Mars perseverance rover rocker-bogie

The Mars 2020 Perseverance rover has 6 wheels. Different from its predecessor, each of the Mars 2020 Perseverance rover‘s wheels has a total of 48 gently curved treads instead of 24 chevron-patterned treads. For the wheels of our Perseverance Mars Rover Replica, all the curved treads will be perfectly replicated.

Other than changing the wheel patterns, the Mars 2020 Perseverance rover‘s wheels are around 8.5mm thick, which is around 1mm thicker than the Curiosity rover, not including the pattern thickness on the wheel surface. Proportionally, the thickness of our 1:2 Perseverance Mars Rover Replica‘s wheel should be 1mm, but in order for the wheels to be strong enough to support the rover body and the loads onboard and bear the rocky terrain, we will make the thickness of the Mars Rover Replica‘s wheel 2 mm.

The diameter of the Mars 2020 Perseverance rover‘s wheels is 52.5 centimeters or 20.7 inches, which is a little bit larger than the Curiosity Mars Rover’s 50.8-centimeter or 20-inch wheels. The diameter of the wheels of our 1:2 Perseverance Mars Rover Replica is 26.25 centimeters or 10.35 inches.

The reason to change the tire pattern and to make the Mars 2020 Perseverance rover‘s wheels thicker is due to the wear and tear that the Curiosity Mars rover’s wheels experienced. And this actually affects Curiosity’s performance on the Martian sand. But now with the new design, the Mars 2020 Perseverance rover‘s wheels are more resistant to the harsh Martian surface condition. The wheels of our 1:2 Mars Perseverance Rover Replica are strong enough as well to survive many kinds of rock terrains.

While the spokes of the wheel were made of titanium, the PMars 2020 Perseverance rover‘s tires were machined from aluminum that is widely used in the airplane industry, and it is a type of shape memory alloys. This shape-memory aluminum allows the tires to adapt to the Martian terrain, which is very much like a shock absorption system to provide the Mars 2020 Perseverance rover with a stable ride and minimize damages to the tires and hence to the instruments carried by the rover. The shape-shifting material makes the Mars 2020 Perseverance rover‘s tires light-weight, more durable and they have better traction performance while driving on the Martian rocky roads. For our 1:2 Mars Rover Replica, the spokes are made of aluminum and the wheel surface is made of steel. The reason we choose these two materials to build our Mars Rover Replica is explained in this post [Designing the Perseverance Mars Rover Replica’s Wheels].

With one full turn of the wheels, the Mars 2020 Perseverance rover can move forward a distance of 1.65 meters, or 65 inches. The Perseverance Mars rover can go as fast as 152 m/h, or 4.2 cm/s, which might not seem very fast compared to Earth’s vehicles, but the slow speed actually helps the Perseverance Mars Rover conserve energy for the long-term mission. In terms of our Mars Rover Replica, how fast it can go is still to be determined, but we will try to match the Mars 2020 Perseverance rover‘s speed.

Compared with the Curiosity Mar rover, the Mars 2020 Perseverance rover is much more autonomous in terms of driving. The software onboard allows the Mars 2020 Perseverance rover to decide which way it wants to go, which means the Mars 2020 Perseverance rover will travel much further without having to confirm with Earth each time about the driving paths. For our 1:2 Perseverance Mars Rover Replica, you will remotely control it with screens showing real-time video captured by the cameras mounted around the body of the Mars rover replica.

The Mars 2020 Perseverance rover‘s wheels work with a Rocker-Bogie suspension system when interacting with the surface of Mars. This Rocker-Bogie design allows the Mars 2020 Perseverance rover to go over obstacles twice the height of the wheel and allows the loads onboard evenly distributed on the 6 wheels. In our 1:2 Mars Rover Replica, the Rocker-Bogie feature is perfectly replicated, so you can expect that our Mars Rover Replica will also be able to drive over obstacles that are twice the height of its wheels and have the loads evenly distributed on 6 wheels.

Synonyms: cleats, raised treads, grousers

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.

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