Category: Mimas Rover

After several days of printing, the first half of the Rocker-Bogie suspension system is ready! The PVC tubes used to connect all printed parts together are not very likely to be used in the final design, since they may be too flexible. At the moment, the plan is to substitute them with aluminium tubes to ensure a higher stiffness as well as a lightweight structure. Nevertheless, the picture below gives an idea of the final shape of one-half of the suspensions, for the first time. A closer look will show that the "C" shaped bracket of the wheel on the left-hand side is missing, so the servo motor mount is simply leaning on the wheel. If everything goes as planned, this assembly should be ready for testing, with bearings, bolts and nuts in the correct place, in three weeks.

• [Hours of work: 1h]
• [People involved: Giorgio]

On Thursday 13th of October 2022, we started updating this logbook. Mimas Rover's journey officially begins now! All posts with dates previous to 13/10/2022 have been written retracing the work done during the months.

• [Hours of work: -]
• [People involved: Giorgio]

Especially if driving on rough terrain, Mimas has to turn in order to avoid potential hazards. The rover has two possible steering options: normal steering, also known as Ackermann steering geometry (the four angular wheels turn on the Z-axis to let the rover draw a circle) and turn-on-spot (where the four angular wheels turn on the Z-axis to let the rover rotate on its Z-axis).

• [Hours of work: 1h]
• [People involved: Giorgio]

Even if the wheels were built in July, the suspension brackets needed to make them functional have always been a major point of concern. The "C" shaped brackets are crucial since the entire rover's weight relays on them: they can not make contact with the ground or with the wheels themself. The result obtained at the end of more than 20 hours of printing, is a strong bracket that can easily handle roughly 2kg of weight. This limitation, however, can be reduced by changing the position of the "U" shaped brackets inside the wheels (wheels structure: 03/07/2022).

• [Hours of work: 1h]
• [People involved: Giorgio]

The Rocker-Bogie Suspension System (RB) is mainly based on trigonometry and inverse kinematics principles and needs several mathematic calculations to make it work correctly. When the rover will be fully assembled, several accelerometers will be placed on the suspensions, in order to evaluate their inclination respectively to the ground. As the name suggests, the RB can be subdivided into two parts: the Rocker and the Bogie, each of them must be at an acceptable range of inclination to avoid the rover from toppling over.

• [Hours of work: 5h]
• [People involved: Giorgio, Akshit]

Ten printed components and several weeks after the first version, the mast structure is finally ready! It is not fully assembled, though: some tiny brackets and holders for the cameras and sensors still need to be printed, and the electronics themselves is not wired yet. The empty space at the bottom of the mast will host a Nema 17 stepper motor to allow a pan rotation of the Imager, thanks to a threaded rod.

• [Hours of work: 1h]
• [People involved: Giorgio]

The first component of the Rocker-Bogie Suspension System has been 3D printed and assembled! The "Rocker" joint is split into two subassemblies and required a total of 18 hours of printing. After inserting four 6mm thick bolts, the structure is rock-steady!

• [Hours of work: 1h]
• [People involved: Giorgio]

In order to increase the production of 3D-printed parts, Giorgio bought a 3D printer (Creality Ender-3) that will run for most of the days until the end of the rover parts production phase. The expected printing time for all components is >200 hours. Since this is an insanely long period of time, it will be split into several weeks, trying to keep the production efficiency as high as possible.

• [Hours of work: 2h]
• [People involved: Giorgio, Akshit]

The camera housing of Imager's first version (last update 08/09/2022) was completely renewed by substituting all components with 3D printed parts. The structure is now pivoted on an "L" shaped piece and tilt rotation is done using a servo motor. This choice was made to ensure a precise movement using angles or radiants, instead of steps. Since the camera housing is not heavy, there is no need to use a stepper motor, so a high-torque servo motor has been implemented.

• [Hours of work: 1h]
• [People involved: Giorgio]

The first component of Mimas that will be used in the actual final assembly has been 3D printed at Edinburgh Napier Merchiston Campus, thanks to Alexandros Gkanatsios' help. The part needs to be sanded and white-painted. However, this represents the first great step towards the final assembly of Mimas Rover!

• [Hours of work: -]
• [People involved: Giorgio, Akshit]