ControlSoft Receives Additional Patent for Model-Based APC

FEBRUARY 11, 2011 - Highland Heights, OH: ControlSoft Inc. announces it has received another patent (US 7,653,445 B2) for its model-based advanced process control suite (APC), extending the functionality to include time-varying systems.

Time-varying systems are a common issue in many process applications. In these processes, operations dictate changes in flow rates, production rate (or line speed), operating temperatures, or pressures. As the process requirements change, control dynamics such as deadtime, time constant, and process gain will change. Many advanced process control solutions fail to recognize or smoothly adjust for these changing conditions.

ControlSoft's newly patented extension to its APC suite provides a way to update the advanced control process models to provide a bumpless response to changing production requirements, while maintaining the tight control promised or expected by advanced control solutions.

The APC functionality is available in ControlSoft MANTRA software; it is licensed by Rockwell Automation for RSLogix5000* and by several other DCS manufacturers. Check with ControlSoft for list of available platforms. The APC suite, which includes the IMC, CC, and MMC controllers, provides much improved performance over PID controllers in most applications.

Internal Model Control Block (IMC) has a single input (Process Variable, PV) and a single output (known as Control Variable, CV, or Control Output, CO). It is comparable to and a direct replacement for a PID controller.

Instead of using PID parameters, IMC controls the process by using model parameters (model gain, model lag time constant, model deadtime).
IMC provides much improved control performance over PID control if there is some deadtime in the process (10 seconds or more).

Coordinated Control Block (CC) (single input, 3 outputs) is the most effective and most widely used APC block as almost all processes are multivariable in nature (for example, they all have disturbances). Two of the three CVs can be either active CV or measurable disturbances.

CC provides much improved control performance in the following situations:

a) processes with long deadtime,

b) processes with measurable disturbances,

c) processes with two or more CVs, such as heat/cool controller.

In the case of multiple CVs, CC can provide fastest response while maximizing the use of lower-cost fuel. CC optimizes both performance and economic benefits.

Modular Multivariable Control Block (MMC) (2 inputs, 3 outputs) is a small multivariable controller that is intended for small process units. MMC effectively addresses the process dynamic interactions. Not only will it maintain the setpoint for two PVs, it will maximize the use of lower cost CV. Hence, it maximizes both performance and economic benefits.

MMC and CC provide the most effective way of handling process constraints (as in the ControlSoft application note, "MANTRA MMC for Constrained Multivariable Control," AN333).

Applications that can benefit significantly by using APC include:

o Chlorination in water & de-chlorination & DO control in WWTP

o Fermentation & dissolved oxygen control

o Glass forehearth & furnace control

o Dryer & evaporator control

o Cooking station feed & temperature control

o pH & ORP control

o Pulp and paper, basis weight & moisture control

o Autoclave pressure & temperature control

o Engine test stand, speed & power control

o Boiler control

o Kiln & moisture control

o Distillation & separation processes

o Chemical reactor, pressure & temperature control

Request data sheet DS311 (IMC), DS312 (CC), or DS313 (MMC) via email:

About ControlSoft Inc.--award-winning, innovative leader in advanced process control

ControlSoft Inc. specializes in advanced control solutions for the process industries. A leader in model-based
control for process applications, ControlSoft was founded in 1985, is headquartered in Highland Hts., Ohio.

ControlSoft's proven PC-based software products work with existing control systems:

o INTUNE Version 5 and INTUNE+ Process Navigator for process control monitoring, tuning, online
diagnostics, and automatic reporting on poor performance;

o MANTRA for advanced process control systems, using model predictive techniques to improve profitability
and quality.

ControlSoft offers custom engineering services, including onsite tuning, consulting, studies, and training in
control loop optimization and control strategies.

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