coord_system"`
	`45`	`+ "import matplotlib.pyplot as plt"`
`50`	`46`	`]`
`51`	`47`	`},`
`52`	`48`	`{`