CtrlSolve — Interactive Bode, Nyquist, and Response Plots

Preview: interactive control plots in the browser

CtrlSolve is a small, self-hosted control-systems helper: type a transfer function G(s), then generate key plots and response curves instantly.

It’s designed for quick sanity checks (stability, margins), lightweight design exploration, and classroom-style demonstrations without heavy tooling.

Plots: Bode (magnitude in dB + phase), Nyquist, Nichols, pole–zero map, root locus.
Time-domain responses: step, impulse, and ramp response curves.
Stability summary: stable/unstable, gain margin (GM) and phase margin (PM).
Extra details: zeros/poles list and a state-space realization (A, B, C, D).
Accepts LaTeX-style input and automatically simplifies/expands many common expressions.

Transfer function G(s)

\frac{10}{s^2 + 2s + 10}

Closed-loop analysis (Feedback)

Controller Design

Controller type Kp Ki Kd Filter tau Gain Zero Pole Time range Omega range

Time Domain

Step Response

Impulse Response

Ramp Response

Frequency Domain

Bode Plot

Nyquist Plot

Nichols Plot

Stability & Design

Pole-Zero Map

Root Locus

Named I/O Interconnect

Build closed-loop systems from named blocks and connection tables.

Minimal SISO Closed-Loop Wizard

Plant P(s) num Plant P(s) den Controller C(s) num Controller C(s) den Feedback sign

r → Σ − → C(s)1 / 1 → P(s)1 / 1, 1 → y

feedback -y

Systems

Num Den

Connections

External Channels

Input Output Analyze

Validation

State Space

Enter A, B, C, D matrices and prepare state-feedback design workflows.

Matrices

A B C D

Model

Name Sample time Input names Output names

Analysis

Input channel Output channel Time range Omega range

Design

Method Q R

LQR / Kalman Closed-Loop Noise Simulation

LQR Q LQR R Kalman G Kalman QN Kalman RN Kalman NN Initial state Initial estimate State reference Input feedforward Duration Samples Process noise std Measurement noise std Random seed

Nonlinear

Explore phase-plane behavior for curated nonlinear system templates.

Model

Template Parameters Constant input Streamline direction

Phase Plane

Window Vector grid Initial states Duration Samples

Time Series

Initial state Duration Samples

Bifurcation

Parameter Parameter range Initial state State index Duration Transient Samples

Poincare

Initial state Duration Transient Samples State index Section value Direction Return state index

Lyapunov Scan

Parameter Parameter range Initial state Duration Transient Samples Perturbation

Validation

Data

Preview CSV and FRD-style data before identification or frequency analysis.

Import

t,u,y
0,0,0
0.1,1,0.05
0.2,1,0.14
0.3,1,0.26
0.4,1,0.39
0.5,1,0.52

Mapping

Delimiter Has header Preview rows Time Inputs Outputs

Identification

Method Input column Output column

Preview

Report

Collect model inputs, summaries, plots, and notes into a shareable analysis report.

Report Preview

CtrlSolve analysis

Run a classic analysis or save a workspace draft and the latest summary will appear here.

Preview: interactive control plots in the browser

Controller Design

Design Result

State Space

Zeros & Poles

Sensitivity & Robust Performance

Step Response

Impulse Response

Ramp Response

Bode Plot

Nyquist Plot

Nichols Plot

Pole-Zero Map

Root Locus

Named I/O Interconnect

Minimal SISO Closed-Loop Wizard

Systems

Connections

External Channels

Validation

Analysis Result

Step Response

Impulse Response

Ramp Response

Bode Plot

Nyquist Plot

Nichols Plot

Pole-Zero Map

Root Locus

State Space

Matrices

Model

Analysis

Design

Analysis Result

Structural Diagnostics

Model Reduction

Reduction Result

Step Response Comparison

Bode Comparison

Design Result

LQR / Kalman Closed-Loop Noise Simulation

Closed-Loop Simulation Result

Step Response

Impulse Response

Ramp Response

Bode Plot

Pole-Zero Map

Nonlinear

Model

Phase Plane

Time Series

Bifurcation

Poincare

Lyapunov Scan

Validation

Analysis Result

Phase Portrait

States over Time

Parameter response

Poincare Section

Largest Lyapunov Exponent

Data

Import

Mapping

Identification

Preview

Identification Result

Report

Report Preview