There is no such crazy thing in robotics than an outdoor robot able to travel on diverse terrains such as sand, concrete, grass or a rough surface.
I do not know how many of you have already built an outdoor robot or wants to build one. But if you are here, you can discover the best chassis designed to build in your garage the absolute outdoor robot with big wheels and a strong chassis.
Why an outdoor robot?
Most of the makers and hackers start the introduction in robotics with indoor robots. The reason is simple. They have many kits to start with and plenty of step-by-step tutorials and guides to building robots for indoor use. To build an outdoor robot usually requires more costs that traditional robots.
All the robots able to travel on rough terrain are built on a strong chassis and feature big wheels. In general, a chassis is a simple structure that includes the suspension system and the frame. Sometimes you can meet the term of the unibody. A unibody chassis is an alternative to the standard design of a chassis. A unibody chassis consists of a frame and body integrated with the same structure.
Why a chassis with wheels?
Land-based robots designed with wheels are the most popular mobile robots for both beginners and advanced users. Compared with other outdoor robots, a wheel is the simplest and cost effective propel system that someone can use in the DIY area.
With such popularity among hobbyists, the wheel comes in different sizes, and it is attached to a variety of robotic platforms. You can use wheels with the diameter of a few centimeters to 30 centimeters and more.
What can you do with one wheel? Properly nothing. But you can add another one, another two, three, or five wheels to build a robot able to travel over a rugged land. An outdoor robot with four or six wheels is the most common combination for outdoor applications.
As a common feature, a robot with four or six wheels uses multiple drive motors (one for each wheel) and reduces the slip. More than that, usually a robot on wheels is cheaper than a robot on tracks or legs. It has a simple design and is an excellent choice for beginners.
In this article, I explore the best chassis with four and six wheels designed to build outdoor robots capable of traveling through rough terrain and in almost all conditions.
4 wheels chassis
Every chassis with four wheels has two things in common: are ideal for DIY projects and designed with adaptive function to rough terrain.
As a maker, I want for me the best chassis and cost effective resources. Below, I choose the ‘crème de la crème’ chassis that can fit into almost any project and provides the ideal ratio between costs and functionality.
At a price of $95, you can have in your garage an aluminum alloy chassis for DIY robots that supports a maximum load of 8Kg. It has a height of 13 centimeters and a net weight of 1.25Kg.
This chassis comes with a structure that can adopt small or big wheels. It is your choice. You can use it with the 130 mm bigfoot tires that look more domineering, or use it with small wheels for more effective maneuvers.
The chassis has attached four electric motors for each wheel. You can control the electric motors with an Arduino microcontroller or with any other AVR or STM32 control platform.
The chassis is designed with a 3mm aluminum alloy place at the base. The place has the role to ensure the sturdiness of the platform and make it suitable for rough terrain.
The body of the chassis can host a large variety of extensions, actuators, sensors, etc. You can use it with an ultrasonic sensor able to detect obstacles, attach a camera or a small robotic arm.
The mechanical side of the chassis is simple. You can use the aluminum structure with small or large wheels. If you use small wheels, you can add six wheels instead 4 and make it a 6WD smart robot. Also you can divide the chassis into two parts. You can build a two-wheeled robot with plenty of space to add components and parts. In other words, you can build a self-driving robot for outdoor exploration.
If you love compact robots, this metal chassis is the right one and has a price of $59. Each wheel has a diameter of 78 mm, enough to travel over grass, gravel, pavement or small obstacles. It is not a platform for mud or sand, but it can definitely run at maximum speed over your lawn.
Its body weight only 580 grams, which is the result of its compact and slim body.
The platform can host a large variety of sensors, controllers, shields, or actuators. It has large attachment points to fix the multitude of components and parts.
Four 48:1 DC gearboxes drive the four wheels. Each gearbox is engineered with a metal output shaft that resists at shocks and damage.
In conclusion, all you need is a battery, a basic motor driver, and a controller to drive this little platform over your lawn.
With a price of around $280, this is not an affordable chassis, but it provides a flexible platform for an outdoor robot. Its structure is easy to assemble and let you discover a large variety of options to attach sensors, actuators, add-ons, etc. All its aluminum channels are adapted to the platform and provide mount holes on all the sides.
In the center of the platform is located a large ABS plastic box with two access panels. If you open up the cavity, you can discover a large enough space to add batteries and electronics.
The chassis comes equipped with four wide heavy-duty tires and 13.7-cm in diameter. The wheels are driven by four ball-bearing planetary gear motors designed with metal gears and a ball-bearing pivot suspension.
This monster with four wheels has a price around $235 and an aluminum body with attachment points for various components.
The kit comes without electronics, but with four 12 V DC 30:1 gear head motors and 12 centimeters tires. These wheels are big enough to travel over a variety of diverse terrains such as concrete, grass, sand or soil.
You can control this platform with an Arduino Duemilanove or the BotBoarduino microcontroller.
Its body has plenty of room inside for additional components such as batteries, electronics, sensors, actuators or a robot arm able to grasp objects.
At a price around $175, this robot chassis comes with independent suspension for each wheel. If we are adding to this equation the 120mm-diameter wheels, the result is a platform with high traction over uneven terrain.
Even it looks like a monster track, the chassis weight only 1.9 Kg. Its body is made from aluminum sheets with a multitude of holes to mount accessories and electronics.
The most interesting feature is the suspension system. This system is designed to support different loads in different conditions.
All the four big wheels are driven by four brushed DC motors. Each electric motor is encapsulated in the suspension system to provide maximum traction even on bumpy surfaces and rough terrain.
The chassis provides enough space for two battery packs. The designers choose to use the same power supply system used in RC cars. Together with the batteries, you have space to add controllers and motor drive shields.
You do not need a ton of specifications to assemble this wild chassis. It features a user-friendly system that allows the user to assemble all the parts in only three steps.
6 wheels chassis
Before starting the work at a 6WD robot, you have to know at least the main reason to build one of these. I can tell you that reason in just a few words: a 6WD robot turn better than a 4WD platform. The secret to turning better the 6 wheeled platforms is found in the location of the center wheels.
Having this configuration in mind, I found the best chassis featured with six big wheels able to travel over a variety of terrains such as sand, concrete, and grass.
At a price around $497, this wild chassis can go your robot everywhere and almost over any terrain. It can carry a maximum load of 5Kg and is designed with a modular platform. The design allows you to expand the chassis and build your custom robot for outdoor activities.
Like the four-wheeled version, this can be assembled easily and with simple tools. Inside the box, you have included a printed manual, but if you are already accustomed to the DIY area, everything will seem familiar.
The body is strong to resist at shocks and damages. It is made from 2mm thick aluminum sheets featured with many attachment points for additional equipments, sensors, actuators, etc.
Each wheel is attached by the “Super twist” suspension system designed to keep the wheel on the ground when the robot travels on uneven terrain.
As a conclusion, this chassis lets your bot travel almost anywhere. This wild chassis is designed for outdoor activities and is strong enough for search and rescue applications.