I am trying to access the physical un-calibrated gyroscope sensor. But I am unable to. Since I can only access the calibrated one, I want to know what method is used for drift compensation in the gyroscope sensor used in the Tango Device.
Nobody knows exactly what Tango uses for drift compensation, my own guess would be that they are heavily reliant on Structure From Motion techniques. If you're asking how to calibrate an already calibrated gyro (calibration quality is a different issue :-) ), that's a topic for an entire stack overflow site, not a single answer :-) And it would leave you battling for computation resources with Tango - if you want to experiment, any phone with 3DOF attitude sensing and a decent camera is a good starting platform for learning about this, but be warned - it's really complex - much nicer to have it packaged and take what you get.
At my university we have several Kinect 1's and Kinect 2's. I am testing the quality of the Kinect Fusion results on both device and unexpectedly Kinect 2 produces worst results.
My testing environment:
Static camera scanning a static scene.
In this case if I check both results from Kinect 1 and 2, then it looks like Kinect 2 has a way smoother and nicer resulting point cloud, but if I check the scans from a different angle, then you can see the that Kinect 2 result is way worst even if the point cloud is smoother. As you can see on the pictures if I check the resulting point cloud from the same view as the camera was, then it looks nice, but as soon as I check it from a different angle then the Kinect 2 result is horrible, can't even tell that in the red circle there is a mug.
Moving camera scanning a static scene
In this case Kinect 2 has even worst results, then in the above mentioned case compared to Kinect 1. Actually I can't even reconstruct with Kinect 2 if I am moving it. On the other hand Kinect 1 does a pretty good job with moving camera.
Does anybody have any idea why is the Kinect 2 failing these tests against Kinect 1? As I mentioned above we have several Kinect cameras at my university and I tested more then one of them each, so this should not be a hardware problem.
I've experienced similar results when I was using Kinect for 3D reconstruction. Kinect 2 produced worse results compared to Kienct 1. In fact, I tried the InfiniTAM framework for doing 3D reconstruction. It too yielded similar results. What was different in my case compared to yours was that I was moving the camera around and the camera tracking was awful.
When I asked the authors of InfiniTAM about this, they provided the following likely explanation:
... the Kinect v2 has a time of flight camera rather than a structured
light sensor. Due to imperfections in the modulation of the active
illumination, it is known that most of these time of flight sensors
tend to have biased depth values, e.g. at a distance of 2m, everything
is about 5cm closer than measured, at a distance of 3m everything is
about 5cm further away than measured...
Apparently, this is not an issue with structured light cameras (Kinect v1 and the like). You can follow the original discussion here.
I am right now working on one application where I need to find out user's heartbeat rate. I found plenty of applications working on the same. But not able to find a single private or public API supporting the same.
Is there any framework available, that can be helpful for the same? Also I was wondering whether UIAccelerometer class can be helpful for the same and what can be the level of accuracy with the same?
How to implement the same feature using : putting the finger on iPhone camera or by putting the microphones on jaw or wrist or some other way?
Is there any way to check the blood circulation changes ad find the heart beat using the same or UIAccelerometer? Any API or some code?? Thank you.
There is no API used to detect heart rates, these apps do so in a variety of ways.
Some will use the accelerometer to measure when the device shakes with each pulse. Other use the camera lens, with the flash on, then detect when blood moves through the finger by detecting the light levels that can be seen.
Various DSP signal processing techniques can be used to possibly discern very low level periodic signals out of a long enough set of samples taken at an appropriate sample rate (accelerometer or reflected light color).
Some of the advanced math functions in the Accelerate framework API can be used as building blocks for these various DSP techniques. An explanation would require several chapters of a Digital Signal Processing textbook, so that might be a good place to start.
I am using LG Optimus 2x smartphone which consists of gyro and accelrometer sensors. I am using it in indoor tracking application by using pedestrian dead reckoning techniques. I want to use gyro sensor to get correct orientation of mobile. I am integrating gyro data over time to get angles. But these angles are not well accurate. how I can get error free angles from Gyro sensor.
navig
I am using the method described in this manuscript and it works like charm in my application. It gives very accurate orientations.
I am curious. What method do you use for tracking the pedestrian? How do you use orientation?
The best pedometer algorithm I have found so far is this. It seems to me you have something better. Could you share it?
I'd like to start messing around programming and building something with an Arduino board, but I can't think of any great ideas on what to build. Do you have any suggestions?
I show kids, who have never programmed, or done any electronics before, to make a simple 'Phototrope', a light sensitive robot, in about a day. It costs under £30 (GBP) including Arduino, electronics and off-the-shelf mechanics. If folks really get into mobile robots, the initial project can grow and grow (which I feel is part of the fun).
There are international robot competitions which require relatively simple mechanics to get started, e.g. in the UK http://www.tic.ac.uk/micromouse/toh.asp
Ultimate performance require specially built machines (for lightness) , but folks would get creditable results with an Arduino Nano, the right electronics, and a couple of good motors.
A line following robot is the classic mobile robot project. The track can be as simple as electrical tape. Pololu have some fun videos about their near-Arduino 3PI robot. The sensors are about £1, and there are a bunch of simple motor+gearbox kits from lots of places for under £10. Add a few £ for motor control, and you have autonomous robot mechanics, in need of programming! Add an Infrared Remote receiver (about £1), and you can drive it around using your TV remote. Add a small solar cell, use an Arduino analogue input to measure voltage, and it can find the sun. With a bit more electronics, it can 'feed' itself. And so it gets more sophisticated. Each step might be no more than a few hours to a few days effort, and you'll find new problems to solve and learn from.
IMHO, the most interesting (low-cost) competitions are maze solving robots. The international competition rule require the robot to explore a walled maze, usually using Infrared sensors, and calculate their optimal route. The challenges include keeping track of current position to near-millimeter accuracy, dealing with real world's unpredictably noisy environment and optimising straight-line speed with shortest distance cornering.
All that in 16K of program, and 1K RAM, with real-time interrupt handling (as much as 100K interrupts/second for some motor systems), sensor sampling, motor speed control, and maze solving is an interesting programming challenge. (You might make it 'easy' with 32K of program, and 2K RAM :-)
I'm working on a 'constrained' robot challenge (based on Arduino) so that robot performance is mainly about programming rather than having a big budget.
Start small and build up to something more complex. Control servos. Blink LEDs. Debounce inputs. Read analog sensors. Display text on an LCD. Then put it together.
Despite the name, I like the "Evil Genius" book for PIC microcontrollers because of the small, easily digestible projects that tend to build on one another. It is, of course, aimed at PIC programmers rather than the Arduino, but the material covered will be useful no matter what you're developing on.
I know Arduino is trendy right now, but I also like the Teensy++ development board because of its low price-point ($24), breadboard-compatible PCB, relatively high pin count, Linux development environment, USB connectivity, and not needing a programmer. Worth considering for smaller projects.
If you come up with something cool, let me know. I need an excuse to do something fun :)
Bicycle-related ideas:
theft alarm (perhaps with radio link to a base station which is connected to a PC by Ethernet)
fancy trip computer (with reed switch or opto sensor on wheel)
integrate with a GPS telematics unit (trip logging) with Ethernet/USB download of logged data to PC. Also has an interesting PC programming component--integrate with Google Maps.
Other ideas:
Clock with automatic time sync from:
GPS receiver
FM radio signal with embedded RDS data with CT code
Digital radio (DAB+)
Mobile phone tower (would it require a subscription and SIM card for this receive-only operation?)
NTP server via:
Ethernet
WiFi
ZigBee (with a ZigBee coordinator that gets its time from e.g. Ethernet or GPS)
Mains electricity smart meter via ZigBee (I'm interested now that smart meters are being introduced in Victoria, Australia; not sure if the smart meters broadcast the time info though, and whether it requires authentication)
Metronome
Instrument tuner
This reverse-geocache puzzle box was an awesome Arduino project. You could take this to the next step, e.g. have a reverse-geocache box that gives out a clue only at a specific location, and then using physical clues found at that location coupled with the next clue from the box, determine where to go for the next step.
You could do one of the firefighting robot competitions. We built a robot in university for my bachelor's final project, but didn't have time to enter the competition. Plus the robot needed some polish anyway... :)
Video here.
Mind you, this was done with a Motorola HC12 and a C compiler, and most components outside the microcontroller board were made from scratch, so it took longer than it should. Should be much easier with prefab components.
Path finding/obstacle navigation is typically a good project to start with. If you want something practical, take a look at how iRobot vacuums the floor and come up with a better scheme.
Depends on your background and if you want practical or cool. On the practical side, a remote control could be a simple starting point. It's got buttons and lights but isn't too demanding.
For a cool project maybe a Simon-style memory game or anything with lights & noises (thinking theremin-style).
I don't have suggestions or perhaps something like a line follower robot. I could help you with some links for inspiration
Arduino tutorials
Top 40 Arduino Projects of the Web
20 Unbelievable Arduino Projects
I'm currently developing plans to automate my 30 year old model train layout.
A POV device could be fun to build (just google for POV Arduino). POV means persistence of vision.