Robotics, just like every other technical subsection, involves theories from several fields such as mathematics, physics, mechanical, etc.... To start building robots for enthusiastic purposes, it is not essential to learn all these things. But knowing about some of the simple techniques can be helpful. While searching for a good articles for those who are looking for building toy robots, I found and interesting site that explain some of the important parts in a very clear manner. It is non other than the site of Society of Robots.
MECHANICS - ROBOT CHASSIS CONSTRUCTION
ROBOT SUSPENSION SYSTEM
ROBOT STATICS
ROBOT DYNAMICS
ROBOT GEARS TUTORIAL
Some of the very good robots can be found here.
