Bode plot
Bode plot of 11th order Butterworth filter

VisSim/Analyze lets you perform a frequency domain analysis of a VisSim model or subsystem. It helps answer the question "Is this a stable system?" VisSim/Analyze approximates the dynamics of a nonlinear system by linearizing the system about a specified operating point. Linearized systems can be represented in ABCD state space or transfer function form. With VisSim Analyze, you can easily access transfer function information; edit zeros and poles; and compute Nyquist, Bode, and root locus plots.

Interactive Controller Design

Designing a controller for a plant model is performed interactively by editing compensator zeros and poles, and observing the combined controller-plant behavior in Bode and root locus plots. Once the desired responses are obtained, the resulting controller block is simply inserted into a VisSim diagram.

Root Locus
Root Locus plot of 11th order Butterworth

The preliminary pole placement controller is connected to a plant model creating a feedforward or a feedback control loop. A simulation is run in VisSim and the results of the simulation are easily viewed in graphical plots. The stability of the closed-loop system can then be determined using Nyquist plots.

Compensator Design

VisSim/Analyze also features a compensator design capability that lets you interactively design feedback control systems. You edit the poles and zeros of the compensator transfer function in a floating window. In return, VisSim/Analyze automatically updates the Bode and root locus plots of the combined plant-compensator system to reflect the effects of the pole and zero manipulation. Once you attain the desired response characteristics, you can place the compensator in the VisSim diagram.

Analysis of Discrete Transfer Functions

VisSim/Analyze supports analysis of discrete transfer functions. This lets you effectively handle the most general closed-loop system scenarios where a plant is modeled as a continuous dynamic system and the controller is a discrete (sampled data) system suitable for easy implementation on micro-controller hardware.


  • Approximates the dynamics of a nonlinear system by linearizing the system about a specific operating point
  • Generates ABCD state-space matrix (screen display or .M/.MAT file exportation)
  • Performs numerical perturbation for creating SISO ABCD state-space matrices
  • Calculates transfer function information, including numerator and denominator polynomials in the powers of the s-plane; gain, zeros, and poles locator; and cleansing of numerical round-off errors
  • Computes Bode phase and magnitude plots, root locus plots, and Nyquist plots
  • Provides interactive compensator design
  • Analyzes discrete transfer functions
  • Generates gain and phase margin


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