Search

A water tank system with control electronics was developed at Rubico AB in Luleå during the summer of 2011. This second order automation control system consists, in short, of two water tanks with individual level sensors, a pump and a tap valve. Today students use the system in laboratory practical as part of an elementary course in automation control at Luleå University of Technology.Reading sensors and controlling the pump in the existing system is done with an external DAC-card coupled with the tank process and a personal computer. Signals between the card and the tank process are analog voltages. Automation control is achieved using RegSim which is a piece of software running on the PC. In order to eliminate the expensive DAC-card and to be able to control the system with MATLAB instead of RegSim, Rubico AB has determined that a digital interface is also desired.The hardware platform, which is pre-determined by Rubico AB, is based on the NXP LPC11U14 microcontroller. This platform specifies that communication between the tank process and PC is USB. On top of that, the platform also states that the existing analog interface should remain.This thesis is devoted to examine which USB class is best suited for the task, and, to implement USB software in the existing system. The thesis also attend to discrete time PID-control for the tank process via MATLAB and a graphical user interface.The result of the investigation is that the software standards VISA and SCPI are suitable to use in conjunction with USB-devices of the Test and Measurement Class (USBTMC). A brief explanation of the standards are included in the report. The thesis also states why these standards were chosen and how they were implemented or used. Validerat; 20130410 (global_studentproject_submitter)