RACHEL GRANT

Two-wheel, Mass-efficient Robot

Hero Image of the Project

ME 104: Mechanical Systems Design

Spring 2023

Skills: CAD, Rapid Prototyping, Mass-efficient Design, Motors, Gear Efficiency Design, FBDs, Project Management

Objective: Our task was to drag a 3 kg mass 1 meter forward with the mass offset to the right by 0.05 meters as fast as possible.

Outcome: We designed a two-wheel design, minimized the friction caused by the mass, and calculated the design and mass-efficiency needed to perform the task.

Requirements & Implementation

Hero Image of the Project
Engineering Requirement Design Implementation
Mass-efficient
  • A 3D-printed PLA with 40% infill design, only include components needed for structure
Able to support considerable external load
  • A truss-triangle design because of its minimal mass and ability to support considerable external load while keeping two-force members in axial tension or compression
    • Truss Design
Maximize the horizontal static friction force from the wheels to create optimal counter moment with the smallest possible counterweight
  • A rear wheel with ability to tilt in the yaw direction to allow for slight +yaw tilt through experimentation and its placement calculated in FBD analysis
    • FBD
Design replicable in FBD
  • Cylindrical nubs on chassis for small area of force application
Optimize speed
  • Calculated the optimal motor speed and torque using the characteristics of our motor
  • Found the ideal gear ratio and wheel radii to achieve the motor set-point
    • FBD FBD
Minimal power loss
  • Compared motor power input to a summation of power loss from friction with dragging load, front wheel rolling resistance, bearing resistance, and gearbox power loss
Factor of Safety = 1.5
  • Evaluated failure modes of buckling and fractures in the pegs, the compressive member, and the tensile member
  • Confirmed in FEA analysis
    • FBD FBD