Description
Project Overview:
The first computer project will require you to read in two files, one specifying the joint positions and velocities
for a robotic manipulator at key frames and another describing the position and orientation of an object at the
same key frames. Using these two files, you will write a MATLAB script to generate a complete trajectory for the
robot joints and object. The two trajectories will then be stored as separate files which can be displayed using the
provided Animate program.
Input File Descriptions:
The input files your program should accept are robot.key and object.key. Both programs are defined as follows:
1. The file robot.key contains the robot joint variable positions and velocities at key frames. From this file, you
are to generate the file robot.ang, used by animate, which contains the values of the joint variables of an n-joint
manipulator for each frame. The format for robot.key is defined as:
k t
q11 q12 . . . q1n
q˙11 q˙12 . . . q˙1n
.
.
.
.
.
. . . .
.
.
.
qk1 qk2 . . . qkn
q˙k1 q˙k2 . . . q˙kn
where k and t are integers denoting the number of key frames described and the number of total frames to
be in the simulation, respectively. Note, t/k may not be an integer meaning during animation, you will not
necessarily display each key frame. Keep this in mind when moving from one interpolant curve to the next!
The position and velocity of joint j for key frame i are denoted by qij and ˙qij respectively.
2. Similarly, object.key provides the homogeneous transformation describing an object’s position and orientation
at key frames. You will need to generate a file called object.traj that contains the homogeneous transformations
for the object at every frame. The format for the file object.key is:
k t
n1x o1x a1x p1x
n1y o1y a1y p1y
n1z o1z a1z p1z
.
.
.
.
.
.
.
.
.
.
.
.
nkx okx akx pkx
nky oky aky pky
nkz okz akz pkz
where k and t have the same definition as above. The interpolation is to be done by maintaining continuity
in velocity. Assume the object is to start and end at rest.
Suggested Coding Procedure:
As with any large programming task, it is highly recommended you break the project into smaller segments. Focus
on generating the joint trajectories for robot.ang first. You will need to use a reasonable position interpolation
strategy for each joint and between each key frame. Once you have equations describing the joint trajectories
between each key frame, you will need to step along the curves using appropriate u-values to generate the joint
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positions for each of the total frames to be displayed. The joint positions should be stored in the file robot.ang
using the format:
t
q11 q12 . . . q1n
.
.
.
.
.
. . . .
.
.
.
qt1 qt2 . . . qtn
where t is again the total number of frames and qij is the position of joint j at frame i. The robot.ang file should be
saved in a folder entitled robot along with provided files which describe the geometry of the robot and the position
of the robot base.
Test your robot trajectory by running animate.exe similar to persp display for the truncated pyramid. The
input file for animate is the provided file labelled script. Before using, open script and make sure you understand
what parameters are being specified. If you do not have an object, remove those lines from the script.
Once satisfied with the resulting smooth motion, begin working on the orientation interpolation needed to
generate object.traj file from the provided object.key file. The format for object.traj is:
t
n1x o1x a1x p1x
n1y o1y a1y p1y
n1z o1z a1z p1z
.
.
.
.
.
.
.
.
.
.
.
.
ntx otx atx ptx
nty oty aty pty
ntz otz atz ptz
with parameters as defined above. The resulting object.traj file should be saved in the object folder which also
contains the point polygon and point of view files for the object.
Useful MATLAB Commands:
The download folder includes a subfolder of MATLAB code which includes several scripts to help you complete the
necessary interpolations. Look at the provided scripts and understand the assumed formatting, what the scripts
accomplish, and how you can incorporate the scripts into your code. Feel free to modify the scripts or write your
own if you prefer though!
As a final nudge, you will need to read in and write to external files. There are many ways to accomplish this
in MATLAB as a Google search will reveal; however, one simple method is to use the commands:
importdata(‘robot.key’)
dlmwrite(‘robot/robot.ang’,output,‘-append’,‘delimiter’,‘ ’)
to read in and and write out data. It is still recommended you use the MATLAB ‘help’ command to understand
the format of these commands.
What to Submit: When you are satisfied with the performance of you code, type a short README document as
described in the Guidelines document under the Computer Projects module on Canvas. Upload a ¡last name¿.zip
folder containing your README file and all MATLAB code to Canvas by the assignment deadline.
Note: Once again, k and t are both variables and will be changed by Megan while grading so make sure your
code allows for these modifications!
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