Hello,
I've modelled a biped robot and now I want to add springs between its "feet" and its "hips" but I'm unsure about the way it works. Right now I've added a prismatic joint set as a spring between the foot and a first dummy. The second dummy is a child of the "hips".
here is an image of my setup
https://drive.google.com/file/d/0B_iCEk ... sp=sharing
Is this the way I am supposed to go ?
Add a spring on leg
Re: Add a spring on leg
Hello,
so, what you basically want to do is to have a loop in each of your legs, when the loop closing is a spring/damper?
Your approach goes in the right direction. You however forgot to add spherical joints at each end of the prismatic joint (with auxiliary shapes in-between), otherwise you have an over-constrained mechanism that will block.
Cheers
so, what you basically want to do is to have a loop in each of your legs, when the loop closing is a spring/damper?
Your approach goes in the right direction. You however forgot to add spherical joints at each end of the prismatic joint (with auxiliary shapes in-between), otherwise you have an over-constrained mechanism that will block.
Cheers
Re: Add a spring on leg
I added spherical joints but i don't think this is behaving the way I'd like it to.
Basically, I want to add some elasticity to the movement of the leg by adding a spring that would damp the movements.
Is there a mistake in the way I built the leg ?
https://drive.google.com/open?id=0B_iCE ... zVYSkNseDg
The whole scene is available here : https://drive.google.com/open?id=0B_iCE ... Vg0Q0trcDQ
Thanks !
Basically, I want to add some elasticity to the movement of the leg by adding a spring that would damp the movements.
Is there a mistake in the way I built the leg ?
https://drive.google.com/open?id=0B_iCE ... zVYSkNseDg
The whole scene is available here : https://drive.google.com/open?id=0B_iCE ... Vg0Q0trcDQ
Thanks !
Re: Add a spring on leg
When you run the simulation, you will see an error icon next to joint Prismatic_joint. In your case, this is because you have following:
But it should be like:
Make sure to carefully read this section, that explains about allowed and forbidden construction schemes.
Cheers
Code: Select all
Spherical_joint --> Spring_anchor2
--> Dummy --> Prismatic_joint --> Dummy0 --> Spherical_joint0
Code: Select all
Spherical_joint --> Spring_anchor2 --> Prismatic_joint --> auxiliaryMass --> Spherical_joint0
Cheers
Re: Add a spring on leg
Thanks for the reply, I modifed my setup
https://drive.google.com/open?id=0B_iCE ... XY5R3JoNmc
but the spring falls off now and I don't get why. Do you know what am I missing ?
Thanks for the replies.
https://drive.google.com/open?id=0B_iCE ... XY5R3JoNmc
but the spring falls off now and I don't get why. Do you know what am I missing ?
Thanks for the replies.
Re: Add a spring on leg
Always look at the scene hierarchy, to see if all objects that should be dynamically enabled are actually dynamically enabled. In your scene, Spherical_joint and Spherical_joint0 are not. They are in passive mode, but should be in force/torque mode.
Additionally, all the auxiliary masses (e.g. Spring_anchor3, Spring_anchor2 and Spring_anchor1_002 should be non-respondable, since currently they are colliding with the robot and generating collision responses.
Finally, you will also have to adjust those auxiliary masses, they are way too different than the other masses in the robot (design considerations 7 & 8 here).
Cheers
Additionally, all the auxiliary masses (e.g. Spring_anchor3, Spring_anchor2 and Spring_anchor1_002 should be non-respondable, since currently they are colliding with the robot and generating collision responses.
Finally, you will also have to adjust those auxiliary masses, they are way too different than the other masses in the robot (design considerations 7 & 8 here).
Cheers
Re: Add a spring on leg
Great ! It starts to work the way I want , thank you very much !