Purdue SIGBots Wiki Development Update 2/20/21 (New Articles, More Progress)

Dear VEX Community -

Today we released another medium sized update to the Wiki. This includes:

  • The Double Reverse 4-Bar Article has been re-vamped! Check it out in one of the links below!
  • Optical Sensor Article Released
  • Distance Sensor Article Released
  • Various bug fixes, related to the naming of certain files internally.

Content requests:

  • Images, videos, and CADs of shooters.
  • We now need images of scissor lifts, 5 wide bracing, and other “good lift building” techniques.

Please, we would like feedback to all the articles (especially the revamped Double Reverse 4-Bar article).
Link to articles:
Double Reverse 4-Bar Article
Distance Sensor
Optical Sensor

We thank you for your support, and are still actively looking for people to help out with the Wiki!

  • The Purdue SIGBots Wiki Development Team
25 Likes

Double reverse four bar lifts keep the weight of a load centered over the base of the robot instead of lifting it up in front of the robot. This helps prevent the robot from tipping over. The double reverse four bar lift has a significant height advantage over a four bar lift without the lifting the load in front of the robot.

This is really a niche thing, but this paragraph could also include the fact that the center of mass of the lift itself shifts forward relative to its starting position. In other words, as the lift goes up, the robot becomes increasingly unstable despite the load moving completely vertical. This is because the midsection of the lift moves towards the load due to the geometry of the DR4B. To combat this, you can power the DR4B from the bottom 4 bar –– lightening the weight of the midsection.

I’m not sure if I’m just misreading this paragraph or if it’s mentioned elsewhere. I just think this distinction should be explicitly stated.

By the way, I think you guys did a fantastic job on this wiki post. It’s very clear and informative.

10 Likes

Depending on the configuration, even rearwards then forwards too. (Not to negate what your saying, merely adding onto it)

3 Likes

Feedback recieved, we will be making modifications soon!

6 Likes

Yeah that is probably something I should mention. Thanks for the feedback and I’ll probably add it next update.

2 Likes

Can you add the existence of the DR8B to the list of weird varieties? We’ve prototyped one for the memes but didn’t get a good enough version to take a picture.

image
Thanks for the suggestion, but I believe we already have an example of this in the last section that talks about how the DR4B design isn’t completely restricted to 4-bars and can be a combination of different lifts.

10 Likes

Yeah, I’d just assumed you’d want to cover as many types as possible.

Double reverse -4 bar