Small homemade robot. BEAM robots What we need

To create your own robot, you don’t have to graduate or read a ton. It is enough to use step by step instructions, which is offered by robotics masters on their websites. You can find a lot on the Internet useful information, dedicated to the development of autonomous robotic systems.

10 Resources for the Aspiring Roboticist

The information on the site allows you to independently create a robot with complex behavior. Here you can find program examples, diagrams, reference materials, ready-made examples, articles and photographs.

There is a separate section on the site dedicated to beginners. The creators of the resource place considerable emphasis on microcontrollers, the development of universal boards for robotics, and soldering of microcircuits. Here you can also find source codes for programs and many articles with practical advice.

The website has a special course “Step by Step”, which describes in detail the process of creating the simplest BEAM robots, as well as automated systems based on AVR microcontrollers.

A site where aspiring robot creators can find all the necessary theoretical and practical information. A large number of useful topical articles are also posted here, news is updated and you can ask questions to experienced roboticists on the forum.

This resource is dedicated to a gradual immersion into the world of robot creation. It all starts with knowledge of Arduino, after which the novice developer is told about AVR microcontrollers and more modern ARM analogues. Detailed Descriptions and the diagrams very clearly explain how and what to do.

A site about how to make a BEAM robot with your own hands. There is a whole section dedicated to the basics, and there are also logic diagrams, examples, etc.

This resource very clearly describes how to create a robot yourself, where to start, what you need to know, where to look for information and the necessary details. The service also contains a section with a blog, forum and news.

A huge live forum dedicated to the creation of robots. Topics are open here for beginners, interesting projects and ideas are discussed, microcontrollers, ready-made modules, electronics and mechanics are described. And most importantly, you can ask any question about robotics and receive a detailed answer from professionals.

The amateur roboticist’s resource is primarily dedicated to his own project “Homemade Robot”. However, here you can find a lot of useful topical articles, links to interesting sites, learn about the author’s achievements and discuss various design solutions.

The Arduino hardware platform is the most convenient for developing robotic systems. The information on the site allows you to quickly understand this environment, master the programming language and create several simple projects.

Choosing a microcontroller to create your robot. First you need to understand the concept of what a microcontroller is and what does it do?

Microcontroller is a computing device capable of executing programs (that is, a sequence of instructions).

It is often referred to as the “brain” or “control center” of the robot. Typically, the microcontroller is responsible for all calculations, decision making, and communications.

In order to communicate with the outside world, the microcontroller has a series of pins or pins to electrically sense the signal. So the signal can be turned to maximum (1/C) or minimum (0/off) using a programming instruction. These pins can also be used to read electrical signals. They come from sensors or other devices and determine whether the signals are high or low.

Most modern microcontrollers can also measure the voltage of analog signals. These are signals that can have a full range of values ​​instead of two clearly defined levels. This happens using an analog digital converter (ADC). As a result, the microcontroller can assign a numerical value to the signal in the form of an analog voltage. This voltage is neither high nor low and is typically in the range of 0 - 10 volts.

What can a microcontroller do?

Although microcontrollers may seem quite limited, at first glance, many complex actions can be performed using high and low pins. low level signal for programming the algorithm. However, creating very complex algorithms, such as intelligent behavior or very large programs, may simply not be possible for a microcontroller due to limited resources and speed limitations.

For example, you can program a repeating sequence to make the lights blink. So the microcontroller turns on the signal level high, waits a second, turns it low, waits another second and starts again. The light is connected to the output pin of the microcontroller and will blink endlessly in a cyclic program.

Likewise, microcontrollers can be used to control other electrical devices. Primarily such as drives (when connected to a motor controller), storage devices (such as SD cards), WiFi or bluetooth interfaces, etc. As a consequence of this incredible versatility, microcontrollers can be found in everyday life.

In almost every household appliance or electronic device At least one microcontroller is used. Although several microcontrollers are often used. For example, on televisions, washing machines, control panels, phones, watches, microwave ovens and many other devices.

Unlike microprocessors (eg. CPU V personal computers), the microcontroller does not require peripheral devices. Such as external RAM or external storage device for operation. This means that although a microcontroller may be less powerful than their PC counterparts. It is almost always much easier and cheaper to develop circuits and products based on microcontrollers because very few additional hardware components are required.

It is important to note that the microcontroller can only output a very small amount of electrical energy through its output pins. This means that it is not possible to connect a powerful electric motor, solenoid, large lighting, or any other large load directly to the microcontroller. Attempting to do this may damage the controller.

What are more specialized functions of a microcontroller?

Special hardware built into microcontrollers allows these devices to do more than simple digital I/O, basic calculations and decision making. Many microcontrollers readily support the most popular communication protocols, such as UART (RS232 or other), SPI and I2C. This feature is incredibly useful when communicating with other devices such as computers, sensors, or other microcontrollers.

While these protocols can be implemented manually, it is always better to have dedicated onboard hardware that takes care of the details. This allows the microcontroller to focus on other tasks and keeps the program clean.

Analog-to-digital converters (ADCs) are used to convert analog voltage signals to digital ones. There the quantity is proportional to the magnitude of the voltage and this number can then be used in the microcontroller program. To make the intermediate energy output different from high and low, some microcontrollers have the ability to use pulse width modulation (PWM). For example, this method allows you to smoothly change the brightness of the LED.

Finally, some microcontrollers have an integrated voltage regulator. This is quite convenient, as it allows the microcontroller to work with a wide voltage range. Therefore, you do not need to provide the required voltage values. It also makes it easy to connect various sensors and other devices without an additional external regulated power source.

Analog or digital?

Which input and output signals need to be used depends on the task and conditions. For example, if your task is simply to turn something on or off, then it is enough for you that the signal at the input pin of the microcontroller is digital. The binary state of the switch is 0 or 1. The high signal level can be 5 volts, and the low 0. If you need to measure, for example, temperature, then you need an analog input signal. Next, the ADC on the microcontroller interprets the voltage and converts it into a numerical value.

How to program microcontrollers?

Programming microcontrollers has become easier thanks to the use of modern integrated development environments (IDEs) with full-featured libraries. They easily cover all the most common tasks and have many ready-made code examples.

Nowadays, microcontrollers can be programmed in a variety of high-level languages. These are languages ​​such as C, C++, C#, Java, Python, Basic and others. Of course, you can always write a program in assembly language. Although this is for more advanced users with special requirements (with a hint of masochism). In this sense, anyone should be able to find a programming language that best suits their taste and previous programming experience.

Programming microcontrollers is becoming even easier as manufacturers create graphical programming environments. These are icons that contain several lines of code. The pictograms are connected to each other. As a result, a program is created that is visually simple, but contains a large amount of code. For example, one image could represent engine control. The user only needs to place the icon where necessary and indicate the direction of rotation and speed.

The developed microcontroller boards are quite convenient to use. And they're easier to use for a long time. They also provide convenient USB power and programming interfaces. Therefore, it is possible to connect to any modern computer.

Why not use a standard computer?

Obviously, a microcontroller is very similar to a computer processor. If that's the case, why not just use a computer to control the robot? So should you choose a desktop computer or a microcontroller?

Essentially, in more advanced robots, especially those that involve complex calculations and algorithms, the microcontroller is often replaced (or augmented) standard computer. Installed on your desktop computer motherboard, processor, device RAM (for example, hard drive), video card (built-in or external).

Additionally there is peripherals, such as a monitor, keyboard, mouse, etc. These systems are usually more expensive, physically larger, and consume more power. The main differences are highlighted in the table below. In addition, they often have more functionality than necessary.

How to choose the right microcontroller?

If you are studying robotics, then you will need a microcontroller for any robotics project. For a beginner, choosing the right microcontroller can seem like a daunting task. Especially considering the range technical specifications and areas of application. There are many different microcontrollers available on the market:

• Arduino
• BasicATOM
• BasicX
• Lego EV3
• and many others

To choose the right microcontroller, ask yourself the following questions:

What is the most popular microcontroller for my application?

Of course, creating robots and electronic projects in general is not a popularity contest. It is very good if the microcontroller has a lot of community support. And it is successfully used in similar or even identical situations. As a result, this can greatly simplify the design phase. This way, you could benefit from the experiences of other users, both amateurs and professionals.

Members of robot design communities share results, codes, pictures, videos with each other, and talk in detail about successes and even failures. All this is accessible materials and the opportunity to receive advice from more experienced users. Therefore, it can prove to be very valuable.

Does your robot have any special requirements?

The microcontroller must be able to perform all the special actions of your robot in order for the functions to execute correctly. Some features are common to all microcontrollers (for example, the presence of digital inputs and outputs, the ability to perform simple mathematical operations, comparing values ​​and making decisions).

Other controllers may require specific hardware (eg, ADC, PWM, and communication protocol support). Also memory and speed requirements as well as the number of pins must be taken into account.

What components are available for a particular microcontroller?

Maybe your robot has special requirements or requires a specific sensor or component. And this is critical to your project. Therefore, choosing a compatible microcontroller is of course very important.

Most sensors and components can communicate directly with many microcontrollers. Although some components are designed to interact with a specific microcontroller. Perhaps they will be unique and incompatible with other types of microcontrollers.

What does the future hold for us?

The price of computers is plummeting, and advances in technology are making them smaller and more efficient. As a result, single board computers have become an attractive option for robots. They can work with full operating system(Windows and Linux are the most common).

Additionally, computers can connect to external devices, such as USB devices, LCD displays, etc. Unlike their ancestors, these single board computers tend to consume significantly less power.

Practical part

In order to select a microcontroller, let's make a list of the criteria we need:

• The cost of the microcontroller should be low
• It should be easy to use and well supported
• Availability of accessible documentation is important
• It must be programmed in a graphical environment
• It must be popular and have an active user community
• Since our robot will use two motors and various sensors, the microcontroller will need at least two ports for controlling the motors and several ports for connecting sensors. It should also be possible to expand the number of connected devices in the future.

Meets these criteria EV3 module from the Lego Mindstorms EV3 set.

EV3 Brick Overview

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. Collect simple robot anyone who knows how to hold a soldering iron correctly in their hands can do it 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. Electronic part The robot consists of a microcontroller (MK) - a chip that contains a processor, 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

Robot diagram

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 must be 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. Also a 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.

My robot board

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 and 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 removal is ensured 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.

The first version of my robot's sensors

Robot firmware

To revive a robot, 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.

Conclusion

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:

/*****************************************************
Firmware for the robot

MK type: ATmega16
Clock frequency: 16.000000 MHz
If your quartz frequency is different, then you need to specify this in the environment settings:
Project -> Configure -> "C Compiler" Tab
*****************************************************/

#include
#include

Void main(void)
{
//Configure input ports
//Through these ports we receive signals from sensors
DDRB=0x00;
//Turn on pull-up resistors
PORTB=0xFF;

//Configure output ports
//Through these ports we control the motors
DDRC=0xFF;

//Main loop of the program. Here we read the values ​​from the sensors
//and control the engines
while (1)
{
//Let's go forward
PORTC.0 = 1;
PORTC.1 = 0;
PORTC.2 = 1;
PORTC.3 = 0;
if (!(PINB & (1< {
//Go backwards 1 second
PORTC.0 = 0;
PORTC.1 = 1;
PORTC.2 = 0;
PORTC.3 = 1;
delay_ms(1000);
//Wrap it up
PORTC.0 = 1;
PORTC.1 = 0;
PORTC.2 = 0;
PORTC.3 = 1;
delay_ms(1000);
}
if (!(PINB & (1< {
//Go backwards 1 second
PORTC.0 = 0;
PORTC.1 = 1;
PORTC.2 = 0;
PORTC.3 = 1;
delay_ms(1000);
//Wrap it up
PORTC.0 = 0;
PORTC.1 = 1;
PORTC.2 = 1;
PORTC.3 = 0;
delay_ms(1000);
}
};
}

About my robot

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).

According to your wishes, I am posting a video:

UPD. I re-uploaded the photos and made some minor corrections to the text.

I decided to smoothly transition to dynamic moving models. This is a project for a small homemade IR-controlled robot, assembled from simple and readily available parts. It is based on two microcontrollers. Transmission from the remote control is provided PIC12F675, and the receiving part for the motor controller is implemented on PIC12F629.

Robot circuit on a microcontroller

Everything went smoothly with the digital part, the only problem was in the “propulsion system” - small gearboxes, which are very problematic to make at home, so I had to develop the idea " vibrobugs"The micromotors are controlled through amplifying transistor switches on the BC337. They are replaceable with any other small n-p-n transistors with a collector current of 0.5 A.

The dimensions turned out to be very small - in the photo there is a comparison of it with a coin and also near a matchbox. The robot's eyes are made of super-bright LEDs, tucked into a housing of small electrolytic capacitors.

Discuss the article SMALL HOMEMADE ROBOT

In this article we will talk about the most interesting robots, the construction principle of which is to use simple analog circuits. We will look at their features and basic principles, and at the end we will try to make a simple robot.
It's easy even for beginner radio amateurs!

It is encouraged to use as few electronic elements as possible when creating a robot, and you can even use electronic waste.

The most important principle of designing a BEAM robot is to imitate the nature of living beings.
BEAM robot must have properties inherent to living beings. Of course, we are not talking about such signs as breathing, growth, reproduction, because the robot does not need this. But food, movement and development for these robots are the main meaning of life.

Movement is an integral sign (property) of any living creature. This is the simplest thing that can be implemented in a BEAM robot. In my understanding, movement can be spontaneous or deliberate (intentional). In relation to smart robots, we can say that only deliberate movements are required of them. For example, in a person, the facial muscles may involuntarily move to convey facial expressions (for example, due to a sudden emotion), but for a robot, any unnecessary movement leads to a waste of energy.

A difficult but interesting task is the creation of artificial intelligence BEAM robot, because according to the philosophy of BEAM robotics, they do not use microcontrollers and microprocessors, but everything is done on analog discrete components. The use of microcontrollers is not prohibited, but the basic instincts of the robot must be based on the use of a variety of behavioral models associated directly with sensors and sensors with a minimum level of signal processing.

Nutrition

In most cases, the power source is a battery. But if you want to create a self-powered robot, you need to use radiation energy (for example, sunlight). A device that converts solar energy into direct electric current is called a solar battery, consisting of semiconductor photocells. Solar panels provide small amounts of electrical energy in real time, but only in the presence of the sun. In order not to “die” in the absence of the sun, it is advisable to use rechargeable batteries to store the accumulated energy for a “rainy day”... or a cloudy day.

Adaptation and behavior

A robot based on analog circuits is more adapted to the environment compared to a digital robot, whose effectiveness ends when it gets into a situation that is not prescribed in the program of its digital brain. In other words, digital robots cannot solve problems for which the answers are not included in their program.

The concept of BEAM robots, proposed by Mark Tilden, was that the response to external factors should be provided at the first stage by the machine itself, without the participation of any “brain,” as happened in living nature, on the way from protozoa to humans. The improvement and creation of more complex robotic systems should follow the same path.

Species

There are different types of BEAM robots that are designed to perform different tasks.
Audiotropes- react to sounds.
Phototropes- react to light.
Radiotropes- respond to radio frequencies.
Thermotropes- react to thermal radiation.

Phototropes are the most common, since finding light is the most obvious task for a solar-powered robot.

Modular structure

Personally, I like the idea of ​​​​creating a BEAM robot from individual functional modules, and following the principle of “from simple to complex” it will be possible to develop the robot by adding more and more new modules. Each module itself can work separately, i.e. no centralized brain will be used to process information.

Chassis

In order for the robot to move, it is necessary to construct a chassis for it.
It comes in different types: tracked, on wheels and even on legs...
Let's take a closer look at them.

1. Crawler.

The picture shows a finished chassis, which is not difficult to find on sale. In most cases, it is driven by a pair of geared motors.
Pros: turns well without using steering mechanisms; has increased cross-country ability; It is convenient to mount electrical boards and individual components on it.
Cons: This chassis is difficult to assemble at home and costs an average of $90.

2. Chassis on wheels.


Pros: the simplest type in terms of the fact that you can assemble it at home yourself (for example, from a children's construction set, etc.) or use a toy car.
Disadvantages: to make a turn, a steering rotary mechanism is required, which means you will have to use an additional electric motor, which entails an increase in the weight of the structure and an increase in electricity consumption.

3. Robot on legs.


This is the most difficult type.
Pros: their appearance is closer to living beings, and their movements look more impressive.
Disadvantages: a large number of mechanisms are used, and very often such a robot needs a system that ensures balance.

WE DO IT OURSELVES!

You can make the chassis for your robot as shown in the figure below.

You can use a box as a basis. Plastic is better because it is a lightweight material. In the same box it is convenient to place the power supply: accumulator, batteries, etc.
Keep in mind that the larger the wheels, the slower the robot will go (and may not move).

Second option. Plastic clamps are used here to secure the motors.

Electric motors can be taken from old equipment: tape recorders, toys, disk drives, etc.

I had three types of motors at home:

The choice fell on the upper motor. It showed good characteristics in terms of traction and current consumption.

We will also need a battery compartment to provide power. The power supply can be organized separately: for the motors (power) and for the logic circuit.

Below is a simple diagram of a robot that follows the light of a flashlight.

Scheme 1. “Coming into the light.”

This circuit uses photodiodes. We select them according to the sensitivity range, i.e. considering what light the robot will go to. For example, to the light from a flashlight (visible range) or to the beam of a TV remote control (infrared range). If you illuminate the photocell VD1, then Motor 1 will rotate, and if you illuminate the photocell VD2, then Motor 2 will rotate. Taking this into account, we will arrange the motors so that when VD1 is illuminated, Motor 1 turns the robot towards the light.

And if the motors are swapped, then the robot, on the contrary, will turn away from the light.

Now let's look at photocells.
Photodiodes, phototransistors, photoresistors, etc. are used as light-sensitive elements. There is a lot of information on these elements on the Internet, so I will describe them briefly.

1. Photoresistor: In the dark, it is a high-resistance resistor, and when illuminated by light, its resistance drops in proportion to the light intensity, showing a linear relationship. Typically they perceive only visible light.

2. Photodiode: a semiconductor device, just like a regular diode, has an anode and a cathode.
If you use direct connection, the illuminated photodiode will generate voltage at the terminals.
When turned back on, the resistance of the irradiated photodiode drops in the same way as that of a photoresistor.
Based on the light range, photodiodes are divided into IR diodes and visible light ones. IR diodes perceive only infrared radiation, but also respond well to incandescent lamps and the sun.

3. Phototransistor: It differs from a conventional transistor in that light is supplied to the base region, which controls the amplification of the emitter-collector current.

Without much success, an LED can be used as a photosensitive element. It has too little sensitivity and can only be enhanced with the help of an additional circuit.

BEAM robot that I made

In my robot I used various photodiodes of unknown origin. The video shows that the sensitivity of one of them is greater.
One of the photodiodes reacts to the beam of the TV remote control.
Also, the entire “filling” is filled with hot-melt glue.
I hope you do better and more beautiful!

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
VT1, VT3	Bipolar transistor	KT3102	2	KT315		To notepad
VT2, VT4	Bipolar transistor	KT361B	2	KT816