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HYGE Sled Control - PC-Based Industrial
Automation
By David Hoadley, Ph.D., Project Scientist, V I Engineering,
Inc.
Products Used
BridgeVIEW
Industrial Automation Server
The Challenge
Update an aging control system for an Automotive Crash
Test Simulator.
The Solution
A BridgeVIEW-based human-machine interface (HMI) incorporating
control and automation, operator security, and data recording.
Introduction
V I Engineering, Inc., a National Instruments Premier
Alliance Member, was contracted by Ford Motor Company
to update the control system for their HYGE sled. The
HYGE system consists of a 12" diameter pneumatic ram that
is used to accelerate a two-ton sled on a 100' track.
The applied acceleration pulses are tailored to mimic
the acceleration profiles observed in vehicle-barrier
crash tests. In HYGE tests, a single ruggedized automobile
frame can be used repeatedly to study air bag and passenger
restraint system performance. Sled instrumentation includes
high-speed video and cameras, accelerometers, and sensor-laden
crash test dummies.
System Description
The system was previously controlled by an obsolete programmable
logic controller (PLC) that provided signals to various
relays which in turn would open valves, start compressors,
and more. These relays incorporate logic that allows failsafe
operation by requiring various permissive signals to pressurize
the ram cylinder. These include closure signals from numerous
doors, automatic locks, and area surveillance light curtains.
All permissive signals are required before the cylinder
can be filled with high pressure air and the ram can be
fired, simulating up to a 35 mph head-on collision.
V I Engineering replaced the PLC and its program, updated
system valves, and produced an intuitive user interface
to the control system. This interface provides controls
for every automatic function of the system, from the automatic
filling of system pressure to the storing of successful
test parameters and environmental data. The tendency for
human error is removed by incorporating proper procedures
into the code and providing a live system schematic on
screen.
HMI Features
The HMI provides an operator with controls and indicators
used to run the HYGE sled system. Several features of
BridgeVIEW facilitated development of the system. One
such feature, the built-in security functions, proved
to be a very efficient means of implementing user authorization
for the control system.
The logical progression of steps that is required to fire
the ram is incorporated into the structure of the control
software. The first screen a user visits after logging
in is dedicated to data entry of test parameters, as well
as to displaying the output of ambient temperature and
humidity sensors. These sensors and several pressure transducers
provide signals to the computer via communication with
PLC input modules. These signals are calibrated by the
BridgeVIEW engine as determined by tag scaling settings.
Users, based on security privilege, are given access to
the Tag Configuration Editor in the application software
to enter calibration information.
Other screens are accessed as necessary to run the test.
They feature controls and indicators that allow the user
to run the pressure systems and receive appropriate feedback.
Pressure system preparation is accomplished on the screen
depicted in Figure 1.
The 'system schematic' design of this screen overcomes
the potential crowding that a complex system requires
for numerous controls and indicators. The user has the
ability to control various doors, compressors, valves,
and other system components while monitoring every pressure
transducer and the state of permissive and control power
signals. System procedure is a major part of the code
in this and other screens. While the relays guarantee
that unsafe conditions are never possible, the system
often requires that a process be carried out in a particular
order to have the desired effect. By incorporating these
requirements, a major source of user error has been eliminated.
A significant benefit of this change is seen in the retraining
of personnel on the new system, which has progressed very
smoothly.
Automation features in the system include filling pressures
to target values, an audible ten second countdown over
a PA system, logging of test parameters and environmental
data after a successful test, and the firing process itself.
As in the original system, the user actuates one control
to start the PLC's ram-firing process. This incorporates
control of various lights, film and video cameras, as
well as the arming and firing of the air bag. This program
also provides a 'T0' signal to the onboard data acquisition
system, signifying exactly when the ram was fired. Automation
is a necessity for this timing, since the acceleration
pulse only lasts on the order of 100 milliseconds.
Summary
V I Engineering has implemented a modern, PC-based control
system for a major automotive test facility in BridgeVIEW.
The built-in user security and tag configuration components
have shortened development time considerably while allowing
the end user the ability to manage the system. This software
is a well-designed HMI, and provides much more functionality
than a mere graphical "front-end" for the embedded programmable
logic controller. The ability to incorporate G code into
the interface has allowed many of the problems associated
with operator error to be removed from the system, easing
the transition for technicians from the familiar control
panel to the more intuitive PC screens.
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