Looking for accelerometer data

[jgavlik]

I've developed a Rocket Performance Monitor based, entirely, on an accelerometer for altitude, speed, velocity and, of course, acceleration (no baro). It seems to work fine on the bench, but being careful not to release such a device to the market until it's thoroughly tested, I'm looking for accelerometer data from either 1) actual flights or 2) simulated flights (like from RockSim). Excel based is best, but anything will do at this point. Any help will be appreciated.

BTW...I'm new to this forum so please excuse any mistakes, etc.

Thanks...john

 

[heada]

Why not fly it along side a known system? There are several commercial systems that use accelerometers. Then you can compare your data to theirs in the same flight.

 

[UhClem]

Assorted data from AltAcc and RDAS in the flight logs here.

Plus of course my Kalman filter code for those that understand PIC assembly.

 

[jgavlik]

Thanks to all...however, I'm looking for Excel-type acceleration data...not just graphs...thanks..jg

 

[UhClem]

Thanks to all...however, I'm looking for Excel-type acceleration data...not just graphs...thanks..jg

The data is there although it is in the original AltAcc and RDAS format.

 

[cerving]

What columns, time and m/s**2?

 

[jgavlik]

What columns, time and m/s**2?

I've looked too, but can't find it either...jg

 

[Voyager1]

I have some data from a recent low power flight that includes 3-axis accelerometer samples from an IMU logging module (Adalogger + BNO055 IMU + BMP280 barometer). It is only 5 samples per second but might be useful for your evaluation. I was only sampling the x, y, and z acceleration and pressure, so there is no gyro or magnetometer data.

 

[gtg738w]

Try the flight logs at FlightSketch. Anyone with the current firmware will have accel data too. Here are a few examples:

https://flightsketch.com/flights/1261/
https://flightsketch.com/flights/1258/
https://flightsketch.com/flights/1220/
https://flightsketch.com/flights/1199/

 

[jgavlik]

I have some data from a recent low power flight that includes 3-axis accelerometer samples from an IMU logging module (Adalogger + BNO055 IMU + BMP280 barometer). It is only 5 samples per second but might be useful for your evaluation. I was only sampling the x, y, and z acceleration and pressure, so there is no gyro or magnetometer data.

 

[jgavlik]

This seems perfect....let me take some time to analyze it...thanks again...jg

 

[jgavlik]

Try the flight logs at FlightSketch. Anyone with the current firmware will have accel data too. Here are a few examples:

https://flightsketch.com/flights/1261/
https://flightsketch.com/flights/1258/
https://flightsketch.com/flights/1220/
https://flightsketch.com/flights/1199/

These graphs match my plotted data...just looking for the actual data...many thanks!....john

 

[gtg738w]

These graphs match my plotted data...just looking for the actual data...many thanks!....john

There is a “Download data” link on each page that will give raw sensor data at 50 Hz too.

 

[BEC]

Russ beat me to it. All of my posted flights (bcawley1) for the past several months will have accelerometer data in them, even if you can't display it on the web pages. Just grab the files from the download link on each flight's page.

The second link in Russ post #9 is a flight I made just yesterday. Here's a link directly to the data file: Download Data (.csv)

 

[jgavlik]

There is a “Download data” link on each page that will give raw sensor data at 50 Hz too.
View attachment 431228

Saw the .csv files...they look very good...plus the graphs are "interactive" as well! Great job...thanks again...john

 

[jgavlik]

Russ beat me to it. All of my posted flights (bcawley1) for the past several months will have accelerometer data in them, even if you can't display it on the web pages. Just grab the files from the download link on each flight's page.

The second link in Russ post #9 is a flight I made just yesterday. Here's a link directly to the data file: Download Data (.csv)

No matter, this looks good and I'll check out your others...thanks...john

 

[John Beans]

I've developed a Rocket Performance Monitor based, entirely, on an accelerometer for altitude, speed, velocity and, of course, acceleration (no baro). It seems to work fine on the bench, but being careful not to release such a device to the market until it's thoroughly tested, I'm looking for accelerometer data from either 1) actual flights or 2) simulated flights (like from RockSim). Excel based is best, but anything will do at this point. Any help will be appreciated.

BTW...I'm new to this forum so please excuse any mistakes, etc.

Thanks...john

Hey, John. Congrats on your project. Fun! (It's how I got started, too.)

Just curious: why not use a baro sensor?

I would gently suggest that for an extra $1.50 in part cost, you can get MUCH more accurate altitude sensing.

Rooting for your project and really don't want to be a downer, but using just acceleration data won't give you super satisfying results.

When you integrate acceleration for speed and position, you make the casual assumption that you know the direction of travel, which you don't. Theoretically it's fine for flights that are straight up (100% of acceleration along the path of the rocket goes into altitude), but even then only until the rocket peaks and begins rotating. After that, all bets are off as to which direction the altimeter is pointing when you integrate. And for arcing flights it's rough from the start.

It also assumes also that the user will mount it in a particular direction as well, or with some clever logic on your part and a 3D accelerometer at least keep it mounted so that it won't move around during flight.

Happy to explain further, or to help you integrate a pressure sensor into your design—including showing you how to use simple integer math instead of floating point and exponents to convert pressure to altitude. I'll even drop the part into your board design for you (assuming you're designing your own board).

 

[jgavlik]

Hey, John. Congrats on your project. Fun! (It's how I got started, too.)

Just curious: why not use a baro sensor?

I would gently suggest that for an extra $1.50 in part cost, you can get MUCH more accurate altitude sensing.

Rooting for your project and really don't want to be a downer, but using just acceleration data won't give you super satisfying results.

When you integrate acceleration for speed and position, you make the casual assumption that you know the direction of travel, which you don't. Theoretically it's fine for flights that are straight up (100% of acceleration along the path of the rocket goes into altitude), but even then only until the rocket peaks and begins rotating. After that, all bets are off as to which direction the altimeter is pointing when you integrate. And for arcing flights it's rough from the start.

It also assumes also that the user will mount it in a particular direction as well, or with some clever logic on your part and a 3D accelerometer at least keep it mounted so that it won't move around during flight.

Happy to explain further, or to help you integrate a pressure sensor into your design—including showing you how to use simple integer math instead of floating point and exponents to convert pressure to altitude. I'll even drop the part into your board design for you (assuming you're designing your own board).

John,

Thanks for your considered analysis of the Rocket Performance Monitor.

You are correct in most of your analysis as it needs to "strapped-down" to work....just like real rockets that go into space do. Also, real rockets don't use a "baro chip" for the same reason...no air in space...so I suppose there's no free lunch.

And being strapped-down, we measure only the z-axis acceleration "going up" for altitude (and only vertical speed - not hroizontal). Going down it's different as the nose cone (where the RPM1 is located) is swinging all over the place, so a combined x,y,z acceleration is measured for altitude, speed, etc.

Finally, thanks (so much) for your offer to "drop in" a barometer chip into the design....we'll see if it needs it. However, what the RPM1 "really needs" is a Bluetooth interface....(to be continued in RPM2 perhaps)....jg

 

[Dan Griffing]

I've developed a Rocket Performance Monitor based, entirely, on an accelerometer for altitude, speed, velocity and, of course, acceleration (no baro). It seems to work fine on the bench, but being careful not to release such a device to the market until it's thoroughly tested, I'm looking for accelerometer data from either 1) actual flights or 2) simulated flights (like from RockSim). Excel based is best, but anything will do at this point. Any help will be appreciated.

BTW...I'm new to this forum so please excuse any mistakes, etc.

Thanks...john

I have found $100 Jolly Logic Altimeter3 a most amazingly useful device because I can Velcro or tape it to the inside of the nosecone of almost any rocket, tether it to any shock cord, or affix it to any airframe. It has a Bluetooth interface for uploading the results of previous flights. And the full *.csv flight altimeter and 3-axis accelerometer can be transferred to a computer by several methods such as a email attachment.

I’ve used the *.csv data with Excel to analyze flight data, motor acceleration performance, calculate parachute descent rates and Cd parameters, and measure ejection charge nosecone and airframe component accelerations to determine optimum BP ejection charges and shock cord lengths during ground testing. Collecting 3-axis accelerometer data is quite useful for many aspects of high power rocketry.

My only complaint with the is that I cannot buy enough of them to put one on every one of my rockets.

If the instrument you have under development works this well, then I’m sure you’ll find a lot of happy customers.

 

[jgavlik]

I have found $100 Jolly Logic Altimeter3 a most amazingly useful device because I can Velcro or tape it to the inside of the nosecone of almost any rocket, tether it to any shock cord, or affix it to any airframe. It has a Bluetooth interface for uploading the results of previous flights. And the full *.csv flight altimeter and 3-axis accelerometer can be transferred to a computer by several methods such as a email attachment.

I’ve used the *.csv data with Excel to analyze flight data, motor acceleration performance, calculate parachute descent rates and Cd parameters, and measure ejection charge nosecone and airframe component accelerations to determine optimum BP ejection charges and shock cord lengths during ground testing. Collecting 3-axis accelerometer data is quite useful for many aspects of high power rocketry.

My only complaint with the is that I cannot buy enough of them to put one on every one of my rockets.

If the instrument you have under development works this well, then I’m sure you’ll find a lot of happy customers.

Dan,
Thanks for your positive comments on your Jolly Logic Altimeter 3. It is, indeed, a great device that has a great deal of thoughtful engineering behind it. And, yes, the Bluetooth feature is worth it all. The only thing that's possibly better (IMHO) are the BT features from www.FlightSketch.com that allows one to upload their BT data to the cloud and compare the results with other users on their website . This is going to be a game changer...again IMHO.

It's further encouraging that (at least part of) this hobby community is dedicated to 21st Century technology along with knowing how to interpret the data that are generated by modern electronics, aka...you and others like you.

Thanks, again, for your positive comments and stay tuned for our RPM1 device....things are looking good at the moment in our testing.....jg

 

[Dan Griffing]

Dan,
Thanks for your positive comments on your Jolly Logic Altimeter 3. It is, indeed, a great device that has a great deal of thoughtful engineering behind it. And, yes, the Bluetooth feature is worth it all. The only thing that's possibly better (IMHO) are the BT features from www.FlightSketch.com that allows one to upload their BT data to the cloud and compare the results with other users on their website . This is going to be a game changer...again IMHO.

It's further encouraging that (at least part of) this hobby community is dedicated to 21st Century technology along with knowing how to interpret the data that are generated by modern electronics, aka...you and others like you.

Thanks, again, for your positive comments and stay tuned for our RPM1 device....things are looking good at the moment in our testing.....jg

Bear in mind that as a retired engineer, I’ve always gotten deeply involved in scientific data collection. Sometimes I seem to regard rocketry as just another opportunity to collect scientific data. I’m just like the kid with a new chemistry set!