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# Summary
* [Glossary](gloss.md)
* [Clever 2 assembly](assemble_2.md)
* [Clever 3 assembly](assemble_3.md)
* [Connecting 4 in 1 ESCs](4in1.md)
* [Types of power connectors](connectortypes.md)
* [Blanching](zap.md)
* [Initial setup](setup.md)
* [Using multimeter](test_connection.md)
* [Possible radio failures](radioerrors.md)
* [Installation of FPV](fpv.md)
* [Safety instruction](safety.md)
* [Soldering safety](tb.md)
* [Connecting GPS](gps.md)
* [Flight modes](modes.md)
* [Pixhawk / Pixracer Firmware](firmware.md)
* [PX4 Parameters](px4_parameters.md)
* [PID Setup](calibratePID.md)
* [Raspberry Pi](raspberry.md)
* [RPi Image](microsd_images.md)
* [RPi Connection to the Pixhawk](connection.md)
* [Wi-Fi connection](wifi.md)
* [SSH access](ssh.md)
* [Configuring Wi-Fi](network.md)
* [Using QGroundControl via Wi-Fi](gcs_bridge.md)
* [Controlling Clever from a smartphone](rc.md)
* [UART settings](uart.md)
* [Viewing images from cameras](web_video_server.md)
* [Coordinate systems (frames)](frames.md)
* [ROS](ros.md)
* [MAVROS](mavros.md)
* [Simple OFFBOARD](simple_offboard.md)
* [Navigation using ArUco markers](aruco.md)
* [Automatic check](selfcheck.md)
* [Code examples](snippets.md)
* [Adjusting the position of the main camera](camera_frame.md)
* [Working with the camera](camera.md)
* [Working with a LED strip on Raspberry 3](leds.md)
* [Using rviz and rqt](rviz.md)
* [Working with the ultrasonic distance gage](sonar.md)
* [PX4 Simulation](sitl.md)
* [Software autorun](autolaunch.md)
* [Controlling the copter from Arduino](arduino.md)
* [Using an external 3G modem](3g.md)
* [Copter spheric guard](shield.md)
* [Copter Hack 2018](copterhack2018.md)
* [Copter Hack 2017](copterhack2017.md)
* [Contribution to Clever](contributing.md)
* [Flashing ESCs using BLHeliSuite](esc_firmware.md)
* [MAVLink](mavlink.md)
* Assembly
* [Clever 2 assembly](assemble_2.md)
* [Clever 3 assembly](assemble_3.md)
* [Installation of FPV](fpv.md)
* [Safety instruction](safety.md)
* [Connecting 4 in 1 ESCs](4in1.md)
* [Types of power connectors](connectortypes.md)
* [Blanching](zap.md)
* [Soldering safety](tb.md)
* [Using multimeter](test_connection.md)
* [Possible radio failures](radioerrors.md)
* [Connecting GPS](gps.md)
* Configuration
* [Initial setup](setup.md)
* [Flight modes](modes.md)
* [Pixhawk / Pixracer Firmware](firmware.md)
* [PX4 Parameters](px4_parameters.md)
* [PID Setup](calibratePID.md)
* Work with Raspberry Pi
* [Raspberry Pi](raspberry.md)
* [RPi Image](microsd_images.md)
* [RPi Connection to the Pixhawk](connection.md)
* [Wi-Fi connection](wifi.md)
* [SSH access to Raspberry Pi](ssh.md)
* [Configuring Wi-Fi](network.md)
* [Using QGroundControl via Wi-Fi](gcs_bridge.md)
* [Controlling Clever from a smartphone](rc.md)
* [UART settings](uart.md)
* [Viewing images from cameras](web_video_server.md)
* [Coordinate systems (frames)](frames.md)
* Coding
* [ROS](ros.md)
* [MAVROS](mavros.md)
* [Simple offboard](simple_offboard.md)
* [Navigation using ArUco markers](aruco.md)
* [Automatic check](selfcheck.md)
* [Code examples](snippets.md)
* [Adjusting the position of the main camera](camera_frame.md)
* [Working with the camera](camera.md)
* [Working with a LED strip on Raspberry 3](leds.md)
* [Using rviz and rqt](rviz.md)
* [Working with the ultrasonic distance gage](sonar.md)
* [PX4 Simulation](sitl.md)
* [Software autorun](autolaunch.md)
* [Controlling the copter from Arduino](arduino.md)
* [Using an external 3G modem](3g.md)
* Clever-based projects
* [Copter spheric guard](shield.md)
* [Copter Hack 2018](copterhack2018.md)
* [Copter Hack 2017](copterhack2017.md)
* Supplementary materials
* [Contribution to Clever](contributing.md)
* [Flashing ESCs using BLHeliSuite](esc_firmware.md)
* [MAVLink](mavlink.md)
* [PX4 Logs and Topics ](flight_logs.md)
* Textbook
* [Theory and Videos](lessons.md)

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PX4 Logs and Topics
===
For detailed analysis of the PX4 firmware behavior, you can view flight logs. Flight logs are messages in [uORB topics](https://dev.px4.io/en/middleware/uorb.html) written to a file with extension `.ulg`. The log file can be downloaded using QGroundControl via Wi-Fi or USB in the *Download Log* tab:
![Logs in QGroundControl](../assets/download-log.png)
The required `.ulg` files may also be copied directly from the MicroSD card in the flight controller.
Analysis
---
The log file can be analyzed using the FlightPlot application. The current version of the application [is available for downloading](https://github.com/PX4/FlightPlot/releases) from GitHub.
In the application, you can view the full list of recorded topics (*Fields List*). In the list, you will have to select the required topics, after which they will appear on the chart:
![FlightPlot](../assets/flightplot.png)
Main topics in PX4
---
[uORB](https://dev.px4.io/en/middleware/uorb.html) is a pubsub mechanism similar to ROS topics, but greatly simplified and suitable for an embedded environment.
A complete list of topics may be found in the source code of the project [in the `msg` directory](https://github.com/PX4/Firmware/tree/master/msg).
Here are some topics:
* **vehicle_status** — quadcopter status (mode, etc.).
* **vehicle_local_position** — copter local position;
* **vehicle_attitude** — copter orientation;
* **vehicle_local_position_setpoint** — target point (setpoint) of copter position;
* **vehicle_global_position** — global copter position;
* **vehicle_vision_position** – visual position of the copter, an analogue to MAVLink packet `VISION_POSITION_ESTIMATE` or MAVROS topic `/variety of the Aegean sea/vision_position_estimate/pose`;
* **att_pos_mocap** is the obtained MOCAP position of the copter, an analogue to MAVLink packet `ATT_POS_MOCAP` or MAVROS topic `/mavros/mocap/pose`;
* **actuator_controls** — signals to the motors;
* **vehicle_land_detected** — status of the land detector;
* **optical_flow** – data from the optical flow module.
Monitoring the topics in real time
---
For newer versions of the Pixhawk circuit board (`px4fmu-v3`), as well as for Pixracer circuit boards, the firmware contains module `topic_listener`, which allows viewing the values of topics in real time (including in flight itself).
To use it, select tab MAVLink Console in QGroundControl:
![listener](../assets/listener.png)
Command `list_topics` displays a list of topics available for viewing (included only in [SITL](sitl.md)).
Command `listener <topic name>` displays the current value in the topic. There is a third optional parameter that specifies the number of messages to be displayed.
Examples of commands:
`listener vehicle_local_position`
`listener vehicle_attitude 5`

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Lesson 1: "Introduction. Principles of designing and building multicopters"
========================================================================
The first drones
-------------------
The impetus for the emergence of remotely operated machines was discovery of electricity and invention of radio. On August 22, 1849, the Austrian army used balloons controlled by wires for bombing Venice. In 1892, the Sims-Edison Electric Torpedo Company presented an anti-ship torpedo controlled by wires. In 1897, a British Ernest Wilson patented a system for wireless control of a zeppelin; however, there is no information about building such a mechanism.
In 1899, engineer and inventor Nikola Tesla demonstrated a radio-controlled miniature boat at an exhibition at Madison Square garden. Despite the fact that the public was primarily interested in military use of his invention, Tesla himself pointed to the potentially much wider use of remote control (called "teleautomatics" by the inventor), for example, in anthropomorphic automatons.
![Tesla](../assets/1_1.png)
### Kettering's Beetle
An experimental unmanned "air torpedo", one of the first predecessor project of the modern cruise missiles. Developed by inventor Charles Kettering and commissioned by the U.S. Army in 1917, it was intended for bombardment of cities, large industrial centers and places of enemy forces concentration from the distance of up to 120 km. It featured a simple design and a very low price. Although the unit passed testing with relative success, the First World War ended, and the projectile remained experimental.
![Bug](../assets/1_2.png)
### Bothezat's helicopter
Multi-propeller helicopters were developed in the early years of the helicopter industry. One of the first quadcopters a four-propeller helicopter, which really took off the ground and could stay in the air, was built by George Bothezat, and was tested in 1922. The disadvantage of these aircraft was the complicated transmission that transmitted rotation from a single motor to several propellers. The invention of the tail rotor and the swashplate put an end to these attempts. New developments started in 1950-s, but did not go beyond the prototypes.
![Helicopter](../assets/1_3.png)
UAV types
---------
An Unmanned Aerial Vehicle (UAV) is an aircraft flying without a pilot (crew) on board, and controlled during flight automatically, by an operator in a control room, or by a combination of these methods. The main classes of such aircraft are UAVs of the airplane and copter types.
Airplane-type UAVs
---------------------
This type of aircraft is also known as fixed-wing UAV. The lifting force of such aircraft is created aerodynamically by the air pressure moving against a fixed wing. Aircraft of this type are usually characterized by longer flight duration, high maximum altitude, and high speed.
There are many subtypes of airplane-type UAVs with various shapes of the wings and the fuselage. Almost all airplane layouts and types of fuselage that are found in manned aircraft may also apply to unmanned ones.
Application of the airplane-type UAVs
--------------------------------
Airplane-type UAVs can cover much larger areas than conventional copters, thanks to the ability to stay in the air for a long time and to develop high speed; however, their price significantly exceeds the price of conventional copters. The main disadvantage of such aircraft (except for the price) - is the fact that the quality of the picture may degrade due to speed, such aircraft often cannot take pictures of the three-dimensional/topographic details.
The areas of use:
* Aerial photography (when there is a need of capturing the terrain at a long distance);
* Military use (heavy UAVs with long flight duration — the take-off weight more than 1,500 kg, the range about 1,500 km);
* Agriculture (spreading fertilizers, field monitoring);
* Security and area monitoring.
Application of copters
-------------------
An Unmanned Aerial Vehicle (UAV) is an aircraft flying without a pilot (crew) on board, and controlled during flight automatically, by an operator in the control room, or by a combination of these methods. It is widely used in various fields:
* Telecom sphere (the use of two-way video / audio communication)
* Transportation (transportation of cargo);
* Rescue missions (investigating hard-to-reach areas during natural disasters, terrorist attacks, searching for people under debris, transportation of medicines, providing first aid in case of accidents);
* Advertising campaigns (the use of a robot for attracting attention at large fairs, etc.);
* Media (aerial photography of various events);
* Video/photo shooting (shooting of movies or commercials from a bird's-eye view);
* Food industry (delivery of food products).
Types and configuration
-------------------
There are many engines configurations: a tricopter, a hexacopter, or an octocopter, but the simplest one in terms of assembly and operation is a quadcopter, i. e., a multi-rotor platform with four engines. In turn, a quadcopter may have + and х configuration. In copters with a "+" configuration, one of the beams faces forward, while in platforms with the "x" configuration, the main direction of movement is between two adjacent beams.
![Types](../assets/1_4.png)
Control
----------
The copter is controlled from a transmitter that sends commands to the radio receiver. The transmitter is powered by batteries, and the radio receiver is powered from the flight controller. The communication is often one-way, from the transmitter to the receiver. The receiver is connected to the flight controller with at least five wires which are used for transmitting the turn signals around 3 axes, the throttle command, and the flight mode command.
![Control](../assets/1_5.png)
**Throttle** — translated as "throttle", "thrust", or "gas" in everyday life. A multicopter throttle is the mean arithmetical between the rotation speeds of all motors is it more the throttle, the higher the total thrust of the engines, and the stronger they pull the copter upwards (in other words, "Step on it" means the fastest ascent possible). It is usually measured as percentage: 0 % — the motors are stopped, 100 % — the motors are rotating at maximum speed. Hovering throttle is the minimum throttle required for the copter to stay at certain altitude.
The axes of the copter (pitch, roll, and yaw) are the angles used to determine and set the quadcopter orientation in space.
**Yaw** The multicopter nose turn. conditionally — turning right or left
![Yaw](../assets/1_6.png)
**Pitch**. In copters, manipulation with this moment of force allows the copter to move forward or backward due to tilting the nose in the appropriate direction
![Pitch](../assets/1_7.png)
**Roll** Multicopter tilting to the left or to the right. Due to the roll, the copter can move sideways in the appropriate direction.
![Roll](../assets/1_8.png)
If you can control throttle, pitch, roll and yaw, you can control the quadcopter. They are also sometimes called control channels. There are many flight modes. GPS, barometer, and distance gage are also used, as well as stabilization mode (stab, stabilize, flying and stab), in which the copter keeps the angles set from the transmitter regardless of external factors. Without wind, the copter can hang almost in place in this mode. And the wind will have to be compensated for by the pilot.
The propellers rotation directions are not chosen randomly. If all motors rotated in the same direction, the quadcopter would rotate in the opposite direction due to the generated moments. Therefore, two opposite motors always rotate in the same direction, and other two motors rotate the opposite direction. The effect of rotation moments is used to change the yaw: one pair of motors starts rotating a bit faster than the other, and the quadcopter slowly turns towards us:
LFW — left front clockwise rotation
RFC — right front counter clockwise rotation
LBC — left back counter clockwise rotation
RBW — right back clockwise rotation
![Parts](../assets/1_9.png)
Elements of the copter
----------------
Usually, when it comes to controlling a model of boat or an aircraft, the operator has absolute, precise control over the engine. Pressing the joystick on the transmitter results in proportional increasing the speed of the screws (rpm). A distinctive feature of multi-propeller aircraft (regardless of whether it is an advantage or a disadvantage) is in the fact that no one can simultaneously control the rotation speed of 3 and more motors precisely enough to keep the aircraft in the air. That is where the flight controllers come into play.
![Flightctr](../assets/1_10.png)
**Flight controller** is the most important part. Ninety percent of flight stability and controllability depends on the characteristics of the flight controller.
A flight controller is intended for translating commands from the transmitter into the signals that set the rotation speed of the motor. It also has inertial measuring sensors that allow keeping an eye on the current position of the platform and performing automatic adjustment
![Flightctr](../assets/1_11.png)
**ESC** are regulators for adjusting the motors rotation. The fact is that multi copters use special brushless motors that can rotate at very high speeds. To control such motors, it is sometimes necessary to form three phase voltage and relatively high currents, which is performed by ESCs. Each motor requires its own ESC. All ESCs are connected to the flight controller. The ESCs are powered directly from the battery. Each motor is connected to its own ESC with three wires. The order of connecting the wires determines the direction of motor rotation.
![Esc](../assets/1_12.png)
**Motor**. Copters use brushless motors. They feature outstanding characteristics and survivability due to the absence of friction units (brushes) for transmitting the current. Unlike a conventional motor, which has a moving part — the rotor, and a stationary part — the stator, in a brushless motor, the moving part is the stator with permanent magnets, and the stationary part is the rotor with windings of three phases. In order to rotate such a system, the direction of the magnetic field in the windings of the rotor is changed in specific order, whereby permanent magnets in the rotor interact with magnetic fields of the stator and start rotating. This rotation is caused by the ability of magnets with the same poles to repel from each other, and magnets with opposite poles to attract to each other.
![Engine](../assets/1_13.png)
**Radio control equipment**. It includes a transmitter with a control unit, and a receiver. They may have various numbers of channels and frequencies. Most transmitters operate at the frequency of 2.40 GHz, there are also several other frequency bands available in the market.
**Propeller** is the blade rotated by the motor and used for converting the torque of the motor into the thrust. Blades of the propeller grab the air and throw it in the direction opposite to the direction of movement. In front of the propeller, a zone of low pressure is created, while behind the propeller, a zone of increased pressure is created. This creates the lifting force.
The propeller has the following characteristics:
1. Diameter;
2. Propeller pitch is one of the main technical characteristics of an air or water propeller, depending on the angle of its blades relative to the plane of circular rotation in a gas or liquid medium; it is the distance traveled forward by the screw in a solid medium in one complete revolution (360°);
3. Material.
### Battery
Powers the ESCs and the flight controller. Special lithium polymer batteries are used in copters.
The main battery characteristics are:
* Capacity (mA*h);
* Maximum discharge (20C);
* The number of cells (2S,3S, 4S);
* Weight.
### Power frame
Usually made of plastic or composite materials.
### Reference questions
1. When did the first quadcopter appear, and what were its disadvantages?
2. In what spheres may copters be used?
3. What quadcopter configurations are there?
4. List the names of copter's axes.
5. What is the principle of copter propellers rotation?
6. What is the flight controller responsible for?
7. What is the purpose of ESC?
8. What kind of electric motors is used in copters? What is their advantage?
9. What are the three parameters of air screws?
10. Will a quadcopter be able to fly in the vacuum?

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Lesson 2 "Fundamentals of electricity"
==============================
Introduction. Electromotive force. Ohm's Law
-----------------------------------------
As we know, all bodies are composed of tiny particles - molecules, molecules are composed of atoms, atoms — of still smaller protons, neutrons, and electrons. Each particle, molecule, or body has its energy charge. Bodies with a positive (+) charge are attracted to bodies with a negative (-) charge, and the same charges repel from each other ( + ) from ( + ) and ( - ) from ( - ). Motion is observed.
The intensity of this motion of particles in the substance depends on many factors: deformation, the effect of light, heating, friction, chemical reactions.
With that, small sources of two polarities (+) and (-) are formed. Each polarity he has its own value — the potential. The more the polarity, the more the difference between (+) and (-).
Therefore, this difference of potentials (+) and (-) is the electromotive force (further referred to as EMF), i.e., electric voltage.
![current](../assets/2_1.png)
Thus, the source of electric power has difference of potentials, the charged particles of which attract to each other. There are also phenomena that restrict their motion.
The first are conductors which are most metals, water, acids, alkali, etc.. The second are dielectrics, such as wood, air, plastics, etc. Good dielectrics, such as porcelain, glass, PCB, rubber, etc., are used for making insulators.
Copper, aluminum, brass, bronze, silver, gold, and their alloys are used as conductors of electricity. If two poles of the power source are connected with piece of conductor, charged particles will start moving from (+) to (-).
This motion is electric current.
Each body can resist the motion of charged particles (electric current). This property depends on the substance that the body consists of, and is called resistance. Conductors have low resistance, while dielectrics have high resistance. Conductors have their own resistance, which is called the inner resistance of the source.
The current flowing in the circuit will depend on the difference of potentials (remember that the more the difference, the stronger attraction) and on resistance of the conductor and the internal resistance of the power source; as a rule, the inner resistance of the power source is very low and maybe neglected.
The dependence is as follows:
The electric current will be equal to the one obtained by dividing the difference of potentials at the section (the voltage) by the resistance of this section (resistance). Let's denote electric current as I, voltage as U, and resistance as R;
![current](../assets/2_2.png)
Using a triangle, working with the formula of the Ohm's law, it is easy to write a formula for any input value.
![current](../assets/2_3.png)
You should cover the value to be found.
If the two remaining values are at the same level, they are to be multiplied by each other.
If one is above the other, the upper one is to be divided by the bottom one.
Let us solve a problem using the Ohm's law
Conditions:
The voltage is 20 V, the resistance is 10 Ω. Find the current value.
U = 20 V, R=10 Ω, I-?
I = U\R
I=2 A
The first Kirchhoff's law
---------------------
In circuits that consist of series-connected source and receiver of energy, the relationship between the current, electromotive force and resistance of the entire circuit, or between the voltage and the resistance in any section of the circuit is determined by the Ohm's law.
In practice, current goes from point to point in the circuits along various paths.
The points where several conductors connect are called nodes, and the sections that connect two adjacent nodes are called branches.
In a closed electrical circuit, electric charge cannot accumulate at any point, as this would cause a change of potentials at points of the circuit. Therefore, all electric charges coming to a node in a unit of time are equal to the charges exiting the same node in a unit of time.
A branched circuit.
At node A, the circuit divides into four branches which connect at node B.
Let us denote the currents in the non-branched part of the circuit as I, and in the branches — as **I1, I2, I3, I4,** respectively.
In such a circuit, these currents will have the following ratio:
**I = I1+I2+I3+I4;**
![current](../assets/2_4.png)
The sum of currents coming to a node in an electric circuit is equal to the sum of the currents leaving this node.
![current](../assets/2_5.png)
In case of resistors parallel connection, the current passes in four directions, which reduces the overall resistance, or increases the overall conductivity of the circuit, which is equal to the sum of branches' conductivities.
Let us denote the current in an unbranched circuit as I.
The currents in separate branches — as I1, I2, I3, and I4, respectively.
The voltage between points A and B is U.
The total resistance between these points is R
According to Ohm's law, let's write:
**I = U/R; I1 = U/R1; I2 = U/R2; I3 = U/R3; I4 = U/R4;**
According to the first Kirchhoff's law:
**I = I1+I2+I3+I4; or U/R = U/R1+U/R2+U/R3+U/R4.**
By reducing both parts of the obtained equation by U, we will get:
**1/R = 1/R1+1/R2+1/R3+1/R4**, which was to be proved.
The ratio for any number of parallel-connected resistors.
If a circuit contains two parallel-connected resistors
**R1** and **R2**, we can write the following equation:
**1/R =1/R1+1/R2;**
From this equation, we find resistance R, which can be replaced by two parallel-connected resistors:
![current](../assets/2_6.png)
The obtained expression is of wide practical use.
Electric circuits are calculated by this law.
The second Kirchhoff's law
---------------------
In a closed electric circuit, the sum of all the EMF is equal to the sum of the voltage drops in the resistances of the same circuit.
**E1 + E2 + E3 +...+ En = I1R1 + I2R2 + I3R3 +...+ InRn.**
In making equations, the direction of circuit traversal is chosen and arbitrarily specified directions of currents are specified.
If an electric circuit contains two power sources, the directions of electromotive forces of which coincide, i.е., connected according to Fig. 1, the EMF across the entire circuit shall be equal to the sum of the EMFs of the sources,
т. i.е.,
**E = E1+E2.**
If a circuit contains two sources of EDS with opposite directions, i.е., connected according to Fig. 2, the total EMF of the circuit will be equal to the difference of EMFs of these sources
**Е = Е1—Е2.**
![current](../assets/2_7.png)
The Joule-Lenz's law
------------------
When electric current passes through a metallic conductor, electrons collide with both neutral molecules and with the molecules that have lost electrons.
The collision of electrons with the molecules, energy is wasted, which is transformed into heat.
Any motion that overcomes resistance, requires a certain amount of energy. For example, to move any body, frictional resistance is to be overcome and the work used for it in transformed into heat.
Electric resistance of the conductor acts the same way as frictional resistance.
Thus, to conduct the current through a conductor, the current source spends some energy, which is converted into heat.
Conversion of electric energy into thermal energy is reflected by the Joule-Lenz's law,
or the law of the Joule effect.
Russian scientist Lenz and English physicist Joule simultaneously and independently found that when current passes through a conductor, the amount of heat generated by the conductor is directly proportional to the current squared, the resistance of the conductor and the duration of the period when the electric current passed through the conductor. This provision is called the Joule-Lenz's law.
If we denote the amount of heat generated by the current as Q (J), the current flowing through the conductor as I, the resistance of the conductor as R and the duration of the period when the current flowed through the conductor as t, then, according to the Joule-Lenz's law, the following expression may be derived:
![current](../assets/2_8.png)
Let us solve an example problem:
![current](../assets/2_9.png)
### Reference questions
1. What is electromotive force?
2. How is resistance in a conductor found using the Ohm's law?
3. What is the difference between a conductor and a dielectric?
4. Where is the first Kirchhoff's law used?
5. What is the reason for heat generation in the conductor, when current is passing through it?
### Interesting facts
When German electrical engineer Georg Simon Ohm put his doctoral dissertation, where he first formulated his law, which is indispensable for every electrical calculation, on the table of the rector of the Berlin University, he got a very negative resolution. It said that electricity defies mathematical description, since electricity is own anger, your own eruption of a body; own angry Self, which manifests itself in each irritated body. The rector of the Berlin University in those years was Georg Wilhelm Friedrich Hegel.
Ohm's mane has been immortalized not only by the law that he had discovered. In 1881, at the Electrical Congress in Paris, the name of the unit of resistance "Ohm" has been approved. Not everyone knows that one of the craters on the dark side of the Moon is named after Ohm, along with the names of great physicists such as Planck, Lorentz, Landau, and Kurchatov.
In 1833, Georg Ohm was already known in Germany, and was Professor of the Polytechnic school in Nuremberg. However, in France and England, Ohm's works remained unknown. 10 years after the appearance of Ohm's law, a French physicist in his experiments came to the same conclusions. However, it was pointed out to him that this law has been discovered by Ohm as early as in 1827. French schoolchildren still study the Ohm's law under a different name; for them, it is the Pouillet's law.

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# Theory
[**Lesson # 1** "Introduction. Principles of designing and building multicopters"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson1.md)
[**Lesson # 2** "Fundamentals of electricity"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson2.md)
[**Lesson # 3** "Theory of soldering"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson3.md)
[**Lesson # 4** "Aerodynamics of the flight. Propeller"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson4.md)
[**Lesson # 5** "Brushless motors and controllers"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson5.md)
[**Lesson 6** "Fundamentals of electromagnetism. Types of motors"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson6.md)
[**Lesson # 7** "Operating principle, types and design of batteries"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson7.md)
[**Lesson # 8** "Controlling the flight of the multicopter. The flight controller operating principle. PID ESCs"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson8.md)
[**Lesson # 9** "Fundamentals of radio communication. Operation principle of radio control equipment"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson9.md)
[**Lesson # 10** "Analog and digital video streaming. Cameras, transmitters and receivers used"](https://github.com/CopterExpress/clever/blob/master/docs/en/lesson10.md)
## Video lessons
A little about types of copters
<iframe width="560" height="315" src="https://www.youtube.com/embed/LFOmZZwg-PE" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Part 1
<iframe width="560" height="315" src="https://www.youtube.com/embed/e9Z1pjW0vQU" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Part 2
<iframe width="560" height="315" src="https://www.youtube.com/embed/jWMGSgiLD_E" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Part 3
<iframe width="560" height="315" src="https://www.youtube.com/embed/WhxxXD4b1MY" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Part 4
<iframe width="560" height="315" src="https://www.youtube.com/embed/jkA9F9lSWDM" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Part 5
<iframe width="560" height="315" src="https://www.youtube.com/embed/Cz7EbJ1-xMw" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Part 6
<iframe width="560" height="315" src="https://www.youtube.com/embed/v00oNVzwICg" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
Autonomous flights
<iframe width="560" height="315" src="https://www.youtube.com/embed/WvIlRG7ShWA" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>