Wheel + Track Design Research
As I am just starting my project, I decided to do some research before learning/creating CAD designs on Fusion360 in order to figure out arguably the most pivotal part of my project, how the rover was going to move. The main challenge that I wanted to tackle was being able to traverse smooth surfaces, complex obstacles, rough terrain and possibly even stairs.
I researched 7 different layouts, which were: 4-Wheel Drive (4WD) Skid-Steer Layout, 6-Wheel Rocker-Bogie Layout, Mecanum Wheel Layout, Omni-Wheels, Tri-star wheels, Tracks and Tracks + 4WD
The main reason for which I rejected the other layouts were mainly due to the fact that most of them could not climb stairs effectively, which was my main, ambitious goal. I narrowed the list down to the bottom three, eliminating the tri-star wheel system due to the fact that the mechanical complexity of the system was substantial – it required a more complicated rotating wheel assembly, increasing the number of moving parts, weight, and potential failure points. The tracks would’ve tackled the issue of facing obstacles perfectly, though would not be as consistent on smooth surfaces, causing the tracks themselves to wear quickly.
As such, the design that I ultimately decided on was the the hybrid 4-Wheel Drive (4WD) Skid-Steer layout combined with two triangular tracks which lower down, supporting the main chassis when needed. I will use a linear actuator to lower the tracks down when required, most likely to climb stairs and traverse complex obstacles. The design was ultimately inspired by the movement system from the Scewo BRO, the revolutionary wheelchair developed by the Swiss medical robotics company Scewo. However, I will be using my own linear actuator system design for my project, due to the differences between the two. As I progress in this project, I will add CAD and preliminary sketches of this system.
