Archive for June 19th, 2015
How to build your own drone (part 2)
Last time we discussed the common parts which you need to buy in order to assemble your drone. This week I have received all parts and I will show how to assemble everything and make it ready to start.
In the first step you need to assemble your frame and place some electronic components there like ESCs, motors and power distribution board. Of course, it’s easy to assemble the frame itself but in order to place all other components you need to use soldering iron before. I would not recommend to connect ESCs directly to power distribution board. In this case you will not be able to remove drone’s legs in case of transportation. Instead of that I used XT60 connectors. So, you need to solder your ESCs and connectors and use some wires to mount connectors to power distribution board as well. Don’t forget to use shrink tubes to avoid short circuit there.
In case of motors I am using banana connectors (3.5 mm) to connect motors and ESCs because you need a way to change sequence of wires there to run motors in the right way. Additionally, you can use insulating type to mount battery. If you don’t have a 3D printer in order to print some components for your frame, insulating type might help you from time to time.
In this step I recommend to connect battery to the power distribution board in order to understand that everything is OK and everything is soldered in the right way. Use multimeter to check that all ESCs produce 5V of power through control wires.
Once you assemble your frame, you need to mount fight control board and RC transmitter. Because these boards require 5V power I used power which is generated by ESCs using control wires. But each ESC contains its own power wire, so you need to remove all power wires except one. You can use knife to do this and use insulating type in order to insulate removed wires.
In the next step you can mount flight board, RC and connect them to each other. Don’t mount propellers in this step because you need to setup you flight controller before.
In the next step you can download OpenPilot software and use wizard to setup your drone. Thanks to the wizard it’s the simplest part there.
So, in the end I spent the following amount of time for each step:
· Frame assembly – 40 mins;
· Soldering (connectors, wires, motors) – 60 mins;
· Motors, ESCs and battery placement – 40 mins;
· Flight controller and RC placement – 20 mins;
· Setup – 10 mins;
Finally, my drone is ready to fly.
How to build your own drone (part 1)
During the Maker Faire event I demonstrated my own drone based on Netduino. And I got lots of questions about hardware but not quite as many about software. Several people even told me that they tried to assemble own drone but failed. That’s why I decided to show my experience there. I am going to have vacation this week, so, I put aside software development and new APIs for some time and have some fun trying to assemble a new drone.
I am going to develop a powerful outdoor drone. So, it should be heavy enough to fly stable despite the wind and at the same time it should have enough power to fly up as well.
Let’s start with components which you need to buy.
Pay attention that in some cases it requires some time to receive it by mail. Usually I use robotshop.ca – if they have something you can get it in 2-3 days but it’s a little bit expensive compared to amazon and they only have a few components in each category. If I am ready to wait some time I use amazon.ca or amazon.com – the second one has many more components and 2-3 days delivery option for some of them but you will need visit the US to get your package.
First of all you need to decide which type of drone you are going to build and select the right frame. I would recommend to start with a quadcopter but during my vacation I will build a hexacopter. It’s better to select a metal (aluminum) frame because it’s not easy to break this frame. Of course, you can build your own frame using wood or metal parts but you spend much more time and lots of money compared to exiting frames which starts from $17. I have tested two frames: X525 and 650X6. They are pretty good and not very expensive.
Once you know number of motors based on your frame you can select motors. For drone, you need to buy brushless motors which can run you propellers with different speeds. Additionally you need to buy a special control board for each motor called ESC. Thanks to ESC you can run your motors with different speed and motors have as much energy as needed. Different brushless motors require different ESC (based on voltage), so you need to read specification for motors before to buy ESCs. For the frames which I mentioned early I would recommend to buy 1000KV motors like A2212. You even can find pack of similar motors with ESC and propellers. I like this pack and usually I buy it.
Motors and ESCs is the most expensive part of the drone but the second one is battery pack. If you want to fly 20-30 minutes you need to buy a good LiPo battery and you need to buy a charger as well. I bought a 5100 mAh battery but you can buy anything from 2200 mAh. Just verify that it produces 11.1 Volts of power – it guarantees that you will have enough power for your motors and control board. Charger is usually expensive as well but you need a way to power your battery.
In order to operate your drone you need to buy radio control receiver and transmitter. I have FlySky RC but you can buy anything. In general you can fly using 4 channels only but you can use other channels for camera or something like this. Pay special attention that from time to time you can find some receivers which don’t work with common transmitters. So it’s better to buy both things together from the same company. Of course, you can use WiFi modules to operate drones from your phone or laptop but in this case your drone will not fly far away.
The most important part of your drone is the control board which sends signals to your motors, receives signal from your RC and implements some algorithms for stabilizing your drone. Usually this board contains several sensors like accelerometer and gyroscope but you can add barometer and GPS as well. For the first drone it’s enough to have just Accelerometer and gyro. I would recommend OpenPilot board because that software supports wizard which helps setup your drone, and drones based on OpenPilot are very stable. I used MultiWii boards as well but you need spend much time in order to setup those boards, and I encountered some problems with algorithms there. You can use Arduino, Netduino and even Raspberry and implement your own algorithms but it requires additional time and good math knowledge.
Finally, you need to buy some components which help to solder the frame like soldering iron, iron wires, connectors, power distribution board. Once you have all these things you are ready to start assembling your drone.
Next time I will show how to assemble my hexacopter step by step but at the end of the post I want to share list of expenses for my drone:
· Frame – $38
· Brushless motors (two packs, because I need at least 6 motors) – $146
· Power distribution board – $7
· Wires – $10
· Shrink Tubes – $3
· Banana connectors – $5
· Connectors – $8
· Battery – $38
· Charging station – $23 (probably, it’s better to buy more expensive charger in order to avoid big boom at your house)
· RC – $100
· Flight control board – $19
· Soldering iron and some stuff there – $30
So, total price of my drone is about $427 but there are still opportunities to cut down the price. For example you can buy cheaper RC, battery etc. At the same time you can increase the price adding camera, GPS, barometer etc.
Microsoft Canada at Vancouver Mini Maker Faire
Last weekend I got a chance to participate in Vancouver Mini Maker Faire event. I still don’t understand why it’s called “Mini” because the exhibition filled all the space at PNE Forum including outdoor exposition. And, of course, we had our own booth there as well. So, what was Microsoft doing there?
Half of our exposition demonstrated ability of Visual Studio to support IoT projects for different boards like Arduino, Netduino, Raspberry Pi 2 etc. I have developed two rovers based on EZ-B controller and based on Arduino. In case of EZ-Robot I used UniversalBot project for developing Windows 10 applications. For Arduino I used the instructions which you can find on windowsondevices.com but you can use Visual Studio to develop and deploy Arduino applications directly using Visual Micro plug-in. Additionally I have developed the drone based on Netduino board, so I used .NET Micro Framework and C# to develop all stabilization algorithms there.
The second part of our exposition was around Kinect and 3D printing. Thanks to 3D printing support in Windows you can develop your own applications very quickly without thinking about how to cut the model in slices or generate G-code. Additionally, you can use existing 3D printing software like 3D Builder to create own models and print it.
Additionally, 3D Builder supports Kinect devices to 3D scan of existing objects.
Of course, we used Kinect not just for 3D scanning but for entertainment as well. All attendees have a chance to dance in our Xbox One area where we used Kinect as well and installed Just Dance Kinect ready game.
I hope that everybody had some fun visiting out booth as well as all other expositions there.
UWP: Speech Recognition (part 2)
So, we already know how to transform text to speech and it’s time to talk about the opposite task.
Universal Application Platform supports Windows.Media.SpeechRecognition namespace and several ways to recognize your speech. You can predefine your own grammar, use existing one or use grammar for web search. In any case you will use the SpeechRecognizer class. Let’s see how to use this class in different scenarios.
Like the SpeechSynthesizer class, SpeechRecognizer has some static properties which allow to understand available languages for recognition. The first property is SystemSpeechLanguage which shows system language and it should be the default language as well. The next properties SupportedTopicLanguages and SupportedGrammarLanguages are not very clear because in case of Text to Speech classes we have just one property for all supported languages. But SpeechRecognizer allows to recognize your speech locally or use several dictionaries online. That’s why SpeechRecognizer has two properties: SupportedGrammarLanguages – for general offline tasks and SupportedTopicLanguages – for online grammars.
Let’s start with showing how to use SpeechRecognizer objects in several ways but first of all you need to declare capability in manifest of your application which will allow you to use recognizer. UAP doesn’t have any special capabilities there like Windows Phone 8.1, so you need just to declare microphone capability. So, usually, you manifest will look like this:
<Capabilities> <Capability Name="internetClient" /> <DeviceCapability Name="microphone" /> </Capabilities>
Of course it’s not enough and you need to implement additional actions to make sure that user grants permissions to your application. In order to do it you can implement the following code:
bool permissionGained = await AudioCapturePermissions.RequestMicrophonePermission(); if (!permissionGained) { //ask user to modify settings }
In Windows 10 user can disable microphone permissions for selected applications or for all applications at once. You can easily find the window which allows to do it (Settings->Privacy->Microphone).
If everything is OK with permissions you can start executing some methods which implement speech recognition logic.
Based on your scenario you can implement the following approaches for speech recognition:
· Predefined grammars – in this case recognizer uses online grammars. So, you should not create your own and there are two opportunities: you can use general grammar or grammar which is based on the most popular web search queries. Therefore, using the first grammar you will able to recognize any text but the second one is optimized for search;
· Programmatic list constrains – this approach allows to create list of strings with particular words or phrases which user can use when speaking. It’s better to use this approach then your application has predefined list of commands. Additionally, you can manage the list in runtime depends on context in your application;
· SRGS grammar – thanks to SRGS language you can create XML document with grammar inside. It allows to create more flexible applications without hardcoded grammar inside;
Despite of selected approach you need to implement the following steps:
· Create an object of SpeechRecognizer class. It’s the simplest step and doesn’t require any special knowledge;
· Prepare your dictionary. In order to do it you need to create an object of a class which implements ISpeechRecognitionConstraint. There are for constraint classes but in this post I am going to talk about three of them: SpeechRecognitionGrammarFileConstraint, SpeechRecognitionListConstraint and SpeechRecognitionTopicConstraint. The first one allows to create grammar based on file. You can just create StorageFile object and pass it as the parameter. The second one allows to use programmatic list like your grammar and the last one supports predefined grammars;
· Once you create a constraint (or constraints) you can add it to Constrains collection of SpeechRecognizer object and call CompileConstraintsAsync method in order to finish all preparations. If you don’t make any errors in your constraints, the method will return Success status and you can go ahead;
· In the next step you can start recognition and there are several options as well: you can start recognition of your commands using RecognizeAsync method of SpeechRecognizer objector you can use ContinuousRecognitionSession property there and call StartAsync method. The first one method allows to recognize short commands and using predefined settings but the second one is adopted for continues recognition of free dictation text. Of course, using RecognizeAsync you can get results in place but using StartAsync method you need to use event handlers for ContinuousRecognitionSession.Completed and ContinuousRecognitionSession.ResultGenerated events;
Additionally, you can use the set of methods which allows to utilize built-in dialog panels for speech recognition – just use RecognizeWithUIAsync method.
If you want to find some examples of speech recognition I would recommend to use the following link. You can find speechandtts example there. Next time I am going to cover more interesting topics related to Cortana.
Sergii Baidachnyi 