Building a fischertechnik warehouse storage/retrieval machine - Page 1
Forum section: electronics / projects

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 13, 2023, 02:26:25 pm
content: It is not really an electronics project, but there will be motors, switches and a computer controlling it so might interest others too.I have always been fascinated with mechanical systems and have a lot of fischertechnik to play with, so I set of on a journey of building a big machine to retrieve and store small boxes from/into a kind of warehouse.The build will involve a lot of trial builds to see if it can be build and will work as I want it to. My first setup became impractical and to heavy to make it do the job, so I took it apart and started over with fresh new ideas.The images show the first step in realizing these new ideas. I'm planing on making several lanes with storage racks where the small boxes will be stored. The store and retrieval lift will be able to move along the racks and bring the box to the exit point. The first build is a proof of concept and only has one lane and one rack. It is possible to have 7 levels and 6 racks per lane with the dimensions I setup now. The height is limited due to the length of the axles available.It will take quite a bit of time to finish the complete build. So sit back and enjoy.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 14, 2023, 06:23:29 pm
content: Well, like I wrote in the first post, it would involve trial builds, and it turned out that the first test build did not move smooth. I added the motor for traversing the track along the racks and it was very jerky due to the sprocket wheels in the rail being pushed down to much.So I decided to start over again but now with a kind of a sled setup. On the top and bottom there will be an aluminum profile on which the lift contraption can slide. Next to the bottom one will be the track to allow the sprocket wheel to move the lift contraption.Attached is a picture of what I constructed so far.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 14, 2023, 08:37:09 pm
content: Wow, that takes me back. I didn't know fischertechnik was still available. I feel an easter treat comming my way!

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 15, 2023, 05:50:36 am
content: Yep, it is still very much alive. But my collection was gathered many years ago and stored in boxes for a long time while building our house. We are finally settled and now I can enjoy playing with it.I bought a big cabinet with drawers that architects used to store big drawings. Filled it with the storage boxes fischertechnik has available and can now easily find the parts. It was a bit banged up but with a good paint job it turned out very nice.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 16, 2023, 09:34:56 am
content: Was quite a bit of building work, but the first rack is finished. Used up a lot of my yellow statics parts. Think I have enough grey statics parts to build a second rack, but that will be it. Also don't have enough of the small boxes to fill all the slots.The left right movement of the lift is still not perfect, but way better than the other try.I have to add the controller and wire it up for some first tests. If it turns out to work as I want it, I will build the next rack. After that a setup for moving the lift contraption from one rack to the other needs to be build.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 17, 2023, 02:24:03 pm
content: The wiring is done and I made a simple test program with the fischertechnik robotpro software. I'm still learning this graphical way of programming and the software does frustrate me, but making my own would be a lot of work, so it has to do for now.I made avideoof the lift moving simultaneous left/right and up/down. Youtube automatically made it a short so no direct watching here.Need to make some structured program that also takes a box and stores it in a free spot and repeats that on some random basis. Have to read the manual to find what is possible with this software. It might take a while to get it done.After that building the second rack is up and then make some provisions for the lift to traverse between the two racks. Lots of work ahead.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 19, 2023, 11:07:36 am
content: There is a bit of a learning curve on the making of the robotpro programs. After the first setup of just moving left/right and up down I had to make separate routines for these motions in such a way that I can specify the row and column to go to. These need a bit of cleanup after learning more of the functionality, but for now they do the job.Had to do the row and column selection based on short distance movements, so it stops at every row and column until it gets to its destination. Have not found a way to do it in one motion yet.For the fetching and placing of the boxes I made some routines today and tweaked them to do the job. I have to look into some protection though, because the lift needs to be perfectly aligned to put the box back in. Otherwise the motor keeps pushing and things will deform. Not sure how to protect against this, but there are some time functions available, so a setup with a limit on the time before the end switch needs to be activated could do the trick.Here is another video where the box is fetched from row 3 and stored in row 6 (row 1 is the bottom one)

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 22, 2023, 09:53:45 am
content: I played a bit more with the RoboPro stuff and adapted the program to randomly select a location to fetch a box from and then place it in the previous location. Also improved on the movement of the lift and it is now moving to the next location in one go instead of stopping at each row or column.The system is not perfect though and fetching or placing of a box goes wrong at times due to misalignment. This can be seen near the end of the video, where it tries to place a box in the top row of the second column. I'm thinking about how this can be improved by mechanically forcing the alignment between the lift and the column. The row select has more accuracy in locating, so no problem there.The video also shows the screen of the RoboPro program running to make it happen.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 25, 2023, 05:01:46 pm
content: Was some work to get the lift transporter and the second rack build, but it is done and it sort of works. A bit of a problem is the power supply and the control of the lift transporter. The cables need to be fed in somehow and they get hooked behind obstacles now and again.I ordered some chain cable guides used on 3D printers but not sure if that will work as needed in this case.Also not fully happy with the complete construction, so might start over with yet an other setup. Since I only have enough of some specific parts to build the two racks, I'm thinking about having them opposite of each other and make the lift turn able, so it can fetch and place from and to both racks from the same alley. This would also make the setup smaller and does away the need for the lift transporter.The problem with the alignment is not solved either. A bit of a problem is the bulkiness of the parts making it hard to create something to fit in the current design.It is still a lot of fun though, building these contraptions.Here are some photos of the setup now. The first one shows the lift transporter with only the first rack.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 29, 2023, 06:20:17 pm
content: Started over again.First build a new elevator contraption with the possibility to rotate the box collector to a delivery position or another rack. Having it slide with a top rail did not work that well, so made it self supporting on a sled. That worked rather well. But with the first version of the racks it still had problems with the alignment, so I looked into building a new rack. The problem with fischertechnik is the standard 15mm dimension. There are basic building blocks to do 5mm and 7.5mm, but with the static building materials these do not exist. Going up a full 15mm would result in the boxes being able to fall of of one of the rails, so it needed to be something in between.These static parts have struts to make the stronger constructions and they also come in steps of 15mm for the normal ones, but do have odd dimensions for the crosses. One of them being 84.8mm which turned out to be perfect for the job. The 90mm could be used for the crosses to make a sturdy construction.Fitted the box collector with sharp angled parts to allow the box to be guided in.The new rack is 6cm wider then the first one (from 46.5 to 52.5) so not a big deal. The overall construction reduces quite a bit in size. The first setup used 4 * 2 of the black bottom plates to house the racks and the rails for the lift. The new one will be 3 * 2.The random pick and place code ran for a while without running into problems. So all in all a good result after several iterations.Now a bit of work on the second rack to reflect the new idea and combine it into one big system. Adapt the code to handle the rotation, and that will be it for the warehouse part.

author: pcprogrammer
author_rank: Super Contributor
timestamp: April 01, 2023, 03:15:58 pm
content: Finally a version that moved all boxes from rack 1 to rack 2 without problems. I had to redo the lift tower construction because it was giving problems with not always hitting the right position when rotating to the other rack. Also added a second end switch for the rotation to tweak both stop positions individually.It takes about 20 minutes to move all 42 boxes from rack 1 to rack 2, starting at the bottom far end going up and then to the column to the left, and so on. It repeats the whole cycle but then from rack 2 to rack 1 and so on.Made a short video that shows the fetching from one rack and then placing it in the other, and a screen shot of the running main program. There are 4 tasks running to allow for simultaneous movement on the three axes.

author: pcprogrammer
author_rank: Super Contributor
timestamp: April 07, 2023, 06:57:53 am
content: I felt the design still used to much space, so I went back to the drawing board again and build a couple of new lift towers. A first one had a lift contraption that was ~550 grams and was a bit to heavy for the lifting motor. Came up with another design with a smaller motor for the rotation but still ~400 grams. The lifting motor seems fine with that and I remodeled the racks to work with this one. Halved the width between the racks.Got another idea to reduce the weight of the lift by removing the rotation back to the base and build that. The lift weighs ~260 grams but the tower is bigger and takes more room to rotate. It incorporates a so called cable drag chain, that I ordered and received the day before yesterday. That works quite well, but makes the needed room for rotating even bigger.So the smallest tower wins, even though the lift is a bit heavier, but the current draw of the lift motor is more or less the same between the two versions.Attached are some pictures of the different versions. The first one shows the heaviest lift. The second one shows the two latest towers side by side. The third shows the cable drag chain and the fourth shows the new rack setup. It now only uses 4 of the base plates instead of 6.