Bode Plot App vs Control System Calc

Bode Plot makes it easy to create Bode diagrams just by entering a transfer function. Visualize frequency response and compare multiple functions on the same graphs. Enter transfer functions, including complex expressions such as G(s)=100/(s*(s+1)^2). Gain (20log₁₀|G(jω)|) and phase (∠G(jω)) plots are generated automatically. Overlay multiple transfer functions in different colors to compare their gain and phase characteristics at a glance. Use sliders to adjust the frequency range and the number of plotted points. Your transfer functions are saved on your device so you can continue where you left off.

Control System Calc (ControlCalc) is an engineering tool for control engineers, R&D staff and students. Enter a transfer function to perform PID tuning, frequency-domain analysis and time-domain simulation — turning textbook control theory into a pocket tool you can use anywhere. Core calculations run locally on your device; ads, purchases and purchase restoration require a network connection. KEY FEATURES ■ PID Tuning Five classic tuning methods built in: Ziegler-Nichols open-loop step, Cohen-Coon, Ziegler-Nichols closed-loop ultimate, plus IMC-Lambda and AMIGO. Each method includes guidance on when to use it. ■ Closed-Loop Step Simulation Simulate the closed-loop step response with an FOPDT model and a PID controller with derivative filtering. View the control effort u(t) to spot actuator saturation, and fine-tune parameters by hand. ■ Bode Plot & Stability Margins Draw magnitude and phase curves on a log scale, with automatic 0 dB / −180° reference lines, gain margin, phase margin and crossover frequencies — stability at a glance. ■ Step Response & Performance Metrics RK4 time-domain simulation that automatically computes overshoot, rise time and settling time. ■ Second-Order Designer Back-solve system parameters from overshoot Mp / settling time ts, or from damping ratio ζ / natural frequency ωn, then push them to the step-response page in one tap. ■ Root Locus & Nyquist (Pro) Root-locus branch tracing with the imaginary-axis stability boundary, an equal-aspect Nyquist plot with unit circle, plus pole/stability analysis for deeper insight. ■ Complete Analysis Example Follow one fixed model from step response and frequency response through Nyquist and root locus to understand what each analysis reveals. The example never reads or changes your model. ■ CSV File Export (Pro) Export the full Bode or step-response samples as an actual .csv file. Save it to Files or share it to an Excel, MATLAB or Python workflow. THOUGHTFUL DETAILS • Built-in library of classic example models — tap to load and go • Draggable readouts on time-domain curves (live t / y display) • Numeric keyboard with a Done button; input parameters persist automatically • Simplified Chinese / English / German / Japanese, switchable in-app instantly PRO UPGRADE (one-time purchase) • Removes all ads • Unlocks IMC-Lambda / AMIGO tuning methods • Unlocks Nyquist plot, root locus and pole/stability analysis • Unlocks Bode and step-response CSV file export Buy once, keep forever. No subscription. WHO IS IT FOR Control, electrical, mechatronics and process engineers, R&D and commissioning staff, students taking control-theory courses, and anyone who needs to quickly validate a control-system design. DISCLAIMER All results are provided for engineering reference only. Real-world system design and commissioning should combine field conditions with professional judgment. Have feedback or questions? Contact us from the Settings page.