Introduction

SimApp is a software tool for evaluating and optimizing automatic control systems in the time and frequency domain. It is based on the idea of block diagrams. The modeling of the systems is done visually simply by some mouse clicks. The numerous block-diagram elements are selected from the object palette and connected in the drawing.
With SimApp you can perform control systems analysis in the frequency (Bode and Nyquist plots, eigenvalues) and time domain. The use of probes gives you the ability to simulate several different subsystem at the same time and to compare the results.
The data of the simulation process are displayed in the form of scalable diagrams and data tables. You can copy all data and diagrams via the Windows clipboard to other applications. Create your own blocks for frequently used systems or subsystems and give them their own symbol and parameter list. Store them in toolbars and libraries.
SimApp is a powerful tool for students, technicians, engineers and scientists, who set great store by easy and intuitive operation.

Picture: SimApp Desktop

Simulation in the time domain

SimApp is designed for the simulation of linear and non linear, time-invariant and time-varying, continuous and discrete times, SISO (single input single output), and MIMO (multiple input and multiple output) control systems. The output data are listed in tables and plotted in scalable time diagrams and x/y graphs.
The sources are the inputs of the dynamic system which include constants, sine waves, step functions, etc. and custom defined characteristics. Sources in a system can be divided into groups for different system stimulations, where as the results can be compared in one single diagram.
Diagrams can be zoomed and printed out. A movable cursor helps you in measuring the signals at individual time points. The results can be stored along with the block diagram.

Simulation in the frequency domain

For linear and time-invariant systems, SimApp creates Bode- and Nyquist diagrams and a table with the eigenvalues of the evaluated control system. Special frequency probes serve to determine different subsystems to be evaluated and compared in the same diagrams, e.g. the open and closed-loop characteristic. You can apply the sinusoidal test signal and determine the input and output points of subsystems without breaking up the system.

Standard block diagram elements

SimApp has numerous basic blocks that are selected in the object palette simply by clicking. They are interconnected by wires to complete systems. Most basic blocks have two alternative symbols. The standard symbol shows the step response, the frequency plot or the graphical representation of the transfer function. The mathematical notation of the transfer function serves as an alternative.

Drawing capabilities

SimApp has similarites to simple drawing tools. In fact, for building block diagrams you need a lot of drawing facilities. Besides block diagram elements, you can draw lines, polylines, polygons, rectangles, ellipses, write formatted text and include pictures. With all these additional objects, you can illustrate your drawings and produce symbols for user blocks. The drawings can be zoomed and unzoomed by a factor of 10. They may consist of several printing pages. Transfer the drawings via the Windows clipboard to other applications. SimApp has a multiple document interface, i.e. you can open and edit several drawings simultaneously. The multithreading capability lets you start several long time simulations while working on other block diagrams at the same time.

User defined blocks

The object palette has numerous basic blocks and drawing tools that can be used in any field. In practice however, you have various subsystem you need over and over with different parameter values. For the sake of clearness, it is also often desirable to condense a large group of wired blocks into one single element.
With SimApp you can do both. You can select several objects in the drawing (block diagram elements or drawing objects) and transform them to one single block. All interconnections inside the group and to external blocks are preserved. All parameters of the included blocks appear under the new block symbol which can be displayed or hidden alternatively.
Use the block folder if you wish new blocks with special parameters and own symbols. The block folder consists of a symbol window, a system window and a parameter table. The parameters of the individual elements inside the user block can be combined by a formula editor to new block parameters.
The symbol of the blocks are designed in the symbol window. All that together build a new block that can be used like a basic block. Store it into the palette or into a SimApp library.

Object palette and libraries

The object palette consists of several pages that store block diagram elements and tools for drawing shapes. You can expand the palette by creating new pages and storing more objects. Objects can be single blocks, drawing shapes, selected or combined groups of drawing objects, user blocks, i.e. all you can create with the drawing capabilities of SimApp. Each new single object in the palette is given a button labeled with text or a picture and showing a tool tip when moving the mouse pointer over it.
Libraries serve as an additional object container. You can create libraries in any number. They behave as standard toolbars and can be stored on disk and distributed to other users. Selected objects or groups of objects can easily be moved or copied to the palette or into an open library being under construction.
With all these features you can fit SimApp to different fields of application.

Generic building blocks and drawing tools

• Sources: Constant, Ramp, Step, Oscillator, Pulse, Pulse width modulator, Timer, Trigger, Driving curve, Noise, User defined, File
• Graphs: Time Probe, Frequency Probe, XY Graph
• Linear: Proportional, Integrator, Differentiator, DT1, PT1, PT2, PT1T2, PTn, Lead/Lag, G(s), Dead Time (PTt, with Padé approximation), 1. Oder and  2.  order allpass, Linear differential equation system.
• Nonlinear: Square, Square-root, Multiplier, Divider, Arithmetic, Multi-function element with single input and 31 selectable distinct functions (sin, cos, tan, cotan, asin, acos, atan, sinh, cosh, tanh, asinh, acosh, atanh, exp, 2^x, 10^x, x^2, x^3, ln, lb, lg, x^A, A^x, logA, Square Root, |x|, sign, DegRad, RadDeg, CycleRad, RadCycle), Multi-function element with two inputs and 10 distinct functions (+, -, :, /, x^y, x^1/y,Sqrt(x^2+x^2),arctan(x/y),Min(x,y),Max(x,y)), User characteristic, Saturation, Dead Zone, Preload, Backlash, Minimum/Maximum, Peak detector.
• Controllers: 2-point and 3-point step, PI Controller (ideal und modified), PD Controller (ideal und real), PID Controller (two ideal implementations and three real respectively modified implementations, anti-windup), Adaptive PID controller, Lead/Lag Controller.
• Time discrete: Sampler,Zero order hold, Sample and hold, Integrator, differentiator, Unit delay, PID controller, G(z), Filter, Linear difference system.
• Converters: Analog to digital (ADC), Digital to analog (DAC), Analog to binary (ABC), Binary to analog (BAC), Quantizer.
• Logic: Logic 0  source, Logic 1 source, AND, OR, XOR, NOT, SR Flip-Flop, JK Flip-Flop, D-Flip-Flop, Monoflop, On/Off delay
• Miscelaneous:  1:2 and 2:1 Switch, 1:n and n:1 Multi-switch, Triggered sample and hold, Controllable delay, Relation, Window comparator, Zero crossing, Step ramp.
• Special: Transmitter and Receiver.
• Drawing Tools: Lines, Polylines, Rectangles, Ellipses, Polygons, Pictures.

System requirements

• IBM compatible Personal Computer
• Windows 95/98/NT-SP6/2000/XP
• 8 MByte RAM und 40 MByte free disk space
• Mouse or other pointing device
• Colour monitor, VGA or better
• Installed printer