# Control System Calc — PID Tuning & Bode plot

> PID Tuning & Bode plot (iPhone/iPad app by 洋 刘.)

- Source: https://appshunter.io/ios/app/control-system-calc/id6791956580 (this page in markdown: same URL + `.md`)
- Developer: [洋 刘](https://appshunter.io/developer/6775317751)
- Category: Utilities, Education
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 6 MB
- Languages: American English, German (Germany), Japanese, Chinese (Simplified, China)
- Released: 2026-08-18
- Data updated: 2026-09-15
- User reviews in markdown: https://appshunter.io/ios/app/control-system-calc/id6791956580/reviews.md

## What is Control System Calc?

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. All calculations run locally on your device, no internet required.

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.

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 CSV data export
Buy once, keep forever. Family Sharing supported.

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.


## Version history (last 1 release)

### 1.0 — 2026-08-18

No release notes.

## More apps by 洋 刘

- [CANviewer](https://appshunter.io/ios/app/canviewer/id6775532457)
- [J1939FaultCode](https://appshunter.io/ios/app/j1939faultcode/id6778431735)
- [Signed Base Converter](https://appshunter.io/ios/app/signed-base-converter/id6779268811)

All apps by 洋 刘: https://appshunter.io/developer/6775317751

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-15.*