Rover Uses Different Kind Of Tracks

Tracked robots usually require at least two wheels inside to work properly. However, [James Bruton] discovered a curious tractor design from the 1940s, the Fordson Rotaped, which only uses a single sprocket wheel inside each track. Being [James], he built a self-balancing robot around the rotaped concept.

Instead of a lot of short track sections, the Rotaped uses six long sections of track, about the same length as the wheel’s diameter. To keep the track on the wheel, a series of chains or an oval frame is used on the inside of the track.

As is usual for [James]’ projects, most of the mechanical parts are 3D printed. To hold the tracks in place, he stretches a bungee cord loop around three points on each side of the track. To make things more interesting, he made the robot balanced on the tracks. This took a bit of PID tuning to get working without oscillations, since the wheels experience a slight cogging effect inside the tracks. The wheels are driven by a pair of brushless motors with O-Drive controllers. The balancing is handled by an Arduino Mega, which reads processed position values from an Arduino Pro Mini connected to an MPU6050 IMU.

This might be a viable alternative to conventional tracks for certain applications, and the reduced part count is certainly an advantage. Let us know in the comments if it spawns any ideas. [James] has previously built another tracked rover, which uses flexible 3D printed track sections. By far, the biggest 3D printed tracked vehicle we’ve seen was [Ivan Miranda]’s ridable tank.

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Should I Use Wheels Or Tracks?

When it comes to dominating offroad performance, many people’s first thought is of tracked vehicles. Bulldozers, tanks and excavators all use treads, and manage to get around in difficult terrain without breaking a sweat. Today, we’re exploring just what makes tracked vehicles so capable, as well as their weaknesses.

It’s All About Ground Pressure

The various parts of a tank’s propulsion system.

Let’s first look at how tank tracks work. There are a huge variety of designs, with differences depending on application. Different trends have been followed over time, and designs for military use in combat differ from those used for low-speed construction machines, for example. But by looking at a basic tank track design, we can understand the basic theory. On tanks, the track or tread itself is usually made up of individual steel links that are connected together with hinges, though other machines may use rubber tracks instead. The tracks are wrapped around one or more drive wheels, often cogged, which directly pull on the track. On the bottom of the vehicle are the road wheels, which ride on top of the track where it lies on the ground.  The weight of the vehicle is carried through the road wheels and passed on to the tread, spreading out the load across a broader area. Outside of this, the track system may also have one or more idler wheels used to keep the track taught, as well as return rollers to guide the track back around without touching the road wheels.

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Tank Track Skateboard

As electric skateboards kits and components become more commonly available, you really need to do something different to make your custom board stand out. [Emiel] [The Practical Engineer] has managed to do this by building a half-track skateboard. (Video, embedded below.)

Except for the front trucks, fasteners and bearings, all the mechanical components on the board were custom-made. The sturdy rear chassis and the track sections were machined from aluminum plate, and the wheels and track linkages were machined from POM/Delrin. The large carbon fiber deck and the polyurethane pads on the tracks were custom molded, which [Emiel] covered in detail in separate videos, also below. Two beefy brushless motors drive the tracks and are powered by LiPos in enclosed in the sheet metal electronics box. The final product looks very well-built and refined, especially considering most of the work happened in a tiny 2 m x 3 m workshop.

It looks like the board handles gravel paths well, but we would really like to see how it performs on soft surfaces like sand, where even off-road skateboards can struggle. It struggled a bit with low RPM torque, so a slight gearing change is in this board’s future.

Everything is cooler with tank tracks. If you’re willing to live with plastic tracks, 3D printing is a viable option, as demonstrated by [rctestflight]’s tracked rover and [Ivan Miranda]’s tank  skateboard. Continue reading “Tank Track Skateboard”

3D Printed Tank Tracks

[Ivan] has been keeping his 3D printers busy with parts he’s experimenting with to build a tracked motion setup for a tank-like vehicle. His design uses several interlocking parts, so if you want to duplicate it, we hope your printer calibration is up to snuff. He’s still printing more parts and promises to release the files once the design proves out.

However, you can see he’s off to a good start. Small pieces fit together and accept a piece of filament as a sort of hinge. Some pins keep the filament from working out. Pads fit into the main parts and hold down with zip ties. The whole flexible tread locks into sprockets and a groove on a drive wheel.

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TrackRobot Sports Welded Steel, Not Plastic

Don’t let the knee-high size of [Hrastovc]’s creation fool you. TrackRobot weighs in at a monstrous 60 kg (130 lbs) of steel, motors, and battery. It sports two 48V motors in a body and frame made from pieces of finger-jointed sheet steel, and can reach speeds of up to four meters per second with a runtime of up to an hour. The project’s link has more pictures as well as DXF files of the pieces used for the body.

Currently TrackRobot is remote-controlled, but one goal is to turn it into a semi-autonomous snow plow. You can see TrackRobot going through its first steps as well as testing out a plow prototype in the videos embedded below.

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Hacklet 81 – Tracked Projects

Sometimes wheels just don’t cut it. When the going gets tough, the tough make tracks. Continuous track drive systems – aka tank treads, or tracks, have been around for centuries. The first known use in relatively modern history is a system designed in 1770’s by [Richard Lovell Edgeworth]. Since then there has been a slew of engineers, hackers, and makers who have contributed to this versatile drive system. Today, tread systems find their way into plenty of robotics and transportation projects. This week’s Hacklet is all about some of the best track drive projects on Hackaday.io!

track1We start with [jupdyke] and Modular Continuous Track System. [Jupdyke] has made a project out of making the tracks themselves. These tracks are strong – shore 70A urethane rubber is no joke! Quite a bit of research and experimentation has gone into this project. [Jupdyke] started with 3D printed parts, before moving on to molded 2 part rubber. The rubber is cast in custom machined aluminum molds. The molds are even heated to ensure a quality casting. Rubber alone doesn’t make a track though. The backbone of these tracks are machined steel pins. The pins go through the treads and connect through roller chain components. We’re betting a set of these tracks could easily carry a person!

robot-tankNext up is [williamg42] with Expandable Ruggedized Robotic Platform. [Williamg42] describes this vehicle as “able to operate in harsh environments”. We would shorten that to “It’s a beast”. Some incredible machine work has gone into this robot, especially on the suspension and idler wheels. Everything is made of metal – the frame is 8020 aluminum extrusion covered in plates. The suspension is aluminum and steel. Motors are mini-CIM motors. This robot isn’t lacking on brains, as a BeagleBone black controls it through a custom cape board. Next time we go out on a desert trek, we want this ‘bot at our side!

ttbn-alphaFrom the mind of [TinHead] comes TTBN Alpha, a TelePresence robot. TTBN alpha is based on a Raspberry Pi. Rather than start with Raspbian, [TinHead] built his own lightweight Linux distribution with buildroot. Control is through a web interface. The operator’s view of the world is through the electronic eye of a Logitech C110 webcam. [TinHead] printed his own tracks, using straightened paperclips as pins. Two servos modified for continuous rotation serve as the main drive motors.

 

surocam

Finally we have [Hendra Kusumah] with Surveillance Robot Camera (SUROCAM). SUROCAM was [Hendra’s] project for both the 2014 and 2015 Hackaday Prize. The chassis is based upon the common RP5 robot kit. This robot’s DC motors are driven by the classic L298n driver chip. Unlike TTBN Alpha above, SUROCAM uses a full Raspbian install, so this Pi is ready for anything. The code is written in Python, and pagekite and ngrok to help make connections to the outside world.

If you want to see more tank treaded rovers, check out our new tracked projects list. Did I miss your project? Don’t be shy, just drop me a message on Hackaday.io. That’s it for this week’s Hacklet; As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!