[20240307]「陀螺仪」分享会

[danfei]

本周四的固定聚会由业超分享

聊一聊陀螺仪相关的话题，包括原理、算法、应用等等。

时间是3月7日 周四晚19:00～22:00
地点：深圳市南山区高新南区粤兴一道9号（香港科技大学产学研大楼314-P）
https://www.amap.com/place/B02F37WPFK

无需报名，直接空降
Happy hacking

[Mitch Davis]

Hello SZDIY hackers!

On Wed, 6 Mar 2024 at 22:45, danfei <df4v...@gmail.com> wrote:

聊一聊陀螺仪相关的话题，包括原理、算法、应用等等。

So, I have a boat.

More pictures: 

  https://photos.app.goo.gl/gg9VUwxRgMjDFQ917

Terry has been on my boat!  Hope you'll come to Melbourne again Terry!

For the past few years, I've been working on a project to build an autopilot.  An autopilot will keep the boat sailing in the same direction when you're not at the wheel steering.  It's necessary for convenience and safety, especially if you're sailing solo.

  https://photos.app.goo.gl/kWuzHooS4Fmwunc19

The autopilot is based on the PyPilot project.

  https://www.pypilot.org/

That website has the software (in Python) and suggested schematics.  I took the schematics and made my own hardware design.

The autopilot needs an "9-axis" IMU.  That's an accelerometer (for translation movement), gyroscope (for rotation) and magnetometer (for direction).  I've been buying IMU modules that use the MPU9255.

There are several problems with these modules: They aren't cheap (about RMB85), the MPU9255 is no longer made, and they often don't work properly - defective when you receive them 😡.

Recently I've been looking at other IMUs, in particular the ICM20948.  PyPilot supports this chip.  I hope I can try the ICM20948, and if it works, add it to the next version of my autopilot directly onto the circuit board.

Here's my breakout board for testing:

I designed it in KiCad.  The board has the IMU, a 1.8V regulator, and two MOSFETs to convert the I2C interface from 3.3V to 1.8V.

  https://github.com/CapnKernel/icm20948-breakout

  https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2FCapnKernel%2Ficm20948-breakout

The small parts are 0402, like this:

While it's easy to design a board in KiCad that uses these parts, I confess that I cannot hand-solder 0402 parts, nor can I solder the ICM20948.  For this I will need a solder paste stencil, and to use solder reflow.  This would be easy in Shenzhen, where you can buy good tools from 华强北 and get a stencil next day from JLC, but it's not so easy or cheap in Australia.  I am currently experimenting with cutting stencils from PET/mylar using a laser cutter:

And I will do reflow with a cheap sandwich press:

It's generally a good idea to remove the sandwich before doing the reflow! 🤪

I would come to SZDIY, but it's a long swim from Australia.  Wish I was there to see you!

Mitch.

[Terry Ouyang]

Cool! I'm about to come for an acceptance test for the Autopilot Sailing project. See you soon!

Terry

Mitch Davis <m...@afork.com> 于2024年3月7日周四 10:32写道：

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