Open Source Rover Gets An Update For Easier Building

September 16, 2023 by Lewin Day 9 Comments

Once upon a time, NASA-JPL put out a design for an open-source rocker-bogie rover. It was an impressive and capable thing, albeit a little expensive and difficult to build. Now, the open source community has dived in and refreshed the design, making it cheaper and more accessible than ever before.

Many parts of the original design have either become prohibitively expensive, gone out of stock, or been discontinued entirely. The new version, developed by the community that formed around the project, focuses on using off-the-shelf parts to bring costs down. Where the original design could cost as much as $3000 to build, the new model slashes that bill almost in half. It also eliminates any need for anything custom fabricated, with no machined or 3D printed parts required.

Other optimizations include cutting the rover’s head out from the basic model, as it’s not necessary for a great deal of applications. There is also better fluid and dust ingress protection, and improved serviceability. The entire rover model can also be loaded in OnShape for those desiring to inspect it or make their own modifications.

Parts lists are on GitHub for those desiring to build their own. Alternatively, check out the original design to learn more. Video after the break.

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Rocker Bogie Suspension: The Beloved Solution To Extra-Planetary Rovers

September 14, 2023 by Lewin Day 18 Comments

When navigating the vast and unpredictable expanses of outer space, particularly on the alien terrains of distant planets, smart engineering often underlies every major achievement. A paramount example of this is the rocker bogie suspension system. It’s an integral component of NASA’s Mars rovers and has become an iconic feature in its own right. Its success has seen the design adopted by the Indian space program and thousands of hobbyists in turn.

So, what exactly is it that makes rocker bogie suspension such a compelling design solution? Let’s dive into the engineering that makes these six-wheeled wonders so special.

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When The Sojourner Mars Rover Nearly Ran LISP

August 7, 2023 by Maya Posch 11 Comments

During the late 1980s NASA’s Jet Propulsion Laboratory (JPL) was busy developing the first ever wheeled robot that would roam the surface of Mars. Due to the long round-trip times of any signals between Mars and Earth, development of the firmware that would control the rover was a major point, with the two teams occupied with the task each picking different levels of autonomy for the rover. In a retrospective, [Ron Garrett] who worked at JPL on the ‘more autonomy’ team describes his recollections.

Whereas [Ron]’s team focused on creating a rover that could be provided with high-level instructions which the sophisticated LISP-based firmware would use as guidelines to navigate and operate by, the other team pursued a more limited autonomy approach whereby a human driver would use explicitly plan out the route which the rover would follow before awaiting new instructions.

Perhaps unsurprisingly, the system requirements for running LISP and the additional uncertainties and complexities with the autonomous approach, as well as testing and validating the firmware, resulted in the Sojourner Mars rover featuring the latter approach, with straightforward C-based firmware. Most of Sojourner’s autonomy was limited to a home return function if communication with the lander was lost, which limited both its range and operations during its 85-day extended mission.

As [Ron] covers with examples from later missions, one advantage of LISP is that it allows you to send instructions which can be interpreted (e.g. to debug the system) without having to program in such functionality explicitly. With later Mars rover missions much more of this autonomy that [Ron]’s team pioneered was implemented, although C remained the language of choice for these later rovers.

Heading image: Ron Garrett standing in front of the Robbie prototype. Rocky III can be see in the lower left, and above him are Rajiv Desai and Robert Ivlev, two other members of the team. (Credit: Ron Garret)

Stair Climbing Rover Gets Up With Rocker Bogies

February 18, 2023 by Lewin Day 8 Comments

Doctor Who eventually made light of the fact that the Daleks were critically impaired when it came to staircases. This rover from [WildWillyRobots] doesn’t share that issue, thanks to a smart suspension design.

The rover itself is built using 3D printed components for everything from the enclosure, to the suspension system, as well as the wheels themselves. It uses a rocker-bogie design, which NASA designed for Mars-bound rovers and we often see copied for terrestrial applications. Gear motors are used for their plentiful torque, and they are placed directly within the wheels. Servos allow the individual wheels to be steered, allowing the rover to crab sideways and perform zero-radius turns.

The rocker-bogie setup does a great job of keeping the rover’s wheels touching the ground, even over rough terrain. It readily tackles a random pile of bricks with ease, in a way that many four-wheeled designs would struggle to match. Given its trials on Mars, it’s easy to call the rocker-bogie setup a thoroughly-proven design.

We’ve featured plenty of other rocker-bogie builds in the past; many of them are 3D printed as well.

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Can You Help NASA Build A Mars Sim In VR?

May 12, 2022 by Lewin Day 40 Comments

No matter your project or field of endeavor, simulation is a useful tool for finding out what you don’t know. In many cases, problems or issues aren’t obvious until you try and do something. Where doing that thing is expensive or difficult, a simulation can be a low-stakes way to find out some problems without huge costs or undue risks.

Going to Mars is about as difficult and expensive as it gets. Thus, it’s unsurprising that NASA relies on simulations in planning its missions to the Red Planet. Now, the space agency is working to create a Mars sim in VR for training and assessment purposes. The best part is that you can help!

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Classic Chat: Arko Takes Us Inside NASA’s Legendary JPL

February 25, 2022 by Tom Nardi 4 Comments

Started by graduate students from the California Institute of Technology in the late 1930s, the Jet Propulsion Laboratory (JPL) was instrumental in the development of early rocket technology in the United States. After being tasked by the Army to analyze the German V2 in 1943, the JPL team expanded from focusing purely on propulsion systems to study and improve upon the myriad of technologies required for spaceflight. Officially part of NASA since December of 1958, JPL’s cutting edge research continues to be integral to the human and robotic exploration of space.

For longtime friend of Hackaday Ara “Arko” Kourchians, getting a job JPL as a Robotics Electrical Engineer was a dream come true. Which probably explains why he applied more than a dozen times before finally getting the call to join the team. He stopped by the Hack Chat back in August of 2019 to talk about what it’s like to be part of such an iconic organization, reminisce about some of his favorite projects, and reflect on the lessons he’s learned along the way.

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Martian Wheel Control Algorithms Gain Traction

February 15, 2022 by Ryan Flowers 13 Comments

Imagine the scene: You’re puttering along in your vehicle when, at least an hour from the nearest help, one of your tires starts losing air. Not to worry! You’ve got a spare tire along with the tools and knowhow to change it. And if that fails, you can call roadside assistance. But what if your car isn’t a car, has metal wheels for which no spares are available, and the nearest help is 200 million miles away? You just might be a Jet Propulsion Laboratory Engineer on the Curiosity Mars Rover mission, who in 2017 was charged with creating a new driving algorithm designed to extend the life of the wheels.

High Performance Rock Crawler, Courtesy Spidertrax.com License: CC BY 3.0

You could say that the Curiosity Mars rover is the ultimate off-road vehicle, and as such it has to deal with conditions that are in some ways not that different from some locations here on Earth. Earth bound rock crawlers use long travel suspensions, specialized drivetrains, and locking differentials to keep the tires on the ground and prevent a loss of traction.

On Mars, sand and rocks dominate the landscape, and a rover must navigate around the worst of it. It’s inevitable that, just like a terrestrial off-roader, the Mars rovers will spin a tire now and then when a wheel loses traction. The Mars rovers also have a specialized drivetrain and long travel suspensions. They don’t employ differentials, though, so how are they to prevent a loss of traction and the damaging wheel spin that ensues? This where the aforementioned traction control algorithm comes in.

By controlling the rotation of the wheels with less traction, they can still contribute to the motion of the vehicle while avoiding rock rash. Be sure to check out the excellent article at JPL’s website for a full explanation of their methodology and the added benefits of uploading new traction control algorithms from 200 million miles away! No doubt the Perseverance Mars rover has also benefited from this research.

But why should NASA get to have all the fun? You can join them by 3d printing your own Mars rover and just maybe some Power Wheels derived traction control. What fun!