Team 8176 2012 GATEWAY Robot Reveal

VEX V5 General Discussion VEX Robot Showcase
1

2012 GATEWAY Team 8176 Robot Reveal

  1. Introduction

  2. Feature

  3. Structure

  4. Code

  5. Latent issue

  6. Contact

  7. Introduction

Team: 8176, Nanjing JinLing High School
Robot is capable of scoring 4 objects in maximum less than two second and scoring high, middle and low goal with no obstacle. Robot could score 23 points in driver skill challenge. Besides, a 28-points-strategy has worked out and workable. Chassis is powered by four 269-motors and accelerated by 15:12 drive-train, which makes chassis straight move speed very fast. A four 393-motors arm, geared at 1:7, could lift to top goal position (more than 76cm) from bottom within 2 seconds. “Roller in-taker”, which is constituted by eight intake rollers, can take objects in a row less than 500 milliseconds each. This smashing performance makes the most efficient robot in China national qualifying match, and the second-best robot in College competition (if we could participate).

Practice video:

Qualifying match video (our alliance mate was absent, therefore we have to face two adversaries. final score was 19:23, red alliance wins.)

http://www.youtube.com/watch?v=EIci77SNDlo

  1. Feature

  2. Ability of scoring all goals.

  3. Capacity of 4 objects.

  4. Fast six-bar arm.

  5. Swift chassis.

  6. Low CoG.

  7. Structure

    Chassis: four 269-motor drive-train, rate at 15:12 using high-strength chain.

Arm: four 393-motor @ normal speed, rate at 1:7 (12:36:12:84, motor mounted at 12-tooth gears). Old 84-tooth and 36-tooth gears are one-side-sanded and spliced together that makes the force transmission more stable than using one piece only. Using six-bar linkage (inspired by AURA’s robot @ VRC 2011 World Championship (Round-up)[LINK]). Two slotted angles used for coordinating two sides. Elastics, mounted at the rear of arm, are used for providing extra force to pull the arm up when lifting from bottom and NOT pulling arm down when lifted. It is highly recommended for mounting two elastics each side. Generally, elastics would not rupture in this circumstance.


Roller in-taker: inspired by Team 3018’s robot in VRC 2010-2011 (round-up). Eight intake rollers are placed on four sides and two rollers each. Four bevel gears are used for connecting two sides in order to ensure that rollers on all sides can run at the same speed, which let objects taken smoothly. The object container is made up of aluminum material, thus the container can be very light that results in lower CoG when lifted at high goal position, which could makes the robot more UNLIKELY fall off.

The most peculiar ablity is, any object can be picked up if it has been half an object higher than the goal post (or any ball at any height that allowed to pick out). it can also score the opposite mid goal from isolation zone. (even putting on black barrel when the opposite mid goal is full)

Special attachments

1.	Battery holder: a 5x5 C-Channel part cut from 1x5x1x25 C-Channel mounted on Cortex Microcontroller by two pairs of screw and nut, which can hold two batteries in a C-shaped groove that contains two batteries luckily. 


2.	Anti-Falling Stick: a stick combines with two 1x25 bars connected by several standoffs, nuts and screws that strengthen it. When robot is, unfortunately, falls off, this stick can brace the arm motor tower. Therefore, chassis can move backward and robot would get back to normal position. The stick is mounted at two pivot gussets that mounted at the motor tower beam. When driving normally, this stick would NEVER hinder any action.

  1. Code

https://vexforum.com/local_links.php?action=jump&catid=26&id=214

1.	Six bumper switches are used for choosing autonomous steps. Three steps included in final v3.1 code.
2.	Driver control has been coded that five hotkeys are available:

Key map:

5U: manual arm lift
5D: manual arm drop
6U: roller in-taker takes in
6D: roller in-taker takes out
7U: arm automatically move to high goal position
7L: arm automatically move to mid goal position
7D: arm automatically move to low goal position
7R: arm automatically move to goal picking position
8R: all motor stall

  1. Latent issue

    1. Chassis 269-motors may halt because of overload protection, however, chassis speed would drop significantly (approximately 20%) if changing motors into 3-wire motors.

    2. Overthrown barrels may stuck when taking in (but there is no problem of letting them out) if they are in a “crossed position”[image] when being picked.

[Photo and Video Storage | Photobucket ( objects could not be picked in this position.)

  1. Contact

Team 8176:
Address:
Jinling High school, No.169 Zhongshan Road, Nanjing, Jiangsu, province, China.
Zip code: 210005
MSN: [email protected] / [email protected]](Photo and Video Storage | Photobucket ( objects could not be picked in this position.))

2

Excellent robot (for first season)
Excellent reveal post (from a Chinese team!)
(+rep just for all that!)

a few questions about the robot:
did you robot EVER tip? (forward or backwards)
how heavy is your robot?
can you push any other robots out of the way?
did it win any awards? :slight_smile:

Great robot overall and im excited to see this robot preform in second season!

3

Glad to see other countries participating in the forums! (besides NZ…)

You mention the failure of some parts… Could you be a bit more specific? Maybe exactly what parts fail, and how they fail? VEX isn’t perfect, and even the brand-new parts I got at Worlds had a few issues…

The robot looks great, especially for this early in the game. It’s encouraging for the rest of the teams to see what is and isn’t working.

Thanks for sharing!

4

Your robot is extremely well built, and driven really well. You have clearly put a lot of work into this robot, and it is amazing for this early in the year. When I first watched the Youtube video I was thinking to myself that this was going to be the winning design. But, then I watched it again…

In the video, your robot doesn’t pick up any cylinders when they are on their side, and the intake seems too inflexible to allow for this one inch change in dimension along one axis. Even if it could pick up cylinders with only four intake rollers contacting the cylinder, it would take a bit of time to line up the square intake with the rectangular top profile of the cylinder. Now, maybe you are actually able to pick up sideways cylinders quickly, but this video makes me think otherwise.

Anyways, thats just me being extremely critical. Your robot is still obviously very good (especially for the isolation zone and skills challenges) for this time of year, and you have a lot of time to work on finding improvements. I am very happy to see a Chinese team participating on the forum, and I hope to read your perspectives on other topics as well.

–Tsauce32

5

wow, this is nearly exactly the same robot i am going to make! same motors and everything, just different looking chassis, and motor speed. also my intake looks alittle bit different. over all greeat design i have to say!

6

Kinda on the same topic, how easy is it for you to pick up the balls/ barrels off the field? By the looks of your intake system I’d assume that picking up off the field is not a strength compared to the conveyor design yet from this video you seem to be doing so quite well.

7

yes, our robot may tip both forward or backward ONLY when lifted to high goal position AND driving drastically. In all other cases it would NEVER tip or be knocked down by other robots.

less than five kilograms without two batteries.

yes it can push or block other robots. Moreover, in one qualifying match our robot knocked out a ball carried by a claw robot when it was trying to score the low goal in our side in interaction zone.

No, we have only entered the finalist in national qualifying match and that was finished yesterday. Have to say that matches in china, even in Hongkong, Taiwan or other regions that “under the charge of” Chinese vex robotics committee, are “tangles” and makes us feel that matches are “black case operated” by them. Hope I could make you understand what it means.

8

As everyone else has said, thats a great robot. :slight_smile: Especially so early in the season. And I have one question, is the roller intake the only part of your robot thats aluminum?

9

four 269-motor mounted on chassis may fail wile driving or after dumping objects,even rotating chassis. An experienced teacher from a certain school in china told me that it may due to the “overload protection” of motor 269. when current increasing dramatically in a short time, maybe less than one second, controller may “think” that motor has been overloaded and motor must stall in order to prevent burning motor. even if the real situation is not the same at all. two motors one the right side of chassis usually fail after driving for more than five minutes but motor on the other side failed only once after being built. However, even if we exchanging motors one both aides, motor on the right side still fail I’m the same situation. we suppose that it may due to the terrible quality of 7.2V batteries we bought from vex agent in china. Reason is that after plugging on batteries sold in the US or Canada that we borrowed from other teams, there was no motor failure any more.

10

maybe something is wrong with our right drive train?
maybe there is a bent shaft?
or too many spacers that cause more friction then the left?
im pretty sure those are the reasons

11

thanks for your suggestions but we have checked all four shaft in the right side drive-train and replaced them with new ones. I am 100 precent sure that there is almost no friction between two mounting plate. bearings are all replaced to make sure the holes for shafts are all polished. we had added some lubricating oil on joints to reduce friction. we have tried those solutions whereas it makes no difference, and that troubles me up to now.

12

I know there’s going to be a lot of haters saying this robot can only hold 5 objects? This robot looks slow… This robot only won by 4 points… sad. But im telling you right now this is the best robot that i have seen for this game so far with my own eyes. I mean my teams robot hasn’t been built yet, but regardless this is probly the best robot online as of today. :smiley:

13

that’s true. before using this “roller in-taker” mechanism, I doubted that whether it would be more efficient than the goal taking method of 24C’s robot or the pneumatic claw 1103 made. then i was shocked by our own robot. with good manipulating skill, this robot could be “omnipotent” – whatever it is in isolation zone or interaction zone, it would be really not easy to find another robot matches it.

besides, too large capacity makes no sense and could only lead to lower efficiency. sorry for saying too absolutely, and it may make you feel offended, but capacity of four objects should be an optimized choice.

14

critical comments are always appreciated as it could, straightforwardly, let us find out where the trouble is. many thanks again.
sorry that I didn’t explain the goal picking method and made you misunderstand. the first I have to say is, robot has no need to orientate correctly towards the objects. when contacting with objects, rollers in four dimensions will sweep it to the centre of the square. also, picking objects, in common situation, don’t need any extra force to push them into the container. gravity and force from rollers in four direction will get them in. even if picking objects do need extra force, there is a hotkey (5D+5U, press 5D first) that makes arm drop at the fast speed and with the largest force (set motor @ 127).

15

I like your chain/wheels/motors arrangement: motor-wheel-motor-wheel
My other idea is face-to-face motors: wheel -idler - motor:motor - wheel - idler

Chassis text description should include “With 4x4” omniwheels".

Chain outside of wheels → narrower wheel base:
Consequences:

  • faster to turn
  • harder to turn
  • more likely to overheat motors when turning
  • also more likely to tip over sideways

Why choose chain outside vs chain inside?

16

thanks for your tips. i’ll add it soon.

I am not sure whether chain outside would cause motor overheating, and changes in turning, compared to chain inside. but anyway, it may be impossible to tip over sideway. at least, I haven’t seen that yet. it may only fall when lifted to high goal position due to force of inertia or being pushed by other robot.

it should be fine with motor:motor arrangement, but may be not suitable for this one. there is not much space available in chassis, and that’s why we mount motors in T-shape.

outer chain may be the cause of chassis halting, although motors still feel cool when they fail. I will change them inside to see what is going to happen.

17

well…in fact this robot is all-aluminum-made (except two slotted angles and several 1x5 bars) and that is why this robot could be less than 12lbs (without batteries).

admittedly, this “pile-hammer” object picking mechanism may not be as efficient as conveyor when picking objects, but it is certain that the object dumping speed is much beyond conveyors. never disdain the power of gravity. i mean that a conveyors is the best solution for picking objects, but what about dumping them then? conveyors have to pull the object they picked before in order to get another one, and when dumping them, the dumping speed is ONLY determined on how fast the conveyor is. I am sure you could grasp the difference between hauling an object and letting it perform a free fall.

As another aspect, this year’s game Gateway, is putting emphasis on strategy than all the past games. it may be more important for us to making out feasible plans or schemes to win. I was really impressed when seeing two robots from No.80 High School of Beijing that even though they adopted conveyor design, the arm could rise to the high-goal-dumping position in less than half a second.

However, that might miss a critical advantage, the ability of match-controlling. it could be a trouble for conveyors to push, or take away doubler or negation barrels. our robot could not pick objects as fast as conveyors with no doubt, but it is extremely easy for us to pick out bonus barrels if it is legal to do so. once in practice, I attempted to pick out one negation barrel on my own goal and one doubler on the opponent’s, and re-dump that negation on that goal, and succeed.

18

here in this video, left side of the chassis failed in the end. (we changed them to the right side after recording and these two motors failed as well)

19

Are the goals on your field official goals or did you make them yourselves? The reason I ask is because the goal rings are gray and not black.

20

yes but not exactly. the wall is made by ourselves and other things like goals, gates, fence and objects, are purchased from the vex agent in china. here is the link:

http://www.bds-tech.com/vex_new_46.php

what included in their kit are only those five things I’ve mentioned and nothing more. moreover, almost all the products they sell are not the same as that you could buy in america or europe, but from their own factories, which are really rough-made. I am confused that how the only official agent of vex in china could do that – selling products at the same price, or even twice or more, and product quality is much worse.