{"id":11037,"date":"2025-09-30T21:00:25","date_gmt":"2025-09-30T20:00:25","guid":{"rendered":"https:\/\/dronesonen.usn.no\/?p=11037"},"modified":"2025-09-30T21:03:31","modified_gmt":"2025-09-30T20:03:31","slug":"hydrawlics-week-6","status":"publish","type":"post","link":"https:\/\/dronesonen.usn.no\/?p=11037","title":{"rendered":"Hydrawlics – Week 6"},"content":{"rendered":"\n
\n

Hello and welcome back!\ud83d\udc4b

We\u2019ve just wrapped up another week of Sprint 2. Here\u2019s a look at what each of our team members has been working on last week:<\/p>\n\n\n\n

\"\"<\/figure>\n<\/div>\n\n\n\n\n\n\n\n
\n\n\n\n

Fredrik:<\/h2>\n\n\n\n

Last week I started designing a hydraulic cylinder, in order to establish a proof of concept for our hydraulic system. This week I mainly focused on tweaking the design such that it can be produced, and actually building the prototype. These design changes included facilitating o-ring attachments, and reducing the amount of sealed interfaces. The final 3d-model of the cylinder is shown in the picture below.<\/p>\n\n\n\n

\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n

I bought a PVC pipe with a diameter of 20mm to use as the base of the cylinder. With the help of Erling, I cut the pieces into the right length, and drilled holes for the ports. For the 3d-printed parts I decided to use PETG, seeing as it is durable and has less moisture absorption than PLA. I needed some adhesive that worked on both PETG and PVC. After some research, I figured my best option was two-component epoxy glue. This is because it will provide a good bond between the two materials, it provides some gap-filling (the two parts don’t need to be totally flush), and it is easily available to me. This is the first time I have used o-rings for my projects, so it was definitely a learn by failing type of experience. I needed to keep in mind how the o-rings would behave during assembly, while making sure it would still keep a tight seal. This ended up being a highly iterative process, learning something with every iteration. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

When it was all printed, prepared, and put together, it seemed to work. I have yet to test it fully, but the chambers appear to be sealed, and the structure held together. The cylinder itself has a length of 80mm, and the piston inside the cylinder has a delta reach of 58mm.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The piston inside the cylinder requires much force to be moved, likely due to the tight fit with the o-rings. To push the piston, roughly 3kg of force is required. The calculations shown in the picture below shows that 1.3 bar is required to push the piston. The pump we have acquired can push up to 9 bar, so this should not be an issue. Next week we will put together the proof of concept for the hydraulic system, hopefully testing if the cylinder works as intended.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n
\n\n\n\n

Lisa:<\/h2>\n\n\n\n

Last week I continued working on the proof of concept from the week before. For now, the conclusion is to keep both the Raspberry Pi and Arduino in the system. This creates a clear separation of tasks: the Pi handles planning and interfaces, while the Arduino focuses on real-time motor control. We also had a productive meeting with Steven, where we got some sensors to test out!

Sensor<\/strong><\/p>\n\n\n\n

After a meeting with Steven, I got a couple of distance sensors to test. I wanted to see how well they could perform in our setup, so I wired them up on a breadboard and connected a LCD screen to easily visualize the measurements. Setting everything up went fairly smoothly, though the LCD gave me a bit of trouble at first since no text would show up. After some fiddling I realized the backlight was simply too bright, and once I dimmed it down the readings appeared as expected.<\/p>\n\n\n\n

    \n
  • TF Luna (LiDAR):<\/strong> Worked fine overall, but the minimum range was about 300 mm<\/em>. That\u2019s not ideal for our needs, since we sometimes need to measure closer distances.
    <\/li>\n\n\n\n
  • HC-SR04 (Ultrasonic):<\/strong> This one could measure much closer and seemed more suitable. The readings did fluctuate slightly, with about \u00b11 mm difference, but overall it felt much more promising.
    <\/li>\n<\/ul>\n\n\n\n

    I filmed both tests, so check out the videos to see how the sensors behaved in practice;<\/p>\n\n\n\n