Tnay has already made some good points.
Let me add some. There are basically two types of motors we call servos: DC servo motors, used in commercial applications, and R/C servo motors, most often used for hobby applications.
The R/C servo motors can indeed be made to closely follow a trajectory, limited of course by their resolution, which is in the order of 255 points along their travel (often 180 degrees). DC servo motors may have thousands
of points of resolution in 360 degrees of revolution.
You get this fine resolution by incrementally (by as small amount as possible) changing position command to the servo.
The SSC-32 does not directly work with Gcode. Gcode is a list of position commands, like "X10 Y20", which would be the X & Y positions of the next point the hardware is to go to. It's a good intermediate language that is easily parsed into move commands. You'll have to scale the numbers into the 500-2500 ms pulse width commands that the SSC32 accepts.
I wrote and use a CNC controller program for my CNC'd Sherline mill and lathe that interprets Gcode programs, and commands DC servo motors or stepper motors. I haven't done that with R/C servos, but I see no reason why it wouldn't be possible.
If your text (?) or drawings are simple enough, you can simply make a list of coordinates for the three axis to travel through.
Is a list of points that define a square. These would typically be put in an array. Then each pair of coordinates would be retrieved and the program would generate the pulse width commands that the SSC32 expects.
Do you know the old plotter code (HPGL)? that would also be an easily interpreted code.
The reason for working with either Gcode or HPGL is the ability to create complex drawings in a CAD or drawing program, and then interpret (decode) the coordinates from the files. A Google of Gcode will bring up definitions and further examples for you to study.
thanks for your quick responce
the question is that , can we use the reqular servo motors to do the trajectory? because I think this kind of servo can't act in small change in position and velocity ?
I use SSC-32 for controlling the servo, does this kind of controller work with Gcod?
where can i find some more information about writing programe in Gcode?
do you do yourself this kind of job with regular servo?
I don't see why you are getting vibration from SSC-32 unless you are putting too much stress on the arm.
Servo motors can do trajectory, however the precision of the arm movement highly depends on your model.
The vibration could comes from the rigidity and stiffness of your model. You can evaluate this behaviour via inertia/stiffness/error matrix. The solution will help you to properly quantify this parameters, and hopefully a solution for your case.
Gcode is the most common machine code for CAD/CAM CNC application, however you may need to add converter or something like that to read and convert it into usable code for SSC-32.
For your thesis, servo motors should be good enough to demonstrate your understanding and application, but it should not be compared to industrial standard. 8)