Computer Science 39a : Homework #3
Due Friday, September 19, 1997

Overview

• Provide everyone with a homepage so that future homeworks may be turned in electronically and immediately available to the rest of the class.
  
• Allow everyone to explore a forward-kinematics application to have a hands-on feel for the material we've been covering / will be covering in class.
• Meet other people in the class and also have someone around to help you if you have problems. To that end you are asked to choose a partner for this assignment but you will work on adjacent computers and turn in individual assignments.

Setting up a homepage

% mkdir ~/public_html
% chmod 755 ~/public_html
% mkdir ~/public_html/gifs
% chmod 755 ~/public_html/gifs
% cp ~cs39a/public_html/template.html ~/public_html/index.html
% chmod 644 ~/public_html/index.html
% emacs ~/public_html/index.html

Running a Forward-Kinematic Application (SPAM)

This is more fun that setting up your own homepage (if you can believe that). Here's what you'll do.

• Run the program in ~cs39a/bin/SPAM from an HP workstation (the executable is called "SPAM.hp")

  % cd ~cs39a/bin/SPAM
  % ./SPAM.hp
  

  • Click the Walk button to see it walk
  • Click the Reset Walker button to reset the walker to the left.
  • Drag the Time scrollbar back and forth to view the animation slowly
  • Note that the curves display the angle of different joints at different points in time. The model uses forward kinematics to describe the motion.
  • Click on Quarter, Half, etc. to control the speed of the motion.
  • The Ground? button indicates at what times and for what angles the feet or knees intersect the ground.
  • Explore the program. See if you can find out what all the buttons do.
• Look at all the existing walks that have been saved so far.
  • Click the Load... button, click on a walk filename, then click Load
  • View the walk as you have just been doing. (You may have to reset it first)
  • Do this for all the walk files in the directory.
  • Do this for all the walk files in the class directory - this contains all of the walk animations of your classmates.
• Create an interesting walk of your own invention (it doesn't have to be realistic!)
  • Click the colored buttons to bring different curves to the foreground.
  • Drag the colored circles up and down to affect the motion at different points along the walk motion - the circles at the left and right control the position of the walker at the rest position, and the circles in the middle control the position in mid-walk.
• Save your walk to a file
  • Click the Save... button.
  • Click in the Filename field.
  • Type the following into that field:
  • ../../fa97/class/cs39a-a??LETTER??/mywalk
  • Where ??LETTER?? is the last letter in your Login (e.g. g for cs39a-ag)
• Mail your walk file (the file ~/mywalk.w) to Dan (cs39a@po.eecs). You can do this one of two ways:
  • mail cs39a@po.eecs < ~/mywalk.w
  • cat ~/mywalk.w | mail cs39a@po.eecs
• Make your walk file visible to the rest of the class.
  • Type the following to the unix prompt:
  • cp ~/mywalk.w ~cs39a/bin/SPAM/class/??LETTER??.w
  • Where ??LETTER?? is the last letter in your Login (e.g. g for cs39a-ag)
• Look at the other walks other students did this year and past years (they are all in class directory for this year's work and in the classFa96, classSp95 or classFa95 for previous year's work. To look at them, run SPAM.hp as in the past but load the walks from the class directories.

WWW Maven: Dan Garcia (ddgarcia@cs.berkeley.edu) Send me feedback