how to lift vertically with gas assist cylynders?

we have an overhead canopy that need to be lifted 3 feet into the air, and then let down to its origianal position at the end of the day.  it now goe's up and down with a smaller tube within a larger tube and pins put in position to hold it at the right height.  the size of the canopy is 4' x 12' and weighs approximately 150 lbs, as the supports are made from aluminum.  As we are not getting any younger it is taking its toll putting it up and down manually.  If there any way that we could re
place the smaller inner tube with some type of gas assist cylynder that would take it up and down mechanically?  Imagine having to lift a box .,and then down again straight up and down.  Any replies would be appreciated. Thank you. JOJO

I think you want a "gas spring", the kind of thing that lifts the tailgate of a car. They're available from folks like Mcmaster-Carr

Seconded. If the cylinder moves inside another then a gas shock is ideal. They come in various lengths and strengths. Just pick one up that compresses to the full closed size, and opens to beyond the full open size, and has a force approximately equal to the weight of the load. Without a lot of math you'll still need to use the latches that held the canopy in place -- just most of the weight will take care of itself.