How do I create tangent forces on two pulleys instead of using ADAMS machinery?

Say I have two arms with a revolute joint in between them. At the end of two arms are two pulleys which has a belt.

Is it possible to create a tangent action and reaction force at each pulley (no slip) so that there is no need to create belt/chain and all complex calculations that come with it. Can it be modeled without using ADAMS machinery?

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0 Jesper Slattengren over 5 years ago

Yes, the coupler will not provide the belt forces for you.

I, and several others, have done similar things, but it most likely will require a subroutine of you. And the build is not simple either. Lot's of complicated jprims involved.

You will need four dummy parts. One at each end of the free span of the belt. So now you have four parts, lets call them A_up, A_down, B_up, B_down. I will only describe how to constrain the 'up' parts and the markers you need.

Create a marker on the dummy part A_up at the tangent point of the upper belt run. Call it A_to_B. In the same way, create a marker on B_up at the tangent point of the free run at wheel B. Call it B_to_A

For A_to_B, use a orientation_in_plane function and point the Z-axis to B_to_A, and the Z_axis to A_center. Do the same thing for B_to_A, but point the Z_axis to A_to_B and x_axis to B_center. So the functions should be:

ORI_IN_PLANE(A_to_B,B_to_A,A_center,"Z_ZX") and corresponding for the B_to_A marker. A_cneter and B_Center of course belongs to the pulleys A and B.

It does help if you created the A_center marker with an ORI_IN_PLANE(A_center,B_center,Common_scissor,"Z_ZX") and then use that marker to position A_to_B at LOC_RELATIVE_TO(0,0,-A_radius,A_center), but this only helps if the radius of A and B are the same, more complicated otherwise.

That was only the creation of the markers. Now you need to lock it up for the solver.

Now create a inline jprim using the i_marker=B_to_A and j_marker=A_to_B and another inline jprim with the markers reversed. This forces the A_to_B to always be positioned along the z-axis of the B_to_A and the B_to_A will in the same way be located along the Z-axis of A_to_B. In other words, they are pointing towards each other.

Are you confused enough, or do you want me to continue? This was the easy first steps. If you are a beginner in ADAMS, this might be a bit overwhelming.
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0 Jesper Slattengren over 5 years ago

Yes, the coupler will not provide the belt forces for you.

I, and several others, have done similar things, but it most likely will require a subroutine of you. And the build is not simple either. Lot's of complicated jprims involved.

You will need four dummy parts. One at each end of the free span of the belt. So now you have four parts, lets call them A_up, A_down, B_up, B_down. I will only describe how to constrain the 'up' parts and the markers you need.

Create a marker on the dummy part A_up at the tangent point of the upper belt run. Call it A_to_B. In the same way, create a marker on B_up at the tangent point of the free run at wheel B. Call it B_to_A

For A_to_B, use a orientation_in_plane function and point the Z-axis to B_to_A, and the Z_axis to A_center. Do the same thing for B_to_A, but point the Z_axis to A_to_B and x_axis to B_center. So the functions should be:

ORI_IN_PLANE(A_to_B,B_to_A,A_center,"Z_ZX") and corresponding for the B_to_A marker. A_cneter and B_Center of course belongs to the pulleys A and B.

It does help if you created the A_center marker with an ORI_IN_PLANE(A_center,B_center,Common_scissor,"Z_ZX") and then use that marker to position A_to_B at LOC_RELATIVE_TO(0,0,-A_radius,A_center), but this only helps if the radius of A and B are the same, more complicated otherwise.

That was only the creation of the markers. Now you need to lock it up for the solver.

Now create a inline jprim using the i_marker=B_to_A and j_marker=A_to_B and another inline jprim with the markers reversed. This forces the A_to_B to always be positioned along the z-axis of the B_to_A and the B_to_A will in the same way be located along the Z-axis of A_to_B. In other words, they are pointing towards each other.

Are you confused enough, or do you want me to continue? This was the easy first steps. If you are a beginner in ADAMS, this might be a bit overwhelming.
Cancel
Vote Up 0 Vote Down

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