Designing a Military Vehicle Turret Drive Test Stand with LabVIEW

Author(s):
Darren Scarfe - Vi Engineering

Industry:
Aerospace/Avionics

Products:
PXI/CompactPCI, LabVIEW

The Challenge:
Creating an automated end-of-line test stand software package to control operation, acquire test data, and generate pass/fail reports during the design and production phases of military vehicle turret drive assemblies.

The Solution:
Developing a LabVIEW-based password-controlled application capable of executing a controls-based sequenced testing structure, while employing data acquisition techniques against military standards limit checking, along with a final report generation.

Twelve Tests, One SoftwarePackage
General Dynamics Land Systems contracted VI Engineering, Inc., a Select Integrator in the NI Alliance Program, to replace an automated end-of-line test stand for validating turret drive assembly units for military land vehicles. The military uses turret drive assemblies in military vehicles for gun elevation, tow lift, and traverse drives, which regulate the control of mechanical operations. We can perform a maximum of twelve different tests using this software package. The type of tests available remain dependent on the type of turret drive selected for test. The software can test seven different turret drive types, each with ether of two motor types.

The comprehensive testing includes calculating testing parameters with respect to distinct turret drive units, executing a maximum of 12 distinct tests, analyzing and data processing of each test, checking limits, printing pass/fail reports, and archiving the reports and test data. The software must run with minimal user intervention and give user-directed instructions for correct operation and testing. All test stand software packages developed by VI Engineering, Inc., for General Dynamics have an analogous look and feel. This allows for ease-of-use by multi-operators and also simplifies the maintenance and upgrade procedures for General Dynamics personnel.

The analogous look and feel also reduces the time and resources required for General Dynamics engineers and technicians when upgrading and maintaining the LabVIEW code on any particular test stand. Since the look and feel of each test stand work identically, when we perform an upgrade or calibration to a test stand, the experience directly relates to performing upgrades and calibrations on all other test stands.

Secure Testing, Secure Calibration
The LabVIEW application consists of a rack-mounted data-acquisition/test control computer, and a GPIB-controlled data acquisition system used to control the different turret drives via relays and digital outputs, along with acquiring data. We also control external power supplies and HP multimeters via GPIB.

The system includes a login/password security function to create security levels. The software restricts user capabilities based on administrator, technician, and operator status. We have full control over all functionality in the software - including creating new users and passwords and designating a security level of either administrator, technician, or operator. A technician-level user can perform calibration functions on the different hardware of the system, and an operator is limited to the running of tests on the IA units. Using the main screen, we can choose among the following functions within the software:
1. Enter Drive Information <F1>
2. Run all Tests <F2>
3. Run Single Test <F3>
4. Print Final Report <F4>
5. Calibration/Functions Screen (Only for higher level security users) <F5>
6. Re-login <ESC>
7. User Access (Only for Administrator level access) <F7>

The "Enter Drive Info" screen prompts us to select the turret drive model type and enter the specific serial number for exact identification of a particular turret drive. We also must select the motor type used within the drive. Specific testing parameters and limit-checking values are then pulled from memory because of the values selected in this screen. We then can run an entire test sequence, determined uniquely depending on the turret drive model selected. We can abort testing at any time during a testing sequence. If any specific test fails because of limit-checking, the system displays a warning and we then have the option to check for possible mechanical problems and then re-run the test.

If the system reports failures during any specific test, we can run single tests in a continuous mode to aid in the debugging of turret drive problems.

Once the system completes all tests for a specific turret drive, it creates a pass/fail report and prints it to a local printer. The comprehensive report includes the turret drive serial number, model type, all relevant test data (both raw and calculated), specific limit-checking statistics, and identification of the operator name and badge number. Also, a report printing function generates archived reports from test runs on previous turret saved to the local computer.

The system provides a calibration/function utility (only accessed by high level users) for the periodic calibration of strain gauges, amplifiers, and power supplies. Technicians and administrators are the only users who can access the calibration screen. Once the system completes all calibration steps, it generates a hardcopy report that includes all calibration parameters, the technician name, and a pass/fail status.

Only the designated system administrator can access the user screen, used to set up new users and organize their security access to specific screens and functions within the program. The administrator designates such security levels for operators and technicians, and allows for creation of additional administrators.

In summary, VI Engineering provided a complete turret drive control and data acquisition testing system for General Dynamics Land Systems. We used the PC-based end-of-line tester, coded in LabVIEW, as a final safeguard in validating turret drive control systems before installing them in military fighting vehicles. Through use of the LabVIEW-based programming environment and a code library reuse concept, we have implemented a standard software interface for different General Dynamics testing systems. This allows for an ease-of-use multi-operator environment and simplifies General Dynamics upgrade and maintenance operations by reducing the learning curve for different software systems.

For more information, contact:

Darren Scarfe

VI Engineering

Tel: 248-489-1200

E-Mail: dscarfe@vieng.com

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