Overview of Loop Scout

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.

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 Guidelines. 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 activities.

Monthly Reporting 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 problems. 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 process. 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 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 more. Control System 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 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 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 requirements.

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.

Expert Guidance 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 ten problems. 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 end users. 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.

OperTune 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.

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 are retained.

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.

Networking Options 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.