# Overview of glands for robotics with children - 2

Under the cut, we tried to somehow generalize and systematize our experience in choosing a platform for studying with children. If you organize a robotics club, it may be useful to you.
There were a lot of fair remarks to the last series , on this occasion I completely reworked the material.

#### Introduction

Platforms for creating robots, as a rule, include the following components:
1. Mechanics;
2. peripheral electronics;
3. control module;
4. software (development environment).

Platforms are closed (Lego, Fischertechnik) and open (Arduino, Multiplo), you can also highlight the intermediate options (Huna). The property of closed ones is that their components are poorly compatible with other platforms, and there are very rarely amateurs, for example, picking up some separate sensors to Lego; therefore, it makes sense to consider closed platforms as a whole; for open, we will consider each of the four components listed above separately.

#### Lego

First lyrical digression.
At one time, I was one of the happiest children in Yekaterinburg, because my father brought me a whole lego bag from Germany (then there were still very few of it in Russia). And I think it really influenced my mental development - fine motor skills, spatial thinking. However, people have this property: when they grow up, they sometimes begin to dislike the environment from which they emerged, and they often reproach me with a bias towards Lego. Now, I still try to overcome this.

So, the main advantage of Legovian mechanics is the speed of assembly. Probably ten times higher than on screws, two times higher than on rivets. By and large, the main connecting element of Lego Technic is the same rivet that does not need to be clamped, it opens itself due to elasticity:

The second element is the axis with a cross-section:

In fact, it is a screw substitute, only the “nuts” on it do not tighten, but are held by longitudinal friction.
Plus, there are special parts in Lego for assembling some specific components, such as a differential. All this allows you to quickly assemble very complex mechanisms, and for children it is really great. It’s only a pity that we do not forever remain children, and then a problem arises: in adulthood such compounds are not used anywhere, and as far as I know, no one has managed to realize a smooth transition from Lego to something else. In addition, there is another nuisance that I myself encountered when growing up: in Lego, everything out of the box is perfectly adjusted to microns, the child gets used to it, takes it for granted. In reality, such accuracy requires enormous efforts, and I have been studying this for a long time as a student, and I seem to have not really learned it yet.

Lego's control module is boring.

On the one hand, it is very durable, hardly breaks, on the other hand it has only 8 connectors and nothing fits into it except for branded Legov wires (by the way, as far as I know, the most fragile part). Of course, only Legov sensors and motors normally work with it.
From the point of view of the teacher, Legovskaya electronics is the least troublesome: everything connects easily, almost never breaks anything, but there is very little space for creativity.

Since Lego is a large company, it took care of the infrastructure: the vast majority of robotics competitions have a limitation - only Lego.

In addition, many different conferences and events for teachers are held.

The summary is the following: the thing is incredibly cool, it really is, however, as for all toys, the sooner the child jumps from it, the better, in our experience, the seventh grade is just right. Lego is also the only designer who does not require serious technical training from the teacher. Well, and in its ideology, it is very similar to Microsoft, some Microsoft do not like.

#### Fischertechnik

habrahabr.ru/company/neuronspace/blog/243929

If I understand correctly, the story with this constructor happened as follows: Lego very successfully patented his connections and Alan Arthur Fisher had no choice but to use some kind of connection not too suitable for these purposes (it seems to be called a “dovetail”).

For this reason, it’s not very convenient to make some simple mechanisms on Fischertechnik, but there are many special elements with which you can do absolutely incredible things: pneumatic actuators, chemotronics, ionistors, electrochemical supercapacitors, etc. (see the link above for more details). In addition, there are specialized sets that simulate a particular production.
In general, the Fischertechnik ideology repeats the ideology of Lego, after all it is a toy, but very technically advanced.

#### Cross Platform Control Modules

First, a little terminology. All peripheral electronics for adult robotics has standard connectors, works according to standard protocols. Fischertechnik, Lego and other closed products creates artificial barriers to connection through these connectors and protocols. Products are simpler, for example, Raspberry, although they are not open source, but all standards support. In general, in our experience, in this case, the iron sensory does not matter so much: all connectors are standard, the development environment is also standard and, as a rule, open-source, and the iron gasket between them does not play a significant role, switching to another piece of metal will not cause any problems. Here you can still talk about our mission for the development of open-source iron, but for brevity we omit this, the topic is not very relevant.

So, the control modules can be divided into 2 categories: arduino-like (with a simple controller) and Rapberry-like (with full Linux on board).
Arduino benefits:
1. Low price.
2. Quick start: stuck a USB-wire, opened the development environment, downloaded an example, let's go. With Raspberry, you’ll still have to torment yourself: upload an image to a card, connect, configure autorun scripts, etc.
3. It’s more convenient to connect peripherals (for example, the board already has analog inputs, it’s difficult to connect ADCs to the Raspberry), a large number of different shields.
4. Low power consumption.

The advantage of Raspberry is that it is a full-fledged Linux, thanks to this, all popular programming languages ​​are supported, you can start parallel processes, start them over the crown, connect different devices via USB, run different softwares, for example, to process an image, there is a web server, in short , a complete set of joy ITshnika out of the box. Separately, I note support for the Python language. This is the most promising educational programming language; in the West, educational institutions are gradually transferring their curricula to it, C ++ in education is the last century.

Compared to its counterparts, Raspberry is the most common and cheapest; by its characteristics, its latest version is not inferior to analogs, therefore we work with it.

Among Arduin, we chose Uno, because, again, the most common and cheapest (in China it costs about 30 yuan or ~ 300 rubles). Her characteristics are not the best, but we seem to have enough.

The direction we are currently working on is combining Raspberry and Arduina, it seems to us the most promising. The following options exist:
1. Integration of arudino connectors into a board similar to Raspberry ( for example ). Thus, Raspberry loses its disadvantage of the inconvenience of connecting external devices.
2. Connection to the original Raspberry special adapter with Arduino connectors ( for example ). This gives the same advantages as in the previous paragraph, plus there is additional flexibility: you can unhook this adapter and use the original Raspberry connectors (rarely, but it is also more convenient with them). In addition, if one board burns out, this will not prevent you from continuing to use another.
3. Integration of the Raspberry processor, processor and Arduino connectors into one board (http://www.udoo.org/). In addition to the advantages from the preceding paragraphs, such a scheme gives the advantages of a dual-processor circuit; some things are much more convenient to do on it.
4. A special Arduino board that has a connector for connecting to a Raspberry (for example, Arduberry ). In addition to the advantages of the previous paragraph, this gives flexibility.
5. Connect Arduins to Raspberry via USB. Not as convenient as the previous version, the data transfer rate is lower, but much cheaper. Actually this is what we are working on now.

Separately, we mention the controller Trick :

It seems like the only domestic development. Motor drivers, and various sensors are already built into it. The thing is cool, but very expensive.

#### Constructors

There are three main areas of work for children in the field of robotics:
1. Assembly of electrical circuits with a microcontroller. The corresponding sets are supplied, for example, by Amperka: wiki.amperka.ru
2. Assembly and programming of the simplest machines, such as this: amperka.ru/product/turtle-chassis . Basically, these cars are engaged in the fact that they ride along the drawn line (line followers).
3. The assembly of more complex mechanisms from designers, they will be discussed later.

We work with Multiplo .

Firstly, he seems to be the only open source. Secondly, cheap. Thirdly, the main parts can be cut with a jigsaw and a drill.

Of the other designers, the most popular is Huna (by the way, it seems to be partly a Russian development):

Trick offers a good designer, but, again, very expensive.

The general principle of all designers is about the same: flat parts and angles connected by screws, in fact, an old Soviet iron designer. At the same time, each has its own peculiarities: in Multiplo, the main parts are cut out of three-millimeter plastic + small aluminum corners + plastic rivets; in Huna, flat metal is complemented by voluminous plastic parts similar to Lego; The trick is just very massive.

#### Conclusion

Our choice is Arduino + Raspberry + Multiplo. The lowest price, the largest scope for creativity. At the same time, a very high qualification is required from the teacher.
In general, we work with children from the third grade, but this is rather an exception, after all, before the seventh grade, you need something else, such as Lego or Fischertechnik.