How to start creating and programming robots

 

Introduction

Create robots requires a lot of different skills and, depending on how sophisticated is the behavior or the tasks that must be performed, can be really complex and extremely difficult.

The three pillars of robotics are electronics, mechanics and programming; there are others, but only with these three you can already start experimenting.

In addition to applicable knowledge you also need some others items such as motors (or other actuators), sensors, a small computer to avoid weight and power consumption (typically a SBC or microcontroller ) and a power source (battery to be autonomous) and some parts that sustain and hold together all these elements and their movements.

These elements can be acquired (some even manufactured) separately, or more easily, and probably cheaper as a kit.

.

What do I need to start?

Mainly, you need wish to enjoy creating and learning.

* Acquire a minimum and basic knowledge of:

+ Electronics or electricity (if only to distinguish voltage and current),

+ Mechanics (the minimum would be screwing and unscrewing or connect Lego type pieces)

+ Computer (at least to run a program on a computer)

* Get at least a microcontroller (Arduino, for example), a pair of motors, a distance sensor, a battery, cables, and a structure to support it. The basic set or kit.

A kit, the best option

A clear advantage of starting with a kit is that you start NOW, spending your time on where is your interest (electronic, mechanical or computer) , because the others areas are already solved, but anytime you can get to work in any of them. When you buy the kit with all the necessary set of elements together, the price is also often cheaper.

From the more expensive and complex to the cheapest and easiest

Bioloid : 18 powerful servo motors, 4 sensors. Ideal for humanoid, quadrupeds, hexapods and even vehicles; software to create them and behave like living beings. Includes programming software RoboPlus Tasks, you can also program in C, and create motion sequences with RoboPlus Motion.  Using other controller, like Raspberry Pi you can use any language and programming tools which generate code to it.

It costs about 1000 euros. Yes, it is somewhat expensive, but if you have enough money and programming skills or willingness to learn, I think it deserves the price.

Mindstorm EV3: 2 servo motors, 1 motor, 4 sensors. Ideal for mechanisms and vehicles. Very easy to use, but it also allows you to create complex robots. Includes programming software NXT-G, NXT is also possible to program in Java with Far and C / C + + with Osek, not yet available for EV3 or very early versions.

It costs about 300 euros, although it may seem expensive compared to other options, its enormous potential and flexibility in all aspects (construction, programming and electronics) make it tremendously interesting.

Mindstorms EV3 is the latest version, released in August 2013.

[caption id="attachment_2226" align="alignleft" width="240"] Robot Arduino[/caption]

Vehicle based on Arduino: at least 2 servomotors and all the sensors  you want to start. Is easy and cheap, for about 40€/50$ - 70€/97$ you can have the a robot. Ideal for deepening in electronics.

It can be programmed with the friendly Arduino programming environment .

Is the cheapest option and you can go further by buying more components as you go. It not offers as much flexibility and ability to build as Mindstorms vehicles or Bioloid articulated robots, but you can really learn a lot more than it may seem.

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And with less money or no money?

For less money, for starters, you can get an Arduino microcontroller or its clones, which cost just over 20 euros/dollars.

Or, completely free of charge, you can start learning to program in C or C + +, which will come very handy to program robots.

Free resources for learning C programming:

C introduction (pdf)

But there are a lot…

C Language Tutorial (html)
How C Programming Works (html)
Several C programming tutorials (html)
... and more from Google

And here you can find free resources for learning C++ programming.

In the next post I will write about a fast comparative between Bioloid, Mindstorms and Arduino based robots and about Arduino programming.

So... let's the Bioloid, C++ and QT games start!

To cretate this workshop I'm using Ubuntu 12.04, GNU g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 (see Synaptic installer capture),

[caption id="attachment_1635" align="aligncenter" width="300"] Synaptic G++[/caption]

QT 5.0.1 and QT creator 2.6.2,

QT creator is a very easy, and good, free IDE with a great design tool for creating user interfaces:

Be careful with this bug: Qt Creator 2.0: UI layout is not updated before launching the application http://qt-project.org/forums/viewthread/292 Is very annoying and time consuming, the solution is in the last comment (setting the UI_DIR in the .pro file)

[caption id="attachment_1637" align="aligncenter" width="600"] QTCreator Bioloid QTWorkshop[/caption]

I also will use it with Windows 7.

I also use Boost to get some C++11 features for threading. For example:

pWorkThread = new thread(&Activity::doWork, this, parameter);

std::lock_guard < std::mutex > guard(myMutex);

Don't bother if you don't understand it right now, it's in the guts of the AXControl_v2 library we will use it in a very easy way, as you will see below. Here you will find a lot of resources to learn basic and advanced C++

Example context fot std::lock_guard < std::mutex > guard(myMutex);

[sourcecode language="cpp"]

short DynamixelCommunication::readSensorValue(int id, AX12Address address,
int port) {
std::lock_guard < std::mutex > guard(myMutex);
short value = -1;
try {
int size = getReadSensorWordCommand(buffer, (byte) (id), address,
(byte) (port));
memset(&result, 0, MaxBufferSize);
serialPort.query(buffer, result, size, WaitTimeReadSensor);
value = getQueryResult(result, size);
if (value <= 0)
Debug::show("DynamixelCommunication.readSensorValue", value);

} catch (exception e) {
Debug::show("DynamixelCommunication.readSensorValue", e.what());
}
return value;
}

[/sourcecode]

And context for pWorkThread = new thread(&Activity::doWork, this, parameter);:

[sourcecode language="cpp"]

class Activity {
private:

protected:
std::thread *pWorkThread;

...

}

void Activity::start(int parameter) {
working = true;
pWorkThread = new thread(&Activity::doWork, this, parameter);
Util::sleepMS(10);
}
Let's see how to open the connection
[/sourcecode]

Let's see how to open the connection to the CM-510:

[sourcecode language="cpp"]
void MainWindow::on_B_Open_clicked()
{
//QString output="Open it";
//QMessageBox::information(this, "Output", output, QMessageBox::Ok);

//dynComm.open("/dev/ttyUSB0",57600); //open with these parameters
if (pDynComm->open()) //open getting the parameter from the configuration fiel
{
//Connection opened
setConnectionButtons(true); //User interface update
updateAX12Parameters(ui->SB_AX12_1_ID->text().toInt()); //User interface update
}
else
{
//Show problem opening the connection
string cantOpenPortName="I can't open port: ";
cantOpenPortName+=pConf->getStringValue(DynamixelCommunication::ParameterSerialPortName);

QMessageBox::information(this, "Error", QString::fromStdString(cantOpenPortName), QMessageBox::Ok);
}
}
[/sourcecode]

and get a beep from the Robotis CM-510 (using this alternative firmware):

[sourcecode language="cpp"]
pDynComm->sendOrder(200, MyCommunications::BeepCM510, 0); //200 is the Dynamixel device ID used for the CM-510, 0 because beep doesn't need any additional value
[/sourcecode]

Getting the AX12 position and showing it:

[sourcecode language="cpp"]
void MainWindow::on_B_AX12_1_GET_POS_clicked()
{
QString qStr;

int id = getAX12_1_Id();

int position = pDynComm->readValue(id, MyCommunications::PresentPosition);

ui->SB_AX12_1_POS->setValue(position);
[/sourcecode]

Setting the AX12 position:

[sourcecode language="cpp"]
void MainWindow::on_B_AX12_1_SET_POS_clicked()
{
int id = getAX12_1_Id();

int position= ui->SB_AX12_1_POS->text().toInt();
pDynComm->sendOrder(id, MyCommunications::GoalPosition,position);
}
[/sourcecode]

Putting the selected AX12 LED on and off

[sourcecode language="cpp"]
void MainWindow::on_CH_AX12_1_LED_clicked(bool checked)
{
int id = getAX12_1_Id();

pDynComm->sendOrder(id, MyCommunications::LED, (checked?1:0));// if checked 1, else 0
}
[/sourcecode]

And an auxiliary UI method to get the id from the selected AX-12

[sourcecode language="cpp"]
{
int MainWindow::getAX12_1_Id()
{
QString qStr=ui->SB_AX12_1_ID->text();
int id=Util::convertToInt(qStr.toStdString());

return id;
}
[/sourcecode]

You can download sources and Linux binaries here

A diagram with all the AXControl_v2 lib classes and their methods:

[caption id="attachment_1384" align="aligncenter" width="600"] c++ signatura[/caption]

[Update]

[caption id="attachment_1722" align="aligncenter" width="164"] QT5 Bioloid Workbench[/caption]

C++, Bioloid and Raspberry Pi (v0.2)

[V.02 updates: AX C++ architecture, core classes diagram and HexaWheels scanning video]

Why C++, Bioloid and Raspberry Pi?

[caption id="attachment_1254" align="alignleft" width="150"] C++ Stroustrup's book[/caption]

C++, specially with the great improvements of the last C++11 standard, joins together a great efficiency in performance and a low memory footprint with advanced high level language features, making C++ a great tool for embedding, robotics, programming.

If you want to know how to use C++ very efficiently these two guides will help you:

- The JSF air vehicle C++ coding standards ( F-35 fighter aircraft)

- ISO C++ committee's report on performance

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.

 

[caption id="attachment_1221" align="alignleft" width="300"] Bioloid Premium[/caption]

Bioloid Premium is a wonderful kit for creating legged and wheeled robots, including (here full parts list):

- 18 powerful and versatile AX-12 servos

- an ATMega 2561 (CM-510) or, recently, an ARM STM32F103RE 32bits (CM-530), based controller. Also you can control the AX-12 with the USB2Dynamixel straight from your USB with a FTDI driver.

- And a lot of parts to create the structure of the robot

.

[caption id="attachment_1257" align="alignleft" width="216"] RaspberryPi[/caption]

Raspberry Pi is the cheaper and more brilliant conceived SBC (more specifications here):

- Broadcom BCM2835 SoC full HD multimedia applications processor

- 700 MHz Low Power ARM1176JZ-F Applications Processor

- Dual Core VideoCore IV® Multimedia Co-Processor

- 256/512 MB SDRAM

One simple example:
[youtube http://www.youtube.com/watch?v=Yhv43H5Omfc&w=480&h=360]

Learning C++

Starting:

C++ is a very powerful but complex programming language, so I think that the better approach is to start step by step, from the most easy features (yes, C++ could be used in an easy way) to the most advanced features it offers. What is C++? I will quote (I try to not explain anything that already is explained), Stroustrup, "his father", from his book The C++ programming language 3th Edition:

"C++ is a general-purpose programming language with a bias towards systems programming that
– is a better C,
– supports data abstraction,
– supports object-oriented programming, and
– supports generic programming."

And wikipedia:

C++ (pronounced "see plus plus") is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features.^[3] Developed by Bjarne Stroustrup starting in 1979 at Bell Labs, it adds object oriented features, such as classes, and other enhancements to the C programming language.

Web resources:

• Learn C++, no previous knowledge required


• www.cplusplus.com Tutorials


• MIT Open Courseware introduction to C++


• C++ FAQ


• Google Code University


• C++ Reference

If you want more C++ links, these found at JUCE will help you.

[caption id="attachment_1385" align="alignright" width="140"] Programming -- Principles and Practice Using C++[/caption]

Free books and documents:

• Thinking C++, download Vol1 and Vol2

• Data Structures and Algorithm Analysis. C++ Version

• More english and spanish C++ free books

• One of the best summarized explanations about C++11


• C++11 new standard, a lot of changes from the previous version of the standard, like:

- Maintain stability and compatibility with C++98 and possibly with C;
- Improve C++ to facilitate systems and library design, rather than to introduce new features useful only to specific applications;
- Increase type safety by providing safer alternatives to earlier unsafe techniques;
- Increase performance and the ability to work directly with hardware

Books:

• Programming principles and practices using C++, by Bjarne Stroustrup


• C++ without fear, by Brian Overland, a very easy way to learn C++

Advancing:

In robotics, and embedded programming in general, we will need some advanced knowledge and practices to reach our goals.

Free books and documents:

• Design principles and patterns, by Robert C. Martin, about developing a sound software architecture


• Design Patterns, to develop a depth understanding of Object Orientation and to improve our designs

• Concurrent programming, threading Our robots we will need to do several actions simultaneously, like perceiving the world with several sensors, moving and deciding what to do to reach is objectives.

• Communications, the serial port communications functions are used for wireless and wired connections, and we will need to communicate between controllers and with sensors and servos.

Books:

• The C++ Programming Language, by Bjarne Stroustrup, in my opinion the best book to acquire a very depth knowledge about C++ programming. The C++ Programming Language (4th Edition, 2013)


• C++ Concurrency in Action, by Anthony Williams, a wonderful book about the new concurrency classes.


• More books

C++ robotics programming

Well, this is really the goal, robotics programming.

As this is a workshop it will follow the creation of the the walker and vehicle Hexapod showed above in the video. This is currently the core architecture and the HexaWheels module (namespace classes):

[caption id="attachment_1391" align="aligncenter" width="300"] AX C++ architecture v2[/caption]

And these are the core classes:



The workshop will include:

- Basics

Like communications with serial port and wireless, using Dynamixels, sensors, ... Language features for robotics, like asynchronous communications and threads and... delays!.

- Intermediate

Combination of basics features using sensors (like scanning) and servos (walking motions). For example, scanning with a DMS sensor:

As a simple example:

[youtube http://www.youtube.com/watch?v=UHKaYuaZi4A&w=480&h=360]

- Advanced

Advanced perception and behaviours

I think this could very funny, using an advanced sensor like Asus Xtion, to detect certain objects to interact, and create configurable and amusing behaviours.

CM-510 mirocontroller programming

- Tools:

PC, Raspberry Pi and Pandaboard, installation and configuration, tool and projects

- GNU C++, Boost
- Eclipse
- QT 5

The contents will come soon, very soon...

C. C++, C# robotics programming Workshop/tutorial with the cheapest robotic platform

[caption id="" align="alignleft" width="108"] My Smart Car construction[/caption]

[Update March 30, 2013: Added photo gallery]

I will start a C. C++, C# robotics programming Workshop/tutorial with the cheapest robotic platform I have found at dealextreme.com: (Arduino based) plus a Raspberry Pi (like this that use Bioloid as the hardware platform):



I have not still received the kit, but I will review the kit and start the workshop as soon as I receive it.

Workshop: USB, serial and remote communications with C#

[Previous post: Workshop: Dynamixel communications with C#]

[caption id="attachment_1117" align="alignright" width="150"] Bioloid SerialPort2Dynamixel C#[/caption]

SerialPort2Dynamixel

Encapsulating  the SerialPort .Net class offers an easy way to use the serial port and receive Dynamixel Zig messages with the Dynamixel protocol.

.

.

Collaborator classes:

[caption id="attachment_1134" align="alignright" width="150"] Bioloid SerialPort2Dynamixel C# Collaborators[/caption]

- The SerialPort .Net class.

- RCDataReader class, which unpack the Dynamixel Zigbee sequence offering the clean data received.

Operations:

The public interface that others classes will use offers principally these operations:

public void setRemoteControlMode(bool on), which sets on or off the reception of data

[sourcecode language="csharp"]

public void setRemoteControlMode(bool on)
{
if (on)
setReceiveDataMethod(rdDataReader.rawRemoteDataReceived);
else
setReceiveDataMethod(null);
}

[/sourcecode]

public void setReceiveDataMethod(remoteControlDataReceived rcDataReceived), that sets the method that will be called when serial port data is received.

And some basics serial port data operations:

[caption id="attachment_1112" align="alignright" width="131"] Raspberry Pi - USB2Dynamixel - CM510[/caption]

public bool open(String com, int speed), to open the serial port which name is in the com parameter. Wireless communications and USB ports, as used by Zig or USB2Dynaniel, are also serial ports  (COM1, COM2, ... or /ttyUSB0, ttyUSB1).

public void close(), it will do nothing if the port is already closed.

public byte[] query(byte[] buffer, int pos, int wait), send (write) a query and gets (read) the result.

public void rawWrite(byte[] buffer, int pos), well... it will write whatever contains the buffer in the first pos positions

public byte[] rawRead() , read and returns the data received.

Notes:

To avoid concurrency problems all the operations that use the Dynamixel bus are protected with a Mutex object that avoids that two or more concurrent objects use SerialPort2Dynamixel simultaneously entering the same operation or using the same resources, like variables, objects or the Dynamixel bus.

[caption id="attachment_1620" align="aligncenter" width="300"] Xevel USB2AX[/caption]

[caption id="attachment_1622" align="aligncenter" width="300"] USB2AX over USB2DYNAMIXEL[/caption]

RCDataReader

[caption id="attachment_1155" align="alignright" width="150"] Bioloid RCDataReader C#[/caption]

[caption id="attachment_1128" align="alignleft" width="112"] RemoteCommunications[/caption]

Its responsability is to receive the Dynamixel Zig packets and extract the data.

Collaborator class:

- The ZigSequence enum, with the Dynamixels protocols data sections

[caption id="attachment_1171" align="aligncenter" width="300"] RC-100 packet[/caption]

Operations:

[caption id="attachment_1146" align="alignleft" width="105"] Robotis RC-100 remote controller values[/caption]

public void rawRemoteDataReceived(byte[] rcData), receives the Zigbee data.

public int getValue(), returns the last value received

Workshop: Dynamixel communications with C#

[Next post: Workshop: USB, serial and remote communications with C#]

As I wrote in the previous post, I am not using Robotis Dynamixel SDK because it only works with the  USB2Dynamixel, and I need that it also should work with the serial port and with zigbee or bluetooth (really all 4 use the serial connection). Also I want to query sensors connected to the CM-510.

[caption id="attachment_1053" align="alignright" width="150"] Zigbee[/caption]

Using the CM-510 and computer serial port (or USB to serial) connection you are free to use any wired or wireless device. Really there are a lot of possibilities.

We will start connecting to the Dynamixel bus and sending commands and queries. These classes do the work:

- DynamixelCommunication

- SerialPort2Dynamixel

- RCDataReader

But there are other classes that offer to them some additional services, like Configuration, Utils, Hex and several enumeration types.

I will use the Class-Responsability-Collaboration template to present the classes.

DynamixelCommunication

The main responsibility of this class is sending commands and queries to any Dynamixel device, including the sensors, sound and other capabilities of the CM-510 controller.

Collaborator classes:

- SerialPort2Dynamixel,  that offers operations to use the serial port encapsulating .Net SerialPort class

- Three enums for easy use and avoid errors, using an specific type is safer that using simple integers.

    public enum AXS1_IRSensor { Left, Center, Right, None };
    public enum AXS1_SoundNote { LA, LA_, SI, DO, DO_, RE }; //Only the first six 
    public enum DynamixelFunction, with all the Dynamixel protocols codes and some that I added for the CM-510.

- Configuration class, that reads a file where are stored basic configuration parameters. like:

        private static string ParameterSerialPortName
        private static string ParameterSerialPortBaudRate
        private static string ParameterWaitTime_ms
        private static string ParameterWaitTimeForSensors_ms

Operations:

The public operations are the interface that other classes will use, like:

- short readValue(int id, DynamixelFunction address), reads the value of any AX-12 parameter (or other Dynamixels)


- bool sendOrder(int id, DynamixelFunction address, int value), send commands, like position, speed or torque.


And the private that do internal work supporting the public interface, like:

-  static int getReadWordCommand(byte[] buffer, byte id, DynamixelFunction address), create the Dynamixel hexadecimal sequence (FF FF 0F 05 03 1E CB 01 FE)


- static short getQueryResult(byte[] res), once the query or command is sent it gets the result.


Let's see readValue and two other called functions:

[sourcecode language="csharp"]

public short readValue(int id, DynamixelFunction address)
{
mutex.WaitOne();
short position = -1;

try
{
int size = getReadWordCommand(buffer, (byte)id, address);
byte[] res = serialPort.query(buffer, size, WaitTimeReadSensor);

position = getQueryResult(res);
if (position < 0)
Debug.show("DynamixelCommunication.readValue", position);

}
catch (Exception e)
{
Debug.show("DynamixelCommunication.readValue", e.Message);
}

mutex.ReleaseMutex();

return position;
}

private static int getReadWordCommand(byte[] buffer, byte id, DynamixelFunction address)
{
//OXFF 0XFF ID LENGTH INSTRUCTION PARAMETER1 …PARAMETER N CHECK SUM
int pos = 0;

buffer[pos++] = 0xff;
buffer[pos++] = 0xff;
buffer[pos++] = id;

// bodyLength = 4
buffer[pos++] = 4;

//the instruction, read => 2
buffer[pos++] = 2;

// AX12 register
buffer[pos++] = (byte)address;

//bytes to read
buffer[pos++] = 2;

byte checksum = Utils.checkSumatory(buffer, pos);
buffer[pos++] = checksum;

return pos;
}

private static short getQueryResult(byte[] res)
{
short value = -1;

if (res != null)
{
int length = res.Length;
if (res != null && length > 5 && res[4] == 0)
{
byte l = 0;
byte h = res[5];
if (length > 6)
{
l = res[6];
}

value = Hex.fromHexHLConversionToShort(h, l);
}
}
return value;
}

[/sourcecode]

Notes:

To avoid concurrency problems all the operations that use the Dynamixel bus are protected with a Mutex object that avoids that two or more concurrent objects use DynamixelCommunication simultaneously entering the same operation or using the same resources, like variables, objects or the Dynamixel bus.

All the operations use the same buffer, but being protected with the Mutex object I think that is the better option, although in a previous version I used a very different approach where there were AX12 objects with their own buffer.

[Next post: Workshop: USB, serial and remote communications with C#]

Workshop: Programming a Bioloid robot workbench using C# and C++

[Next post: Dynamixel communications with C#]

It would be a workshop using C# .Net and C++ with Qt 5. The code presented here is used in this two different robots and boards, a HP 214 Ipaq with Windows Mobile and a Raspberry Pi, using the Robotis CM-510 as the servo and sensors controller:

[youtube http://www.youtube.com/watch?v=mvaMTdlb48E&w=281&h=210][youtube http://www.youtube.com/watch?v=Yhv43H5Omfc&w=281&h=210]

These will be the first steps, using C# and .Net , here the code and the exe for the Workbench UI:

Using this enhaced Toss Mode that adds some new functions.  Some of them:

HexaWheels: hexapod & 6x6 wheel robot / Hexapodo y ruedas traccion 6x6

A workshop based on this hexapod robot

[youtube http://www.youtube.com/watch?v=Yhv43H5Omfc]