PLM, Control Design

Best practices matter when designing control systems

When lives depend on control system design (and even when they don’t), best practices matter. Here’s what I’d like control system designers to know.
By Mark T. Hoske November 13, 2019
Operators always need a clear view of what’s happening. Courtesy: Mark T. Hoske, Control Engineering

When lives depend on an automated control system, the system should fail safely. When components fail in a control system, operators should receive clear, immediate guidance on status so proper decisions can be made immediately in manual mode. If a set of circumstances could occur where the failure of one sensor causes a control system failure before operators can recover safely, then the system needs a sensor backup or two to provide data instead. Best two-out-of-three voting designs decrease risk.

Education and training matter

Information continue to emerge in the Boeing 737 Max grounding, and some details seem contrary to what was said earlier. Through it all, I keep thinking:

  • People get degrees in control engineering for a reason.
  • People earn safety certifications for a reason.
  • Listen to people with training and experience who use standards and best practices.
  • Listen to operators who know the process.
  • If you see something that doesn’t seem right, and lives (and/or livelihoods) depend on it, be a whistleblower.

Before I get onto another Boeing 737 Max, I will find out if there’s a backup angle of attack sensor also delivering measurements and what happens to the control system when that sensor and/or the backup sensor fails. If I don’t like the answer, I’ll think again and book another aircraft.

Mark T. Hoske is content manager, Control Engineering, CFE Media, mhoske@cfemedia.com.

KEYWORDS: Critical control systems, safety systems, single point of failure

Control system design best practices

Safety system design best practices

Be a whistleblower if something doesn’t look right.

CONSIDER THIS

Will you be a whistleblower when lives and/or livelihoods are on the line?

Control Engineering has many articles on related topics; it’s hard to pick a few.


Mark T. Hoske
Author Bio: Mark Hoske has been Control Engineering editor/content manager since 1994 and in a leadership role since 1999, covering all major areas: control systems, networking and information systems, control equipment and energy, and system integration, everything that comprises or facilitates the control loop. He has been writing about technology since 1987, writing professionally since 1982, and has a Bachelor of Science in Journalism degree from UW-Madison.