Technical interview guide

Control Systems & PID

The feedback loop that keeps a robot at a target state — proportional, integral, and derivative control, and why all three matter.

Read: 45 min
Practice MCQs: 25
Interview QA: 25
Edition: v4
Editorial status: Reviewed
Relevant for: Robotics Engineer

Scope: Current MathWorks, NI, Rockwell Automation, Arduino PID, python-control, SciPy, NIST SP 800-82 Rev. 3, IEC functional-safety, and OSHA guidance reviewed 2026-09-04.

Interview QA

Treat each question like a live interview question: answer out loud first (structure, assumptions, tradeoffs), then open the model answer to spot gaps and rehearse a tighter follow-up.

Curated: 2026-10-05 · Written: 2026-09-09 · Reviewed: 2026-10-03

QA-1

Choose open-loop or closed-loop control for a process.

QA-2

Explain P, I, and D contributions and tradeoffs.

QA-3

Design integral action for a biased process.

QA-4

Design derivative action without excessive noise or setpoint kick.

QA-5

Shape setpoint response separately from disturbance rejection.

QA-6

Commission feedback sign and direction safely.

QA-7

Design timing for a digital PID loop.

QA-8

Make PID gains and sample time configuration safe.

QA-9

Migrate a PID tune between controller implementations.

QA-10

Implement and test anti-windup.

QA-11

Design manual-to-automatic and restart transitions.

QA-12

Specify output, rate, and operating-envelope constraints.

QA-13

Add feedforward to a feedback loop.

QA-14

Design and tune a cascade control system.

QA-15

Control a process with substantial dead time.

QA-16

Define control performance acceptance criteria.

QA-17

Use gain and phase margins in controller validation.

QA-18

Plan a safe controller identification and auto-tuning procedure.

QA-19

Design and validate gain scheduling.

QA-20

Design controller behavior for sensor timeout and bad quality.

QA-21

Secure setpoint and mode changes in an OT control loop.

QA-22

Separate basic process control and protective functions.

QA-23

Design observability for control-loop diagnosis.

QA-24

Define control-loop performance and reliability metrics.

QA-25