Let's Make Robots!

The Climber - Third ride - It works!!!!!

Climb stairs

Hi guys !

I'm working on a robot from plywood. He should the stairs up and down ride.

He receives four strong (12kg/cm) servos modiefied for continuos rotation and one Sharp IR and probably two bumper switches.

My first Climber was finished, but he had two problems:

- first and last stair, so I had to change the design.

I hope that now everything is good.


 24 June 2009 - First ride

Without sensors.


 25 June 2009 - Second ride

 

He is too heavy!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 


 26 June 2009 - Third ride

 It works!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

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So the problem with the first and last stairs have to do with the weight distribution, I think.

during mid-flight, (i.e. flight of stairs...um. another bad pun..), the rear wheels are taking about 70% of the weight (square root of 2, assuming that the robot is at 45 degrees!), rather than half of the weight. In the case of the last step,  the downward weight vector on the front wheel is much smaller than it is while it's climbing, i.e. it's not pulling "up" as strongly, so has relatively smaller traction.

So you need to either have some way to dynamically change the weight distribution, which would make it more complex, or you could try using "stickier" rubber on the wheels - that would increase the normal forces that are the traction.

There's an important point here, in response to one of your comments - adding rubber spikes to the wheels actually DECREASES your traction, this is because by using spikes, you decrease the amount of contact between the wheel and the ground. If you want maximum traction, you need very smooth, sticky rubber - this is exactly why formula 1 race cars have "slicks", which provide maximum traction with the ground.

Great idea. Have you tried more traction to get over the first stair?

I can imagine that as 1 foot(toes not inches) of a full standing robot walking up stairs with the ankle above the controller board,

don't ask me how it could balance but it would look awsome if it could work.

 

 

Very cool. I love the simplicity. 
Super simple! It should be a manual for beginners.

awsome!!!

Love it. Great and simple. 

 

what's the next step (pun intended)?

That is amazing, very cool idea! Pretty fascinating to watch it work!

Hi!

And now, I will show you the first ride (without sensors)
Interesting. Do you have any video yet?
Not yet. I am still waiting for my servos (4 x Tower Pro Servo MG946R with Stall torque 12kg/cm).