What Happens When Millions of Test Cycles Run in an Automotive Test Rig?

Learn how a dual watchdog architecture using LabVIEW and NI Compact RIO monitors PC, controller, communication and test parameters during millions of durability cycles running in an Automotive Test Rig

PROLABS team

9/30/20262 min read

A rack and pinion, steering column, EPS system, drive shaft, ball joint or universal joint may undergo hundreds of thousands or millions of durability cycles.

During that time, the test system is also working continuously:

  • LabVIEW test application

  • Industrial PC

  • NI Compact RIO real-time controller

  • DAQ and sensors

  • Servo/actuator system

  • Communication network

  • Data logging

  • Cycle counting

  • Limit monitoring

    What happens if the PC hangs at Cycle 782,463?

    What happens if communication between the PC and cRIO is lost?

    What happens if torque, force, temperature or pressure suddenly exceeds the test limit?

    And who stops the machine if the software responsible for running the test stops responding?

This is where a Dual Watchdog Architecture becomes important.

Why Does an Automotive Durability Test Need a Watchdog?

A conventional test application assumes that the computer and controller will continue operating correctly.

But long-duration testing introduces additional risks:

PC failure
LabVIEW may freeze, crash, or Windows may become unstable.

Communication failure
The Ethernet connection between the Industrial PC and real-time controller may be interrupted.

Controller failure
The Compact RIO may stop responding or encounter an unexpected fault.

UUT failure
The automotive component may fail during the test.

Out-of-limit condition
Torque, force, temperature, pressure, position or other parameters may exceed their defined limits.

Cycle-count uncertainty
If the PC stops unexpectedly, relying entirely on the PC for the cycle count can compromise test traceability.

A million-cycle test needs more than a test application.

It needs continuous supervision of the test system itself.

What If the PC Freezes?

Imagine the test is running at: 782,463 cycles

The Industrial PC suddenly becomes unresponsive.

The PC and cRIO exchange periodic heartbeat messages containing sequence information, test state and health status. Each watchdog monitors the expected response within a defined timeout. If the handshake is interrupted or an abnormal condition is detected, the watchdog changes the system to its predefined fault state and records the last known test information.

Cycle: 782,463
Fault: PC Heartbeat Timeout
cRIO: Healthy
Test State: Running

One Watchdog Is Good. Two Watchdogs Provide Mutual Supervision.

The fundamental philosophy is:

PC Watchdog ↔ cRIO Watchdog

They continuously supervise each other while the machine performs the actual endurance test.

The architecture can be reused for:

Developed and Tested by PROLABS

The Dual Watchdog Architecture has been developed and successfully tested by PROLABS using LabVIEW, providing an additional layer of supervision for long-duration real-time automotive test systems.

The concept can be implemented as a reusable LabVIEW watchdog module and integrated into suitable existing or new automotive durability test rigs.