Endurance Test System for Safety Belt Pretensioners

An endurance test system was developed for a car industry supplier; this tester is custom made for two pairs of safety belt pre-tensioners with continuous recoding and monitoring of electrical and mechanical values as well as CAN-messages. The endurance run is executed over a time period of up to 90 days under various climatic conditions. The climate-chamber software allows execution of different climate profiles with corresponding test sequences.


  • Easy implementation
  • Low cost
  • Scalable and flexible assembly Platforms
  • Modular systems
  • Real time compatibility
  • Reusability in Production


  • Acquisition of four length, force and temperature signals, separately for each one of the four belt pre-tensioners
  • Measurement of supply voltage and current consumption in different measurement ranges, from min. 1mA to max. 50A for each one of the four belt pre-tensioners
  • Implementation of specific firmware on the NI-CAN board in order to simulate realistic environment conditions in the vehicle
  • Logging for all arising data
  • Control for a climate chamber
  • Porting of all existing sequences from NI LabVIEW to NI TestStand as well as parameter-based test steps
  • Script-Editor based on tables for the simplest creation of endurance test sequences
  • Sequential control of the two pre-tensioner pairs, so that one GPIB-controlled 20V/120A power supply adapter is sufficient for peak currents of up to 50A per pre-tensioner 


The endurance test system consists of one 19" rack, 40U tall, which include

  • The industrial PC with data acquisition board
  • CAN interface and GPIB controller
  • Keyboard and mouse are also integrated into the rack, through a keyboard drawer, as well as the 17" touch screen monitor.
  • Further space is occupied by the Konrad power supply unit, the Agilent 20V/120A adapter and the UPC.
  • Additional custom made hardware was integrated in a 6U 19" slot module, including four Konrad current measurement modules and the signal conditioning system NI SC-2345 with measurement transducers for force and temperature signals.
  • All plugs for the pretension and sensor power supply have been integrated into the front panel of this slot module. The rack also offers the possibility of extension by a second industrial PC, if the user wishes to add a CAN-rest bus simulation. If necessary, the unused space in the rack may be used for controlling a third pair of belt pre-tensioners.
  • The 24 analog values are acquired at a maximum sample rate of 1 kHz; the 36 CAN signals at 100Hz.
  • The measurement values are time-synchronized, so that signal variations from the external sensors can be compared to the pre-tensioner sensors. A Measurement Server-PC collects the data of all three test rigs and presents these for evaluation, while data acquisition is still active.


  • NI TestStand: Sequence control Editor, Debugger
  • NI LabVIEW: Test Step libraries
  • KT-Operator Interface: Operator interface Debugging
  • KT-Project: Test step library Functional test
  • Custom developments: Konrad Endurance Test Software, Konrad Climate Chamber Software


PCI-based test system


  • NI PCI-6259 16Bit, 1MS/s, 32 single-ended analog inputs
  • 48 Digital-I/O, 4 analog outputs
  • Signal conditioning system NI SC-2345:
  • SG-24 for force sensor acquisition
  • TC-02 for temperature acquisition
  • 4x KT current measurement modules,
  • measurement range: 1mA to 50A
  • Measurement range change via 4 TTL digital inputs
  • Output voltage: 0 to 5V
  • Measurement accuracy: 1% full scale.
  • Custom-specific hardware control
  • NI PCI-6528 24 digital I/O.


  • 2 x NI PCI-8461/2 Series 2, high-speed CAN 2 port, 1MBit/s
  • NI PCI-GPIB interface.
  • Power adapter and energy supply
  • Agilent 6031A 20V / 120A, controlled via GPIB
  • KT power supply unit.


  • Pretensioner-specific recording for force and length measurement, suitable for operation within a climate chamber.


Customer-specific hardware interface with all electronics and connections for the original cable tree of the pretensioner, connections for length, force and temperature sensors

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