pic: Team 610's 2011 robot design
 

Re: pic: Team 610's 2011 robot design
 

I'm confused by the placement of the gas spring. Wouldn't the gas spring be pushing the arm into the ground, increasing the load?

Re: pic: Team 610's 2011 robot design
 

if i remember correctly that is a pneumatic cylinder to aid in lifting.

Re: pic: Team 610's 2011 robot design
 

can you post a link to the CAD File :P

Thanks

Re: pic: Team 610's 2011 robot design
 

Re: pic: Team 610's 2011 robot design
 

The gas spring probably pulls inwards rather than pushing outwards, in which case it would make sense because it will be tugging the lever-arm on the other side of the pivot down, making the manipulator rise.

Re: pic: Team 610's 2011 robot design
 

If the electrical/pneumatics side of the team was as diligent about CAD, it would be a lot more clear.

There is pressurized air supplied to only one side of that pneumatic cylinder, such that it is constantly pulling downwards. We had that air supply regulated to about 40 PSI, and it perfectly counterbalanced the arm uniformly through its entire length of travel, on both sides of the robot.

Unfortunately, whenever we ran the arm downwards, the air in the cylinder would compress, and the regulator would bleed excess pressure. While this was desired for both safety and uniform counterbalancing reasons, it used up a lot of the air whenever we moved our arm downward.

We ended up replacing the setup with a few loops of surgical tubing.

Re: pic: Team 610's 2011 robot design
 

The reason for using an air cylinder instead of a gas spring was because we wanted the arm to swing both ways to pick up on either side of the robot. Most gas springs push instead of pull, and putting one underneath the arm would have caused interference with the arm pivot, limiting the range to less than 180 degrees. Pulling from the back end of the arm allows the cylinder to swing underneath the pivot and then serve to balance the arm when it is facing the other direction.
I have since learned from an 1114 mentor that "pull" gas springs are readily available. Good to know.