Angle Constraint Options

[Chris]

How does DD_0.1 decide the initial direction of an angle constraint? It seems like CCW is positive but what determines the initial zero line?

Chris

[Alexey I]

How does DD_0.1 decide the initial direction of an angle constraint? It seems like CCW is positive but what determines the initial zero line?

Chris

Hello Chris,

In v0.1 angle is measured between two directed objects (lines, cylinders,
planes etc.). The direction of the first object is zero angle
direction. Angle is measured in 3D and it takes values from 0 to 180
degrees, value of 90 means perpendicularity of directions, but as
we're in 3D the second direction may rotate around the first. Value of
180 degrees means that directions of object are opposite. Other values
mean intermediate positions.

As we're in 3D there are no CCW/CW notions, to have them
third direction (axis) must be specified. The possibility of explicit
(or some implicit) specification of an axis is planned to appear in
one of the next releases.

Best regards,
Alexey(LEDAS Driving Dimensions Team)

[akz]

How does DD_0.1 decide the initial direction of an angle constraint? It seems like CCW is positive but what determines the initial zero line?

Chris

Chris, now (in Rhino Assembly 1.0) there is an option to specify an axis for angle measurement. Just select two directed objects
and type "C" when asked about the angle value, then select third directed object as an axis (perpendicular to both first and the second).

In this case the angle is measured CCW from the first object to the second one looking in the direction opposite to the axis.

This topic is explained in the help and tutorial.

[Gunnar]

I have a question regarding angle constraints between two axles that do not rotate along the same axis? For example, if one is vertical and the other has a 10° slant on it, each has a lever on the end and the levers are linked with an arm that has tie rod ends or double joints on each end. Imagine a steering setup in a car, where the alignment between the axis of components (arms, levers, joints) is constantly changing when the car is being driven, due to suspension and heading.

Is it at all possible to make something like that work out using Rhino Assembly 1.0?

Thank you.

Gunnar.

EDIT:

Here is a link to an example model https://docs.google.com/leaf?id=0ByYJFg_xkd...hZDE4&hl=en

Constraints are applied but Coincidence 26 is not working properly and Angle 9 will not work either. By aligning the two axis so that they are parallel, I can get it to work...but that is not how the system is supposed to be.

Is there an error in my model or is Rnino Assembly not capable of doing this at all?

[akz]

Hello Gunnar,

Thank you for the interest to RhinoAssembly.

We're analyzing if your model is correct. Generally, I can say that RhinoAssembly supports mechanisms of such kind. We'll return back to you next week.

[Gunnar]

Thank you.

Gunnar

[akz]

Gunnar,

The model you attached has less degrees of freedom than needed for the movement. Even without Angle 9 constraint the model is rigid due to other constraints.

To make it movable I propose to cut the arm into two parts and attach them together with Concentricity+Coincidence. See the model attached. It can be moved by varying the Angle 9. Also it shows why initial model isn't moved - new parts are rotated w.r.t. each other.

Other solution that I could imagine is to use spherical joints instead of the double cylindrical joints at the ends of the arm.

If you have other questions, don't hesitate to ask.

Attached File(s)

 control_rod.zip ( 481.7K ) Number of downloads: 59