Academic trouble: Robotics toolbox

Hi. This is my first post on this group. I study Automatics & Robotics and while working on an assigned project for my university I've came
across a problem I cannot solve. My goal is to control a robotic arm by the use of Denavit-Hartenberg's notation and forward and reverse kinematics. For this we're using Matlab + Robotics toolbox to make the necessary computing and Roboworks where we draw our virtual manipulator. I've written a program that creates a circular trajectory, and here's where the problem is. I don't know why, but the manipulator instead of making circles, makes ellipses or goes totally crazy. I've tried to rewrite my Denavit Hartenberg matrix, but this doesn't seem to help. The same thing happens when I'm trying to make a square.
So could you tell me what am I doing wrong in this project? Maybe the DH matrix is wrong, or i'm giving the wrong joint coordinates.
Thanks in advance for any help.
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snipped-for-privacy@poczta.onet.pl wrote:

some crap
ignore DH convention
Do it by simple transforms
See previous posts to this group
Regards
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