CAS - Samarbeidsprosjekt

CAS - Samarbeidsprosjekt

Collaboration Project

 LEGO Go-Kart Set

For the Samarbeidsprosjekt (Collaboration project) I have teamed up with fellow student Marte Morell Aasjord. During this module I will be working in parallel with CAVm4, so in practice the CAS module will have a duration of 4 weeks with halftime dedication (4 hours per day). Interestingly enough my team partner lives in Harstad, in northern Norway, so we are roughly 1800km appart. This makes us rely 100% on electronic means of comunication and file sharing, since there is absolutely no chance of meeting in person or collaborating on the same PC.

Selecting the project for CAS

Both of us new we wanted to work with Inventor and were more inclined towards the MEK branch of the studies. I was interested in working with 3D modeling , but it was difficult to find a well documented machine or assembly that would be complex enough for the project. After discussing with my partner we both coincidentally had thought of working with LEGO. The main advantages with LEGO are that it is a universally known product and it is safe to say that it is complex enough for the project. So we focused on finding a suitable model, having in mind that the main contrain we had for the project was time.


Finally we selected the Go-Kart set from the LEGO Creators series which includes intructions for a total of 3 models.

Project Definition

It was obvious that the core of the project would be building the assembly of the Go-kart in Inventor. To make an efficient splitting of the work load, listed all the needed activities and also the ones we wanted to include to make the project more interesting:

• List all needed parts according to the set's instructions. Divide the parts into two groups that would be of almost equal workload.
• Develop a method to import a measurable 3D model of the parts into Inventor
• Make the 3D model of each part in Inventor
• Share the parts to form a complete set.
• Make the assembly of the go-kart and of the quad bike. Each of us would make half one assembly for the other one to complete it.
• Animation and rendering in 3ds Max.

List of parts

I decided to get the actual physical LEGO set, although all the needed documentation is available online officially from LEGO.  We analysed and discussed the parts list and decided on dividing the parts into two groups so that similar parts with possibility of copy effect would be together. Also complexity was taken into consideretion. This is the final list: 

Procedure for importing a measurable Lego part to Inventor

We developed a short procedure to get the 3D LEGO parts into Inventor so that we could measure its features. The procedure is not working 100% of the time but there are walkarounds the problems, so at the end all parts could be imported for us to get the dimensions.

Required software:

• Lego Digital Design (LDD):

Can be downloaded here.

• LDraw set of programs:

Can be downloaded here for Windows.
If possible install the complete set of programs and features, but at least be sure to install the following:

• 3Ds Max

• Inventor 

Procedure 

As mentioned above, the target is to get in Inventor a 3D model of the Lego part that can be measured in order to create the 3D part in Inventor itself. Below are two procedures for doing this. Some parts work only with one procedure, some work only with the other, some work with both.  It is best to work with 1 part at a time.

Procedure A (Starting from LDD)

1. Open LDD.

2. Searh for part in LDD and place it in the modelling area.

3. Export as .ldr

4. Open the .ldr file in LDView

5. Export as .STL

6. Import the .STL file in 3Ds Max. Keep the settings as they are.

7. Scale the part to 10x (this is not a must but it is easy to do it in 3ds Max)

8. Export as .sat file. Select "Export mesh objects" in the export options

9. Open the .sat file in Inventor.

10. Check that the dimensions are correct.

Procedure B (Starting from LDCad)

1. Open LDCad.

2. Searh for part in LDCad and place it in the modelling area.

3. Export as .ldr

4. Open the .ldr file in LDView

5. Export as .STL

6. Import the .STL file in 3Ds Max. Keep the settings as they are.

7. Scale the part to 10x (this is not a must but it is easy to do it in 3ds Max)

8. Export as .sat file. Select "Export mesh objects" in the export options

9. Open the .sat file in Inventor.

10. Check that the dimensions are correct.

Note: the export feature in both LDD and LDCad is not working correctly 100% of the time for all parts. An alternative to .STL files is using .3ds format.

3D Modelling of parts

With the dimensions obtained, now the task is to build our own parts. Since the parts are to be created in two different groups, and to avoid dimensional issues, we agreed to using only one decimal place for the dimensions in mm. The imported 3D parts are very accurate, so we want to use that to our advantage to save time in the process.

Sharing of parts

After each of us was finished with the respective group, we exchanged the parts. The first big issue was that we had not checked which version of Inventor we were using. I had Inventor 2015 while my partner had Inventor 2014. That meant that I had no issues working with her files on my PC, but she was completely unable to work with the files I sent. There were several options to fix this. but we decided that the best option was for my partner to install Inventor 2015 in her machine.

After this issue was solved, we had minor issued with some of the dimensions. Since LEGO parts are designed to fit with any other LEGO part, it was very important to keep consistent dimentions. This was quick to fix. The other minor issue was the color of the parts, so we had to use the same tone for each color.

Assembly of the models

The initial idea for the assemblies was that each of us would work on the first half of one of the models following the instructions of the manual and after completing the first half we would exchange the models and finish the second half of the instructions. However because of the issue with inventor we had to make a quick decision and I started both models and my partner made the second half for both models. For this step it was very useful to use Inventor projects' feature so as not to mix any of the previous versions of the parts so that the models were always very stable and we didn't lose any references.

Go-Kart

Quad-Bike

Animation and rendering

When the models were completed in Inventor the next step was to use 3Ds Max to make the final rendering of each of the models and also to make a short animation. However since my partner I had not yet completed CAVm3 module, I decided to work on this task by myself. It was natural to decide to show the Lego model  being built during  the animation. 

Final rendering Go-Kart.

Test rendering for animation.

Final render Quad-Bike.

 

Timeplan Evaluation

In general terms  the estimated times prooved to be accurate. I think this is mainly because the activities are spread over several days  so it is easier to keep good control of the time used.

However, the activities for controling  work quality used almost twice the estimated time. This seems to be  in accordance to working withinn a team since any issue  affects  all participants.  It must be mentioned that  the activity for assembly drawings had  to be droped mainly because  of the time lost fixing a mismatch in the  versions of Inventor that we were using. 

 

 

Final comments

During this collaboration project it was very nice working with my partner Marte. I feel that we worked very well together and that both of us showed a good level of skill with inventor and also responsibility for completing the project. We are a good team.  The end result was very satisfying, the Lego car rendered in Max was a success and it shows the good quality of the 3D model. The end result was so good that we think there is potential to do much more complex animations and renderings, but due to the schedule of the project it was not possible to include them. The most fun part was making the assembly since the lego parts were well done, so it was easy to follow the building instruction. There were almost no issues with constraints and the model was very stable, considering that it went back and forth several times between my partner and I. Throughout all the modules in which I have worked with Inventor I have had a very good experience and the small deal is no exception. I can definitely say that I see myself working with inventor on a day-to-day basis once I find a job.

Link to video presentation
https://youtu.be/ftMB90AdDfo 

Link to animation video
https://youtu.be/JOfzx7Inpk8