SimHydraulics "Failed to solve using iteration matrix. Initial conditions solve failed to converge."

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Dear Community,
I'm working on a project that aims to integrate a Hydropneumatic Suspension System ( HPS ) model into the IPG Car Maker-Simulink co-simulation model using Simscape toolboxes. To get used to the toolbox and signalization differences, I made the basic spring-damper tutorial of the simscape toolbox and it worked. Then I decided to make a simple HPS model which isn't connected to IPG Car Maker's model. Then I tried to see if I could give a displacement/velocity to the mechanical translational ports ( R and C ) of the Double Acting Cylinder ( DAC ) element (whose A and B ports are connected to gas accumulators via orifices) to the HPS System and measure the force generated between R and C ports as a result of the suspension displacement dictated to the system.
I used Signal Builder, S-PC converting blocks and Ideal Translational Velocity Source to give velocity difference between two ends of the DAC. I also used Ideal Translational Force Sensor to measure the force generated between two ends of the DAC.
.mdl file of the model is attached to the question.
The error I get:
Nonlinear solver: Linear Algebra error. Failed to solve using iteration matrix. Initial conditions solve failed to converge. 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: 'HPS_Basit/Ideal Translational Velocity Source' 'HPS_Basit/Force Sensor/Ideal Force Sensor'
Dependency found among topology equations. Check for missing reference node.
Is there a logical mistake on the construction of the model, or a numerical error caused by the bad initial values of HPS elements?
Anyone can help me? Thanks
Best regards, Halil

Answers (1)

Yifeng Tang
Yifeng Tang on 14 Sep 2022
Force sensor should be placed inline with there the force passes through, just like measuring a current. The force sensor in your model is placed in parallel with the cylinder and that'll give you trouble.
You also need a mechanical reference for your model. It's like electrical ground in a circuit. Usually I would connect the C port of the cylinder to the ground.


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