Which is better for picking up sections claw or passive?
Really depends on your design. In general, passive is (usually) easier to build and doesn’t use motors or pneumatics, but a claw (or other active system) is easier to use and faster. This is just a generalization, and both have many advantages and disadvantages depending on how they work. Experiment around a bit and see what works.
What about for a bar lift?
If you are talking just about what is actually gripping the skyrise section, it’s performance is nearly independent from what kind of lift you are using. If you have the option though, a pneumatic or motor activated skyrise grabber will be faster and you will have more control. In my opinion, passive should only be used in this case if you don’t have pneumatics or motors to spare.
A Passive claw, with a servo that pulls a string that opens the intake if needed.
I have an eight bar massive robot that only uses 5 motors one on a anti slip mat claw any suggestions
Wait, really? If you are using 1 for a claw, does that mean you have 2 on drive and 2 on the lift? If that works, that is really impressive, but you might want to add more motors to the drive and lift. You are given 10, so I would use all 10.
I think he is referring to 5 motors for the lift/intake. My guess is that one for the claw, and 4 for the lift. The drive is irrelevant to the conversation so I think he wasn’t counting those.
No, five over all one the claw, two on drive, and two on arm. Also the lift gets five feet
As far as the claw vs. passive intake goes, I believe the cost-benefit analysis for both suggests that a passive intake is superior.
Claws have the advantage of being controllable during the match, and they are easily constructed, especially if you have a pre-built Vex claw. However, claws use motors to operate, and this is where they become costly. If that motor can be used on another system (the lift, the drive, anything that can offer strategic advantage) it should be. (This also applies to pneumatic pistons, especially now that there is a limit on how many tanks can be used)
In “Gateway”, the B-Team at my high school built the lift and intake with as few motors as possible while ensuring that the lift was still effective (this was an NZ style bot, popular that year). They had two motors left over, which they used to expand two 18" arms out of the sides of their robot in order to incorporate some defensive strategy into the mix. They could block off entire zones in Gateway while still being mainly focused on offense. This worked extremely well, especially in the last 30 seconds, when defending against the negation barrel was important.
So, NOW THAT MY TANGENT IS OVER, I have to say that a quick listing of the costs and benefits of a passive intake show that it is a better option. Even though it involves more precision and can be time consuming to construct effectively, a passive intake does not use motors to operate, and thus is (theoretically) easier for the driver to operate during a match. It also offers the chance to use those motors elsewhere.
This is much like a design choice made on 1103’s robot from “Round Up.” While many teams used active mechanisms to hang on the ladder, 1103’s machine had a passive hook that attached to the side of the ladder. This allowed the motors that would otherwise be used in a latch mechanism to be allocated elsewhere. As it turns out, 1103 had a four motor high speed drive and a six motor lift (and pneumatic claw), a combination that was quite effective.
Well, my team went with a basic passive intake for our robot in our first competition. It worked well, aside from the fact that it would get stuck in some skyrise sections and worked well in others. Curse you tolerances. :o