Homemade chassis for a robot. Review of ready-made frames for creating robots on Arduino. Two- and three-wheeled chassis for creating riding robots

« « Chassis for a robot for 200 rubles

Every roboticist, when starting to create a robot, thinks about chassis. Here is a brilliant idea for its simplicity and low cost. robot chassis from Chinese cars.

To create the chassis we need two the most disgusting Chinese toy tanks electric. They don't have to be able to turn at all - it's much cheaper that way.

Unsightliness has two advantages: low price and lack of pity when dismantling tanks.

As Ideas warns, such cheap creations of Chinese industry stink like hell, so you won’t feel sorry for them.

So, we have donor tanks. Let's go!

We remove the covers from the donor tanks.

The battery compartments will still be useful to us, so we simply clean them of excess plastic.

We will need both compartments (from each tank).

Glue the battery compartments together.

We bite off and saw off the axles right down to the gearboxes in order to get half a chassis for a robot from one tank chassis.

Two gears used for pumping the muzzle have been removed as unnecessary.

Good day, brain engineers! Here is a guide on how to how to do a simple, small, mobile, stable and all-terrain robot, without unnecessary devices and with all driving wheels.

I've been experimenting with this design for quite some time. brain games and achieved good results, which I post in this article. For example, the robot's chassis is assembled from Actobotics aluminum parts, which makes it easy to assemble and ensures stability, light weight and reliability.

Each of the six wheels has its own engine, which increases traction, while the engines of each side, left and right, are combined into groups of three, that is, the robot maneuvers like a tank. Large wheels increase maneuverability and shock absorption, and also prevent damage from falls.

Managed craft an Arduino microcontroller, which is responsible for all electrical components and also has the potential for further improvements. The basis of the remote control remote control is the XBee module, which is easy to use, reliable and gives a signal range greater than required.

Step 1: Aluminum Frame

To assemble the frame we will need:

3 aluminum corners "Actobotics" 40cm each.
6 aluminum motor brackets
6 12V motors with 6mm shaft diameter
6 wheels 127 x 62mm
6 tires 5.6cm
6 hex wheel hubs
36 M3x8 screws
aluminum sheet 343x190mm
8 hex spacers M3x40mm

Step 2: Preparing the Frame

We cut one of the aluminum corners in half with a metal file. On the other two, solid corners we mark the places for the brackets brain engines, drill 3mm holes for the fastening bolts (blue color in the photo) and screw the brackets themselves to the corners.

Step 3: Frame Assembly

We mount the engines on the brackets, placing them as low as possible. Then we fasten the long corners to each other with two short ones (which were cut earlier), in the places shown in red.

After that, we mount 8 spacers on the aluminum sheet, and with the help of them we attach it to the frame from the corners.

Step 4: Electronics

This step requires you brainiac work in the field of electronics, in particular assembling circuits with Arduino and XBee.

For assembling an electrical circuit crafts necessary:

Lithium battery 3S 4000 mAh
digital electronic switch - needed for a possible subsequent upgrade, and it can be replaced with a simple switch rated for a current of no more than 10 amperes.
Arduino Mega 2560 module
XBee Explorer board
XBee Pro 60 mW transmitter with antenna
Sabertooth 12A control board for two motors
ULN 2803 and IC connector

On the aluminum plate we mark three lines corresponding to the three axes of the motors (marked in red in the photo), then we attach a lithium battery between the first two axes, and then install an electric switch if you decide to use it.

Let's start with the Arduino: solder a red wire to Vin, a black wire to two GNDs and a white wire to TX1 (18th pin) on the back of the board, using the photo as a guide. When installing the board, try to place it between the wheels so that USB port was easily accessible for programming. We attach the board itself to the plate with six bolts with two washers on each to lift the board above the plate. Also use plastic washers and nuts to avoid short circuits.

We mount the Sabertooth control board directly onto the aluminum plate and secure it with four bolts and nuts. The plate also plays the role of a radiator here. Next, focusing on the diagram, we connect the components homemade products with each other.

We mount the XBee module itself on the board for XBee and make 4 connections: 5V to 5V, GND to ground, DIN to TX3 (pin 14) and Dout to RX3 (pin 15).

And finally, on a small circuit board we assemble the circuit responsible for the operation of the LED headlights on the front of the craft; during assembly we also look at the diagram.

Step 5: Xbee Programming

Before you start programming the XBee module, it is advisable to read the manual.

In addition to knowledge, we will need:

USB XBee explorer board
USB cable

After installing and updating the X_CTU program, we configure each XBee module as a receiver and transmitter at the same time. Set three brain parameter:
For the receiver: DL=321, MY=123 and BD = 3 (9600 baud).
For transmitter: DL=123, MY=321 and BD = 3 (9600 baud).

Step 6: Assembling the Control Panel

Required materials:

Lithium battery 3S 800 mAh
Arduino Nano 5V, 16 MHz or similar
XBee Explorer board
XBee Pro 60 mW module with antenna
joystick
LED
resistor 220 Ohm
two miniature switches
plastic case

After assembling the basic circuit, making the remote is a simple step. In this case, as usual, we focus on the diagram. Code for Arduino

Step 7: Finally

Collected brain trick has the following characteristics: length - 42 cm, width - 32 cm, height - 12.5 cm, weight - 3.430 kg.

The speed depends on the selected engines, mine brain robot with a gear ratio of 100:1, it reaches 0.7 m/s (2.4 km/h). If you reduce the gear ratio, the speed will increase as the thrust decreases. On the contrary, if you increase the gear ratio: the speed will decrease, but the traction will increase.

The video shows off-road performance homemade products.

Important points:
When installing LEDs, observe polarity;
if the wheel rotates in reverse side, then simply change the polarity of the motor;
if the entire group of wheels rotates in the opposite direction, then change the polarity on the Sabertooth board;
if all the wheels rotate in the opposite direction, then change the polarity of the supply wires to the Sabertooth board.

The Sabertooth board has a built-in battery voltage sensor, so if homemade stops functioning, simply charge the battery.

Upgrade plans: for starters, on your own brain trick I want to add a miniature video camera and audio-video transmitter, which are used in aircraft modeling. There are also plans to install a robotic manipulator arm on the craft.

But this is in the plans, but for now thank you for your attention and good luck in your work!

Today I am starting to publish articles dedicated to creating my own mobile robot. At the family council, it was decided to give him the name Robotosh, which is actually why I named my blog that way. The purpose of its creation is to study various algorithms and elements of robotic systems in practice.

At the moment, my robot is a four-wheeled platform with a microcontroller board installed on it and hung with a number of sensors and interfaces for user interaction. Software is in its very infancy, so I will analyze in detail what and why exactly it is implemented this way at the moment and gradually move on, adding functionality and endowing it with “intelligence”. This is my first robot, so perhaps some stages of its creation will be erroneous or dead ends.

Idea

The idea as a first approximation looks like this: autonomous robot, having the following features:

4 wheel platform
Indoor use (apartment)
Non-contact methods for identifying obstacles to avoid collisions
Control modes:

offline “random walk” mode to build a room map
remote control mode
execution mode voice commands with voice recognition

Battery charge monitoring and self-charging
Displaying information on a character LCD display
Sound alarm

Robot chassis

As a chassis, I decided to use a purchased four-wheeled platform for purely economic reasons (no matter what I thought, it was more expensive in parts, but this is one of the cheapest I could find). My choice fell on the DAGU 4WD chasis kit chassis, which is a 4-wheeled platform with motors. This is what the package looks like.

Platforms for installing various attachments are made of red acrylic glass with a large number mounting holes for installing sensors, controllers, servomotors. Acrylic glass, I must say, is drilled very easily, so even if something does not fall into the finished holes in the future, you can always easily make additional ones. The wheels are rubberized. Commutator motors with plastic gearboxes.

Boards

Dimensions: 175 x 109 x 3 mm

Distance between boards (height of included racks): 24mm

Ground clearance: 45 mm

Wheels

Wheel diameter: 67 mm

Rim width: 26mm

Motors

Voltage: 4.5 - 7.2 V

Idle speed: 90 ± 10 rpm

No-load current: 190 mA (max. 250 mA)

Torque: 0.8 kg cm

Maximum current: 1A

It takes about twenty minutes to assemble. The assembled chassis looks like this:

To be honest, I had an ambush with the engines. These motors are not designed to accept encoders, and this is important to me since I plan to use encoders to provide feedback for more precise positioning. Therefore, most likely, if it is not possible to remake these engines, I will change the engines to others in the future.

Overall, the assembled platform looks quite nice. If it weren't for the problem with the encoders, I would be 100% satisfied.

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