VIPER – Plotter system for drawing images on vertical surfaces

Drawing pictures on vertical surfaces requires a lot of effort. If a graphic must be drawn on a wall, then in most cases it is painstakingly handcrafted by a painter or artist, or you need to use stickers, stencils and wallpapers. In the first case, there is rarely a way to create detailed and impressive images in a short time and in any size directly on the surface.

The idea of VIPER is a system with which exactly this is possible. At first, a picture should be selected on the computer and then drawn automatically on a vertical surface like a wall or house facade with a mechanical construction. In addition to the actual project, it is also our goal to show that very precise and reliable positioning tasks on arbitrarily large vertical surfaces are possible with very little effort. Applying colour to these surfaces (drawing images) is merely a visual feedback on the accuracy of this system.

Implementation

VIPER consists of three core components, which together form the overall system. These three components are the VIPER desktop application, the gondola and the VIPER box.

The first part is the VIPER desktop application. It is the operating software for the system, which is available for Linux, macOS and Windows and forms the interface between man and machine. With the desktop application, the desired images are converted into motor commands, managed if desired and also sent to the VIPER box, which is the heart of the system.

The gondola, also called the drawing tool, is the second part of the system and applies the color to the vertical surface. Basically, it is a holder for any pen, which can also push the pen away from the surface in the desired case. There is a toothed belt on the left and on the right side of the gondola, which first leads to the left or right upper corner of the drawing area and from there is diverted to the VIPER box by pulleys. For example, if you pull the two straps, the nacelle will move in the corresponding direction. And the VIPER-Box creates exactly these movements.

Last but not least, the VIPER box. It is part of the hardware and, in addition to two actuators, it also contains several important control and communication elements. The box's task is to move the gondola to the desired coordinates, which result from the image of the desktop application. The gondola is moved by switching the actuators on and off, which move forward or backward through this targeted activation. As a result, the toothed belt, which is connected to the gondola by rope pulleys, is pulled or released, causing the gondola to move.

Operation of the system

At the beginning, the VIPER box is set up on the floor or, if desired, on a table in front of the drawing surface. Then two rope pulleys are attached to the two upper corners of the drawing area, which deflect the toothed belts to the VIPER box and keep the gondola in the air.

The desktop application then converts any black and white image into motor commands and manages already converted images on the computer. If you have decided on an image that has already been converted, it will be sent at the touch of a button via a wireless connection provided by the VIPER box.

In short: You connect to a Wi-Fi network, which is provided by the VIPER-Box, as soon as it is supplied with power, then the VIPER desktop application starts, converts an image and sends this converted image, which is now a file with coordinates for the motors, to the VIPER box.

Then the file containing the coordinates is processed by the microcontrollers in the VIPER box. The microcontrollers control one motor each, which is connected to the gondola by toothed belts. Through targeted movements, the desired image is created on the surface step by step.

Results

This project was part of the diploma thesis and was developed in collaboration with my partner Elias Stefaner.

The first VIPER prototype was finished at the end of the project phase. Thanks to the clever implementation, the system can be developed further after the completion of the fifth year. In the future, the system should be modulatable and allow various modules like an airbrush gun, next to a common pen, to draw images. The system should also be adaptive converted in just a few steps to a system for the third dimension. It could then be possible to use other modules such as cameras, measuring devices or 3D printer nozzle’s