Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: airman00 on September 17, 2008, 03:38:54 PM

Title: Pneumatics or Motors
Post by: airman00 on September 17, 2008, 03:38:54 PM

I am still designing the giant bipedal robot of mine and was wondering whether or not to go with motors and use the BRAT biped design ( I'd use giant wheelchair motors)
(http://www.trossenrobotics.com/store/p/Controls/i/is.aspx?path=/images/Pimages/RK-WLK-BI-BRAT.jpg)

or using pneumatics

I want this thing to be able to walk , and it wlll be pretty large

So which to use , pneumatics or DC motors?

,Eric

Title: Re: Pneumatics or Motors
Post by: Ro-Bot-X on September 17, 2008, 06:33:31 PM

DC motors.

Pneumatics are noisy, at least the air compressor and if you PWM the electrical valves it will make you wear headphones. I was in Italy at a contest in 2006 and I saw a guy that built pneumatic legs with the same degrees of freedom as human legs. When they were moving you couldn't stay near because of the prrr-prrr noise coming from the PWM-ed electrical valves... As a funny note, the next day I showed him my version built on the spot with Lego pneumatics, much more silent since I could not use PWM for the mechanical valves... He was knocked over, never knew Lego makes pneumatics and that anyone could build the legs that fast (all it takes is to have lots of Lego parts)!

Title: Re: Pneumatics or Motors
Post by: Trumpkin on September 17, 2008, 07:29:55 PM

DC motors :P. I think it would be less expensive.

Title: Re: Pneumatics or Motors
Post by: Admin on September 19, 2008, 08:38:11 AM

Pneumatics are overrated ;D

You should add a hip joint so it doesn't wobble a lot when it walks. Got any new vids of it?

Title: Re: Pneumatics or Motors
Post by: jamort on October 27, 2008, 05:34:39 PM

could you add springs to reduce wobble... and yeah i know how un normal it is to use springs

Title: Re: Pneumatics or Motors
Post by: jamort on October 28, 2008, 12:58:45 PM

Let me elaborate on that a bit more... have motors and springs attatched i think would counter nthe weight or you could have motors on the feet and than mtors say were the hips would be and say the left leg go forward just a little bit then the left foot motor could turn to make the foot flat
But i'm not 100%  sure but I am sure that it is hard to get a robot to walk with two feet because of the processes that it takes humans I guess best advice would be... Is it esier to walk with your legs bending or completely straight?

Title: Re: Pneumatics or Motors
Post by: gamefreak on October 29, 2008, 07:11:24 AM

Out of curiosity what about air muscles? or using two way pneumatic pistons and putting air in both sides, although I hear its hard to precisly control them that way....