While studying field of Innovative Technologies and Advanced Materials at the university, I was simultaneously working on my Bachelor of Engineering thesis which the precise title is: Project of a numerically controlled plotter platform.

The decision to make this project as my thesis was made because I wanted to do something related somehow with electronics which I started to interest more at this time and this was really my first true beggining with electronics. The field I was studying was also extensive enough to give me the opportunity to make such project as it must be related to the studied field in some way.

Model of the designed plotter

The whole device was designed in CAD program: Autodesk Inventor Professional 2020. The model consists of three types of parts: electronical, mechanical and structural.

Plotter's movement mechanism

To set the platform or its arm in computer-controlled motion, a mechanism was used based on a V-belt, which was tensioned around a number of pulleys and gears connected to the motor shafts. In order to best explain the principle of operation of this mechanism, in addition to the simplified graphic of the device (Fig. b), I have also showed a graphic illustrating the mechanism itself (Fig. a). The purple slider in the first graphic corresponds to the device platform arm in the graphic below, and similarly, the dark gray platform corresponds to the actual plotter platform below. Individual linear pulleys with different colors also represent a simplified example of the pulleys and gears used in the device. To move the purple slider in the direction indicated by the green arrow in the graphic, rotate the blue and orange linear puck outwards at the same time.

To move the arm in the opposite direction to that indicated by the arrow, the linear pulleys should be rotated inside the structure. However, if you want to move the entire platform along the X axis, the disks should rotate simultaneously, in accordance with the direction in which the platform is to move, left or right, respectively. In the case when only one linear pulley rotates and the other one is blocked, the movement takes place both in the X and Y axes. The above-mentioned combinations of linear pulley rotations occurring in this mechanism allows movement along a freely programmed path. The blue and orange discs in the graphic illustrating the mechanism have been replaced in the constructed plotter by gears attached to the stepper motor shaft, which rotates them precisely and allows them to move at different speeds at the same time.

Block diagram

As this webpage shows only the preview of the whole thesis, I have decided not to describe each detail related to operation of the plotter and placed only the general block diagram where each important software, hardware and actions were detailed.

Short video of the plotter work

Sources

[a] thang010146, "Controlling two linear motions of an object 1b", [Online]. Available: https://www.youtube.com/watch?v=_nzxGOKhHSY. [Accessed 20 January 2021].