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by jb63
Mon Feb 22, 2016 8:32 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 12531

Re: catapult project ( raspberry pi ) - physics - need help

Obviously this might be 'uncharted' territories, though I'm sure someone at NASA has worked on something similar a while back ... Now, the 'slowly learn' part typically means how many iteration cycles before the filter becomes good at predicting the object's trajectory. This is why I wrote earlier t...
by jb63
Mon Feb 22, 2016 5:27 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 12531

Re: catapult project ( raspberry pi ) - physics - need help

jb63, I keep hearing about the Kalman filter for this task. So far I have no idea how that works. I have to look into it one day. I'll try to put it in simple words. Think of the Kalman filter as an algorithm that slowly learns the dynamics of the system at hand, and then builds a model to 'predict...
by jb63
Mon Feb 22, 2016 12:20 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 12531

Re: catapult project ( raspberry pi ) - physics - need help

Heater, Maybe I spoke too early. It's a given that it's always easy unless you have to do it yourself :). In any event, I was thinking primarily of fusing the data, as you indicated. The idea is to use the magnetometer data to 're-orient' the frame for the accelerometers and gyros data, then resolve...
by jb63
Mon Feb 22, 2016 7:01 am
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 12531

Re: catapult project ( raspberry pi ) - physics - need help

The math is rather easy, it's about resolving three vectors along three directions, and can be tweaked (debugged) afterwards. What I would do, is capture raw data (9 channels) time histories at whatever rate the RPi can handle, during many trial launches. I would then post-process that data in e.g. ...
by jb63
Wed Jan 13, 2016 7:51 pm
Forum: General discussion
Topic: Naming Convention - rather basic question
Replies: 7
Views: 1569

Re: Naming Convention - rather basic question

Thank you. That reminds me of an article in the latest MagPi (#41?) about that specific computer.
by jb63
Wed Jan 13, 2016 7:50 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 12531

Re: catapult project ( raspberry pi ) - physics - need help

You got it right! Sensor fusion is the answer here. Though, we need to make sure the sensors have sufficient bandwidth and sensitivity to capture all we're after. Not all accelerometers and not all gyros are created equal.
by jb63
Tue Jan 12, 2016 6:31 pm
Forum: General discussion
Topic: catapult project ( raspberry pi ) - physics - need help
Replies: 98
Views: 12531

Re: catapult project ( raspberry pi ) - physics - need help

Interesting discussion. I'll simply add this. If the RPI is attached to the projectile, then you won't be able to measure acceleration, as there won't be any net force between the sensing elements of the accelerometer and the base (PC board). This, assuming the projectile does not turn or change att...
by jb63
Tue Jan 12, 2016 4:29 am
Forum: General discussion
Topic: Naming Convention - rather basic question
Replies: 7
Views: 1569

Naming Convention - rather basic question

I've tried to decipher the logic behind the naming convention of all the different RPIs out there but to no avail.

What is the difference between A vs. B? what does the + really stand for?
Is there any logic to this or is it just a 'mangled up' after thought ?
by jb63
Tue Jan 05, 2016 4:11 pm
Forum: General discussion
Topic: DVB-S Tuner
Replies: 12
Views: 9173

Re: DVB-S Tuner

Sorry for reviving an old thread. What is the latest if one is to integrate multiple sources in the an Raspberry Pi 2? Today I have 1. an RPI2 running OSMC 2. a laptop running some Internet TV channels, and ... 3. a stand-alone box for Satellite (FTA) channels. Would love to bring all of this togeth...
by jb63
Mon Jan 04, 2016 9:21 pm
Forum: Media centres
Topic: Satellite TV Receiver with RPI 2 ?
Replies: 0
Views: 1783

Satellite TV Receiver with RPI 2 ?

I've seen only fragmented information on the web, and I'm sure this is of interest to many. What I'm after is: 1. Best supported DVB-S (USB?) adapters that work 'seamlessly' with Raspberry PI 2. Best Route: Add-On in OSMC/Kodi/Openelec or something else? I'm interested primarily in FTA (internationa...
by jb63
Sun Jan 03, 2016 8:20 pm
Forum: Beginners
Topic: Building an IMU+GPS Unit
Replies: 7
Views: 3415

Re: Building an IMU+GPS Unit

A bit more clarification about what I'm after. This is really for a work-related project and I want to replicate/compare the specs of a 'home-made' sensor unit against more expensive options. Some instrumentation vendors (RaceLogic VBOX, SoMAT) already sell combination/integrated units that consist ...
by jb63
Sun Jan 03, 2016 3:32 pm
Forum: Beginners
Topic: Building an IMU+GPS Unit
Replies: 7
Views: 3415

Re: Building an IMU+GPS Unit

Uhhhmmm, cough, you do realise that the Sense Hat already has the Accelerometer, Gyro & Magnetometer built-in via a single chip IC, don't you?! See https://www.raspberrypi.org/documentation/hardware/sense-hat/README.md, and which has info on RTIMULIB which is a C++ and Python library that makes it ...
by jb63
Sat Jan 02, 2016 6:09 am
Forum: Official Foundation Display
Topic: Using the Pi Touchscreen with a second monitor
Replies: 9
Views: 4578

Re: Using the Pi Touchscreen with a second monitor

I'm planning on doing exactly that. The 7" display + a regular hdmi display. I've read nowhere that it should not work ... only thing is I'm still waiting for my 7" to arrive, and should be able to start experimenting in a week or so.
by jb63
Sat Dec 26, 2015 2:23 am
Forum: Media centres
Topic: Car MP3 Player - Need Advice
Replies: 12
Views: 3432

Re: Car MP3 Player - Need Advice

drgeoff wrote:Unless you use an oscilloscope or some means of "seeing" the control signals, you will have a tough job figuring out how they work.
Agreed, I got one coming from eBay ... nothing professional, it's actually a parts pack and have to solder it myself ... promises to be lots of 'fun'.
by jb63
Sat Dec 26, 2015 2:21 am
Forum: Media centres
Topic: Car MP3 Player - Need Advice
Replies: 12
Views: 3432

Re: Car MP3 Player - Need Advice

My car is a decade old ... MY 2006, and yes, I suspect the wires of the AUX to be a mix of analog (audio) and digital (controls). Of course, I could be wrong, but it's something I should be able to answer 'easily'. Thank you for the many links. Those promise to be an interesting read. I may have cro...
by jb63
Fri Dec 25, 2015 7:12 pm
Forum: Media centres
Topic: Car MP3 Player - Need Advice
Replies: 12
Views: 3432

Re: Car MP3 Player - Need Advice

Since the head unit (Radio+CD) is detachable and can be powered 'easily' off 12 Volts, my thinking is to simply remove it, and monitor the instructions/signals on the wires in the AUX connector. This would be a tad easier is there was a target/slave unit attached, as I'm sure many of the 'instructio...
by jb63
Tue Dec 22, 2015 9:14 pm
Forum: Other projects
Topic: LS20031 GPS + RPI 2
Replies: 0
Views: 417

LS20031 GPS + RPI 2

I managed to get the LS20031 to work with an UNO R3 board. Now, the next challenge is to repeat that with an RPI2. Most tutorials I've found talk about going through a USB interface. However, I want the RPI 2 to 'talk' to the GPS module when it's connected DIRECTLY to the RPI GPIO. Anyone tried this...
by jb63
Tue Dec 22, 2015 7:14 pm
Forum: Troubleshooting
Topic: Arduino on Raspberry - Need Help
Replies: 4
Views: 901

Re: Arduino on Raspberry - Need Help

Thank you, I will for sure look it up tonight (at work now).
by jb63
Tue Dec 22, 2015 4:46 pm
Forum: Beginners
Topic: Building an IMU+GPS Unit
Replies: 7
Views: 3415

Building an IMU+GPS Unit

I have acquired few components to build a combination IMU+GPS unit IMU - Inertial Measurement Unit (acceleratios and rotations) GPS - obvious The components I have on hand are: 1. RPI 2 2. GPS Receiver - LS20031 5Hz 3. Sparkfun Gyro (3directions) 4. Sparkfun Magnetometer (3 directions) 5. Sense Hat ...
by jb63
Tue Dec 22, 2015 3:00 am
Forum: Troubleshooting
Topic: Arduino on Raspberry - Need Help
Replies: 4
Views: 901

Re: Arduino on Raspberry - Need Help

Does your Arduino really appear as /dev/ttyACM 1 ? Usually it will appear as /dev/ttyACM 0 unless that port is in use. It first appeared on /ttyACM0, but when it did not work, I physically changed the USB port, and then moved it to ttyACM1. At first the Arduino was connect on the same USB bank as a...
by jb63
Mon Dec 21, 2015 8:48 pm
Forum: Troubleshooting
Topic: Arduino on Raspberry - Need Help
Replies: 4
Views: 901

Arduino on Raspberry - Need Help

I get the following message when I try to download the compiled code to the UNO. Anyone with a clue? avrdude: Version 6.1, compiled on Jul 7 2015 at 10:29:47 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2014 Joerg Wunsch System wide configuration file is "/usr/share...
by jb63
Mon Dec 21, 2015 5:21 pm
Forum: Media centres
Topic: Car MP3 Player - Need Advice
Replies: 12
Views: 3432

Re: Car MP3 Player - Need Advice

... Do you have the equipment/skills/desire to figure it out for yourself? Yes/No/Yes ... It is something I have wanted to learn, as a hoby of course, never for professional purposes. I have some solid background in some disciplines and should be able to handle this. One question: Where would one b...
by jb63
Sat Dec 19, 2015 2:05 am
Forum: Media centres
Topic: Car MP3 Player - Need Advice
Replies: 12
Views: 3432

Re: Car MP3 Player - Need Advice

Good point, and an omission from my side. One of the main motivation for this project is that, well, my current system does not have BT or not even an audio jack input. It is a Honda Odyssey 2006. The CD player failed and I do not care for after-market systems. Honda sells an MP3 player (disc-based)...
by jb63
Sat Dec 19, 2015 1:28 am
Forum: Media centres
Topic: Car MP3 Player - Need Advice
Replies: 12
Views: 3432

Car MP3 Player - Need Advice

This project has been simmering for a while, and with the holidays, I have few days to spend on it. I want to build an MP3 player, that plugs into the AUX input of the stock car system. I have collected the following components: 1. Raspberry PI (B+) 2. Arduino UNO R3 3. MP3 Shield for Arduino (Spark...
by jb63
Fri Dec 18, 2015 2:08 pm
Forum: Media centres
Topic: How to optimize my MediaPi?
Replies: 16
Views: 5151

Re: How to optimize my MediaPi?

Not sure I agree that HDD is the fastest. I switched to SSD on my windows PCs, and the performance is way better.
Has anyone tried RPI with HDD vs. SSD ?

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