pic: Madtown Marauders DT of DOOM-2

[artdutra04]

Unless you are using two sets of chains, as the front module goes up and down, the center to center distance between the center wheel axle and the front axle will change. If a single section of chain is used, then this will create tensioning nightmares (sans dynamic tensioning system), as well as issues with clearance heights (if the front dips down, the chain will probably hit the corner of the ramp).

A much simpler solution would be to make the pivot axle concentric with the center axle of the drive train and use a single loop of roller chain.

Also, by using an active system to adjust the angle of the front pivot module, this adds a lot of complexity, and slows down the response time of the system (as it has to sense->think->respond). The robot must get to the ramp, "know" the ramp exists, change the front pivot angle, and then proceed up the ramp.

Compared to a well designed rigid frame robot (with a low and centered center of gravity), which can just gun it up the ramp without any necessary change in the state of the machine, an active flexible frame might actually slow down the performance of the system.

[Akash Rastogi]

Sorry folks, pictures got posted twice for some reason. Could a mod please delete the 3 extras that don't have writing? Thanks.

[R.C.]

Originally Posted by artdutra04

Unless you are using two sets of chains, as the front module goes up and down, the center to center distance between the center wheel axle and the front axle will change. If a single section of chain is used, then this will create tensioning nightmares (sans dynamic tensioning system), as well as issues with clearance heights (if the front dips down, the chain will probably hit the corner of the ramp).

A much simpler solution would be to make the pivot axle concentric with the center axle of the drive train and use a single loop of roller chain.

Also, by using an active system to adjust the angle of the front pivot module, this adds a lot of complexity, and slows down the response time of the system (as it has to sense->think->respond). The robot must get to the ramp, "know" the ramp exists, change the front pivot angle, and then proceed up the ramp.

Compared to a well designed rigid frame robot (with a low and centered center of gravity), which can just gun it up the ramp without any necessary change in the state of the machine, an active flexible frame might actually slow down the performance of the system.

Art, great comments. What we were thinking: since the new camera came out and if there is a light above the ramp. That we could have the robot sense on its own and start lifting before it hits the ramp or it could be driver activated and then the encoders could tell whether it is up or down the ramp.

BTW, we as a team are going to be heavily depending on sensors this year. A lot of our crazy offseason ideas depend on them. The reason for not making it coecentric with the middle is because it has an adjustable drop. There will be two sets of chain running to the front.

As for a rigid frame, the reason we did this was because we had a solid DT at nationals for the past few years. We could previously climb ramps easily. The problem we noticed was that while climbing the ramp was that on four of our wheels were in contact. The front and the back and noticed that a couple of our regional matches, we tipped right there. With this DT, at any point we will have all 6 wheels in contact with the ramp and our cg will be closer to the front. The next point where a rigid drive can tip is when you are climbing and the middle wheel hits the top of the ramp. Through some of the older vids, I saw this was also a point in which bots tipped. So this is why this DT flexes both ways. Hope that answeres a lot of questions.

[R.C.]

http://video.google.com/videoplay?do...49860332436870

Vid shows what I mean! Pretty funny vid!

[AustinSchuh]

Here is some food for thought.

You might be able to use a piston instead of the gas spring, or in addition to the gas spring, so you can use that to raise/lower the front. Although I have never done it, I imagine that you could find some clever use of solenoids to be able to switch the pressure levels you are putting into the piston, or something like that to gain a bit more control. Or use 2 pistons, or some variation of that.

[NickE]

Originally Posted by AustinSchuh

Although I have never done it, I imagine that you could find some clever use of solenoids to be able to switch the pressure levels you are putting into the piston, or something like that to gain a bit more control. Or use 2 pistons, or some variation of that.

Here's one of the numerous threads about this.

We used a center-closing solenoid this past year to control our roller claw arm. However, it was purely to allow the robot to fit within the box, and was programmed to act as a normal double solenoid during the remainder of the match.

[Akash Rastogi]

Originally Posted by AustinSchuh

Here is some food for thought.

You might be able to use a piston instead of the gas spring, or in addition to the gas spring, so you can use that to raise/lower the front. Although I have never done it, I imagine that you could find some clever use of solenoids to be able to switch the pressure levels you are putting into the piston, or something like that to gain a bit more control. Or use 2 pistons, or some variation of that.

Read the previous post I made about why pneumatics are not being implemented.

[Akash Rastogi]

Due to a lot of feedback about this design that RC and I received and reviewed, we have decided to create a mailing list for anyone who wants updates on our design progress up until and during build season.

This is not to keep it a secret but to have teams that want to use this design, work and branch off of this base design and create their own iterations. There will be no further posts on CD but we may still have questions that we'd love to have everyone's input on.

If you would like to be added to our mailing list and receive updates and pics between RC and I, please email me at lilstogi@yahoo.com with subject as "DT Design List" Again, this is not to exclude any teams, if you wish to see our design updates join the mailing list.

Thank you so much for everyone who gave us feedback either on here or through PM's. It really means a lot to get suggestions and comments from such insanely awesome mentors and designers who we look up to. Also to those whose ideas we didn't use, we did not disregard them and I want to make that clear. We discussed all changes together and with a few other mentors from various teams. No design was shoved out the window.

[Akash Rastogi]

Lol awwww man....I wish we had finished this design.....and if those bumper rules didn't exist.....