The two ideas I personally find best for the lift are linear elevator lift (like 1103) or a double reverse 4-bar.
double reverse four bar benefits: the 2 arms are on the left and right sides of the bot, leaving space for cubes in the middle, hopefully about 6.
double reverse four bar downsides: with big heavy robots this year, pneumatics will be useful to take the strain off the electric motors (add needed power), but this design (roller intakes) wouldn’t use them.
(The same goes for scissor lifts, I guess )
Elevator lift benefits: I could use a pneumatic needle intake, allowing for more motors elsewhere.
Elevator lift downsides: less payload capacity, with a design similar to 1103’s. (If I moved the towers away from the robot’s center, it would not turn as well.)
-I have already made a reliable elevator lift that can lift enough weight.
Questions : -weight? -how could I use pneumatics for the double reverse four bar?
I know people wont like me linking this again, but in this situation, i’m not trying to promote the idea or name. (I might not even use it).
Look at https://vexforum.com/showpost.php?p=357558&postcount=67 and put the pneumatics where I put the rubber bands. The pneumatics will pull just like the rubber bands if you use dual acting with tubing/power/air on only the retract side(leave the other open because you should not need a pneumatic assist to go down, just up). then you can use a single acting solenoid to conserve air, or use the other air line for something else, I dont know what.( a claw???)
I personally prefer the scissor lift to the elevator lift, mostly because we can distribute the weight of our manipulator across the entire bot, and have better control over our COG. Some issues are that, unless done right, however, the lift could be really unstable or have too much friction if not spaced out enough. Plus, the C-channel can get pricey, especially if you have to cut the parts specifically for the lift.
A well-made scissor lift will always have more friction and weight than a well-made reverse double 4-bar that reaches the same height, as the scissor lift must use sliders on both the top and the bottom, and the bottom sliders will be bearing the weight of the entire scissor lift. Sliders bearing that much load on them tend to have a great deal of friction.
A reverse double 4 bar is prone to have some slop in between the 2 stages, especially if you use gears to connect them, but this can be reduced by using metal linkages to connect the stages, or by powering the lift in the middle.
I totally agree. Each joint of a scissor lift adds up the friction, which is one thing annoying about scissors.
Despite this, i know i want a hollowed lift in order for designers to fit cubes in the middle. I know that i want the lift to be thin enough so that i have no space issues, more like less than 2 inch each side. I know i want to intake and hold 5 cubes at a time so i need space for rollers. Due to these reasons i do prefer scissors. Just my needs when it comes to lift choice~