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Welcome to my Blog on robotics and embedded systems.

All normal pictures have a resolution of 1280x960 and can be viewed in full.
All pictures and videos: copyright Huub van Niekerk
The 2016 blog has been moved to the "Blog 2016" page
2017
24 March

BB: The ground rod loses power at some point: time for a small reconstruction. Will it help? Then incidentally/accidentally I find out why the carriage loses speed: seems due to the way it's constructed. But how to change that? Then the code seems to have a few flaws and needs some changes. Click the first image to watch the video.

RPi2/ROS: In another experiment it shows that a powermotor doesn't work when a small motor does. So how is it here? With the transistor removed, do the LEDs work? Then the switch: measuring reveals some oopses. But how to solve them? Click the image to watch the video.

Mydfir: Changing the wiring a bit to see if the behaviour is anything different. Then weird stuff happening. A good look at the code leads to some changes. Will it matter? Auto correcting is nice, but why does it happen the way it happens? Questions but what are the answers? Click the first image to watch the video.

Arduino Yún: Experiences leads to a change of motor, but will it help? Then a dive into pwm: where does it go wrong? Will code-changes help? Wrong info leads to more questions. Click the first image to watch the video.

Mirft2: Staying with the community firmware, I test the front sensors again and get remarkable results which also raises questions. I decide to change the code to get clearer screen output and also decide for a wiring change. This leads to a conclusion, another addition, test and ideas for next time. Click the first image to watch the video.

RPi: Diving once more into hard pwm, and a camera experiment: it is possible to stream video according to this info. Several code changes look promising but will it really work in the end? So far it's still doubtful. I like the camera change though. Click the image to watch the video.
 
Arduino Mega2560: To get code working, I first meet with an oops. Then, after fixing this, further implementing SPI and another oops. In the end, does it work? Click the first image to watch the video.

Hand: The arm pivot motor needs to be reconstructed, but will this work? It seems easy enough. Then the wrist pivot motor has stopped working. Why? It can't be software, and the diagnostics already showed it's not an electrical problem. Several attempts, but will the problem be solved? Click the first image to watch the video.
 

17 March

BB: The carriage doesn't behave as it should with respect to propeller speed and direction. Would a reconstruction solve it? A look at the code shows why the screen output starts with the wrong sensor, the code needs a change. But does it all help? Click the first image to watch the video.

RPi2/ROS: I an attempt to solve the 1== 0 (?) problem, I decide to overrule the switch and change some more code. Then some measurements reveal the probable reason the motor doesn't work. So what then? Click the image to watch the video.

Mydfir: After the last time, I decide to observe both the map more closely and a different direction. Also: when exactly does it lose track, some weird behaviour and auto correction. Finally, some code and ideas. Click the first image to watch the video.

Arduino Yún: Time to recheck on pwm, voltage and adding another check-pin for the pwm. The results raises several questions and leads to a code change. But will it help? Click the first image to watch the video.

Mirft2: After studying an example with the LED on the controller, I find I made a mistake and the LED is of no use. Then the idea is the use a front sensor on Cx. This brings an unexpected result. Then a leg gives a problem...but how to solve it. Click the first image to watch the video.

RPi: Question: what's the voltage on the motor? And on the LED? Then the code is a mix and has to be cleaned. Will it work or not? Click the first image to watch the video.
 
Arduino Mega2560: Checking to replace a motor by another model to see if it works out with an unexpected result but which might explain other results as well. Then the motor-stopping algorithm/mechanism works better than expected. New experiment: a combination with the Arduino Uno and SPI. Click the first image to watch the video.

Hand: The arm needs an extra weight, but what to use and where to apply it? Then, the vertical gear lower switch has to be fixed. Also, the arm pivot has problems, but how to fix that? Finally, the wrist doesn't work. But why? Click the first image to watch the video.
 

10 March

BB: Starting with code: improving motor speed, time. Then a bit of reconstruction and test: will it work? Next, how can the lamps stay working? Will it work? Click the first image to watch the video.

RPi2/ROS: Studying the odd results I find results that actually can't be there. This leads to some rewiring and a GPIO test. But will this reveal the cause of the problems? Click the image to watch the video.

Mydfir: Starting with the top tool on Linux, and finding the difference in lighting. Then using sonar for line following correction and some remarkable observations. Any closer to a solution? Click the first image to watch the video.

Arduino Yún: Starting with a little oops, I try pulsewidthmodulation here as well. After some trying with code from the Mega2560, I find some more info which shows the Yún is a bit different. When applying some changes, I'm in for a little surprise, but will things work? Click the first image to watch the video.

Mirft2: Using the original firmware again, I get 2 oopses. After that: adding an LED to test a counter, but are those results correct? Is this the way to test it? Click the image to watch the video.

RPi1: Since the current situation is not working, I search for another solution and find some code. Will this work? Some rewiring is needed as well. Does the single LED work? Click the first image to watch the video.

Arduino Mega2560: Letting the motors actually stop is delayed by some unexpected communication issues. After temporarily solving these the wrong way, it show that it works, kind of. Timing isn't perfect, but it's not a perfect situation either. Click the first image to watch the video.

Hand: Replacing wrist motor and adding bi-polar switch solves a problem and saves code. Then the lower gear box: this can be solved too but then some analysis. Why doesn't the axis reach the upper switch? One conclusion, but how to solve it? Click the first image to watch the video.



3 March

BB: Because of a threatening short-circuit, I have to reconfigure 1 of the power-rods. Then: what to do with the wires? And the 2nd motor needs attention: it's attached too flexible. Next is software, because timing is obviously too short now. And a lamp issue. And some more. Click the first image to watch the (bit lengthy) video.

RPi2/ROS: Trying to tackle timing and circuit issues leads to rewiring and questions about values instead of answers. Is there a delay somewhere? Click the image to watch the video.

Mydfir: Trying the combination of colour recognition and line following, both don't go really well. But why? Then: sonar works good but how does the combination go? Letting it go and then weird stuff happens. Click the first image to watch the video.

Arduino Yún: I first take a look at the network settings again: why is there no internet? Then back to the code: with which value does the motor LED work? How about mapping? Electronics: voltages are there, but why doesn't the motor respond? Click the first image to watch the motor.

Mirft2: Leaving ftrobopy for the time being, I try the software using the original firmware again. This gives unexpected problems and oopses and once those are more or less dealt with, remarkable results. Click the first image to watch the video.

RPi1: With the found max of 1999 for pulsewidth, I change the circuit and add a potmeter to adjust the power. Then I find that using the opamp does have influence, but not the way I want. Does the hardware pwm work on the LED? Another change in the software makes me realize I probably need a different approach. Click the first image to watch the video.

Arduino Mega2560: Changing the new switch setup brings a bit more work than expected. Then a rewire is needed and a bit of recoding. Will the idea work? Electronically, it works, but how about the mechanics? Click the first image to watch the video.

Hand: Starting with a small but necessary reconstruction, followed by a all-system test. It becomes clear that not all is working as expected: a sensor gives problems. But is that all? Click the first image to watch the video.


24 February

BB: I need to rewire and want to reconstruct the carriage. Then there's no power..? After somehow restoring the power, the speed is still a problem, But how to solve it? And will it work? Click the first image to watch the video.
 
RPi2/ROS: Several items to check: is there any voltage over the transistor (GPIO pin 7), is the switch input (pin 11) acurate, does the motor work anyway? The answers are surprising but leave questions as well. Click the first image to watch the video.

Mydfir: I start with the discovery of a tire issue. Then more colour checking, now with 2 lamps and "day"light. Once again, some questionable results. Then driving leads to changing the code. New insights, and then some odd events. But why? Click the first image to watch the video.

Arduino Yún: First I want to resolve an unresponsive LED, then it's time to add electronics and a motor. The motor kind of works, but not the way I want. Also, the LED works, but why this "bright"? Measuring gives an unexpected result, but why? Click the first image to watch the video.

Pictures: Melexis Safety Trophy 2004 robot challenge (scanned from analog..).
Mirft2: With 1 sensor, it gives unreliable results, so what will happen with 2? Some improvisation is necessary.  Counters give still 0, so time for another change of counters with noticeable results. Click the first image to watch the video.

RPi1: Why doesn't the motor just run on pwm? Time to check the code and values. Should things change? If so, how? Testing leads to an oops, conclusions and more questions. Click the first image to watch the video.

Arduino Mega2560: First task: find out why an LED doesn't work. After fixing this, what more can be done? Time for a new experiment: expanding a motor to touch a switch. Already have one doing so, but this one offers challenges. Question: how to solve them. Click the first image to watch the video.

Hand: The wrist problem forces a reconstruction and a recoding. When both are done, it turns out the wrist motor has a severe issue, but how to solve that? Also, it looks like the hand gives more than one problem. Click the first image to watch the video.


17 February

BB: Before doing a power test, the ground rail should be extended. Then, how to get power? And there are both ground and power to be used. Staples? And how? Will it work? Click the image to watch the video.

RPi2/ROS: Getting the motor to run, I change the setup bit by bit: electronics, wiring, software. Measurements give unexpected results. Click the first image to watch the video.

Mydfir: My old riding model needs an improvement in colour recognition, so the calibration can be merged. This shows more harder than anticipated: values and wires need to be checked. Do they match? Red = red, green = green, right? Click the first image to watch the video.

Arduino Yun: Now the console is functional, it takes a moment to realize that I need a pin for the switch. So I start "reading" it (capturing is a better description) and get nice output...which doesn't work for the algorithm. A change in code works much better, but when more electronics is applied, both could work out very nicely. Click the first image to watch the video.

Compilation: I created a short compilation video from the 2008 conventions in Schoonhoven, Vlissingen and Veghel, all in the Netherlands. It was the first year I made some videos. Pictures can be found here.
Mirft2: Adding a touchsensor between the front legs is a nice idea. It requires some code and testing. Will it work nicely or just like the rest: sometime yes, sometimes no? Click the first image to watch the video.

Pictures: Pictures from the fischertechnik convention 2007 in Moershausen, Germany are added to the movies&pictures page. It was the first convention I visited.
RPi1: Adding a transistor didn't work and adding an LED and measuring shows why: voltage too low after the resistor. Replacing it shows a big difference, but is it due to PWM or voltage. Tests bring questions rather than answers. And then a big oops. Click the first image to watch the video.

Arduino Mega2560: Pins 4 and 13 have gone weird, but first I have to fix some electronics...which is controlled by software, as it to be expected. So after changing it a bit, the only unexpected result is a frequency. But why? Click the first image to watch the video.

Hand: The wrist pivot need improvement, but how? Software seems a solution, but somehow this seems to disable the rest. Why? An improvised switch shows an oops which leads to an even bigger oops and the finding of a software flaw. How to go on from here? Click the first image to watch the video.


10 February

BB: To get rid of the wire, a solution is to power the rail. This needs serious reconstruction but how to do it? How to power the rail anyway? Click the first image to watch the video.

RPi2/ROS: When trying out the circuit again, I realized I didn't install all of the software and some settings are yet missing after the big oops. When done, it's time for recoding and trying. And, oops, forgot to use the inscreen-webcam. Will it (or something) work? Click the first image to watch the video.

Discovery: Expanding the tests on pulses and counts gives some remarkable results with differences between ROBOPro and ftrobopy. But why? The hardware is an unlikely cause. Click the first image to watch the video.

Arduino Yun: First, finding the difference between connected and available. Then, what does a keyboard have to do with it? Why not a switch? Then, does the difference between an integer and a character really makes a difference? At least something seems to work, finally. Click the first image to watch the video.

Mirft2: Testing counters again, starting with ROBOPro followed by ftrobopy. Just with the Discovery: remarkable differences, assuming that I'm not doing something wrong. Too bad I've had no technical feedback yet. Click the first image to watch the video.

Compilation: I created a short compilation of the 2009 fischertechnik convention in Erbes-Büdesheim, Germany. Click the image to watch it.

RPi1: Pulse-width should indicate a frequency and voltage. But why doesn't that show on the multimeter? Then, adding some electronics should improve the situation like it did with other test. But will it work? Click the first image to watch the video.

Arduino Mega2560: Looking into the code again, I think I find a solution. This leads me to review the wiring again and replace some. Why do LEDs test ok but don't work on the circuit? Weird behaviour..Then another pin goes weird. Oops.
Click the first image to watcht the video.

Hand: Because the wrist motor is pushed away from the pivot plate, I have to fix it, But how? Then, time to get the wrist motor working with software..it works, but gives me the creeps. This really needs a bi-polar switch, somehow. Click the first image to watch the video.


3 February

Website: The links on the Software page have been fixed and the page is cleaned up.
BB: Time for recoding since the sonar is gone. Will it work with the wire carriages? Last time they were pushed off the rail, so would more weight help out? Click the first image to watch the video.

RPi2/ROS: Booting the RPi2 starts with a major oops: "m: Unknown command" at boot. Fortunately, the microSD card on which everything resides is readable by the laptop. By accessing the contents I find my valuable source code: publisher and subscriber. Next action is to copy everything inside ~/catkin_ws to the server. Now, what should I do next? Reinstall the SD card? Seems the only thing I can do but will it work? Click the image to watch the video.

Discovery: Continuing with the counter, some tests and recoding. This shows some very odd results, but are they wrong? Click the image to watch the video.

Arduino Yun: First a problem: I can't connect. This turns out to be a wire problem: the LAN cable isn't there and after connecting, a reboot is needed. Then, no internet. But why? Back to code: somehow it doesn't work right, but with the console going some things get clear. Click the image to watch the video.

Mirft2: For checking the counters or pulses of the motors, I change the code. Then some surprising results come out giving doubts on the hardware, but which part? In a final test, the results are even odder. How come? Click the first image to watch the video.

RPi1: Using hard pwm turns out to be my second attempt, in a way. I have to switch to python, and install some software. Then making a choice between GPIO and RPIO? Finally, some calculation or/and conversion. Will it work? Click the first image to watch the video.

Arduino Mega2560: Checking the frequencies with the alternative method gives unexpected results. Why are the values different? Also, why the factor change? Pin 13 is a very odd case, but why? Click the first image to watch the video.

Hand: The wrist needs to be wired, but a reconstruction is necessary. After the wiring, how does it work? The diagnostics reveals a 2 problems. How to solve those? Click the first image to watch the video.


27 January

BB: Back to wiring issues: how to solve it? This leads to new ideas and reconstruction. Will they work out? Click the image to watch the video.

RPi2/ROS: Examining the code leads to changes: using switch input, separation of both data. But also some odd behaviour. And then there's a motor... Click the image to watch the video.

Discovery: So the pulse count seems to be an issue. After some recoding and re-thinking, I decide to make the screen output more clear, which leads to some odd finding. Click the image to watch the video.

Arduino Yun: First I try the wired USB connection, then back to Wifi and finding how to add it to my own network. Next, the serial monitor, which isn't serial and needs some code. But does it work? Click the first image to watch the video.

Mirft2: Looking at the gears there's 1 part on both sides that needs improvement and another that maybe can't be improved. So how to go on? Does the code need a change? Click the first image to watch the video.

RPi: Pwm testing keeps revealing odd and possibly contradicting results: the motor doesn't work and the LED works. Then some new searching reveals a solution: soft vs. hard pwm (RPIO.PWM?). Click the first image to watch the video.

Arduino Mega2560: Since pin 4 and 13 don't match in frequency, it's time to find out more using a different way in code. This shows something is wrong, but can it be corrected? And how about the desired 40-120 Hz range? Click the first image to watch the video.

Hand: Time for the wrist motor: which one to use, where to put it and how to wire it? Does it take yet another reconstruction? Click the image to watch the video.


20 January

BB: Adding a wire-carriage for smooth movement, does that work? Adding 1 or 2 springs to prevent bumping, will that work? Some oops, unexpected results and conclusions. Click the image to watch the video.

RPi2/ROS: Trying to use ROS and the GPIO at the same time takes quite an effort. Then, making the switch do what it should do, takes additional electronics. Showing it all on in-screen video, requires 1 more step. Click the first image to watch the video.

Discovery: Sound and motor tests again on both firmwares as well as ROBOPro. This reveals a surprising problem. Another problem seems to have returned: wiring. Click the first image to watch the video.

Arduino Yun: Last time, testing didn't go as well as hoped. So, it's time to rewrite some of the code and check some of the wiring. Will it work? Click the image to watch the video.

Mirft2: After the frame reconstruction, it's time for testing. However..some things aren't as they should be: gear not aligned, knots at the wrong place, teeth not fitting. After fixing(?) some testing follows. Click the first image to watch the video.

RPi: Checking on pwm only: showing way to high frequency at the lowest setting. Can I change the code? Can I change my own code? Click the first image to watch the video.

Arduino Mega2560: Measuring frequencies leads to changing the circuit a bit and inspection of the code. Then a new test casts doubts on basic information. What's right and what's wrong? Click the image to watch the video.

Hand: A pivot gear modification badly needed and this time it seems to end up fine. Except for the motor, but how to fix that? Finally, a look at the arm. Click the image to watch the video.


13 January

BB: Replacing a broken lenslamp solves 1 problem, but the carriage still doesn't do what I want. Some testing reveals the issue: recoding is needed with a nice result. Click the first image to watch the video.

RPi2/ROS: Trying to figure out how to use my own msg file and getting the GPIO to work together with ROS leads to unexpected results and questions. Click the first image to watch the video.

Discovery: Time to relocate the motor tests to the original firmware. Any other different (better?) behaviour? Click the first image to watch the video.

Arduino Yun: Time to connect the Yun to a breadboard and bring the circuit there. Will it work as well? Something needs to be changed, including some additional hardware. Click the first image to watch the video.

Mirft2: After doing the feet, it's time to let the gears go properly. This takes some serious reconstruction of the frame but will it work out as intended? Click the image to watch the video.

RPi: Some new attemtps to simulate pwm brings questions. Then, back to the real circuit: how does the motor work anyway? Is it really pwm controlled? Click the first image to watch the video.

Arduino Mega2560: Some more simulation gives some clarity, but in what exactly? Then back to the real circuits, with some oopsies and code changes with clear effects. Click the first image to watch the video.

Hand: Reconstruction (again!) of the pivot gears seems to go fine. Then a (final?) test reveals the real problem (oops), which leads to yet more(!)  reconstruction to be done. Click the image to watch the video.


6 January

BB: Checking the code leads to some changes and testing leads to questions about wires, lamps and the interface. Click the image to watch the video.

Discovery: Considering the results of last time, some more code changes are necessary. Testing shows it doesn't really look promising. Click the image to watch the video.

RPi2/ROS: Going on with trying to publish a number meets with some hurdles: C++ isn't Python, several adjustments, and why don't examples always work out? Click the image to watch the video.

Arduino Yun: It's time to explore some more by doing some more programming and add electronics. Click the first image to watch the video.

Mirft2: A gear is not aligned anymore which shows a continuing problem. Then, feet need to be fixed and the hind legs need to be reconstructed. Click the image to watch the video.

RPi: The pwm simulation isn't yet really what it's supposed to be. Also, the motor isn't a DC motor. So things need to be redesigned. Will it work? Click the image to watch the video.

Arduino Mega2560: Improving simulation leads to unexpected results and necessary changes. How do toolboxes interact? Click the image to watch the video.

Hand: Considering the space around the wrist, I go for a slight reconstruction. Then tests show there's a wiring problem, which is solved quickly. But that's not all. Click the image to watch the video.