It is nice to have body parts that maintain control without using clumsy work-arounds such as gigantic feet like Robosapien uses to maintain some balance.

Here's a simple project that can be solved using my SAM program posted in the Software BASIC section.

Get a human style plastic leg with realistic proportions that cannot stand on its own. Make it bendable at the ankle on the x and y axes so that it can be controlled. Mount 8 micro switches on the bottom of the foot in a long rectangular arrangement so that they are at the four corners and in the middle of each side.

Provide means, either servos or muscle wires, to pull the robot back into balance. There should be eight such muscles, one corresponding to each microswitch.

The rudimentary SAM operates on a single byte environment, represented by the on/off state of the eight switches. It reacts in one of 8 ways, represented by the eight muscles.

An equilibrium state, represented by all the eight switches depressed, is SAM's goal. When he reacts by contracting one muscle it will cause that muscle to contract, either improving his balance, having no effect on his balance, or making it worse.

At first provide a ring about the top of the leg that keeps it from tipping over. Once SAM learns how to use his muscles to maintain balance he will be able to do the job without any intervention.

A function must be provided that causes him to react only when there is a departure from the balanced state. That can be simply implemented by an interrupt signal.

If you study and understand SAM and his workings this will be a simple project and teach you how to make autonomous functions in your robotic systems.