Mars Rover Robotics Club
Science Subsystem, Mechanical Design
Overview
I work on the science subsystem for the Oregon State Mars Rover Robotics Club, a student team that designs and builds a rover for outdoor competition. My focus is the mechanical hardware that holds and protects the science instrumentation, primarily a spectrometer housing used for rover based soil sampling and a mechanism that retains sample flasks during operation.
The problem and constraints
- Rough terrain. The rover drives over uneven, outdoor terrain, so mounted hardware has to survive vibration and shock, not just sit still on a bench.
- Secure retention. Flasks containing soil water slurry samples need to be held firmly during pump driven testing and material transfer, while still being easy to load and remove.
- Tight packaging. The science subsystem shares limited space and weight budget with the rest of the rover.
- Fabrication limits. Parts have to be manufacturable with the tools and materials actually available to the club.
My contribution
- Designing and iterating CAD assemblies in Fusion 360 for a spectrometer housing used in rover based soil sampling
- Engineering a clamping and flask retention mechanism for containing soil water slurry samples during pump driven testing and material transfer operations
- Running tolerance analysis on mating parts and fasteners
- Working on component mounting strategies to improve structural rigidity, manufacturability, and serviceability under off road operating conditions
- Collaborating on subsystem integration with electrical and software teammates
Tools and technologies
Design decisions
- Retention approach. The clamping mechanism holds the flask firmly without over constraining it, leaving room for tolerance stack up between parts.
- Fabrication compatibility. Housing and clamp features are designed around the fabrication methods and materials the club actually has access to.
- Vibration margin. Fastener selection and clamp geometry include margin for the shock and vibration loads of off road driving, not just static holding force.
Testing and iteration
Fit and clearance are checked against the mating rover components as parts come together, and the design is revised based on those fit checks and feedback from teammates on the subsystem. Testing and integration work is ongoing as the rover build continues.
Challenges
The hardest part is balancing structural robustness for off road vibration against the tight packaging and weight limits of the science subsystem, all while designing for the specific fabrication tools the club has on hand. Coordinating those tradeoffs with electrical and software teammates, who have their own constraints on the same subsystem, adds another layer to the design process.
Current status
In progress
The spectrometer housing and clamping mechanism are under active development as part of the club's current rover build. Design and fabrication work is ongoing, and this page reflects the current state of the subsystem.
What I learned
- How to design mechanical hardware for real world vibration and shock, not just static loads
- How tolerance analysis changes part design when parts are fabricated with limited equipment
- How to coordinate a shared subsystem across mechanical, electrical, and software teammates