Page Comparison

Flexible Frame Styles 

#1: Rocker + Differential (4wd)

• Intention: have at least one wheel making contact with the ground
• Each side of the 4-wheel drivetrain is mounted on a "rocker", which connects to the chassis on a pivot joint
  • ITU Rover Team, 2020

Image Removed

• • • No evidence of welding → using machined hubs to connect straight aluminum tubes via regular fasteners (rivets?)
    • #5 overall ranking for SAR 2020
  • UW 2020/2021 Drivetrain

Image Removed

• • • Members are composed of machined box-tube, assembled using bolts and nuts
• To keep the chassis level with the rest of the drivetrain, a differential system is required. The idea is that – relative to the chassis – when one rocker swings forward, the other one swings back. Without a system like this, there is nothing stopping the chassis from swinging forwards/backward when the rover is still, for example
  • Differential bar
    • Note: ball joints are important in this mechanism because they can swivel, thus protecting the joint

      • [Mars Rover 2020 Project] Bogie suspension Tests

Image Removed

Image Removed

• • • • UW 2020/2021 Drivetrain

Image RemovedImage Removed

• • • Used on NASA's Curiosity and Perseverance Mars rovers
  • Differential gearbox
    • Used on NASA's Spirit and Opportunity Rover

Image Removed

• Specific drivetrain style is being frequently used for low-cost rover design
  • Ex. on the CSA's developmental lunar rovers

#2: Rocker-Bogie + Differential (6wd)

• Intention: have all wheels contact the ground at all times
• The front part of the rocker has the first set of wheels, while the back of the rocker implements a bogie system that hosts the other two sets
• Gives the simple, familiar design of rocker + differential additional flexibility
• Overall style used on all of NASA's most recent Mars rovers
  • Team Anveshak, 2020

Image RemovedImage Removed

• • • Modeled their drivetrain angles in MATLAB to increase its performance through bumpy terrain
    • Constructed using carbon fibre box tube + aluminum gussets + fasteners
    • #8 overall ranking for SAR 2020
  • UW 2019 Drivetrain

Image Removed Image Removed

#3: "W-Drive" + Differential (6wd)

• Intention: have all wheels contact the ground at all times
• W-frame pivots at the middle wheel and is constrained by the V-shaped linkage
• A simpler version of rocker-bogie?
  • Nova Rover 2019/2020/2021

Image Removed 

• • • Members composed of aluminum tubes that are welded together 

#4: 4-Bar Linkage Suspension (4wd)

• Intention: allows each wheel to move independently while keeping the wheel perpendicular to the ground by using a 4-bar linkage
• Space efficient – allows for more mounting space on the sides of the rover
  • NASA's Viper Prototype

Image RemovedImage Removed

• • • Has a motor to drive each linkage. Unnecessary for our design, would likely look to implement a passive suspension system
  • Nova Rover 2018

 Image Removed

• • • Uses double-wishbone suspension on each wheel

Questions to Explore

...

Inspired by the Arm team's research topic list, here are some topics that I (Emily Adam) would like to look more into. Feel free to take any of my topics, join someone else on a topic, or add your own suggestions! In general, I think we should be researching our options, their pros/cons, and what is required to implement that technology.