At around and inch per step and using all motor/sensor ports just for walking I dont think it would fair to well in FLL! :)

Take a look at this.

This picture is of the biped taking its first non human powered step. It is not being controlled by the RCX, but instead by the battery box in the left bottom corner of the picture. I am very close to having this thing walking on its own but there are just two problems that have to be delt with first. The first minor problem is that the motor that controls the spinning of the body around the foot that it is balancing on is not quite strong enough. I already have plans to gear a second motor into the system to help it out.

The second major problem is that one of my small pneumatic pumps does not seem to pump. I am not sure if this is something I can fix myself by opening it up, or if I should order/ask for another one from LEGO. But until I fix it/order a new one this robot aint walking anywhere!

The last thing I wanted to talk about is a name for this robot be sides the LEGO biped. Anyone have any ideas?

This amazes me. I never thought that you could take legos, and turn them into a robot with bipedal movement. I applaud your'e hard work!

Thanks Dan, Its comments like those that really keep me motivated!

Check out this link for a ton of different lego biped designs:

http://www.geocities.com/technicpuppy/lblinks.html

Also check out:

http://home.ctlnet.com/~robotguy67/Homepage.htm

There is a link to a lego biped that I built as well as another I built with RC servos (Mechadon) using the multi-processor approach that Dave suggested. On the lego 'bot I used a single motor to move both ankles and shift the weight. As you found out, getting a very low gear ratio is key when using motors. I also found that using a worm gear drive at each ankle helped a lot because it couldn't be back-driven so the motor didn't have to exert torque continuously to hold a position.

One of my other robots, MiniMechadon, will use the "tip toe" technique to begin shifting it's weight similar to your 'bot.

Looks like you are on the right track and have made great progress so far!


Mike

It’s been awhile so I thought I should post an update to show that this project is not dead! :)

Ok I got fed up with waiting for my replacement pump to arrive so I went ahead and started programming the robot to walk. I have taken a video of the biped taking its first fully autonomous step. As you can see from the video it takes the robot quite a while to shift the weight over one foot. My only solution to that right now is to have each pump assembly running two pumps. But seeing as how I do not have that many pumps at the moment, it will have to implemented into version 2 of the biped.

The robot is using three LEGO rotational sensors to coordinate walking. One of the sensors measures the rotation of the body as it swings around a foot. The other two are used to count the number of times the pump has pumped. So far this has worked fine.

That is truly amazing!
Why do you need to measure the pumps tho?

Without measuring the number of times the pump has pumped there will be no other way to accurately ‘guess’ when the pneumatic piston is fully extended or retracted.

If I did not use a rotation sensor to count the number of pumps I would be forced to rely on the length of time the pump motor was running. You can get this to work but as the voltage of the batteries in the RCX varies this method will become less accurate, or even useless. (Motor speed/power is proportional to the supplied electricity)

By using the rotation sensor the pump will always pump the correct number of times to lift the leg (assuming there are no leaks). The program simply runs the pump motor until it has pumped X amount of times.

I received my replacement pump a few weeks ago but have had little time to do anything with it until this weekend.

It was working with the new pump but I realized that the motors were really straining to run the pump. The reason for this is that I was using the pistons to pull rather then push.

I have now redesigned the legs so that the pistons are between the legs and push the weight over each foot rather then pull them.

This picture shows the front view of the walker.
This picture shows the back view.
And this last picture gives you a view of the pump which is now located on the ‘hip’