Nonlinear Control Systems Simulation Using Spreadsheets

In this paper, a method for simulating nonlinear control systems using spreadsheets is presented. Various nonlinear blocks are simulated using graphics and cell formulas, and are generated by clicking on specially developed toolbar buttons. These blocks can be connected to one another using a simple and intuitive procedure again based on graphics and toolbar buttons. A complete nonlinear system can thus be created by generating and connecting its constituting basic blocks, using the simple graphics interface provided. The corresponding data may then be entered in the familiar manner as illustrated, and finally the system can be simulated literally at the click of a button. Such a system can be analyzed by calculating its time response to any input signal or by using other methods such as phase-plane trajectories. The simulation is characterized by its availability, flexibility, and simplicity. The paper provides several examples to illustrate the simulation capabilities available. The first example considers a servo with a dead-zone and a saturation amplifier, the second illustrates the steps required to obtain a phase-plane trajectory, and the third example considers a nonlinear system having a PI controller and nonlinearity consisting of soft saturation. The final example illustrates a relay-controlled servo system.