SurveyFit (User Guide)
Overview
Met Dynamics SurveyFit is a parameter estimation tool for fitting SysCAD process simulation models to plant survey data. The software integrates directly with SysCAD and automatically adjusts selected model parameters so that simulated results reproduce measured plant data as closely as possible within the configured measurement uncertainties.
This page provides the User Guide for SurveyFit, including installation, workflow guidance, and interpretation of fitting results. For detailed descriptions of commands, fields, dialogs, and options, see Reference. For worked examples, see Examples.
SurveyFit is primarily intended for calibration of mineral processing circuits such as crushing, grinding, flotation, and other beneficiation processes. When used together with the Met Dynamics Models library, parameter estimation can be applied across complete mineral processing flowsheets including both comminution and downstream beneficiation processes. This allows unit operations across different processing stages to be calibrated simultaneously within a single consistent process model.
SurveyFit is primarily designed for SysCAD ProBal projects. Dynamic projects can also be evaluated, but only after explicit acknowledgement and only when the Dynamic scenario is configured to stop automatically and restart for every model evaluation.
Because the flowsheet structure enforces mass conservation and model equations, the calibration process naturally respects the physical constraints of the process. The resulting parameter set therefore produces a model that is both consistent with measured plant data and internally consistent within the flowsheet model.
Motivation
Plant surveys are commonly used to evaluate the performance of mineral processing circuits and to calibrate process simulation models. Historically, survey analysis has been performed using a two-stage workflow.
In the traditional approach, plant survey measurements are first adjusted using data reconciliation techniques so that the flowsheet satisfies mass balance constraints. The reconciliation problem is typically formulated as a weighted least-squares adjustment in which measured values are modified within their estimated uncertainties while enforcing the linear mass balance equations for the flowsheet. The result is a reconciled stream table that exactly satisfies material conservation and is treated as the best estimate of the plant state. Model parameters are then calibrated in a second step so that the process model reproduces the reconciled data.
The mass reconciliation methodology originated at a time when detailed flowsheet simulation models were not widely available. The linear structure of the mass balance equations allowed plant survey data to be analysed using relatively simple optimisation methods, making reconciliation a practical tool for interpreting plant measurements. Process model parameter calibration was later incorporated as a second step in which models were fitted to the reconciled stream table.
Modern process simulators now incorporate detailed models of equipment behaviour and circuit interactions. Grinding and classification circuits, for example, are governed by population balance breakage models, classification partition functions, and recirculating load relationships. These nonlinear process models already enforce strong physical constraints on the feasible flowsheet solution.
SurveyFit takes advantage of these models by estimating parameters directly from the measured survey data. During the optimisation process the flowsheet simulator itself enforces mass conservation and equipment behaviour while parameters are adjusted to minimise the difference between simulated and measured values.
In this formulation the process model effectively replaces the traditional reconciliation step. The optimisation searches for the parameter set that produces a flowsheet solution consistent with both the measurements and the physical constraints of the circuit.
Simultaneous parameter estimation using a strongly constrained flowsheet model therefore provides a modern alternative to the traditional two-step reconciliation workflow for circuit survey analysis. While this approach is not universally superior in all contexts, it is a practical and often simpler approach in situations where the underlying process physics are well represented by the simulation model.
Applications
SurveyFit is primarily intended for calibration of steady-state SysCAD process flowsheets using plant survey data. Typical mineral processing applications include grinding circuits, flotation circuits, gravity concentration systems, dense medium separation circuits, and other beneficiation flowsheets.
The same approach may also be applied to other types of process flowsheets modelled in SysCAD, including hydrometallurgical circuits, pyrometallurgical processes, chemical refining systems, and other metallurgical or chemical processing operations.
Measurements used during fitting may include plant survey data such as particle size distributions, assay grades, and solids fractions. Instrument measurements such as flow, density, pressure, and equipment power draw may also be incorporated.
In practice, any process variable represented by a readable SysCAD tag can be included as a measurement, while any writable numeric SysCAD tag can be selected as an adjustable parameter. This allows measurements and parameters from multiple unit operations across an entire flowsheet to be incorporated into a single fitting problem.
Key Features
SurveyFit provides a set of capabilities specifically designed for calibration of process simulation models using plant survey data. These features support the definition of calibration problems, execution of parameter estimation, and interpretation of the resulting model fit.
Key features include:
- Direct parameter estimation against SysCAD process simulation models
- Integration with SysCAD ProBal projects, with guarded support for appropriately configured Dynamic projects
- Calibration of complete flowsheets including recirculating circuits
- Parameter bounds and Linear, Log, or Sigmoid transforms
- Composition Groups for closed fractional compositions that must remain summed to one
- Fixed and Whiten (PSD) measurement error models
- CSV import and export for parameter and measurement tables
- Graphical diagnostics including parity plots, residual histograms, residual statistics, and largest-residual ranking
- Plain-text report export and a command-line interface for validation and solve execution
Installation and Licensing
This section describes the procedures for installing, updating, uninstalling, and licensing SurveyFit on a client PC.
SurveyFit is distributed as a digitally signed 64-bit Windows Setup package. The installer installs the application and required runtime components, creates the standard Windows application registration, and provides optional desktop and file-association tasks.
Installation
System requirements
The following hardware and software are required to use SurveyFit:
- 64-bit Microsoft Windows 10 version 1809 or later
- A licensed installation of SysCAD with COM automation available
The SysCAD project used during fitting must evaluate reliably over the intended parameter range. ProBal projects should solve successfully before being used with SurveyFit. A Dynamic project must be configured to stop automatically and restart for every model evaluation.
Step One: Obtain the SurveyFit installer
Download the current SurveyFit Setup package from the Met Dynamics Downloads page.
Access to SurveyFit distributions is provided to authorised Met Dynamics customers. Where download credentials are required, they are provided through the Met Dynamics customer download system.
The installer filename includes the SurveyFit version, for example:
SurveyFit-1.0.0-Setup.exe
SurveyFit Setup packages are digitally signed by Met Dynamics Pty Ltd. Windows should identify Met Dynamics Pty Ltd as the publisher when the installer is launched.
If required, the latest SurveyFit distribution may also be requested from support@metdynamics.com.au.
Step Two: Run Setup
Run the downloaded SurveyFit Setup executable.
SurveyFit uses a standard Windows installation wizard. The wizard:
- displays the Met Dynamics SurveyFit welcome page
- displays a Software Licence Notice
- installs SurveyFit to the standard Windows application folder
- allows optional installation tasks to be selected
- installs the application and supporting runtime files
- optionally launches SurveyFit when installation is complete
The default installation folder is:
C:\Program Files\Met Dynamics\SurveyFit
Because SurveyFit is installed for the computer rather than only the current user, Windows may request administrator approval through User Account Control during installation.
The Select Additional Tasks page provides the following options:
- Associate .sfit files with SurveyFit — selected by default. This allows SurveyFit project files to be opened from Windows Explorer by double-clicking the
.sfitfile. - Create a desktop shortcut — not selected by default.
A Start Menu shortcut is created as part of the standard installation.
On successful completion, Launch SurveyFit is selected by default. Clear this option if SurveyFit should not be started immediately.
Step Three: Verify SysCAD connectivity
SurveyFit communicates with SysCAD using the SysCAD COM Automation interface.
Before using SurveyFit, confirm the following:
- SysCAD is installed and licensed on the machine.
- The project to be fitted can be opened and evaluated successfully in SysCAD.
- SysCAD is registered as a COM application on the system.
- The selected project file is the
Project.spjfile within the SysCAD project folder, for example<SysCAD Project>.spf\Project.spj.
Instructions for registering SysCAD for COM automation are available in the SysCAD documentation on COM Automation.
If SurveyFit reports that it cannot find the SysCAD COM automation registration, reboot the PC, run C:\SysCAD139\bin\RegAll.cmd as Administrator, then reopen SurveyFit and try again.
SurveyFit connects to SysCAD when the selected project is opened from the Solve tab or when a solve requires a model-evaluation session.
Application logs are stored in:
%LOCALAPPDATA%\MetDynamics\SurveyFit\Logs
The same folder can be opened using Help > Open log folder.
Installing a newer version
A newer SurveyFit installer may be run over an existing SurveyFit installation. Close all running SurveyFit windows before installing or uninstalling the application. Setup will prevent installation from proceeding while SurveyFit is running.
SurveyFit can check the current published version using:
- Help > Check for Updates...
When a newer version is available, SurveyFit provides a link to the Met Dynamics Downloads page. Updates are downloaded and installed using the normal signed SurveyFit Setup package; SurveyFit does not automatically download or install software.
Uninstallation
SurveyFit can be removed using the normal Windows installed-applications interface:
- Open Windows Settings.
- Select Apps > Installed apps.
- Locate Met Dynamics SurveyFit.
- Select Uninstall and follow the prompts.
Close all SurveyFit windows before uninstalling. The uninstaller will not proceed while SurveyFit is running.
Uninstallation removes the installed application files, Start Menu entries, installer-created shortcuts, and SurveyFit file-handler registration.
SurveyFit project files, user-created data, and normal per-user application settings are not intentionally removed by uninstalling the application.
Licensing
SurveyFit licenses are normally issued for a particular machine using the Site Code reported by the licensing system.
The SurveyFit installer does not install or activate a SurveyFit licence. Licensing is configured from within the installed application.
If no valid license is configured, SurveyFit operates in Demo Mode. Detailed information on the License dialog and Demo Mode behaviour is provided on the Reference page.
Obtaining a license
To obtain a license for SurveyFit:
- Start the SurveyFit application.
- Open Help > License....
- Select Copy details to copy the available licensing information, including the Site Code and required authorisation.
- Paste the copied details into an email message and include your contact details.
- Send the request to accounts@metdynamics.com.au.
After the request has been received, Met Dynamics will generate a .lic license file and return it by email.
Installing the license
Once the license file has been received:
- Save the license file to a stable location on the local system.
- Open Help > License....
- Select Browse... and choose the
.licfile. - Select Check license if the check has not already run automatically.
- Confirm that License status reports Licensed.
The licensing state is updated immediately. SurveyFit does not need to be restarted after selecting a valid license file.
Trial licenses
Trial licenses may be issued upon request.
Trial licenses:
- operate for a limited evaluation period
- provide full software functionality during the trial period, subject to the terms of the issued license
Please contact support@metdynamics.com.au to request a trial license.
Uninstallation
SurveyFit may be removed from the system by deleting the installation folder containing the application files.
Configuration settings stored for the current user may remain in the Windows registry after removal of the application files.
Further support
If any step of the installation or licensing procedures fails, use Help > Copy system info and Help > Open log folder to collect support information, then contact support@metdynamics.com.au.
User Interface
SurveyFit uses a tab-based interface organised around the fitting workflow. The main workspace contains the Parameters, Measurements, Solve, and Results tabs. A resizable diagnostics pane on the right contains the Issues, Issue details, and Log sections. Detailed descriptions of fields, table columns, menus, dialogs, and solver options are provided on the Reference page.
Parameters tab
The Parameters tab defines the model parameters that may be adjusted during fitting. Each parameter corresponds to a writable SysCAD tag representing a numeric model variable.
Lower and upper bounds constrain the allowable parameter range, while the Transform field controls the internal parameter mapping used by the solver. The table also contains a Composition Group field for closed fractional compositions. Rows assigned to the same Composition Group are constrained to values from 0 to 1 that sum to 1.
The result columns show the Initial Value, Current Value, and Best Value associated with the latest solve.
Measurements tab
The Measurements tab defines the plant measurements used during parameter estimation.
Each measurement corresponds to a readable SysCAD tag and includes the Measured Value, Error Model, and SD representing measurement uncertainty. Result columns show the Estimated Value, Residual, Std Residual, absolute standardised residual, and the measurement contribution to the current objective.
Particle size distribution measurements may optionally use the Whiten (PSD) error model.
Both data tables support sorting, multi-cell selection, spreadsheet-style copy and paste, row insertion, duplication, removal, and manual row reordering through the # column. Selecting multiple rows and changing the On checkbox for one of those rows applies the same On or Off state to the complete selection. Pasted data starts at the upper-left selected cell and overwrites existing editable cells rather than appending rows. The Delete key clears selected editable cells, or removes rows when complete rows are selected. Shift+Delete removes every row represented in the selection, while Ctrl+Delete clears selected editable cells.
Solve tab
The Solve tab controls execution of the parameter estimation solve. It contains Start, Stop, and Pause controls, an objective history chart, the SysCAD project selection and evaluation options, a solver configuration summary, and a Solve events table. In the SysCAD configuration section, the Project path field and Browse..., Open, and Close SysCAD controls are arranged together on the Project row.
During a solve SurveyFit maintains a SysCAD simulation session and repeatedly evaluates the model using updated parameter values. The objective chart displays the current and best objective together with elapsed time and iteration rate. Pause and Stop are requests that take effect after the current SysCAD evaluation completes. When the solve ends, SurveyFit reports a specific outcome such as convergence on a stopping tolerance, maximum evaluations reached, a stability-pass stopping condition, or user cancellation.
Results tab
The Results tab provides graphical and numerical diagnostics for evaluating the quality of the parameter estimation. These include a measured-versus-estimated parity plot, a standardised residual histogram, residual diagnostics and interpretation, and a table of the five largest residuals.
The parity plot always uses equal axis scaling. Optional logarithmic axes exclude points with non-positive measured or estimated values and report the number excluded.
Issues and Log sections
The right-side diagnostics pane contains the Issues, Issue details, and Log sections.
The Issues section lists configuration and validation problems detected in the current SurveyFit project. Selecting an issue displays its full text and location in Issue details. Double-clicking an issue, or pressing Enter, navigates to the related table cell where possible.
The Log section displays execution and support messages generated during model evaluation and parameter estimation. It is the primary source of diagnostic detail when investigating solver behaviour or communication with SysCAD.
The Issues and Log sections can be shown or hidden from the View menu. View > Reset layout restores the default workspace and diagnostics arrangement.
Project Files
SurveyFit projects are stored using the .sfit file format. A project file contains the information required to define, reproduce, and review a fitting problem. Further details are provided on the Reference page.
A project typically contains:
- project metadata
- the selected SysCAD project and model-evaluation options
- parameter definitions, including Composition Groups
- measurement definitions and uncertainty settings
- solver configuration
- fitting results, objective history, and solve telemetry
- selected user-interface state such as active tab, chart options, table widths, and sort order
A .sfit file is a packaged project rather than a plain JSON document. Legacy .surveyfit.json projects can still be opened and are saved in the current .sfit format.
Project files allow fitting problems to be saved, reopened, and refined as additional measurements become available or as the SysCAD model evolves.
Typical Workflow
A typical workflow when using SurveyFit is outlined below. Detailed descriptions of the related tabs, controls, and dialogs are provided on the Reference page. The same sequence is also summarised by Help > Getting Started.
- 1. Prepare a SysCAD model
- Prepare a SysCAD project representing the process to be calibrated. A ProBal model should solve reliably over the intended parameter range. A Dynamic model must stop automatically and restart for every model evaluation, and requires explicit acknowledgement when the solve starts.
- 2. Create or open a SurveyFit project
- Launch SurveyFit and create a new project or open an existing
.sfitproject. On the Solve tab, select the SysCADProject.spjfile used for the fit.
- Launch SurveyFit and create a new project or open an existing
- 3. Define adjustable parameters
- Add parameter rows manually or import a parameters CSV file. Enter the SysCAD tags, bounds, and transforms, and enable the rows to be fitted. For a closed composition, assign at least two rows to the same case-sensitive Composition Group and ensure the starting SysCAD values are fractions from 0 to 1 that sum to 1.
- 4. Define measurements
- Add or import the plant measurements used as fitting targets. Enter each measured value and select either a Fixed SD or the Whiten (PSD) error model as appropriate.
- 5. Validate the project
- Select Data > Validate data and review the Issues pane. Resolve errors such as missing tags, invalid bounds, incomplete measurement uncertainty, duplicate enabled tags, or invalid Composition Groups before solving.
- 6. Configure the solve
- Select the SysCAD project, decide whether SysCAD should be reset between evaluations, and review Solver settings.... Resetting between evaluations may improve model robustness but usually increases solve time.
- 7. Run the solve
- Select Start. SurveyFit repeatedly updates the enabled parameters, evaluates the SysCAD model, and minimises the configured residual loss. Monitor the objective chart, Solve events, Issues, and Log. Start also resumes a paused solve.
- 8. Analyse results
- Examine the Best Value parameter results, parity plot, residual histogram, residual diagnostics, interpretation messages, and the largest residual contributors. Review both statistical agreement and the engineering plausibility of the fitted parameters.
- 9. Save and export results
- Save the SurveyFit project to retain its configuration and results. Use Data > Copy report to clipboard or Data > Save report to file... when a plain-text record is required.
- SurveyFit restores the connected SysCAD session to the parameter values present at the start of the solve. To write the fitted Best Values to the SysCAD project on disk, enable Save SysCAD project after solve before starting. SurveyFit saves the fitted state and then restores the live connected session to its starting values.
Mathematical Formulation
The parameter estimation problem is formulated as a nonlinear regression in which the difference between measured plant data and model predictions is minimised.
For the Standard least squares residual model, the objective is:
- [math]\displaystyle{ S(\theta)=\sum_{i=1}^{N} \left( \frac{y_i^{\mathrm{sim}}(\theta)-y_i^{\mathrm{meas}}} {\sigma_i} \right)^2 }[/math]
where:
- [math]\displaystyle{ \theta }[/math] is the vector of adjustable model parameters
- [math]\displaystyle{ y_i^{\mathrm{sim}}(\theta) }[/math] is the simulated value predicted by the flowsheet model
- [math]\displaystyle{ y_i^{\mathrm{meas}} }[/math] is the measured survey value
- [math]\displaystyle{ \sigma_i }[/math] is the measurement standard deviation
- [math]\displaystyle{ N }[/math] is the number of enabled measurements
The quantity inside the square is the standardised residual. Measurements with smaller standard deviations therefore exert greater influence on the fit.
SurveyFit also provides Soft L1, Huber, and Cauchy robust residual models. These replace the least-squares loss applied by the optimiser and reduce the influence of large outliers. The displayed residual diagnostics, the measurement Objective % values, and the reported diagnostic objective remain based on squared standardised residuals so that they retain a consistent interpretation across residual models.
Model Preparation Guidelines
Reliable calibration requires that the SysCAD flowsheet model behaves robustly during repeated evaluation.
Use a simplified flowsheet
- Parameter estimation is generally easier when the model used for fitting is kept as simple as possible. Additional model complexity can be introduced after the primary model parameters have been calibrated.
- Where possible, remove equipment that does not influence the survey measurements or replace complex downstream sections with simplified boundary conditions.
Avoid discontinuities
- Discrete switching logic or other discontinuous model behaviour can make regression unstable. Optimisation algorithms assume that model outputs change smoothly with parameter variation. Sudden discontinuities may therefore prevent the solver from converging.
- Continuous model behaviour is generally preferred during parameter estimation.
Avoid PID controllers
- Closed-loop control elements such as PID controllers should be avoided during parameter estimation. Active controllers continuously adjust manipulated variables while the fitting algorithm is simultaneously adjusting model parameters, introducing additional nonlinear feedback into the flowsheet and increasing SysCAD solve time. Because the flowsheet must be solved many times during optimisation, the presence of active control loops can significantly increase the overall time required for parameter estimation.
Ensure stable solver convergence
- SurveyFit repeatedly solves the SysCAD flowsheet during the fitting process. Models that do not converge reliably may significantly reduce fitting performance.
- If the model is unlikely to converge for a given parameter set, it is generally preferable for the flowsheet to fail quickly rather than consume excessive solver iterations.
Use realistic initial parameter values
- Parameter estimation generally converges faster and more reliably when the starting parameter values are already physically reasonable. Where possible, parameters should be set to typical values based on engineering judgement before running the solve.
- Previous calibrated survey models can provide very good initial values when a similar circuit or ore type has been modelled before. Standalone calibrated unit models may also provide useful starting values, even if they were developed outside the full flowsheet environment, for example using the Met Dynamics Models Excel Add-In or other single-unit calibration tools.
- In practice, the user should aim to begin from a flowsheet state that is already approximately correct. For example, solids flow rates, water balances, circulating loads, and major stream conditions should be broadly consistent with the surveyed plant. Starting from a roughly correct solution can significantly reduce solve time and improve the likelihood of successful convergence.
Watch for recirculating load runaway
- Certain parameter combinations may lead to rapidly increasing recirculating loads in recycle streams. When this occurs the flowsheet may fail to converge or require excessive solver iterations.
- If this behaviour is observed, parameter bounds may need to be tightened or the parameter set adjusted to prevent unstable operating regions.
Fit circuit sections in logical stages
- For complex flowsheets it is often beneficial to calibrate different parts of the circuit separately before performing a full circuit fit.
- For example, a grinding circuit may first be calibrated for the primary SAG mill and pebble crushing section. Once these parameters are stable, the secondary ball mill and cyclone circuit can be fitted. A final full-circuit fit can then be used to refine the overall solution.
- This staged approach can significantly improve convergence and reduce fitting time compared with fitting all parameters simultaneously.
Results Interpretation
SurveyFit provides several diagnostic outputs to assist interpretation of the fitting results. These diagnostics should be interpreted together when evaluating the quality of a calibration.
These include:
- measured versus estimated parity plots
- distributions of standardised residuals
- residual statistics and automated interpretation messages
- the five largest residuals and their contributions to the diagnostic objective
- fitted parameter values and objective history
Detailed descriptions of the corresponding plots, statistics, and results displays are provided on the Reference page.
Parity plots allow rapid visual assessment of model accuracy. Ideally the estimated values should lie close to the parity line, indicating that the calibrated model reproduces the survey measurements without systematic bias. Point colouring is based on the magnitude of the standardised residual, which helps distinguish large discrepancies even when measurements have very different scales.
Systematic deviations from the parity line may indicate model bias or structural issues in the flowsheet model. For example, points consistently above or below the parity line may indicate biased model predictions, while curvature or separation between groups of measurements may suggest that particular unit operations or measurement types are not being reproduced correctly.
Residual distributions provide additional insight into the statistical consistency of the fit. When measurement uncertainties are specified realistically and the model structure is appropriate, the standardised residuals should be approximately centred around zero and display a roughly symmetric distribution.
As a practical guideline, most residuals would typically be expected to lie within approximately ±2 when expressed in units of the measurement standard deviation. Occasional larger residuals may occur, but systematic clustering away from zero or many values exceeding this range may indicate underestimated measurement uncertainty, inconsistent survey measurements, or deficiencies in the flowsheet model.
The Residual diagnostics section reports the measurement count, objective, RMS standardised residual, residual standard deviation, maximum absolute standardised residual, and counts outside ±2σ and ±3σ. The Interpretation section applies simple diagnostic rules to bias, spread, outliers, and trend with measurement magnitude. These messages are advisory and should not replace engineering review, especially for small data sets.
The Top 5 largest residuals table identifies the measurements with the greatest absolute standardised residuals and reports each measurement's Objective %. A high percentage identifies a measurement that contributes strongly to the current diagnostic fit error.
Objective statistics summarise the overall goodness of fit across all enabled measurements. These statistics should always be interpreted together with engineering judgement regarding the plausibility of the estimated parameter values and the appropriateness of the stated measurement uncertainties.
A satisfactory result should demonstrate good agreement on the parity plot, residuals centred around zero, no unexplained concentration of large residuals, and parameter values that remain physically realistic.
Examples
Worked SurveyFit examples, where provided, are documented separately from the portable application package. The standard distribution should not be assumed to contain example projects.
Examples may include typical mineral processing applications such as grinding circuits, flotation circuits, and other beneficiation flowsheets.
Detailed descriptions of available examples are provided on the SurveyFit (Examples) page.
Next Steps
Once a satisfactory calibration has been obtained, the fitted model can be used for further analysis of the circuit within the SysCAD simulation environment. The calibrated parameter set represents the best estimate of the circuit behaviour consistent with both the plant survey data and the underlying process model.
The calibrated model may then be used to evaluate circuit performance, investigate operating conditions, or assess potential circuit modifications. Because the parameters have been estimated directly from plant survey measurements, the resulting simulation provides a practical basis for engineering analysis and scenario evaluation.