How to model a pressure compensator in simulink?

This is my SimHydraulics circuit. Basically I would like to simulate what will be the pressure increase inside the constant volume chamber (which is tank in my case). The pump pumps oil and moves piston (which is pressure compensator in my case along with that spring - the spring will exert some pressure in fluid) which is restricted by a stiffness spring hence the fluid in chamber is getting pressurized. When the pump stops, the spring will push the fluid to constant volume chamber, hence further more increase in pressure. But the MATLAB doesn't run this circuit and shows error message,

First solve for initial conditions failed to converge. Trying again with all high priorities relaxed to low.

Component:Simulink | Category:Model warning

Unable to satisfy all initial conditions. The variables involved are listed below. The following variables are involved in a constraint that conflicts with their targets: 'Constant_Volume_Hydraulic_Chamber.pressure' (Pressure (gauge)) 'Single_Acting_Hydraulic_Cylinder.conv.chosen_converter.pressure_chamber' (Fluid pressure in the chamber) Here are the equations involved: all components involved'untitled/Constant Volume Hydraulic Chamber'Equation location is: 'C:\Program Files\MATLAB\R2018a\toolbox\physmod\simscape\library\m\+foundation\+hydraulic\+elements\constant_chamber.ssc' (line 79) 'untitled/Single-Acting Hydraulic Cylinder'Equation location is: 'C:\Program Files\MATLAB\R2018a\toolbox\physmod\simscape\library\m\+foundation\+hydraulic\+elements\translational_converter_compressible.ssc' (line 103) The following variables' targets could not be honored: 'Translational_Spring.x' (Deformation)

Component:Simulink | Category:Model warning

What could have gone in my circuit?

I am using version 2018a

Your advice is highly appreciated.

Thanks

Immanuel

INDIA

[Hitesh]

Hi @immanuelkeba,

Could you share the simulink file so that I can reproduce the error ?

[immanuelkeba]

Hi @Hitesh

Here is the file, please peruse it and comeback ASAP. YOur help is highly appreciated.

Thanks

Immanuel Keba

India

[Yifeng Tang]

The warning message suggest that the pressure in the chamber is in conflict with the pressure in the cylinder. When Simscape tries to reconcile those two, the resulting hydraulic force is likely in conflict with the initial deformation of the spring you've specified. Simscape is complaining about us asking it to solve for conflicting initial conditions.

[Hitesh]

Hi immanuelkeba,

I understand from the error that the Simscape solver is not able to solve the initial conditions target in your model. The possible reasons for the error and their fixes are mentioned below.

• For the Warning Message, as there was conflict in pressure value between "Constant Volume Hydraulic Chamber" and "Single -Acting Hydraulic Cylinder" , you need to set pressure to 0 in "Constant Volume Hydraulic Chamber" block.
• If you have set the initial conditions of different blocks, ensure the "Start from steady state" check box in the Solver Configuration block is unchecked.
• Prior to simulating the model, you can use the Variable Viewer (Debug > Simscape > Variable Viewer) to check the results of the initial condition computation for the model and to see which of the block-level variable initialization targets have been satisfied. There you can see for your model, it shows unable to solve for all varaibles. Could you share the reference link of model so that I investigate the root cause of the error ?

[immanuelkeba]

Dear HItesh,

I don't get what is actually a reference link. Could you pls guide me the way to get it in my MATLAB Version R2018a?

Thanks

Immanuel Keba