90 degree motion

Altair Forum User

Hi

I am new to motionview/motionsolve and am trying to setup a simulation that requires a body to move in space in a straight line in 1 direction, then move in a straight line 90 degrees to to the first motion. At the moment I'm just trying to model each task as a form of practice, so this is purely an exercise

I can simulate this with a template, the issue I'm having is that when it goes to do the second motion, the body jumps back to its origin before moving in a straight line in the correct direction. imagine trying to model a body moving around a corner when viewed from above

So If we are looking at X and Y coordinates its should go something like this

t = 0, x = 0, y = 0

t = 4 x = 0, y =4

t = 8, x = 4, y = 4

but instead this is whats happening

t = 0, x = 0, y = 0

t = 4 x = 0, y =4

t = 4.01 x = 0,  y =0

t = 8, x = 4, y = 0

Please let me know if there is a way to set this up so that it works properly, Thanks

Set up info below

j_3 and j_4 are translation joints 90 degrees apart

mot_0 = displacement STEP(TIME,0,0,4,4)

mot_1 = displacement STEP(TIME,4,0,8,4)

Template info below

<Deactivate

element_type = 'MOTION'

element_id = '{MODEL.mot_1.idstring}'

/>

<Deactivate

element_type = 'JOINT'

element_id = '{MODEL.j_4.idstring}'

/>

<Simulate

analysis_type = 'Transient'

end_time = '4'

print_interval = '0.01'

/>

<Deactivate

element_type = 'MOTION'

element_id = '{MODEL.mot_0.idstring}'

/>

<Deactivate

element_type = 'JOINT'

element_id = '{MODEL.j_3.idstring}'

/>

<Activate

element_type = 'MOTION'

element_id = '{MODEL.mot_1.idstring}'

/>

<Activate

element_type = 'JOINT'

element_id = '{MODEL.j_4.idstring}'

/>

<Simulate

analysis_type = 'Transient'

end_time = '8'

print_interval = '0.01'

/>

 

asajd_20372

Hello,

If you were using Inspire Motion (2020) you could just use two actuators, like shown in attached video and model.

Using Inspire you can export to MDL file and use that in MV/MS, if you wish.

 

Regards,

asajd

Unable to find an attachment - read this blog

Chris Coker_21312

You could also do this in MotionView completely without templates.

You will have a 'dummy body' between your main body and ground.  One of the translational joints connects your main body to the dummy body, the other translational joint connects the dummy body to ground.  Your two motion statements are defined as expressions, using the same STEP() function.

 

Hopefully this will get you started, if I have time later this week, I'll update with a simple demo model.

Altair Forum User

Hi Thanks for the response. I worked it out. I ended up using the dummy bodies. I was thinking about it in the shower after I posted the question, and thought of 'piggybacking' the bodies and joints to each other. tried the next morning and it worked