Page date 3rd December 2003
Biped 'flatfoot' by Math Vos

Bipede "flatfoot"

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Bipede "Flatfoot"

Circuit H-bridge
Print H-bridge
Circuit Bipede
Printed Circuit Bipede

Flatfoot is my first Bipede, but I'm sure it won't be my last. I really like this guy.
It is very easy to build with only minimum tools needed. Just 14 pieces of aluminium or plastic and some screws.

The electronics are my own design. Not BEAM but logical integrated circuits. Just imagine that you can build a "human like walker" with so few. It is driven by two servos. I took out the electronics and put in a H-bridge. How you can make one is seen here.

As mentioned earlier it is not BEAM.
The schematics of the electronics you can find here.
Power is given by a 4,8 volts rechargeable battery , 250 mAh. With a power consumption of ± 150 mA, it can walk for 1,5 hour without recharging.

By the way, when bumping into something with one of it's feet's, it reverses for several seconds. Some times it even turns away, just depending on how slippery the floor is.
I think this fellow also proves that you don't need sophisticated electronics (computers, PIC's) to drive a robot. Compared with my Hexapod2, I like this idea a lot. The challenge is bigger, especially when it is done without using exotic and hard to get components.

Want to build one, just try. It isn't that difficult. You just need some time to get it walking. Balancing is very important.

How it works? Well, with the electronics I make four signals: 1-2-3-4. With the LEDs you can follow the steps it makes.
Signal 1: Motor 1 turns "left"
Signal 2: Motor 2 turns "forward"
Signal 3: Motor 1 turns "right"
Signal 4: Motor 2 turns "backward"
Signal 1: and so on…….

Because the signals are just time related, you need "end stops" for the movement of the servos. In one of the pictures you can see that the "left-right"servo has adjustable end stops.
With the variable resistor in the electronics you can adjust the walking speed (speed of pulses). At a certain speed you get to the resonance frequents of the bipede. Each left-right movement is getting bigger, and your bipede will fall on its side. Just do some experimenting, and it will walk great. The feelers on its feet's are made bigger, just look at the picture. They also make the bipede turn a bit when bumping into something, so when going backward it goes in another direction as where it came from. So simple as that, and looks really cool.