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1:2 Perseverance Mars Rover Replica Design and Building Diary

The Robotic Arm of the 1:2 Mars Rover 2020 Perseverance Replica’s Design is completed

The robotic arm and the turret at its front end is one of the most complicated components in the Mars Rover 2020 Perseverance.

It requires five motors to realize its five degrees of freedom.

In the real Perseverance Rover, the turret is like a hand that carries cameras, analyzers for on-site studying and sample catching. The scientific tools mounted on the turret are SHERLOC and WATSON and PIXL.

In our 1:2 Mars Rover 2020 Perseverance Replica, all the parts are rebuilt in a ultra-detailed way.

The following 7 screenshots are from the 3D model we are building. The next step is to use advanced techniques to build them in the physical world. Stay tuned!

Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 1
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 1
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 2
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 2
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 3
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 3
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 4
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 4
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 5
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 5
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 6
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 6
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 7
Mars Rover 2020 Perseverance Replica Robotic Arm Turret Drill 7
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Sample Handling System of Mars 2020 Perseverance Rover

Adaptive Caching Assembly of the Mars 2020 Perseverance Rover – part 1

The Mars 2020 Perseverance Rover‘s adaptive caching assembly is one of the three main components of the sample caching system. The other two main components are the robotic arm and the turret assembly, which are introduced in more detail in [Robotic Arm the Mars 2020 Perseverance Rover] and [Turret of the Mars 2020 Perseverance Rover].

The Mars 2020 Perseverance Rover‘s adaptive caching assembly is located inside of the rover and on the front of the body. There are mainly 6 sub-assemblies of the Mars 2020 Perseverance Rover‘s adaptive caching assembly: the sample tube storage assembly, the sample handling arm, the dispenser, volume, tube assembly, the vision station, the sealing station, and the bit carousel. For our 1:2 Mars Rover Replica, we will replicate the part on the front of the body, and we will try our best to perfectly replicate the part that is inside of the rover’s body.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s sample tube storage assembly is for storing both empty sample tubes and filled sample tubes. Although they are placed together, there are sheaths to protect them from contaminating each other. There are a total of 39 sample tubes in the sample tube storage assembly.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s sample handling arm is for transferring the sample tubes to different stations in the adaptive caching assembly or for moving the sample tubes to the bit carousel so that the sample tubes are inserted into the drill bits for sample caching purposes.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s dispenser, volume, tube assembly is to calculate the number of samples collected and to reduce possible contamination. There are 3 sample tubes in the dispenser, volume, tube assembly. There are 7 seal dispensers, and each seal dispenser has 7 seals, so there are 49 seals in total, 7 of which are spares.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s vision station not only takes photos of the sample cached but also performs a second-time calculation for the amount of each sample collected.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s sealing station is to seal a sample permanently by triggering seals in the sample tubes.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s bit carousel is to keep all the drill bits and helps to insert a sample tube into a drill bit for sample caching.

For our 1:2 Mars Rover Replica, we will try our best to perfectly replicate these 6 sub-assemblies. Although they will not have the same functions as the real Mars 2020 Perseverance Rover‘s adaptive caching assembly, they will be fully motorized and you can simulate the sample handling movement with the remote control.

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Sample Handling System of Mars 2020 Perseverance Rover

Robotic Arm the Mars 2020 Perseverance Rover

The Mars 2020 Perseverance Rover‘s robotic arm is located on the front of the rover’s chassis. It has a length of 7 feet or 2.1 meters, which is the same length as its predecessor, the Curiosity rover.  Our 1:2 Mars Rover Replica‘s robotic arm has a length of 3.5 feet or 1.05 meters. The Mars 2020 Perseverance Rover‘s robotic arm wields a rotating 45kg (or 99 lbs) turret assembly, which is 15kg (or 34 lbs) heavier than the Curiosity rover’s turret assembly because it carries bigger science instruments and a bigger corer for drilling compared to the Curiosity rover. The weight of our Mars Rover Replica‘s robotic arm will not be that heavy, because the instruments on it will only be decorations (but ultra-realistic decorations), and the material we use will be lightweight.

The purpose of the Mars 2020 Perseverance Rover‘s robotic arm is to help with exploring the Martian surface and collecting valuable Martian samples. It mimics the human arm – it has joints at its “shoulder”, “elbow” and “wrist” for maximum degrees of freedom. Our Mars Rover Replica‘s robotic arm will also have as many degrees of freedom as the real Mars 2020 Perseverance Rover‘s robotic arm. If the Mars 2020 Perseverance Rover is a human scientist, then the robotic arm is his human arm. At the end of the robotic arm, there is a turret assembly or a hand, and on the hand, there are the science instruments (SHERLOC, WASTON, PIXL), the gDRT, the Corer, and the ground contact sensor which are for Martian rock and soil sample caching. The gDRT and the ground contact sensor are introduced in [Turret of the Mars 2020 Perseverance Mars Rover].

There are some small motors or rotary actuators on the Mars 2020 Perseverance Rover‘s robotic arm, and with these actuators, the Mars 2020 Perseverance Rover‘s robotic arm has 5 degrees of freedom or 5 flexible joints: the shoulder azimuth joint, the shoulder elevation joint, the elbow joint, the wrist joint and the turret joint. Our Mars Rover Replica‘s robotic arm will also have these motors – not the same type or the same size, but the function of the motors is the same –  so that the Mars Rover Replica‘s robotic arm is also 5 degree of freedom. The flexibility of the Mars 2020 Perseverance Rover‘s robotic arm allows it to rotate the turret accurately to a location of interest so that the corer can start its initial abrading operation for the later sampling process, or for the science instruments analyzing process.

After the science team on Earth decides which rocks or regolith to sample, Mars 2020 Perseverance Rover will give the robotic arm the “go” for sample caching. The Mars 2020 Perseverance Rover’s robotic arm will rotate the corer to an angle that is best for the drill bit to operate. Depending on the condition of the drilling site, the drill will choose the rotary mode or the percussive mode for the sample caching. After the sample rocks or regolith are collected, the Mars 2020 Perseverance Rover’s robotic arm will transfer the sample tubes to the bit carousel for the later processes. Although the Mars Rover Replica‘s robotic arm doesn’t have the function like the real Mars 2020 Perseverance Rover, users can control the Mars Rover Replica to drive and mimic the movement of the robotic arm.

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Sample Handling System of Mars 2020 Perseverance Rover

Turret of the Mars 2020 Perseverance Rover

The Mars 2020 Perseverance Rover‘s turret is located at the end of the 2.1-meter-long, 5-degree-freedom robotic arm. It carries the science instruments SHERLOC, WASTON, and PIXL to help with the sample handling process. Besides the three instruments, there are also the gDRT(Gaseous Dust Removal Tool) and the Corer. The Corer is positioned in the middle of the instruments. SHERLOC and WASTON are by one side of the Corer, while gDRT and PIXL are on the opposite side of the Corer. Collectively, they form the Mars 2020 Perseverance Rover‘s turret assembly. Our 1:2 Perseverance Mars Rover Replica will perfectly replicate the structure appearance of the Turret including the SHERLOC, WASTON, and PIXL instruments, the gDRT, and the Corer. 

The Mars 2020 Perseverance Rover‘s SHERLOC, WATSON, and PIXL instruments are introduced in more detail in [PIXL of the Mars 2020 Perseverance Rover Part 1], [PIXL of the Mars 2020 Perseverance Rover Part 2], [SHERLOC of the Mars 2020 Perseverance Rover], and [WATSON of the Mars 2020 Perseverance Rover]. With these scientific instruments the Mars 2020 Perseverance Rover‘s turret carries, the Mars 2020 Perseverance Rover is able to analyze the minerals and chemicals to study whether or not there was life or if it will be possible for humans to live on Mars by carefully and scientifically selecting the most valuable rock and soil samples to collect. Our Perseverance Mars Rover Replica‘s PIXL and the tools on it won’t have the functions as the real Mars 2020 Perseverance Rover, but the Perseverance Mars Rover Replica‘s PIXL replica will stimulate the movement when operating.  

After the Mars 2020 Perseverance Rover‘s robotic arm accurately transports the turret assembly to the location of interest, depending on what this specific mission’s purpose is, the corer will get one of the bits and will do an initial abrading operation. The Mars 2020 Perseverance Rover‘s turret then will rotate and find a position for gDRT to remove dust from the surface to prevent contamination preparing for the sample caching process. The gDRT is a sophisticated tool that consists of the following 7 components:

1. A supply tank with 159g of gaseous Nitrogen

2. A gas tank, or plenum tank which fills gas before every operation

3. Two supplementary supply valves for transferring gas from the supply tank to the plenum tank

4. A valve that releases the plenum tank’s gas

5. A nozzle that will blow the gas to the target surface

6. A valve that acts as the supply tank’s switch for releasing and loading gas before launch

7. A pressure transducer for the pressure reading

In the end, the Mars 2020 Perseverance Rover‘s turret will rotate to positions to allow SHERLOC, WASTON, and PIXL to work.

Our 1:2 Perseverance Mars Rover Replica will perfectly replicate the appearance structure of the gDRT down to very fine details, but it will not have the dust-removing function or the many components. 

Other than the mentioned tools, the Mars 2020 Perseverance Rover‘s turret assembly carries a sensor, the Ground Contact Sensor. The Ground Contact Sensor’s job is to prevent the Mars 2020 Perseverance Rover‘s turret from accidentally touching the ground by giving the robotic arm signals to stop if the turret gets too close to the ground. Our Perseverance Mars Rover Replica will perfectly replicate the appearance structure of Ground Contact Sensor but it will not actually be a sensor.

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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.