Mechanism Design

Draft: July 11, 1997.

In this section you learn some of the fundamental principles of DC motors, of geartrain design, of batteries, and mobile robot chassis design. You will also learn some practical elements of designing Lego structures.

Lego design workshop
- Readings:
  - Fred Martin, "The Art of Lego Design"?, reprinted from The Robotics Practitioner, vol 1, number 2, Spring 1995. (An FTP postscript file can be found at Fred Martin's web site.)
  - Printout of Lego Engineering and Robot Design pages from UWF Lego Robots web site.
  - REL Lego design notebook. (Doesn't exist yet!)
- Lab work:
  - Skip the stuff on gears until tomorrow.
  - Build copies of Martin's Figures 1, 2, 22, 23, 24, 25, 26, 27, 28, 29.
  - Build a box that holds a big marble and survives a six inch drop. The lightest design wins.
Power train: batteries, motors, transmission, mobility
- Readings:
  - On batteries: Jones and Flynn, Chapter 8: Power
  - Oregon State course notes on batteries.
  - On motors: Jones and Flynn, Chapter 7: Motors
  - Geartrain sections of Martin's article and the UWF web pages.
  - Jones and Flynn: Chapter 6
- Questions
  - What happens if two motors in parallel share a common shaft?
  - How about in series?
  - How can you use a differential gear to gang up motors?
- Lab work:
  Design a chassis: synchro, skid steering, steered, or whatever, using Lego components including motors and geartrain. You may also use the Lego-ized hobby servos.
  or
  Design a race car to go in a straight line.
  or
  Tractor pull? Winch?
- Lecture outline:
  - Power = force * vel = torque * angvel = voltage * current
  - Levers, Gears, and transformers
  - Motors, generators, batteries
  - A few design points on Lego geartrains