ME 449 Assignment Draft 2021 - Revision history

Lynch: /* Part 2: Joint Angle Calculations */

2021-10-05T16:33:39Z

Part 2: Joint Angle Calculations

Lynch at 16:32, 5 October 2021

2021-10-05T16:32:42Z

Lynch at 16:32, 5 October 2021

2021-10-05T16:32:25Z

Lynch: /* What to turn in to Canvas */

2021-10-05T16:31:39Z

What to turn in to Canvas

Lynch: /* What to turn in to Canvas */

2021-10-05T16:31:27Z

What to turn in to Canvas

Lynch: /* What to turn in to Canvas */

2021-10-05T16:28:00Z

What to turn in to Canvas

Lynch: /* What to turn in to Canvas */

2021-10-05T16:27:31Z

What to turn in to Canvas

Lynch at 16:25, 5 October 2021

2021-10-05T16:25:52Z

Lynch at 16:21, 5 October 2021

2021-10-05T16:21:36Z

Lynch at 16:20, 5 October 2021

2021-10-05T16:20:09Z

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 * Find the six-vector of joint angles <math>\theta</math> given the <math>R_{ij}</math> above.  (You will likely want to calculate the rotation matrices <math>R_{i,i+1}</math> and use the MR code library, e.g., MatrixLog3.)
-* Enter the joint angles you found into Scene1_UR5 in CoppeliaSim to see the configuration of the robot.
+* Enter the joint angles you found into your modified Scene1_UR5 in CoppeliaSim to see the configuration of the robot.
 * Calculate ''R<sub>sb</sub>'' using the information given, and verify that your joint angle vector <math>\theta</math> is correct by entering the joint angles into the scene and comparing your ''R<sub>sb</sub>'' to the rotation matrix portion of the ''T<sub>sb</sub>'' calculated by the scene under the "Enter Config and SE(3) Value" tab.

← Older revision		Revision as of 16:32, 5 October 2021
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	A scene also includes a [https://www.coppeliarobotics.com/helpFiles/en/mainScript.htm main script], which handles the simulation loop. At each simulation step, the main script calls (a) "actuation" functions that simulate the motion of the system and (b) "sensing" functions that simulate the sensors. Generally this main script should not be edited.		A scene also includes a [https://www.coppeliarobotics.com/helpFiles/en/mainScript.htm main script], which handles the simulation loop. At each simulation step, the main script calls (a) "actuation" functions that simulate the motion of the system and (b) "sensing" functions that simulate the sensors. Generally this main script should not be edited.


	===Part 1A: Building a world for a mobile robot===		===Part 1A: Building a world for a mobile robot===

← Older revision		Revision as of 16:32, 5 October 2021
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	'''Introduction'''

	In Chapter 4, we will study the forward kinematics problem for open-chain robots: finding the configuration of the robot's end-effector <math>T_{sb}(\theta) \in SE(3)</math> given the vector of joint positions <math>\theta</math>. The forward kinematics problem is easy to solve using a formula called the "product of exponentials," which uses the matrix exponential of this chapter. In this project, CoppeliaSim will solve the forward kinematics for you.		In Chapter 4, we will study the forward kinematics problem for open-chain robots: finding the configuration of the robot's end-effector <math>T_{sb}(\theta) \in SE(3)</math> given the vector of joint positions <math>\theta</math>. The forward kinematics problem is easy to solve using a formula called the "product of exponentials," which uses the matrix exponential of this chapter. In this project, CoppeliaSim will solve the forward kinematics for you.

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 ==What to turn in to Canvas==
 Turn in a single zip file.  The file name should be FamilyName_GivenName_asst1.zip (for me, it would be Lynch_Kevin_asst1.zip).  This file should have:
-* Part 1A: A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure your video is a common format and reasonably sized (e.g., less than 20 MB).
+* Part 1A: A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure your video is in a common format and reasonably sized (e.g., less than 20 MB).
 * A single pdf file including:
 ** Part 1B: A screenshot of your changed code in the child script.  Explain what you changed about the scene/UI.  (A small change suffices.)

@@ Line 97: / Line 97: @@
 ==What to turn in to Canvas==
 Turn in a single zip file.  The file name should be FamilyName_GivenName_asst1.zip (for me, it would be Lynch_Kevin_asst1.zip).  This file should have:
-* Part 1A: A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure we can play your video!
+* Part 1A: A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure your video is a common format and reasonably sized (e.g., less than 20 MB).
 * A single pdf file including:
 ** Part 1B: A screenshot of your changed code in the child script.  Explain what you changed about the scene/UI.  (A small change suffices.)

@@ Line 97: / Line 97: @@
 ==What to turn in to Canvas==
 Turn in a single zip file.  The file name should be FamilyName_GivenName_asst1.zip (for me, it would be Lynch_Kevin_asst1.zip).  This file should have:
+* A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure we can play your video!
 * A single pdf file including:
 ** 1B: A screenshot of your changed code in the child script.  Explain what you changed about the scene/UI.  (A small change suffices.)
 ** 1B & 2: A screenshot of the scene, clearly showing the modified UI, the SE(3) calculation, and the robot at the correct configuration.
 ** 2: The list of the six joint angles you calculated and a brief explanation of the method (including your code, which likely calls the MR code) you used to calculate them.
-* A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure we can play your video!
 The contents of your zip file should look like the below (with your name):

@@ Line 10: / Line 10: @@
-'''Part 1: CoppeliaSim Simulation and Exploration'''
+==Part 1: CoppeliaSim Simulation and Exploration==
 In part 1, you will explore some of the functionality and built-in models for CoppeliaSim. Go to [http://hades.mech.northwestern.edu/index.php/Getting_Started_with_the_CoppeliaSim_Simulator this page] for a refresher on getting started with CoppeliaSim.
@@ Line 22: / Line 22: @@
-'''Part 1A: Building a world for a mobile robot'''
+===Part 1A: Building a world for a mobile robot===
 In this part, you will explore the CoppeliaSim model browser and learn how to create your own scene using the default models. Anything in the model browser can be dragged and dropped onto the checkerboard floor of the scene. It can then be moved or reoriented using the '''Object/item shift''' and the '''Object/item rotate''' buttons in the top toolbar (the cubes with the arrows around them). Also try using the controls at the top of the window to zoom the camera in and out, pan the camera, etc.
@@ Line 38: / Line 38: @@
-'''Part 1B: Exploring the UR5 Scene 1'''
+===Part 1B: Exploring the UR5 Scene 1===
 Open Scene 1 for interactive manipulation of the Universal Robots UR5 robot, a popular 6R robot. (You can go to the [http://hades.mech.northwestern.edu/index.php/CoppeliaSim_Introduction CoppeliaSim Introduction] to download Scene 1 and the other scenes used in this course). In this scene, there is a model of a UR5 robot, which consists of a collection of [https://www.coppeliarobotics.com/helpFiles/en/joints.htm joints] connecting shapes (links), from the base out to the end-effector.
@@ Line 69: / Line 69: @@
 -->
-'''Part 2: Joint Angle Calculations'''
+==Part 2: Joint Angle Calculations==
 The 6R UR5 robot is shown below at its home configuration. Eight frames are defined:  the fixed frame {s} at the base, frames {1} through {6} attached to links 1 through 6, and the end-effector frame {b} which is fixed relative to link 6.  (The frame {b} is not shown in the image.)  The red arrow is the x-axis, the green arrow is the y-axis, and the blue arrow is the z-axis.  Frames {s} and {1}-{6} are aligned when the robot is at its home configuration, i.e., each rotation matrix <math>R_{ij}</math> (where <math>i, j</math> could be <math>s</math> or any number 1 through 6) is the identity matrix.
@@ Line 95: / Line 95: @@
 * Calculate ''R<sub>sb</sub>'' using the information given, and verify that your joint angle vector <math>\theta</math> is correct by entering the joint angles into the scene and comparing your ''R<sub>sb</sub>'' to the rotation matrix portion of the ''T<sub>sb</sub>'' calculated by the scene under the "Enter Config and SE(3) Value" tab.
+==What to turn in to Canvas==
-'''What to turn in to Canvas:''' A single zip file.  The file name should be FamilyName_GivenName_asst1.zip (for me, it would be Lynch_Kevin_asst1.zip).  This file should have:
+Turn in a single zip file.  The file name should be FamilyName_GivenName_asst1.zip (for me, it would be Lynch_Kevin_asst1.zip).  This file should have:
 * A single pdf file including:
-** 1A: A screenshot of your custom scene and bump UI showing your custom settings
 ** 1B: A screenshot of your changed code in the child script.  Explain what you changed about the scene/UI.  (A small change suffices.)
 ** 1B & 2: A screenshot of the scene, clearly showing the modified UI, the SE(3) calculation, and the robot at the correct configuration.
-** 2: The list of the six joint angles you calculated and a brief explanation of the method (including the MR code) you used to calculate them.
+** 2: The list of the six joint angles you calculated and a brief explanation of the method (including your code, which likely calls the MR code) you used to calculate them.
-* A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure we can play your video
+* A single video file showing a screen recording of your Pioneer_p3dx robot moving through your custom scene. NOTE: make sure we can play your video!
 The contents of your zip file should look like the below (with your name):
@@ Line 108: / Line 108: @@
 If you do not know how to take a screenshot, you can use one of the following:
-*''Mac'': Cmd-Shift-3 and look for the screenshot on your desktop.
+*''Mac'': use Preview>File>Take Screenshot, or Cmd-Shift-3 and look for the screenshot on your desktop.
 *''Windows'': Use the PrtScn button (or Windows Key + PrtScn or Alt _ PrtScn, etc.). You can also search for the Snipping Tool.
 *''Linux'': you can use Screenshot or PrtScrn.

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 '''Your task:'''
-Modify the UI_Script to change an aspect of the scene. For example, you can choose to change  the Custom UI layout, change the titles and words of the Custom UI, or change font sizes in the Custom UI. Some example changes include:
+Modify the UI_Script to change an aspect of the scene, and you will use this modified scene for Part 2, below. For example, you can choose to change the Custom UI layout, change the titles and words of the Custom UI, or change font sizes in the Custom UI. Some example changes include:
 *Changing the  layout: consult the XML syntax and change <group layout="vbox"> to another type (hbox,form, grid,  none). Using line 257, changing <group layout="vbox"> to <group layout="hbox"> changes the  orientation of the items in the  group containing "Configuration Entry", "Current configuration", and "Messages" on the  "Enter Config and SE(3) Value" tab of the Custom UI from vertically arranged to horizontal.

@@ Line 34: / Line 34: @@
 Add at least five 80cm high walls to the scene (find them in infrastructure/walls/80cm high walls" in the model browser). Arrange and orient the walls such that when the simulation is started, the Pioneer_p3dx interacts with at least three of the walls and drives over the bump at least once. To interact with a wall means to drive towards it and avoid bumping into it.
-'''Your Task:'''
+'''Your task:'''
-* Take a screen recording of the robot moving through your world and interacting with at least three walls and driving over the bump at least once. (See [http://hades.mech.northwestern.edu/index.php/CoppeliaSim_Introduction CoppeliaSim Introduction] for how to take a screen recording if needed.)
+* Take a screen recording video of the robot moving through your world and interacting with at least three walls and driving over the bump at least once. In the video, use the zoom, pan, and other buttons to move the camera view while the robot is moving. You can change the robot's default speed in its child script to make it easier to capture your video with the moving camera. (If you don't know how to take a screen recording, you can check out [http://hades.mech.northwestern.edu/index.php/CoppeliaSim_Introduction CoppeliaSim Introduction].)
 '''Part 1B: Exploring the UR5 Scene 1'''
-Open Scene 1 for interactive manipulation of the Universal Robots UR5 robot, a popular 6R robot (You can go to the [http://hades.mech.northwestern.edu/index.php/CoppeliaSim_Introduction CoppeliaSim Introduction] to download Scene 1). In this scene, there is a model of a UR5 robot, which consists of a collection of [https://www.coppeliarobotics.com/helpFiles/en/joints.htm joints] connecting shapes (links), from the base out to the end-effector.
+Open Scene 1 for interactive manipulation of the Universal Robots UR5 robot, a popular 6R robot. (You can go to the [http://hades.mech.northwestern.edu/index.php/CoppeliaSim_Introduction CoppeliaSim Introduction] to download Scene 1 and the other scenes used in this course). In this scene, there is a model of a UR5 robot, which consists of a collection of [https://www.coppeliarobotics.com/helpFiles/en/joints.htm joints] connecting shapes (links), from the base out to the end-effector.
 When you run this scene you will see a window with two tabs:  "Enter Config and SE(3) Value" and "Joint Angle Sliders". Go to the "Joint Angle Sliders" tab, move the sliders corresponding to the six joints, and watch how the robot moves.
@@ Line 48: / Line 48: @@
 [[File:CoppeliaSim_scripts.PNG]]
-Double-click the "Non-threaded child script (UI_Script)" to open it.  You will see a script written in the Lua programming language.  Early in the file, you might notice that some functions look similar to functions written in the Modern Robotics Library. For example, ''so3andp2se3(R,p)'' in this script resembles ''RpToTrans(R,p)'' in the Modern Robotics Library.
+Double-click the "Child script (UI_Script)" to open it.  You will see a script written in the Lua programming language.  Early in the file, you might notice that some functions look similar to functions written in the Modern Robotics Library. For example, ''so3andp2se3(R,p)'' in this script resembles ''RpToTrans(R,p)'' in the Modern Robotics Library.
 Scroll down to line 242.  From here to the end of the file, this code examines the type of "call" to the child script by the main script and performs the appropriate functions.  For example, if the sim_call_type is sim.syscb_init, the simulation has started and the user interface should be generated.  (There is a lot of XML code here defining the user interface.)  If the sim_call_type is sim.syscb_actuation, then the joint angles entered by the user in the UI are applied to the UR5 model, the UI is updated, and the transformation matrix for the end-effector is calculated.  If the sim_call_type is sim.syscb_sensing, nothing happens, and if it is sim.syscb_cleanup, the UI is destroyed as the simulation ends.
@@ Line 55: / Line 55: @@
 '''Your task:'''
-Modify the  non-threaded child script (UI_Script) to change an aspect of the  scene. For example, you can choose  to change  the Custom UI layout, change the titles and words of the Custom UI, or change  font sizes in the Custom UI. Some example changes include:
+Modify the UI_Script to change an aspect of the scene. For example, you can choose to change  the Custom UI layout, change the titles and words of the Custom UI, or change font sizes in the Custom UI. Some example changes include:
 *Changing the  layout: consult the XML syntax and change <group layout="vbox"> to another type (hbox,form, grid,  none). Using line 257, changing <group layout="vbox"> to <group layout="hbox"> changes the  orientation of the items in the  group containing "Configuration Entry", "Current configuration", and "Messages" on the  "Enter Config and SE(3) Value" tab of the Custom UI from vertically arranged to horizontal.
@@ Line 62: / Line 62: @@
 *Changing the font: Using line 258 <nowiki>label text="<big>Configuration  Entry:</big>"</nowiki>
-**The font can be changed to small  using: <nowiki>label text="<small>Configuration Entry:</small>"</nowiki>
+**The font can be changed to small using: <nowiki>label text="<small>Configuration Entry:</small>"</nowiki>
 ** The font can be changed to a specific size using: <nowiki>label text="<font size=20>Configuration Entry:</font></nowiki>", where 20 is the desired font size.