Principles

Simplicity

  • Simplicity is the key to durability
  • To come up with a complex solution to a complex problem is hard; to come up with a simple solution to a complex problem is even harder

Design for Disassembly

  • Access holes
  • Common tools
  • Think twice about glue welding etc.
  • Think about how hard it would be to remove a part for repair

Multifunctionality

  • Figure out where you can use one part or mechanism for multiple tasks
    • One arm to pick up a ball and hang from a bar
    • One rod as both a pivot and a structural member
    • One shaft for both arms and wheels
  • Can save weight and complexity
  • Careful of conflicting requirements

Theory

  • BREAKING NEWS: Theory actually works
  • Calculate gear ratios
  • Determine whether a motor has enough torque
  • Calculate forces and torques on joints
  • Swerve drive kinematics
  • Work-energy arguments

Qualitative Theory

  • Self-locking mechanisms
  • Directions of forces or torques
  • Rate of change of force/stress/torque etc.

Iteration

  • Design is iterative!
  • Rethink old ideas
  • Eliminate leftovers
  • In the early stages, it is often a good idea to throw out designs and redo them from scratch
  • Every time you restart, you know the problem a lot better
    • As my Grade 9 math teacher used to say, "Expand, then simplify"

Weight

  • FIRST has a weight limit
  • Very easy to exceed the weight limit without noticing
  • Drilling holes can only get you so far
  • Think twice before using steel parts, large bolts, or thick plate
  • Lighten parts as you go
  • Weight is bad; weight up high is much worse
  • Consider alternate materials: Lexan, nylon, HDPE/LDPE, or wood