Soft Shutdown satellite Qualification Safety System

A Vibration Test System that Protects Against the Unexpected

From the ground up, Data Physics and NVT Group partner company Team Corporation have engineered and refined a test safety system capable of protecting valuable test articles from unexpected events – even a complete loss of 480 V power. Complete design control of all components – vibration controllers, shakers, amplifiers and accessories – ensures the system’s exceptional ability to detect potential failures and reliably protect valuable flight hardware.

Ready for all Contingencies

The soft shutdown safety system executes a controlled, transient-free shutdown during in all test stop conditions – those that are predictable and those that are typical unpredictable. These include:

  • Complete, sudden loss of 480V power to the amplifiers
  • Hydraulic pressure loss for guidance bearings
  • Control PC crash or power loss
  • Amplifier trip on overcurrent, overvoltage, or over travel
  • Typical control or limit/notch tolerance abort
  • External measurement system abort trigger
Electrodynamic Shakers from Data Physics

How the System Works

Data Physics’ and our NVT Group partner company Team Corporation’s complete design control of all components – vibration controllers, shakers, amplifiers, guidance bearings, and accessories – enables us to develop a comprehensive safety system with all components working together to protect the test article.

All shutdowns – whether triggered by an interlock, loss of power, or a tolerance abort – are executed by the vibration controller.

Each component in the soft shutdown system has been modified to handle failures gracefully – they signal the controller to shut down instead of abruptly stopping on their own.

Each component is also over designed, and able to execute the soft shutdown after a normally-catastrophic failure, such as a loss of 480V power.

Previously Independent Subsystems, Now Functioning in Unison

satellite vibration qualification safety system soft shutdown

Shaker/Amplifier Synergy

The Shaker/Amplifier in a SoftShutdown system gracefully handle interlocks and power loss conditions.
  • All interlock signals controller to immediately trigger a soft shutdown
  • Interlocks do not abruptly shut down the amplifier – they gradually shut down the field allowing time for a soft shutdown
  • 480V power health is continually monitored – and any failure triggers the controller to shut down
  • Amplifier fitted with extra capacitors to function after 480V power failure
Data Physics Power Amplifier Gain closeup
Vibration test table at NASA's Goddard Space Flight Center

Hydraulic Guidance

Hydraulic pressure health monitored electronically at key locations.

  • A drop in hydraulic pressure signals the controller to immediately trigger a soft shutdown
  • Hydraulic system is fitted with extra accumulators to function in the case of any failures or loss of power

Vibration Controller

The vibration controller plays a critical role in the Soft Shutdown system – it controls every ramp down regardless of what triggers it.

  • All shutdowns – whether triggered by an interlock, loss of power, or a tolerance abort – are executed by the vibration controller.
  • The vibration controller is optimized to initiate the ramp down quickly – with minimal latency
  • The controller executes a controlled ramp down in a pre-defined time
  • The pre-defined ramp down time ensures the amplifiers’ extra capacitors will not run out of charge ; and the hydraulic accumulators will not lose pressure in the event of a 480V power loss
Vibration Controllers from Data Physics

Analysis System

A 900 Series measurement system is an additional part of the soft shutdown system; monitoring hundreds or thousands of channels. The measurement system can quickly trigger the controller to issue a soft shutdown, based on the acquired data.

  • Sine Data Reduction – Control / Abort profiles can be entered into the Analyzer; and the Analyzer can trigger the Controller to shut down if any tolerances are exceeded.
  • Monitor (gap-free) for Transients – To trigger a soft shutdown if any are detected.
  • Multi-Measurement – run secondary measurements (such as FFTs) live during a test.  Generate waterfalls live during test to visualize harmonic distortion, for example.  All without the need to post process. 

Cutting the Power

During execution of a Sine sweep on a 50,000lbf shaker, the 480V power was abruptly cut.  One would expect to see a large transient imparted onto the armature, with potentially damaging results.  But that did not happen here – this is a soft shutdown shaker system. 

Below is data from that test. The test was performed on a Data Physics soft shutdown vibration test system. The system utilized a 50,000 lbf. electrodynamic shaker, a SignalForce power amplifier, and was driven by our controller. The plots show the controller’s drive output; the acceleration measured at the armature, and the voltage driving the armature. The test was ramped down, imparting no transients onto the armature.