||Loop Scout® Tool Suite Overview
Designed primarily for the busy I/E Technician and non-PhD Control Engineer,
Honeywell’s Loop Scout monitors control systems, detects and prioritizes
problems, proactively notifies appropriate personnel to take action, and
intelligently diagnoses and resolves root causes.
Loop Scout uses a workflow approach to optimize and maintain control system
performance. This approach augments intuitive control loop, alarm, and system
diagnostics with notification, reporting, and resolution tools focused on
empowering your existing staff to systematically increase plant profitability
and reduce operating costs.
Since 1998 the Loop Scout team has worked with hundreds of customers in a
workshop environment with the Loop Scout tool suite to identify and resolve
control loop problems. This gave the Loop Scout team an opportunity to observe,
develop and refine maintenance best practices with intense customer interaction
all the way. The current Loop Scout tool suite is designed to enable a workflow
that embodies these best practices.
Day-to-Day Operations—Loop Scout compliments your existing
reactive break-fix workflow by proactively finding and resolving the high
opportunity problems that receive no attention currently.
Maintenance & Turnarounds—Loop Scout avoids unnecessary
valve maintenance and positioner upgrades by addressing valve performance using
software-enabled, reliability-centered maintenance methodologies.
Abnormal Situations—Loop Scout improves plant control and
enables better alarm management that minimizes the impact of abnormal events
and avoids plant incidents.
Troubleshooting—Loop Scout accelerates problem-solving and
resolution efforts by summarizing loop interactions, system events, historical
performance, and configuration information.
Project Planning and Execution—Loop Scout provides objective
guidance and baseline metrics for control system upgrades, advanced process
control implementation, and process changes.
The Loop Scout® Tool Suite
Loop Scout Benchmark
The Loop Scout Benchmark is the first step in systematically identifying and
resolving control loop performance issues in your facility. The benchmark
report ranks the overall performance of your regulatory control loops and
provides drill down information categorized by DCS Unit and loop type.
Using our world’s largest database of over 160,000 control loops, the Loop
Performance Benchmark analyzes your control data and provides you with an
overview analysis including graphs and distributions that depict your plant’s
control performance relative to “Best in Class” and “Worst in Class” criteria.
Quartile Ranks by process unit and loop type are also provided.
Alarm Scout Benchmark
The Alarm Performance Benchmark is the first step of Honeywell’s alarm
improvement process pioneered through the ASM® Consortium. The benchmark report
ranks your console alarm performance against effective alarm management
guidelines to provide insight into worst acting alarms, alarm flooding, and
other alarm performance areas.
Using the Engineering Equipment and Materials Users Association (EMMUA)
Guidelines, Honeywell’s Alarm Performance Benchmark analyzes alarm system data
and provides a status report including tables and graphs that depict alarm
performance in the context of the EMMUA Publication 191 Alarm System
As part of the assessment process, a follow-up consultation can be scheduled
with a Honeywell expert to review your results using effective alarm management
practices to help you understand, prioritize, and justify alarm improvement
Monthly reports provide a clear view into performance trends at the corporate,
plant and area level. One click drill down capability quickly details the
contributing factors behind performance. Both loop performance and alarm
performance metrics show the progress of an effective workflow over time.
Deteriorating performance trends in specific areas or sites are quickly
identified. Comparisons are made against Loop Scout and Alarm Scout benchmarks
as well as plant and area baselines.
Sort and Filter
An effective loop management workflow will always focus on the problems that
affect profit and safety first. For most manufacturing facilities, there aren’t
enough resources to get to the bottom of the list. Prioritization is essential
to the busy maintenance group. The Loop Scout daily workflow approach starts
with prioritization and then leads to root cause analysis and resolution of
high impact problems.
The Loop Scout Sort and Filter was first prototyped in Excel to solve a
specific customer maintenance planning problem. This prototype quickly grew as
we worked with more customers to support daily prioritization of high impact
From the Sort and Filter display, users can quickly use filters and
user-defined sorts to identify and prioritize sticking valves, poor performing
control loops, oversized or undersized valves, loops in manual, oscillating
level loops and much more.
For more complex analysis, users can drill down to loop detail reports that
provide key performance metrics, data plots, and performance history on
individual control loops. Using intuitive hyperlink navigation, users can
quickly jump between the various displays and reports to quickly diagnose
control loop problems. This information allows the user to diagnose root causes
of control problems and begin identifying resolution actions.
Interactions in control loops always have something in common. The obvious
common element is the oscillation period but often the problem is more subtle
than a clear consistent oscillation. Multiple sorting by unit, area or even key
words in the description often highlight a problem that statistics alone would
never bring to the surface.
Alarm Scout Daily Reports
Alarm Scout has a simple goal – to monitor alarm performance and
to support a common sense workflow that reduces nuisance alarms.
When operators are not distracted by a high volume of nuisance alarms, less
time is wasted in second guessing the alarm and more time is spent operating
The key to this workflow is pushing the right information to the right person
every morning. The typical reduction of alarm frequency is 50%.
Loop Scout provides a wide range of pre-configured standard reports that fall
into 4 categories: Safety, Control System, Maintenance, and Custom.
Safety related reports monitor control system alarms and events as they relate
to plant health, safety, and environment. Examples include Alarm Change
Reports, EMMUA Alarm Benchmarks, Environmental Reporting, disabled alarms, and
Control System reports monitor control loop events, operator interventions, and
system configuration changes. Examples include mode change reports, tuning
changes, process historian impacts, disabled alarms, and more.
Maintenance reports track system maintenance issues that should be investigated
by control system engineers and/or DCS technicians. Examples include Cable and
HPM Faults, BADPV reports, Engineering Configuration reports, and more.
Custom report formats offer users alarm and event reports outside of the
standard libraries provided with Loop Scout. Using standard XML technologies,
Loop Scout is quite flexible is displaying data to meet unique customer
Loop Scout Detail
The Loop Scout Detail report summarizes everything we collect and compute for
each control loop. It provides a comprehensive reference from which a practical
assessment and root cause analysis are based. Many factors including process
condition, control design, operating decisions and maintenance practices
influence both current and historical performance. Simple loop problems can be
diagnosed just by viewing a few of the current conditions while complex
intermittent problems require much more insight. For these complex problems,
the Detail report helps by providing historical evidence of intermittency, list
of possible loop interactions, operator behavior and maintenance history.
|The Loop Scout Detail report is used together with Loop Scout Expert Guidance
to determine whether there is a problem and get to the root cause quickly.
The only commercially available loop management tool with patented non-invasive
valve stiction detection (U.S. Patent No. 6745107) was invented by Loop Scout
researchers. Our valve stiction detection has since helped hundreds of users to
target sticky valves and plan turn-arounds.
A key step in an effective loop management workflow is root cause analysis.
Treating symptoms too often results in no improvement in performance at all. A
common example of this is applying a loop tuner to every poor performing loop.
Root cause analysis can be a challenge because it is time consuming and
requires a great deal of control know how. Only the root causes of very simple
loop problems can be detected automatically. If applied to all loops, false
alarms and misdiagnosed problems would likely result from six or seven out of
The Loop Scout approach is to engage the end user in the root cause process
using our interactive Expert Guidance root cause analysis tool. Expert Guidance
is driven from two databases – a performance metrics DB and a knowledge base.
The knowledge base is a collection of best practices that we have observed,
refined and tested thousands of times in a workshop atmosphere with one or more
In some cases, the recommended resolution action may be as simple as re-tuning
the loop. However, in other cases, the tool will request additional information
to better identify appropriate resolution actions. For example, if the valve
performance is suspect, the Expert Guidance interface will walk the user
through a manual valve test to validate this condition. If loop interactions
are likely, the interface will help the user systematically identify other
loops that might actually be the source of the identified problem.
The responsibility for control loop management often belongs to the I/E Tech
who is not a control expert and already has a full plate of work. Loop Scout
Expert Guidance is designed to get to the source of the problem and recommend
the solution quickly and accurately.
Tuning techniques and results are as varied as the people that use them. Most
loop tuners require time consuming manual steps and the right know how to
produce a good result. In our data repository, we see thousands of loops
obviously tuned by a loop tuner (K=1.345534 is a giveaway) with poor
performance so we know first hand that there is plenty of room for improvement.
OperTune is different. We started with the end result that we were trying to
achieve – enable the busy non-expert (I/E Tech or control engineer) to quickly
and effectively tune loops. OperTune uses next generation robust control theory
to simplify the tuning process rather than make it more complicated.
OperTune is a ‘closed loop’ tuner. During the auto-tuning process, the control
loop maintains automatic control while OperTune simply inserts a test signal on
top of the controller output signal. The test continues until tuning constants
are computed with a high level of confidence. After the test is complete, a
spectrum of valid tuning parameters from aggressive to sluggish are provided.
All of this is achieved with a simple button click.
|Loop Scout Performance Classification Algorithm Research Process
The Loop Scout suite of algorithms blends a rigorous scientific process with
intense customer interaction. Our algorithm R&D follows a seven step
evolutionary process of continuous improvement.
|1. Data collection. Loop Scout is available as a remote
service. From our remote service customers, we have
amassed nearly two Million high frequency real time control loop datasets.
2. Manual performance classification. From our data
repository, we created a representative sample containing 26,000 loop datasets.
Each of these datasets was manually ranked with an intuitive label such as
‘poor’, ’fair’, ‘acceptable’ or ‘excellent’. This ranking was based on feedback
received in hundreds of customer workshops as well as our own experience
solving real world control problems.
3. Postulate Algorithm structure. Loop Scout uses nearly
thirty advanced metrics and statistics including methods in the open literature
as well as our own proprietary research. We postulated a non-linear algorithm
to map these metrics to the intuitive classification ranks in step two. Each
loop type (flow, pressure, level and temperature) has its own algorithm. Only
those metrics that contribute significantly to the practical performance rank
||4. Objective function. There are four possible outcomes of
fault detection. Sustaining effective use of monitoring technology requires
that Type I errors (false alarms) and Type II errors be kept to tolerable
levels. Our interactions with over five hundred customers taught us that
typical users have a tolerance of approximately one false alarm in ten and one
missed alarm in ten to sustain trust in the monitoring results. Our
optimization objective functions are balanced to detect performance problems
and meet user error tolerance expectations.
5. Regression test algorithms. The postulated algorithms in
step three are optimized against the reference set described in step two
according to the objective in step four. Regression testing consumed nearly six
months of CPU time for the third generation of algorithms.
|6. Accept, change or repeat cycle. At the end of each
regression testing cycle, error distributions were computed and analyzed. This
analysis shows systemic errors in algorithms or limitations in the underlying
metrics. These error patterns motivate modification to algorithms, metrics and
creation of new metrics to improve the balanced objective. This cycle was
repeated more than one thousand times to develop the current suite of
7. Implement in production. Once we are satisfied that the
algorithms satisfy our balanced objectives, we put them into production. We
reprocess all previous analyses with the new algorithm suite to ensure
consistent comparisons and benchmarking.
Loop Scout uses asynchronous transfers of data from the data collectors to the server and asynchronous transfers of result updates from the server to the results repository. Users use the Loop Scout tools that reside in the results repository or folder. This asynchronous transfer methodology enables a very flexible ,secure and robust solution.