Error with Simulink Simulating

High pressure unit ^

Low pressure unit ^

Abdominal cavity ^

Trocar ^

PPR ^

DC Motor ^

PID for motor ^

PID for pneumatic ^

Pneumatic ^

When I am trying to simulate I get the following error:

An error occurred while running the simulation and the simulation was terminated

Caused by:

['ResearchPaper/Low Pressure Unit/Solver Configuration']: Initial conditions solve failed to converge.

Nonlinear solver: Linear Algebra error. Failed to solve using iteration matrix.

The model may not give enough information to make it possible to solve for values of some of its variables. Specific advice is given below.

all components and nodal across variables involved

Cannot solve for one or more variables:

'Trocar.T2_P3_sensors.A.p' (Pressure)

all components and nodal across variables involved

Cannot solve for one or more variables:

'Low_Pressure_Unit.Pressure_Reducing_Valve_0_16_Bar.B.T' (Temperature)

'Low_Pressure_Unit.Pressure_Reducing_Valve_0_16_Bar.B.p' (Pressure)

'Low_Pressure_Unit.Pressure_Reducing_Valve_0_16_Bar.orifice.L' (L)

'Low_Pressure_Unit.Safety_Valve_0_26_Bar.B.T' (Temperature)

'Low_Pressure_Unit.Safety_Valve_0_26_Bar.B.p' (Pressure)

'Low_Pressure_Unit.Safety_Valve_0_26_Bar.orifice.L' (L)

'Low_Pressure_Unit.Safety_Valve_0_26_Bar.orifice.T_A' (Temperature at port A)

'Low_Pressure_Unit.Safety_Valve_0_26_Bar.orifice.T_B' (Temperature at port B)

'Low_Pressure_Unit.Safety_Valve_0_26_Bar.orifice.convection_A.ht_I' (Specific total enthalpy for outflow)

'PPR.Pneumatic.Controlled_Pressure_Source_G.B.T' (Temperature)

'PPR.Pneumatic.Controlled_Pressure_Source_G.B.p' (Pressure)

'PPR.Pneumatic.Controlled_Pressure_Source_G.T_in_A' (Temperature for inflow at port A)

'PPR.Pneumatic.Controlled_Pressure_Source_G.T_in_B' (Temperature for inflow at port B)

'PPR.Pneumatic.Controlled_Pressure_Source_G.T_out_A' (Temperature for outflow at port A)

'PPR.Pneumatic.Controlled_Pressure_Source_G.T_out_B' (Temperature for outflow at port B)

'PPR.Pneumatic.Controlled_Pressure_Source_G.convection_A.ht_I' (Specific total enthalpy for outflow)

Equations (including nonlinear equations) of one or more components may be dependent or inconsistent. This can cause problems in transient initialization. Here is the set of components involved:

all components involved

'ResearchPaper/Low Pressure Unit/Pressure Reducing Valve 0.16 Bar'

Equation location is:

'/MATLAB/toolbox/physmod/fluids/fluids/+fluids/+gas/+valves_orifices/orifice.sscp' (no line number info)

Equations (including nonlinear equations) of one or more components may be dependent or inconsistent. This can cause problems in transient initialization. Here is the set of components involved:

all components involved

'ResearchPaper/Trocar/safety valve (80 mmHg)'

Equation location is:

'/MATLAB/toolbox/physmod/fluids/fluids/+fluids/+gas/+valves_orifices/orifice.sscp' (no line number info)

It's a lot to take in but how can I fix this error?

Answer 1

[Pravarthana P]

Hi Adrian,

These errors can occur due to the following reasons:

1. When the Consistency Tolerance parameter in the Solver Configuration block is enough for the model.
2. When there are electrical components without electrical reference.
3. Every node in a pneumatic network must have a defined temperature as well as pressure. In effect, every node should have a volume of fluid associated with it. When the ideal gas law is applied, this volume of fluid determines the relationship between temperature and pressure.

The following workaround may help to resolve the issues mentioned above:

1. Increase the Consistency Tolerance parameter in the Solver Configuration block.
2. Add electrical reference to the model.
3. There are few elements which already have volume of fluid, such blocks include Constant Volume Pneumatic Chamber, Pneumatic Piston Chamber, Rotary Pneumatic Piston Chamber, and Pneumatic Atmospheric Reference. Adding and connecting any one of these blocks to the model might help.

For more information, refer to the following documentation links:

Physical network environment and solver configuration - MATLAB (mathworks.com)

Connection to electrical ground - MATLAB (mathworks.com)

Refer to “Connection Constraints” section in the following documentation link:

http://www.mathworks.com/help/releases/R2012b/physmod/simscape/ug/modeling-pneumatic-systems.html