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1:2 Perseverance Mars Rover Replica Design and Building Diary

A 1:4 Mars Perseverance Rover Static Replica First

We realize the job to build an ultra-detailed Mars 2020 Perseverance Rover replica with all the parts motorized movable exactly the way as the one on Mars is more difficult than we thought at the beginning. Therefore, we plan to build a 1:4 Mars Perseverance rover static replica before we physically build the 1:3 motorized one. All the movable components of the 1:4 Mars Perseverance rover static replica can at least do the same actions as the real Mars 2020 Perseverance Rover replica can manually, while for some components we will design motorized mechanical structure.

As I mentioned in my first two diaries, the major two challenges in the design and building of the Mars 2020 Perseverance Rover replica are the wheels and the robotic arm.

The wheel tread challenge is solved already using steel instead of aluminum, although the spokes are another challenge in wheels.

However, the 1:3 Perseverance Mars rover replica’s long robotic arm with a heavy turret at the end of it is THE big challenge. All the mechanical structures, especially the motorized structures, require a high level of machining accuracy, motors with high ratio gearbox to provide large torques, and little compromising to the external shape in all positions.

Our technologies can achieve the goal for sure but it is always sweet if we can plan something to facilitate this journey.

One good option is to build a 1:4 Mars Perseverance rover static replica first. A smaller model is a widely used approach in industrial design and mechanical engineering which allows designers and engineers to verify designs in a much more cost-efficient way.

In our 1:4 Mars Perseverance rover static replica, we will keep the following features.

  1. precise external shape and detail replica to the Perseverance Mars rover.
  2. functional wheels with their own individual motors and the “rocker-bogie” suspension system exactly as they are in the Perseverance Mars rover.
  3. mast with motors can do exactly the same actions as the Perseverance Mars rover can
  4. steerable X-Band High-Gain Antenna can do exactly the same actions as the Perseverance Mars rover can
  5. a simplified remote control
  6. maybe more features

We are also considering building the long robotic arm with light-duty motors to realize all the same actions as that of the Perseverance Mars rover. To reduce the challenge, the turret will be just an empty shell so as to minimize the weight but keep the appearance.

Meanwhile, we will also build another version of the long robotic arm for the 1:4 Perseverance Mars rover replica. In this version, all the internal motorized mechanical structures to realize the drill function, cameras, electronic components will be designed and built into the turret so that we can have a relatively precise estimation of the weight for the turret in the 1:3 Perseverance Mars rover replica. What’s more, the arm will be thoroughly designed to have all the external details and internal motorized mechanical structure while the motors will not be installed inside joints. Instead, in those positions, there will be specially designed bearing structures to allow manually pose change for the arm. This specially built arm will help us get a relatively precise estimation of the torque required in each joint of the robotic arm in the 1:3 Perseverance Mars rover replica.

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1:2 Perseverance Mars Rover Replica Design and Building Diary

Designing the Perseverance Mars Rover Replica’s Wheels

The wheels of the Mars 2020 Perseverance Rover are made of special aluminum. There are cleats on the outer surface to add traction. This is actually the first challenge during our building journey of the Perseverance Mars Rover Replica.

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The rendered screenshot of the Perseverance Mars Rover Replica wheel design

The special aluminum NASA used to build the Mars 2020 Perseverance Rover’s wheels is obviously very tough so as to bear at least 1/6 weight of the real Perseverance Mars Rover of which the total weight is 2,260lb or 1,025kg. When the Mars 2020 Perseverance Rover driving over the uneven Martian terrain, each wheel may have to bear up to 1/5 weight or even more of the Mars 2020 Perseverance Rover. But the real challenge comes from the cleats. The cleats of the 1:3 Perseverance Mars Rover replica’s wheels are only around 2mm thick. Unless we could find a kind of really awesome aluminum, the 1:3 cleats will easily break on terrains with sharp rocks due to that the burden of a single wheel will all come to the contact point between the cleat and the rock.

The endurance of the wheels of Perseverance Rover’s predecessor – Curiosity Rover is actually good but while driving over sharp, pointy rocks they did break. Mars 2020 Perseverance Rover’s wheels are redesigned to be more robust – narrower than Curiosity’s, but bigger in diameter, 20.7 inches (52.6 centimeters) versus 20 inches (50.8 centimeters) and made of thicker aluminum, have twice as many treads and are gently curved instead of chevron-patterned. But still, they will damage if the terrain harshness is beyond their design standard.

When we choose the material for the 1:3 Perseverance Mars Rover replica’s wheels, our goal is to build them to withstand pressure from almost all kinds of terrains. The reason is quite simple – people would love to enjoy the excitement of manipulating the 1:3 Perseverance Mars Rover replica on terrains similar to Mars but they also would love to see all parts intact after each and every ‘mission’. Dust is OK but damages are definitely a heartbreaker.

In the end, after weighing the pros and cons, we decided to use steel to build the 1:3 Perseverance Mars Rover replica’s wheels. The building cost of each 1:3 Perseverance Mars Rover replica’s wheel is around 1,000 USD. Six wheels are almost 6,000 USD. The cost is high but they don’t break. They are heavy than aluminum but the 1:3 Perseverance Mars Rover replica doesn’t go on the rocket.

A close-up image showing the broken position on Curiosity rover’s left-middle wheel. Credit: NASA/JPL-Caltech/MSSS
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Displacement analysis of the Perseverance Mars Rover Replica’s wheel
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Displacement analysis of the Perseverance Mars Rover Replica’s wheel