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Customer Solutions

Team Torsional Vibration Damper Test System

Author(s):

Naresh Shenkeshi, VI Engineering

Industry:

Automotive

Product:

LabVIEW, PXI/CompactPCI

The Challenge:

Develop a turnkey system to interface with an Engine Simulation System Controller designed for use with the Torsional Vibration Test System developed by TEAM Corporation. The system requirements include: performing various torsional vibration tests on the parts connected or used in the engine assembly, perform data acquisition, graphical display of results, waveform generation, phase detection, PID control, data saving and report generation.

The Solution:

A LabVIEW based application has been developed, which performs data acquisition and the control of the test stand through a PCI-MIO-16E-1 and PCI-6713 DAQ cards. National instrument LabVIEW software and the NI hardware is integrated into the Torsional Vibration Damper Test System developing a complete turnkey system.


Introduction
TEAM Corporation a major vibration test equipment provider located in Burlington, Washington approached V I Engineering, Inc., a premier National Instruments Alliance Member and Select Integrator for replacing their manually operated hardware controlled test system with a cost efficient and robust automated turnkey software system.

VI Engineering developed a PC-based machine control software written in National Instruments Lab VIEW Version 5.1 for controlling, monitoring and performing various automated tests on the TEAM Torsional Vibration Damper Test System. The Test stand simulates vibration conditions in the engine and is used to find resonant frequency and durability characteristics of the parts used or connected to the engine. The software allows for calibration of the signals, test setups, execution of selected tests and report generation apart from waveform generation, phase detection and PID control. The data acquisition and the control of the test stand are achieved through a PCI-MIO-16E- 1 and PCI-6713 DAQ cards. The developed LabVIEW software and the NI hardware is an integral part of the test system, and it is sold as a complete turnkey system.

Salient Features of Team Vibrational Test System

  • Login/Password security function to allow for security levels within the software.
  • Calibration utility for calibrating the signals connected to the test system.
  • System switches to control the rotational motor and hydraulic pump.
  • PID Tuning utility for system tuning to perform closed loop tests for up to three PID loops running simultaneously.
  • Test Setup for five different tests.
  • Bessel filter settings for each individual channel.
  • Manual mode to independently control Hub Amplitude, Frequency and Rotational Speed.
  • View Old data utility for plotting x-y graphs of data from past tests.
  • Report Generation utility for generating reports on tests performed.

Overview of Team Vibrational Test System
The test system consists of a hydraulic system, an actuator drive and a rotating drive. The hydraulics is controlled using digital I/O on the NI DAQ Card. The actuator is controlled through a sine wave generated from a PCI-MIO-16E- 1, which shakes the test parts at desired amplitude and frequency. The rotating drive is controlled by a PCI-6713 DAQ card. Accelerometer signals are used to read Hub and Ring amplitudes in g’s and a speed sensor reads the rotating drive speed. The phase difference between the Hub and Ring is calculated using software algorithms. Two CA-1000’s stacked on top of one another provide a clean interface for all I/O signals, terminal blocks, and accessories.

PID Tuning
A dedicated PID tuning screen is used effectively to tune each PID loop within the application. The test system controls the following parameters: hub amplitude, phase control between hub and ring, and temperature control. Hub amplitude is controlled through the amplitude and frequency of the sine wave generated. The phase difference between ring and hub is controlled through the frequency of the sine wave. Temperature control is achieved through control of the phase difference between the hub and the ring. The closer the phase difference of the hub and ring gets to resonance, the hotter the part gets. The further away the system gets to resonance, the cooler the part gets. The data acquisition ( DAQ) has loop times of 33ms to assure accurate PID control of up to 3 PID loops running simultaneously.

Rotating Durability Test
Rotating Durability test is one of the 5 different tests. In this test, the test sample is subjected to desired torsional vibration amplitude selected by the user. These vibrations mimic the real world engine firing pulses. With the test sample being subjected to torsional vibration the sample is rotated at the desired speed entered by the user corresponding to real world engine RPM. The drive frequency is adjusted to maintain the specified rubber temperature or phase shift for desired duration, as selected on the Setup Screen.

Performance and Challenges

Software Phase and Amplitude Detection
Originally, the system had hardware tracking filters to filter the signals from the accelerometers, plus a circuit board to give the phase difference between the hub and ring accelerometer signals. The tracking filters we quite expensive. Team Corporation requested to replace the hardware tracking filters and phase detection board with software algorithms to keep the system compact and save the cost on the hardware, so V I Engineering implemented a software solution using LabVIEW. The software dictates the frequency output to the actuator drive. The frequency sent out is used to calculate the low and high cutoff frequencies of the Bessel coefficients and number of points of the waveform based on the sampling rate. When at least 1.5 cycles of data are collected, they are sent to the phase and amplitude detection algorithm, which out puts the phase difference between the hub and ring signals plus their respective amplitudes. Phase and amplitude algorithms were integrated into the system successfully eliminating the need of the hardware tracking filters and phase detection saving TEAM Corporation money and man-time.

Amplitude Control of Generated Sine Wave
As the control of the actuator drive is achieved through the frequency and amplitude of the sine wave, continuous amplitude and frequency control of the generated sine wave was needed. This is achieved by loading one sine wave into the FIFO buffer, continuously regenerate this sine wave, and use external referencing of the generated sine wave. An analog output from a different DAQ board is connected to the external reference pin of the first DAQ card, thus it changes the amplitude of the sine wave without having to reconfigure each time the amplitude needs to change. By using one of the lower level clock vi’s in LabVIEW, we are also able to change the frequency of the analog output sine wave. In order to have better resolution on the frequencies, an alternate clock setting of 20MHZ was used for the internal clock.

Summary
VI Engineering has developed a cost efficient turnkey system by integrating National Instruments hardware and software into the Team Torsional Vibrational Test stand thus replacing the expensive hardware for generating and controlling the sine wave, peak detection with tracking filters and phase detection with custom phase detector board and provided a user friendly software system for performing various tests to determine the characteristics of the test specimen. The developed LabVIEW software and the NI hardware is an integral part of the Torsional Vibration Damper Test System and it is sold as a complete turnkey system.

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