Dragonfly kinematic motion study - Doubt in creating joints and motion

[Anonymous]

Hi everyone,

I was reading a journal paper titled "Design of an active flapping wing mechanism and a micro aerial vehicle using a rotary actuator". In this journal paper they have carried out a kinematic simulation using MATLAB. But I am trying do the same simulation using FUSION 360. I have tried so many times to model the motion. I couldn't find the reason for my failure. In the attached file, I have added all the snapshots of my steps. Also I have attachd the complete geometry.

Accourding to my understanding

1. Link 1 has to rotate 360 degree with respec to that joint

2. Link 2 has to rotate in a such a way that when (a) Crank angle is 0 degree, coupler angle = 0 degree

                                                                             (b) Crank angle is 90 degree coupler angle = 30 degree

                                                                             (c) Crank angle is 180 degree, coupler angle = 0 degree

                                                                             (d) Crank angle is 270 degree, coupler angl = - 30 degree

                                                                             (e) Crank angle is 360 degree, coupler angle= 0 degree

The rotation has to be accourding to this way

3. Link 3 has to slide in a inclined plane accouring to the link 2's rotation

All three has to be in this order Link1, Link2 and Link 3. Can any of you help me in simulating this? Atleast give me proper steps. I tried so many times, but I am not getting the rotation accourding to my need. What should I do? 

Explanation of the mechanism used in this simulation:

The mechanism consists of a crank,coupler, drive-arm, pivot and main-arm spaced by specific distances. The design consists of four rota-tional joints. The crank and the coupler form a rotational joint, the coupler and the drive-arm form a rotational joint. The crank, drive-arm and main-arm axes lie in the same plane. As the crank rotates it pushes or pulls the drive-arm along an arc (since the drive-arm is constrained by a pivot).  The crank’s rotation also inclines the coupler with respect to the stroke plane. This inclination of the coupler twists or rotates the drive-arm and the wing.This mechanism was a modified slider-crank mechanism, but differs by the facts that (1) the slider (coupler–drive-arm joint) in the MSC mechanism moves along an arc as it is constrained by the pivot and (2) the coupler–drive-arm joint form a revolute joint whose axis is orthogonal to the drive-arm and coupler axis

[Anonymous]

Hi everyone,

I have attached the remaining two steps here and graph for the variation of crank angle with coupler angle.

[Anonymous]

Hi everyone,

If you want to see the values of the graph .. please find the attached graph.

Your help would be very much appreciated.

[sachlene.singh]

Hi @Anonymous,

Wow! That's quite the mechanism. 

Do you have a Fusion model with the components built out that you can share? That would be a good start for us.

[TrippyLighting]

Two things:

1. Fix the yellow icons in the timeline glaring at you. These are warning messages and if things don't work as expected, often it's those warnings that create problems down the line.

2. Please share your design. It is quicker to analyse that then reading your explanations anbd also helps analyzing said warings 😉

[Anonymous]

Hi Sachlene.singh and TrippyLighting,

I have shared my design... Please help in creating the joints, drive joints, motion link, contact sets and motion study for this geometry. I am working on this geometry for last 14 days to create the motion. Please if possible create a video and send. If I understand one complicated geometry, I would definitely comfortable in creating any geomtry in this platform. Thank you so much.

http://a360.co/21MUY7b

[TrippyLighting]

Sure, if you really want me to do the work for you, let me know and I'll PM you my hourly rate 😉

But honestly, I've looked at your design and you've stepped into several problems and I am wondering wheter some of the 14 days incuded watching any of the video tutorials in the Learn section.

But let's start:

1. Instead of creating and activating components and then start sketching, you've started sketching and then converted the resulting bodies into components. Not good!
2. It also looks like you've clicked on bodies in the 3D viewport and used the move tool on them. That resulted in all the bodies being moved away from their orinis in the components. Or perhaps what I see is a result of not following Rule #1.
3. It looks like you mixed direct modeling using the primitives from the "Create" menu and modeling with sketches. When you start out I would recommend not to do so.

You should also name your components and generally anything that will need to reference later.  That's one of the easiest things to do and will help you very much later. That is also specifically true for all the joints.

Another thing that you should be doing  right from the beginning is to design plausible movement profiles with the help of some basic sketches. For this simple mechanism there are no 3D components necessary. As you can see in the screencast the mechanical properties of what you've designed don't allow for much movement and that dragonfly would never fly 😉

Also, a it is currently designed, one of the U-Shaped components is entirely unnecessary.

[Anonymous]

Hi Trippy Lighting,

Thank you so much for your help and suggestions. Being a student I don't have enough money to pay you.

But I will surely improve upon everything you have mentioned. May be I should watch so many videos. 

Accourding to the journal, this is the deisgn they have used. If it is possible please share the design? I will try to improve.

Once again, thank you so much for your help.

[TrippyLighting]

Here is a 30 minute timelapse (2x) screencast showing how this can be designed.

https://youtu.be/1QXuW2ZqvG8

[TrippyLighting]

Also, at the end of the video the assembly appears to be not be fully functional and there are some limitations as to how far the crank arms can actually be rotated.

The only thing it took to fix this is to move the joint origin in the wing rod a little closer toward the wing.

I could post teh design as wel, but I'd like to see you giving it a real good hard try 😉

And follow Fusion 360 Rule #1 : Before doing anything, create a component and activate it (activation is actually automatic now for a new component)

Fusion Rule # 2 : Name your stuff!

[Anonymous]

Hi Trippy Lighting,

Your video will be good starting point to learn more about autodesk. You are a genius. Thank you so much for your help. I will try to improve upon this if possible. Also I will surely implement all your suggestions in my next work.

[danolson1]

Awesome demo.  My project has nothing to do with the dragonfly thing, but I learned a lot by watching.