3 ms·

Here's an interesting article about the gyroscopes / related tech used on the JWST. TL;DL — it uses reaction/momentum wheels to change orientation, and it uses

Here's an interesting article about the gyroscopes / related tech used on the JWST. TL;DL — it uses reaction/momentum wheels to change orientation, and it uses non-mechanical gyroscopes to detect changes in orientation. https://www.universetoday.com/143152/spacecraft-gyroscopes-and-reaction-wheels-you-can-never-have-enough/ https://www.universetoday.com/143152/spacecraft-gyroscopes-a...

ddingus 4y ago
I just went down a small, but very interesting rabbit hole: I was not aware of non mechanical gyros! Apparently, light travelling along a fiber optic cable will travel a slightly different distance when the device has angular momentum. That is COOL. https://en.wikipedia.org/wiki/Sagnac_effect https://en.wikipedia.org/wiki/Sagnac_effect
- jimsmart 4y ago
  I believe that the tech you mention is the same tech as used by the flat-earthers in Behind The Curve in the $20k gyroscope they bought, to try and prove that the Earth did not rotate (except they found it picked up a 15-degree-per-hour drift, debunking themselves, so then doubted the technology, heh) [1]. But, aside from the laser/fibre-optic tech, there are also MEMS [2] gyroscopes also — which is almost nanotech IMO — which are used as sensors in modern phones/tablets, and also on drones (to assist with navigation), plus various other robotics uses, and more. MEMS gyros — often with an accelerometer (aka IMU / inertial measurement unit) and maybe a magnetometer (compass) — can be bought from folk such as Adafruit [3], SparkFun, etc. (I've got a few different ones myself), and hooked up to e.g. an Arduino or similar MCU (or indeed anything else that speaks can speak the appropriate protocol, e.g. I2C/SPI/etc depending on the board in question). Hmm, just looked for a good image of how a MEMS gyro works, and didn't come up with what I was looking for / recall seeing before (I'm a bit pushed for time), but there's a diagram on this WP page [4]. Edit: ah, here's a better diagram [5] [1] https://www.triplem.com.au/story/flat-earthers-spend-20-000-trying-to-prove-earth-is-flat-accidentally-prove-it-s-round-129953 https://www.triplem.com.au/story/flat-earthers-spend-20-000-... [2] https://en.wikipedia.org/wiki/Microelectromechanical_systems https://en.wikipedia.org/wiki/Microelectromechanical_systems [3] https://www.adafruit.com/category/521 https://www.adafruit.com/category/521 [4] https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope#MEMS_gyroscopes https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope#... [5] https://www.researchgate.net/figure/Block-diagram-of-the-MEMS-gyroscope_fig1_266022526 https://www.researchgate.net/figure/Block-diagram-of-the-MEM...
  - ddingus 4y ago
    The FE link is awesome! The others are interesting and informative. I am gonna buy me a few parts to play with. Thanks!
    - jimsmart 4y ago
      No problem, have fun! — and if you enjoyed that FE article, you will likely enjoy the 'Behind The Curve' movie too, it's really quite amusing :)
  - dekhn 4y ago
    I've used the MPU6050 to build a two-wheel self balancing robot (roughly this: https://www.instructables.com/Arduino-Self-Balancing-Robot-1/ https://www.instructables.com/Arduino-Self-Balancing-Robot-1...). Basically, apply PID to the motor angle to keep the robot level with the gravity vector. I still think MEMS sensors are very cool and extremely convenient/cheap for what you get.
    - jimsmart 4y ago
      Nice! I've done some projects myself with MPU6050 and some with its 9-axis "bigger brother" the MPU9250 (same as 6050, but with added 3-axis magnetometer/compass). I've also used the LSM9DS1 — another 9-axis IMU, just a different chip. — Yeah, definitely amazing tech for the price. Cheap as chips! /me gets coat. Ingenuity, the Mars helicopter/drone, apparently includes a bunch of off-the-shelf kit like this — IIRC I think a bunch of the parts are made by SparkFun. I don't recall any specifics though.
- Dave_Rosenthal 4y ago
  Yep, ring laser gyro :) They are pretty awesome. Once got some data that seemed to be bad out of one and realized that the entire error was exactly accounted for by the Coriolis effect from the rotation of the earth.

ddingus 4y ago

I just went down a small, but very interesting rabbit hole: I was not aware of non mechanical gyros! Apparently, light travelling along a fiber optic cable will travel a slightly different distance when the device has angular momentum. That is COOL. https://en.wikipedia.org/wiki/Sagnac_effect https://en.wikipedia.org/wiki/Sagnac_effect

jimsmart 4y ago
I believe that the tech you mention is the same tech as used by the flat-earthers in Behind The Curve in the $20k gyroscope they bought, to try and prove that the Earth did not rotate (except they found it picked up a 15-degree-per-hour drift, debunking themselves, so then doubted the technology, heh) [1]. But, aside from the laser/fibre-optic tech, there are also MEMS [2] gyroscopes also — which is almost nanotech IMO — which are used as sensors in modern phones/tablets, and also on drones (to assist with navigation), plus various other robotics uses, and more. MEMS gyros — often with an accelerometer (aka IMU / inertial measurement unit) and maybe a magnetometer (compass) — can be bought from folk such as Adafruit [3], SparkFun, etc. (I've got a few different ones myself), and hooked up to e.g. an Arduino or similar MCU (or indeed anything else that speaks can speak the appropriate protocol, e.g. I2C/SPI/etc depending on the board in question). Hmm, just looked for a good image of how a MEMS gyro works, and didn't come up with what I was looking for / recall seeing before (I'm a bit pushed for time), but there's a diagram on this WP page [4]. Edit: ah, here's a better diagram [5] [1] https://www.triplem.com.au/story/flat-earthers-spend-20-000-trying-to-prove-earth-is-flat-accidentally-prove-it-s-round-129953 https://www.triplem.com.au/story/flat-earthers-spend-20-000-... [2] https://en.wikipedia.org/wiki/Microelectromechanical_systems https://en.wikipedia.org/wiki/Microelectromechanical_systems [3] https://www.adafruit.com/category/521 https://www.adafruit.com/category/521 [4] https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope#MEMS_gyroscopes https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope#... [5] https://www.researchgate.net/figure/Block-diagram-of-the-MEMS-gyroscope_fig1_266022526 https://www.researchgate.net/figure/Block-diagram-of-the-MEM...
- ddingus 4y ago
  The FE link is awesome! The others are interesting and informative. I am gonna buy me a few parts to play with. Thanks!
  - jimsmart 4y ago
    No problem, have fun! — and if you enjoyed that FE article, you will likely enjoy the 'Behind The Curve' movie too, it's really quite amusing :)
- dekhn 4y ago
  I've used the MPU6050 to build a two-wheel self balancing robot (roughly this: https://www.instructables.com/Arduino-Self-Balancing-Robot-1/ https://www.instructables.com/Arduino-Self-Balancing-Robot-1...). Basically, apply PID to the motor angle to keep the robot level with the gravity vector. I still think MEMS sensors are very cool and extremely convenient/cheap for what you get.
  - jimsmart 4y ago
    Nice! I've done some projects myself with MPU6050 and some with its 9-axis "bigger brother" the MPU9250 (same as 6050, but with added 3-axis magnetometer/compass). I've also used the LSM9DS1 — another 9-axis IMU, just a different chip. — Yeah, definitely amazing tech for the price. Cheap as chips! /me gets coat. Ingenuity, the Mars helicopter/drone, apparently includes a bunch of off-the-shelf kit like this — IIRC I think a bunch of the parts are made by SparkFun. I don't recall any specifics though.
Dave_Rosenthal 4y ago
Yep, ring laser gyro :) They are pretty awesome. Once got some data that seemed to be bad out of one and realized that the entire error was exactly accounted for by the Coriolis effect from the rotation of the earth.