×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

AVIEW: initial conditions for a manipulator with stiffness

AVIEW: initial conditions for a manipulator with stiffness

AVIEW: initial conditions for a manipulator with stiffness

(OP)
I am using ADAMS view 12.0, Im trying to do a simulation of a manipulator. The manipulator holds a heavy payload, and they are connected by bushing. I set the initial conditions that are rotation displacements for each joint, and if I run the simulation for 0.2sec, the joint rotate unexpextedly due to the stiffness by the bushing connected with the heavy payload, so I can not make an expected initial pose. In the case of rigid connection, there is no problem. How can I solve this problem?.

Thank you in advance.

RE: AVIEW: initial conditions for a manipulator with stiffness

Run a solution with relaxed error settings (etc) to establish equilibrium and then use that position as your final starting point.

The effect you see is real, we see it all the time on large models, so our custom pre-processor actually goes through a static convergence funnel (as it is known) every time.

In effect we assemble the car in mid air, then drop the car onto the ground from a small height and let it sort itself out, then we start testing.

MSC support probably has some articles on the subject, here's our funnel

!  Static Funnel
equil/maxit=75, err=10000, imb=10000, stab=10000
con/fun=user(1010,555)
equil/maxit=75, err=1000, imb=1000, stab=100
con/fun=user(1010,555)
equil/maxit=75, err=100, imb=100, stab=10
con/fun=user(1010,555)
equil/maxit=75, err=0.1, imb=0.1, stab=0.1
con/fun=user(1010,555)
equil/maxit=75, err=1.0000e-03, imb=1.0000e-01, stab=5.0000e-02

The other solution is to work out the correct, static, geometry and then entering preloads in the bushes. Not very easy.




Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources

White Paper – Your Construction ERP RFP Checklist
Selecting business software for a medium to enterprise-sized construction concern is extremely challenging in large part because most enterprise resource planning (ERP) suites originated in the world of repetitive manufacturing and are therefore a poor fit for a project and asset-centric business. However, midsize to large contractors need the predictable, auditable processes that ERP delivers. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close