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About xendelaar

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    Spacecraft Engineer

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  1. xendelaar

    Stock helicopter with cyclic

    wow it's really flies great huh! amazing job
  2. what kind of projects were you thinking of? my colleague uses several raspberries in his home. one for video security and another to temperature monitor his garden pizza oven! very cool stuff! im more into arduino myself. I've been making a odometer for a silly rally i compete in for farts and giggles... and I want to make a temperature controlled fermentor for my home brewing someday.
  3. xendelaar

    tips on building a trip master/ tachometer/ odometer

    GPS is not the right way to go for my case. My odometer also works with the # of the wheel turns. only my setup uses only one wheel, whereas the odometer from my car probably uses all wheels or just the ones from the main shaft (I think). Averaging the distance between two wheels would be the perfect solution! I'm sure of it! Thanks for your Ramblings. yesterday I did another test. Aims of the test Test the arduino over a large distance in urban area with a lot of corners. If the inaccuracy is less than 200 meters (0.124 miles) per 100 km (62.1 miles), then the setup is acceptable! Method I drove 10 km (6.2 miles) on the freeway, I then calibrated the Arduino I drove into an urban area and started driving through the neighborhood. I took as many corners as possible. I didn't count the left or right turns and just drove a bit at random. This will happen also during the real "rally", but in less extreme extend.. After 26 km I stopped and measured the difference between the Arduino and car odometer. Results The difference was 21 meter at 26 km. Which corresponds with < 80 meter (0.05 miles) per 100 km (62 miles).. This is far from perfect, but for my application is accurate enough... Well.. it is acceptable I would still like to install another sensor on the opposite wheel, but the car we are using isn't my own and the owner (my father in law) doesn't want another magnet on a tire. So there is little I can do about that.. What's next? The rally will take place next week. There is little time to think of another way to measure the number of wheel turns on a car without placing a marker on the tire. I’ve been flirting with the idea of using sonar to measure the spacing between the tire rims, but I don’t know if this method is fast enough. If I don’t find a way, the current method will perform ok, but it does feel a bit sloppy… If any of you have any suggestions I’m eager to listen.
  4. xendelaar

    tips on building a trip master/ tachometer/ odometer

    Thanks for the reply! Wouldn’t the pressure being governed by the ideal gas law (p * V = n * R * T)? In that case, the pressure would be independent of the gas composition, assuming all vapors remain gaseous during the trip, right? If condens is formed then you're completely right off course! Also, if the composition/temperature or pressure does change the circumference of the tire, the same error would be measured by both car odometer and Arduino. In other words, the error would occur in both systems at the same order of magnitude so you wouldn’t measure any differences at any given temperature or pressure.
  5. xendelaar

    tips on building a trip master/ tachometer/ odometer

    Last week I performed several tests with my Arduino setup. I drove 20 km and performed measurements with the cars odometer and my arduino for every km. The only free variable I have is the circumference of my tire. So, after 20 measurements I adjusted the theoretic circumference of the tire so that the Arduino measurements fitted the odometer perfectly, using the root of least squared method. I got a perfect fit (R^2 = 1,0000 and y = 1,000 * X ) in every case. I did this experiment 3 times during one week. 2 days were sunny days, while one day was rainy. The results were a bit troublesome. I noticed the circumference is different every day/experiment: Day 1: 2,07369 m (a comma is a dot in the netherlands) Day 2: 2,07301 m Day 3: 2,07265 m (cold and rainy) The theoretic circumference also changes during the test: At the hot days the circumference increased while driving until it reached a certain ceiling after a couple of km’s (>5 km) At the cold day the circumference decreased while driving until it reached a certain plateau after a couple of km’s (>5 km). So I notice a difference in the calculated circumference of 1 mm, which doesn’t sound like much, but adds up to a deviation of >200 m in 200 km’s, which is quite unacceptable. I’m thinking this deviation could be caused by two things: The air inside the tires expands and contracts due to the hot or cold/wet weather It could be that the difference is caused by the fact that I’m only measuring the right back tire and neglecting the influence of corners. For instance.. when I only make left turns, the right wheels spins faster than the left tires, which could cause for non-correctable deviations compared to the odometer of the car. If the deviation is caused by the temperature, then I can’t do anything about it. It still is a bit weird that the theoretic circumference varies while the cars odometer isn’t influenced by the temperature. So come to think of it.. It quite unlikely that this is the case… If the deviation is caused by measuring at only one tire, I could make another sensor and stick it onto the left back tire. Tomorrow I will perform another test. I will drive 10 km’s… fit the data to get a correct theoretic circumference and then drive 10 km to test is the fit stays perfect! If it deviates. I’ll have to change my setup… Well.. I just wanted to get this of my chest. If anybody has any suggestions or ideas, I’m all ears!
  6. xendelaar

    tips on building a trip master/ tachometer/ odometer

    I tried making an emitter follower and fried my hall sensor. So excluded that thing during the next iteration. I just read your post after finding another (potential) solution. I attached the cars 12 volt directly to the laptop. So this way, I don't need an DC to AC to DC converter. It seems to work, but I'll have to perform a big experiment tonight in order to be sure! 12 Volts is not enough to charge the laptop (which needs 19 Volts) but I'm hoping it will prolong the battery life by a couple of hours! I will read into your advanced techniques! It sounds fascinating! I do not have access to an oscilloscope, but my colleague told me I could make one from a simple microphone plug and a computer? I'm not sure what he was talking about though hehe.
  7. xendelaar

    tips on building a trip master/ tachometer/ odometer

    @Shpaget funny that you mentioned this. I got much noise from the computer Power plug! it totally messed up the readings.i think it's caused by the alternator switching 12V dc to A.C.220v to 19V DC... ill have to find a way to shield the arduino signal from that noise
  8. xendelaar

    tips on building a trip master/ tachometer/ odometer

    yesterday I mounted the sensor and magnet onto my car and performed a test. the results were perfect! check this out. here you can see the sensor being activated by the magnet! http://imgur.com/a/cFvfqFR and here you can see the results from de arduino versus the tachometer measurements! it's almost perfect http://imgur.com/a/PQZIDeJ
  9. xendelaar

    Anyone watched "Europa Report" yet?

  10. xendelaar

    tips on building a trip master/ tachometer/ odometer

    Yeah, wel.. i ran into a wall (is that a correct English expression) when I went to car shop and learned that they couldn’t retrieve the ABS signal for me. Especially knowing that GoSlash showed that it should be possible! Maybe I asked the wrong questions or maybe the mechanic didn’t feel like doing it.. I don’t know… It was kind of frustrating. Interesting idea! So you’re saying that the radius from the ground to the middle of my tire determines the frequency at which my wheel revolves? Fascinating! I will definitely have to look into that. I don’t think it will be necessary for the “rally” though. During the rally, I have a description of the route as a text document. The document gives directions of where we need to go. For instance: At the red house, turn left At speed limit sign go right At chapel turn left Etc Etc During the first 5 km(or so) the exact distance is given per direction, so: At the red house, turn left (0,51 km) At speed limit board 50 kmpu go right (1,43 km) At chapel turn left (4,78 km) <entering unkown zone> at crossing go left Etc I can use these distances to calibrate the system. The real circumference of the wheel is in this case not relevant, since this is the free variable I use to fit my Arduino data with the given data. I will use the wheel circumference for testing purposes. It's Always better to start with a near calibrated system! On a completely different note: I finally mounted all everything onto the car and wheel. Tomorrow I will perform my first tests (YEAY). If anybody is interested: I will post some pictures and results afterwards. I will post them even if you guys are not interested..
  11. xendelaar

    tips on building a trip master/ tachometer/ odometer

    I think you're right about that. I also later found out that my tire was rather flat, so that could also explain some of the deviation. These things are all pretty easy to solve. I just need some way to calibrate the system. Using a football field or google maps are both really great ideas. I was thinking of using the hectometer signs on the freeway. Maybe I'll check all of the options.
  12. xendelaar

    tips on building a trip master/ tachometer/ odometer

    So hi guys! it's been a while! Sorry for necroing this post, but I made some progress! @GoSlash27 I went to my local autoshop and asked if they could hack the signal of my ABS. The engineers didn't know what I was talking about and said it wasn't possible. It was kind of frustrating because I know it should be possible. GOslash told me so! After that I started tinkering with an arduino board, a hall effect sensor and big magnet. I wrote a small program and performed a test on "lab scale". I used the program @Shpaget suggested to import all the juicy data to excel! In the video below you can see the setup (please don't mind the clutter)... This test worked perfectly, but I needed some validation. So... next, I attached the magnet to my scooter-wheel and mounted the sensor near the wheel. After that, I started the program and took my scooter for a spin.... Here are the first results! In the left graph you can see the distance I travelled plotted against the time I spent driving. I stopped 5 times to make a picture of the scooters' analogue odometer. These "stop" points are highlighted with the red circles. I then plotted the arduino measurements versus the analogue odometer readings, which are displayed on the right side. You can see there is a big 7,51% scalar error between the two measurements, but the R^2 is near perfect! I'm very pleased with the results! This was just a simple proof of principle. My next step will be mounting the sensor onto my car and perform more long distance tests! thanks for all the help guys! If you have any tips for improvements, please let me know!
  13. xendelaar

    Which VR headset to get?

    just watched some PR video's of VR with Skyrim and to be honest... I was pretty amazed! Maybe I will buy one too
  14. xendelaar

    Solar System In 3D! [Japanese Clay] [Panel]

    wow that is really stunning! how long did you work on this project. looks like it took a lot of work.
  15. xendelaar

    Which VR headset to get?

    I don't agree with you one this one. As I recall, if the camera is rotating while you're standing still... your brain will literally flip because it doesn't understand what is happening. This will result in an instant headache. That's what I noticed during the flight simulator. SO when you're plotting a course and rotate the camera to see where your orbit is heading, things will get messy. Maybe your brain can get used to this… I don’t know.. hmm… come to think of it.. you could use the kerbal as a fixed viewing point and have the internal dashboard as a tool for plotting courses.. for instance.. you could look on a large 2D screen in the cockpit to plot your course? You’ll be the kerbal the whole trip… damn… I want VR goggles as well now… darn you! It would be awesome to peform Eva tasks in Low orbit arount a moon/planet. I haven't played the VR mods for skyrim or fallout though, so I don't know if it is any good.