Opened 11 years ago

Last modified 6 years ago

#1929 assigned defect

Multibody USR and SSR joints have wrong initialization values

Reported by: bruno Owned by: wbraun
Priority: high Milestone: 2.0.0
Component: Backend Version: trunk
Keywords: Cc:

Description

ModelicaTest.MultiBody.FourbarVariants.JointUSR and
ModelicaTest.MultiBody.FourbarVariants.JointSSR models simulate with wrong results, this is due to wrong initialization of some variables including derivatives of state variables, see for example j2.a in JointUSR or

Body1.w_a[1]
Body1.z_a[1]
Body2.v_0[2]
Body2.a_0[2]

in joints.SSR

The initial conditions and values for the states are completely specified in the models but OMC wrongly computes the initial value of some variables in the USR and SSR joints.

Change History (16)

comment:1 Changed 11 years ago by wbraun

  • Owner changed from somebody to lochel
  • Status changed from new to assigned

comment:2 Changed 11 years ago by lochel

  • Resolution set to fixed
  • Status changed from assigned to closed

Initialization works fine using the new initialization method (+d=solveinitialsystem). Simulation results are still wrong.

comment:3 follow-up: Changed 11 years ago by wbraun

  • Resolution fixed deleted
  • Status changed from closed to reopened

The models are still initialized different to Dymola.

comment:4 in reply to: ↑ 3 Changed 11 years ago by lochel

Replying to wbraun:

The models are still initialized different to Dymola.

It would be very helpful, if you can also say what actually initialized different. Just to make work more efficient.

comment:5 follow-up: Changed 11 years ago by lochel

OpenModelica: ModelicaTest.MultiBody.FourbarVariants.JointSSR
Warning: Parameter jointSSR.rod1.rodLength has no value, and is fixed during initialization (fixed=true), using available start value (start=1.0) as default value

is different to Dymola, where jointSSR.rod1.rodLength is initialized with 1.04881.

comment:6 in reply to: ↑ 5 Changed 11 years ago by lochel

Replying to lochel:

OpenModelica: ModelicaTest.MultiBody.FourbarVariants.JointSSR
Warning: Parameter jointSSR.rod1.rodLength has no value, and is fixed during initialization (fixed=true), using available start value (start=1.0) as default value

is different to Dymola, where jointSSR.rod1.rodLength is initialized with 1.04881.

OpenModelica: ModelicaTest.MultiBody.FourbarVariants.JointSSR
jointSSR.rod1.rodLength is now correctly initialized with 1.04881

OpenModelica: ModelicaTest.MultiBody.FourbarVariants.JointUSR
is properly initialized according to the test ModelicaTest.MultiBody.FourbarVariants.JointUSR_init.mos
simulation results are still different!

Last edited 11 years ago by lochel (previous) (diff)

comment:7 Changed 11 years ago by sjoelund.se

  • Milestone changed from 1.9.0 to 1.9.1

Postponed until 1.9.1

comment:8 Changed 10 years ago by lochel

  • Owner changed from lochel to wbraun
  • Status changed from reopened to assigned

It seems that the example ModelicaTest.MultiBody.FourbarVariants.JointUSR misses an event somehow and produces therefore wrong simulation results.

The other example (ModelicaTest.MultiBody.FourbarVariants.JointSSR) fails during compilation while generating a symbolic jacobian matrix. (That issue is also reported in other tickets.)

Originally, this ticket was about initialization issues, but I think we should not close it until both models simulate as expected.

comment:9 Changed 9 years ago by sjoelund.se

  • Milestone changed from 1.9.1 to 1.9.2

This ticket was not closed for 1.9.1, which has now been released. It was batch modified for milestone 1.9.2 (but maybe an empty milestone was more appropriate; feel free to change it).

comment:10 Changed 9 years ago by sjoelund.se

  • Milestone changed from 1.9.2 to 1.9.3

Milestone changed to 1.9.3 since 1.9.2 was released.

comment:11 Changed 9 years ago by sjoelund.se

  • Milestone changed from 1.9.3 to 1.9.4

Moved to new milestone 1.9.4

comment:12 Changed 8 years ago by sjoelund.se

  • Milestone changed from 1.9.4 to 1.9.5

Milestone pushed to 1.9.5

comment:13 Changed 8 years ago by sjoelund.se

  • Milestone changed from 1.9.5 to 1.10.0

Milestone renamed

comment:14 Changed 7 years ago by sjoelund.se

  • Milestone changed from 1.10.0 to 1.11.0

Ticket retargeted after milestone closed

comment:15 Changed 7 years ago by sjoelund.se

  • Milestone changed from 1.11.0 to 1.12.0

Milestone moved to 1.12.0 due to 1.11.0 already being released.

comment:16 Changed 6 years ago by casella

  • Milestone changed from 1.12.0 to 2.0.0
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