2017-01-20
Will Hobbs11:54 AM

@Will Hobbs has joined the channel

Will Hobbs11:54 AM

@Will Hobbs set the channel purpose: To discuss all things climbing

Bo Baird11:55 AM

@Bo Baird has joined the channel

Alex Larson Freeman11:55 AM

@Alex Larson Freeman has joined the channel

Chris Rininger11:55 AM

@Chris Rininger has joined the channel

Clio Batali11:55 AM

@Clio Batali has joined the channel

Enrique Chee11:55 AM

@Enrique Chee has joined the channel

Jon Coonan11:55 AM

@Jon Coonan has joined the channel

Timo Lahtinen12:57 PM

@Timo Lahtinen has joined the channel

Jack Stratton4:14 PM

@Jack Stratton has joined the channel

Kenneth Wiersema9:26 PM

@Kenneth Wiersema has joined the channel

Chris Rininger9:43 PM

Maybe we can crowd source some analysis of the climber. A good first step may be to break the overall problem into small sequential steps and analyze each piece. I'm thinking about these steps: driving to the area of the rope, seeing the rope precisely enough to approach it for climbing, approaching the rope, manipulating/guiding the rope for connection to the robot, connecting the rope to the climbing mechanism (the hardest part possibly), spooling the first couple revolutions of rope onto the climbing mechanism, the start of the climb when part of the robot is still on the ground, the in-air climb, the end of the climb, pressing the trigger plate, stopping the robot climb while sustaining pressure on the trigger plate & without descending.

What am I missing as far as the process broken into small steps?

Enrique Chee10:51 PM

method to remove robot after game is over ?

2017-01-21

@Riyadth Al-Kazily has joined the channel

Chris Rininger12:53 PM

Trying out the new Thread feature of Slack. Copying coach's addition to the list of small sequential climber steps: Enrique Chee [10:51 PM]
method to remove robot after game is over ?

Jack Chapman7:41 PM

@Jack Chapman has joined the channel

Chris Rininger7:44 PM

Coach thought of a post-match step. How about a few pre-match steps: Prepare the rope (including backup ropes), prior to each match place the rope on the field according to the rules. Also another in-match step: pilot drops the rope when there are 30 seconds left.

Chris Rininger9:52 PM

One assertion I'd like to make about the climber is that it may be best to mount it to the chassis since it has to hold the entire robot's weight. If placed elsewhere, there will be stresses on connected joints/structures due to torque & those joints/structures may have to be overbuilt (vs. the requirements of their other purposes) as a result.

2017-01-22
Binnur Alkazily1:33 PM

@Binnur Alkazily has joined the channel

Chris Rininger5:33 PM

Another post-match step: Disconnect the rope from the field

John Sachs8:17 PM

@John Sachs has joined the channel

Chris Rininger11:30 PM

Here's a link to a collection of pictures of RI3D & FRC team climbers: https://drive.google.com/open?id=0B4PZHoaYufG1WmdMcHRiUVZfRUk

Chris Rininger11:30 PM

@Chris Rininger pinned a message to this channel.

Enrique Chee11:32 PM

Thanks !!

Enrique Chee11:38 PM

Wow , Chris .!!!
Let's get some cad folks to add climber modules to our existing cad file next week. I have ordered paracord , webbing , Velcro , and the rope from the game manual as Chris R suggested .

2017-01-23
Chris Rininger11:36 PM

OK, I moved the climber steps to a spreadsheet & added some framework for analysis. I did not fully fill this out, but I did do a few rows. Here's the Google Sheet: https://docs.google.com/spreadsheets/d/1dnWTJIN4CAGP5R1NSg4AeI0IX9QV2BJsT1ecEZcycqk/edit#gid=0

I encourage anyone interested to go to the sheet and add knowns (including rules), requirements, solution options, etc. I think if we do this pre-work it can help the team hit the ground running when there are resources available to work on the climber.

Chris Rininger11:37 PM

@Chris Rininger pinned a message to this channel.

2017-01-24
Dana Batali8:39 AM

@Dana Batali has joined the channel

Kaedric Holt9:32 AM

@Kaedric Holt has joined the channel

Jim Carr5:00 PM

@Jim Carr has joined the channel

Cruz Strom9:16 PM

@Cruz Strom has joined the channel

2017-01-27

@Conrad Weiss has joined the channel

2017-01-28
Chris Rininger10:22 PM

2017-01-29
Enrique Chee1:52 AM

Thanks !

Finn Mander9:06 AM

@Finn Mander has joined the channel

Chris Rininger10:41 AM

looked at team update 5 - some good news in my opinion - Velcro binding coating on the back of sew-on Velcro is not a disqualifier & as long as the associated knot is not more than 2" below the davit fingers a loop may be used around the davit fingers as a retaining feature... Rope must...

D. consist entirely of (except for an adhesive applied by the VENDOR as part of the normal manufacturing process for a COTS item and no longer tacky, e.g. a “binder coat”) flexible, nonmetallic fibers sewn, twisted, tied, woven, or braided together except for the last 4 in. (~10 cm) of any cut end (E) which may be whipped (with material that is flexible and non-metallic) or fused only to prevent fraying.

E. be configured such that it engages securely with the FIELD. with a Retaining Feature (RF) that does not extend more than 2 in. (~5 cm) below the DAVIT fingers.

Chris Rininger10:52 AM

With these and other clarifications, they have really made climbing doable. The most prominent field pieces are the airships - even in district matches they want the spectacle of robots ascending for takeoff! And so they're making it doable. I thought the hard part was going to be connecting the robot to the rope, but Velcro works for that. Now I think the hardest part is stopping at the top so there is sustained pressure on the plate (without burning out the motor & without breaking the dang plate). From looking at Chief Delphi, I believe over 90% of teams will attempt to climb and I believe over 50% of teams will be able to do it reliably - too many points to leave them on the table - better believe teams are investing in this. I personally view this as a must-have. Viva la escalador!

Enrique Chee11:17 AM

Good to see you are reading rules. Hope the students are . Again, I agree about having a climber but the priority is LIA right now .

Chris Rininger11:28 AM

agree... just need to reserve some volume somewhere on the robot for the climber... can't afford to achieve LIA in a way that prevents climber IMO - should be on the list of requirements for LIA

Enrique Chee11:33 AM

Please reshare with engineering channel . Thanks

Michael Nelson1:38 PM

@Michael Nelson has joined the channel

Noah Martin4:25 PM

@Noah Martin has joined the channel

Noah Martin4:25 PM

Ri3D robot with cool climber example https://www.youtube.com/watch?v=AphXNa4PqlU

Enrique Chee10:14 PM

Thanks for sharing !

2017-01-30
Enrique Chee8:40 PM

Should we get ?

Chris Rininger9:02 PM

Worth trying as an option. I like the compactness & that it already has flanges. There are still unsettled factors that could lead us to use something different, of course, but it could end up being the best choice.

Enrique Chee9:24 PM

The spool seems a bit narrow for velcro to attach to paracord/velcro . I think we need a wider spool, greater surface area.

Chris Rininger10:19 PM

Agree more surface area = easier/faster catch the rope

Chris Rininger10:20 PM

Looking at AM, depending on available space something like this might come in handy http://www.andymark.com/product-p/am-2622.htm

Chris Rininger10:20 PM

would have to adapt 3/8 to 1/2 - I assume that's doable

2017-01-31
Chris Rininger2:39 PM

I did a little math at lunch, and depending on diameter of climber cylinder I think something closer to 35:1 may be better than 70:1. If we happened to use the 3.1:1 winch we bought, then a ratio of closer to 10:1 or 12:1 would probably be better. Do we have the right gear kit(s) for the versaplanetary to support different gear ratios for different options?

2017-02-01
Tom Wiggin7:27 PM

@Tom Wiggin has joined the channel

Tom Wiggin7:27 PM

k

2017-02-02
Chris Rininger9:28 PM

Chris Rininger10:14 PM

Looking at Q&A, the premise of a knot that comes untied (like our slipknot) was discussed and not rejected - requirement is location of knot must be the same - no problem, we can mark the rope

Chris Rininger10:15 PM

Q175 Inspection Policy If Rope Is Untied Then Retied Identically
If the actions of a ROBOT result in a knot in a ROPE being untied, and the rope is then retied in the same way it originally was, would that rope have to be reinspected?
asked 18 days ago by FRC 639
ROPE
If the ROPE were re-tied in an identical manner, it would not need to be re-inspected. If there were any change in knot location, materials, etc, it would require a new inspection.

2017-02-03
Chris Rininger12:15 PM

Q152 makes it absolutely clear a slipknot or other rope-length-changing knot may be used as long as the rope is always within the specified length range. https://frc-qa.firstinspires.org/qa/152

Note that if we somehow extend the rope (pull on the slipknot) and then release it, we would be in violation. What kind of foul is that? (ie, point cost?)

Just want to also present the risks.

(and is it possible for the other team to pull on our rope to release the slip knot, resulting in a foul against us?)

Chris Rininger2:57 PM

From Q152, as long as the rope length from the retaining feature to the end is within the acceptable range (5'3" - 8'), there's no foul. The default rope is 7'2" and goes from the retaining feature to the ground, so an 8' rope would be laying on the ground for 10 inches. If we wanted to have the rope go to the ground with a slipknot in it, we'd have those 10" to incorporate into the knot. 10" would allow for over 1 1/2 revolutions around the 1 1/4 cylinder with little load, which should be enough.

We'll definitely keep looking at rules for things we've missed & anyone who sees risks, please keep them coming.

Chris Rininger3:34 PM

Rather than an untied slipknot I think it'll likely be better to do something like this... https://www.youtube.com/watch?v=zJzF1IeQQck

Won't that be two ropes tied together? Is there a rule that might prevent that?

Chris Rininger4:46 PM

9.104.D from manual: [Rope must] consist entirely of (except for an adhesive applied by the VENDOR as part of the normal manufacturing process for a COTS item and no longer tacky, e.g. a “binder coat”) flexible, non-metallic fibers sewn, twisted, tied, woven, knitted, crocheted, intertwined, or braided together except for the last 4 in. (~10 cm) of any cut end (E) which may be whipped (with material that is flexible and non-metallic) or fused only to prevent fraying.

Chris Rininger4:47 PM

2 ropes tied together can compose 1 rope is my read

Yep, it definitely says 'tied'. Cool! And I think that is a very elegant way of creating an extendable rope.

Chris Rininger5:04 PM

According to this https://frc-qa.firstinspires.org/qa/22, a rope can be composed of two or more different kinds of rope, straps, or whatever other material meets the spec - some team will surely prank this by trying to pass inspection with 17 different rope remnants tied together

2017-02-05
Chris Rininger3:32 PM

There have been so many rules clarifications and Q&A items on climbing and the team-provided ROPE in particular. I've attempted to collect everything in one place so it is easier to get a broad understanding of all the relevant rules, constraints, etc. Here it is...

Chris Rininger3:33 PM

@Chris Rininger pinned their PDF thingsclimberfromrulesqandaetc.fieldpics.pdf|All Things Climber from Rules, Q and A, etc. + field pics.pdf> to this channel.

2017-02-09
Chris Rininger7:38 AM

In the next meeting or two we will be making design decisions for the final climber. If you want to be in on that, please review the "All Things Climber" compilation of rules and Q&A above before the next meeting. There are lots of rules, nuances, clarifications, etc. on this (covered thoroughly in the above), and I would like NOT spend a lot of time educating folks on that & instead spend the time on design, build, and test.

Paul Vibrans9:23 AM

@Paul Vibrans has joined the channel

Paul Vibrans11:30 AM

I thought the gear handler was to be moved closer to the launcher to provide more space for the climber.

Dana Batali5:10 PM

see climber, plus shooter...

Is it me, or do other folks see the possibility that their climber extends out of the robot volume? (I suppose this could be a "tall" envelope, hard to tell)

Chris Rininger9:37 PM

Thanks Dana - looks pretty cool. We're thinking of using a variable length rope (i.e. it slips) to allow low-load spooling, but we're not ruling out something like what the 1598 robot has. I'm a little concerned about how much space the pivoting mechanism might require.

Chris Rininger9:39 PM

Here's a summary of the design decisions already made and still to be made for the climber. Intention is to use this to facilitate a discussion with the students and then close in on decisions so we can build the final climber. If anyone has additional options or pros/cons for the existing options, go ahead and send them my way.

Chris Rininger9:46 PM

@Chris Rininger pinned their PDF designdecisions.pdf|Climber Design Decisions.pdf> to this channel.

Chris Rininger9:46 PM

Reminder: Read the "All Things Climber" rules and Q&A summary if you want to be in on the climber design decision discussion

Enrique Chee9:53 PM

Thanks !!

Paul Vibrans10:40 PM

My review of the posted cad picture tells me the climber must be made with the motor and winch drum parallel and connected by a chain drive. There are two good choices for the drum: 1/2" pipe (0.84" OD) and 1-1/2" pipe (1.90" OD). There is one choice for the rope: 1/4" diameter. The drum axis should be angled so a perpendicular to the axis at mid length passes through the robot center of gravity. The assembly should be mounted so it can take up 5.3 inches of rope with the big drum or 2.7 inches of rope with the small drum before lifting the whole robot weight.

Paul Vibrans10:47 PM

Gear ratio for the big drum is 70:1. Gear ratio for the small drum is 35:1. The drum absolutely needs a brake for lowering. It is very easy to incorporate in the drum design. I can provide details on Sunday.

2017-02-10
Chris Rininger10:18 AM

Thanks Paul. I'm not sure that's the final CAD. As you're indicating, the final CAD will potentially eliminate some options for some of the decisions we need to make. As far as making the design decisions, the plan is to have a collaborative discussion with students, making sure nonviable options are crossed off (& explain why) and the viable options and associated pros/cons are identified. Of course, sometimes it is really a set of decisions & how they work together (e.g. combination of drum size and rope diameter), and we'll get into that as well. I will add 0.84 OD to the list of drum options. As far as gear ratio decision by option, I'd have to look at your math, the motor power curve, etc. to understand, and it would be good for the students to also see that. At least one team on Chief Delphi indicated they are having success with CIM+1.25 diameter+35:1, which would climb faster than 70:1, so again... I'd like to see your rationale. As far as the absolute need for a brake for load, I need to understand that more. If the ratchet takes the load & if teams are allowed to hold the robot, disconnect the rope, and lower the robot with the rope still around the winch I don't understand the "absolute" nature of the need.

Dana Batali10:49 AM

and one additional thing to keep in mind: the electronics haven't been considered in CAD drawings that I've seen. There was a plan to "go vertical" which I interpretted to mean to consume 4-5 inches along a side (from top to bottom). NB: This is pure speculation on my part.

Paul Vibrans12:16 PM

I have a motor spreadsheet and a design calculations spreadsheet but I am limited in my knowledge of Slack to distribute them. My computer is not connected to Slack and I want to keep it that way.

Kaedric Holt12:53 PM

Can you get the docs on to your phone?

Dana Batali12:57 PM

@Paul Vibrans : or you could email it to someone for them to post it to slack

Chris Rininger3:44 PM

Chris Rininger5:43 PM

Here's a Chief Delphi thread that covers very well rope length, various field dimensions, etc. https://www.chiefdelphi.com/forums/showthread.php?t=154450&highlight=davit+measurements

Chris Rininger9:11 PM

@Paul Vibrans: you were talking about the need for a fairlead including rollers on on or both sides. Would it make sense to ask the coach to order something we could adapt faster that custom building? Would something like this be adaptable? https://www.amazon.com/gp/aw/d/B00426L7DM/ref=mpsa131?ie=UTF8&qid=1486789565&sr=8-31&pi=ACSX236SY340QL65&keywords=fairlead+roller&dpPl=1&dpID=41YLgwr6EWL&ref=plSrch

Chris Rininger10:03 PM

@Conrad Weiss Here are instructions for the versaplanetary we need to assemble https://content.vexrobotics.com/vexpro/pdf/VersaPlanetary-v2-User-Guide-20161123.pdf

Paul Vibrans11:01 PM

The fair lead from Amazon looks way too big and heavy for our application. It is probably for a 2000 lb rated winch. It is certainly intended for wire rope. I have had second thoughts about the fair lead if we have the right shape for at least one drum flange.

2017-02-11
Chris Rininger10:32 AM

Seems like FRC 5459 (Ipswich TIGERS) agrees - here's a picture of their climber: http://imgur.com/3IrnYXR. Looks pretty heavy duty

Chris Rininger11:14 AM

Paul emailed me his calculations underlying recommendations he made yesterday - here they are

Chris Rininger11:23 AM

@Paul Vibrans - thanks for sharing that. Much more complete analysis framework than my back-of-napkin quality spreadsheet :slightlysmilingface:. Based on what I'm reading on Chief Dephi, teams using CIMs for climbing are achieving sub-5 second climbs with no issues. We'll need to prove it through testing, but I believe we'll have more current available than assumed in your calcs & be able to use a more aggressive gear ratio accordingly. I have an idea that will allow us to (mostly) use the very small diameter 550 paracord rope, which should also help. One thing you pointed out that we'll need to mitigate is the risk of the rope dragging across something & increasing load... that'd slow us down.

Paul Vibrans11:34 AM

Torque and current are directly related. RPM and current are inversely related. To use more current you will slow down. This assumes constant voltage. Everybody that is testing at this stage is probably using fully charged batteries with output voltages near 12, which gives either 20% more speed or 20% more torque. Also testing may be going on with the bumpers off.

Chris Rininger11:40 AM

I was thinking speed on the other side of the gearbox (slower motor with more torque + more aggressive gear ratio could mean faster), but I will defer to your experience. Good news is the coach acquired for the team a new versaplanetary v2 gear box with a bunch of different gear kits that will allow many different ratios between 3:1 and 70:1, so we can flexibly try some different options and make a choice.

2017-02-12
Enrique Chee10:03 AM

Chris, can you make sure someone print out the new instructions for Vex gear box before they assemble the new one. The one in our binder is for a different version from 2 years ago. Here is the link:

Enrique Chee10:04 AM

After it is printed out , we will 3 hole punch it and put in binder for reference. Thanks

Chris Rininger10:33 AM

coachchee: yes

Chris Rininger10:34 AM

Here are Paul's climber concept drawings based on his calculations + the assumption that motor and winch drum will be in parallel

Chris Rininger10:36 AM

There is some confusion in the programming team about how the code will end control of the climber when it reaches the top. We were originally under the impression that the driver would turn the motor on and off with a button on the joystick, and would observe the climb visually. When the robot reaches the top of the rope, and the light illuminates, then the driver would turn off the motor. The design I observed included a ratcheting wrench to keep the rope from unwinding.

Dana mentioned that Paul suggested using the motor to maintain position on the rope (ie, always keep some voltage on the motor after reaching the top). I'm concerned about this for a couple of reasons. The primary reason is that we don't have encoder position feedback of that motor, and therefore won't be able to control position by varying the current to the motor. Instead, we will just have to pick a voltage (percentage) and leave it applied, resulting in some forward force pushing up against the switch. This percentage will need to be fairly high to account for variable voltage drain through a match, and therefore will dump excess current into the motor that would make it hot. (If we do need this solution due to the lack of a ratchet, then please heat-sink the motor and controller.)

My second reason for concern about using the motor to hold us in position is that motor current will be cut off by the field management system at the end of the match. The system needs to not "drop" the robot to the ground. Even if the gearbox back-winds fairly slowly, the motor will be generating power as it falls, and I am concerned about what that energy might do to the motor controller.

@Adrien Chaussabel has joined the channel

Rose Bandrowski4:27 PM

@Rose Bandrowski has joined the channel

Rose Bandrowski4:28 PM

2017-02-13
Paul Vibrans8:02 PM

With the climber design we have today it won't drift down when the power is off.

Paul Vibrans8:07 PM

Someone needs to make dimensioned drawings of the climber parts by tomorrow's meeting to give to the people who make them.

Chris Rininger8:43 PM

@Bo Baird @Will Hobbs @Alex Larson Freeman @Lucas Rininger Re: the parts drawings Paul mentioned, who would you recommend? Paul gave Bo the draft CAD, and I believe they were saved in the centralized repository where everything else is located. @Paul Vibrans please note that Bo indicated there is an opportunity to make the drum longer if we want (space under the gear I think)

Alex Larson Freeman8:48 PM

I can help out with manufacturing if needed, if that's what you were wondering

Will Hobbs8:49 PM

I will do the drawing if the CAD is complete

Paul Vibrans8:54 PM

If the drum under the gear can still grab the hanging rope then more length is useful. Otherwise it is not likely to have rope wind on it.

Lucas Rininger10:42 PM

@Lucas Rininger has joined the channel

2017-02-14
Bo Baird6:05 AM

I can have the drum under the gear. It will mean making a new climber with the same components just in a different orientation.

Bo Baird6:05 AM

I am working on that now

Bo Baird6:07 AM

I will consult you guys to confirm my design but the way the things are now they will not fit and mount well into the frame.

Chris Rininger6:58 AM

Paul reminded me on Sunday that any increases to the distance between motor and drum need to be done in increments of 3/8 due to adding pitches to the chain. Also, he said the starting distance should be slightly less than the drawing indicates, also because of a need for a bit of slack in the chain.

Paul Vibrans7:13 AM

The gear can't block the dangling rope from touching the drum.

Chris Rininger7:18 AM

@Paul Vibrans: Need a guard of some kind on the chain? Seems like a good idea

Paul Vibrans8:30 AM

We need to keep the rope out of the chain. Keeping fingers out of the chain is good too.

Chris Rininger12:19 PM

I'm not positive, but I think it may be wise to add a bearing to support the 1/2 inch hex shaft coming out of the gearbox. It seems like the current configuration has the sprocket pretty far out on the shaft. If all are confident we're fine, then so am I - just wanted to raise it as a possible concern. 35:1 is the max recommended 2-stage gear ratio with simple load when driven by a CIM. I think teams commonly push the gearbox more than that without problems (though I have heard of failures).

Lucas Rininger12:55 PM

In the gearbox manual it has distances from the base of the output shaft that is recommends based on the torque on the shaft. An easy solution (I haven't seen the design) would maybe be to put a bearing mounted on something as close to the base of the output shaft as possible.

Chris Rininger1:19 PM

yep, agree that would mitigate - thanks

Chris Rininger1:21 PM

if you scroll up to Feb 12, you'll see a couple drawings in PDF files

Paul Vibrans3:05 PM

We have room to add a bearing and we have the correct bearings in inventory.

Chris Rininger11:28 PM

FYI: I probably will not be at the meeting tomorrow until 6:15.

2017-02-15
Enrique Chee12:17 AM

Thanks for letting us know.

Chris Rininger7:03 AM

As far as work on the climber, it seems like a couple things can be done in parallel: 1) manufacture parts other than the drum (because drum length may change) and the housing side plates (because distance between motor and drum may change) and 2) finalize the CAD so dimensions of those two excluded parts above are finalized & the parts can be manufactured. Part of finalizing the CAD is also adding a chain guard to prevent rope getting caught and adding a bearing to support the hex shaft coming out of the gearbox... sound right?

Paul Vibrans8:10 AM

We can make a drum if we start with the longest anticipated length. It is easy to shorten. The rope guard is not difficult to make from sheet metal or sheet plastic.

Terry Shields7:37 PM

@Terry Shields has joined the channel

Chris Rininger9:57 PM

@Bo Baird I saw that the design went back to motor and drum inline & 1/16" wall aluminum tubing with OD of 1 1/4 (same stuff as the intake rollers) as the drum. I originally bought a length of 1 1/8" oak wood dowel that will fit inside that tubing if sanded down a bit (for added strength). If the drum length is very short, then we may not need it, but if the drum length is longer then it would be easy to add the dowel inside the tube for peace of mind. The rope we're using is 550 paracord (except for a small length of derby rope at the bottom for catching the velcro), and the small diameter rope combined with relatively thin-walled tubing could potentially cause a failure. I believe the moments of greatest force may be the very ends of climbs when the climber reaches the top - could be several hundred pounds of force with the weight of the robot and the stall force from the motor. I have no intuition about how significant a risk it is. Anyway, let me know if interested in the oak dowel.

2017-02-16
Chris Rininger9:32 AM

Will there be any opportunity to do a quick and dirty mount of the final climber onto an old robot to test climbing at full robot weight? We only tested the prototype at 30-40 lbs with the knowledge from history and other teams that a CIM appropriately geared is strong enough to lift the robot, and it would be good to test the overall solution (climber + rope) at full load without putting the competition robot at risk.

Chris Rininger9:59 AM

I checked WCP's manuals again on the aluminum tubing, and it is clearly designed as an easy-to-use material for rollers rather than heavy weight bearing, though teams are obviously using it for climbers. I strongly recommend putting the sanded dowel inside the tubing - should take very little time to spin the dowel and sand it down a bit with a sander block so it can be inserted.

Paul Vibrans11:37 AM

The tube is strong enough without the dowel.

Chris Rininger1:00 PM

even if it gets a dent in it?

Paul Vibrans2:24 PM

Even with a dent

Chris Rininger2:32 PM

okey dokey :slightlysmilingface: thanks

Enrique Chee3:37 PM

can use Aries to test

2017-02-17
Chris Rininger3:29 PM

will be there around 5pm

Samantha Rosen7:24 PM

@Samantha Rosen has joined the channel

2017-02-20
Binnur Alkazily6:36 PM

First test

Jim Carr7:04 PM

Very nice!! Thanks for shooting the video and sharing!

Dana Batali11:06 PM

Dana Batali11:07 PM

(will aborted before it reached the top, so no current spike at the end, initial spike is motor-on)

Dana Batali11:09 PM

Interesting. I wonder if we should put a 30A breaker on that line, for additional safety. Looks like it would start tripping when the robot reaches the top. (I wonder if the 40A breaker was tripping...)

Paul Vibrans11:22 PM

The breakers are thermal only which means they won't trip right away at 40 amps. Typical trip curves indicate one minute delay before tripping at rated current.

Paul Vibrans11:45 PM

A close look at the motor current shows two current levels. The first is when the winch is lifting halvf the robot (and the ground is supporting the other half). The second current level is when the robot is hanging entirely from the rope. If the voltage is being limited for speed control purposes, current greater than 40 amps may not be possible. Shutting off the climber automatically at 35 amps looks like a reasonable control setting.

Chris Rininger11:54 PM

I was going to say 38, but... :grin:

2017-02-21
Chris Rininger12:00 AM

In all seriousness, thanks Dana for collecting and sharing the data, and I agree with Paul that auto stop based and current seems viable

Paul Vibrans10:36 AM

I think optimum control would be to start at a reduced speed to engage the rope then go to full speed/voltage when the current rises as the load is applied the auto shut off at 35 amps or whatever stall current is with a depleted battery.

Noah Martin12:07 PM

We can easily make it so there are two different speeds for the climber in the code

Noah Martin12:08 PM

And use the current as the change but it requires testing

Paul Vibrans1:04 PM

Yes testing is necessary.

Everything you need to know about the climber and rope system and important rules to know

I recommend making some more monkey's fist ropes as backups. We should probably assume we'll need to change the rope out between events, and maybe even one rope per day would be a good estimate. And if not monkey's fists, then maybe some other stopper at the end of the rope? (I think the monkey's fist is the cooler way to go, and maybe someone can teach others on the team how to do it.)

Enrique Chee10:42 PM

I believe Cruz is the expert on that knot. And Chris made a form for it.

Chris Rininger10:51 PM

Yes the plan is to create more ropes. I've calculated the rope needs to be 76" long from the bottom of the stopper knot to the bottom of the rope. I think we should create maybe 3 to 5 ropes.

Chris Rininger10:52 PM

Here are the rope specs to assist anyone who helps creating additional ropes. Please also review the rope rules in the pinned "All Things Climber" PDF file created a while back.

Enrique Chee11:11 PM

Thanks Chris !! Ok, whose doing this ?

2017-02-22
Chris Rininger12:38 AM

Cruz is most familiar with our rope - he could teach others if he has time

Chris Rininger12:42 AM

I also recommend we have ropes of slightly different lengths be inspected... try the 76", if a bit too long move to 75.5", etc. Of course, the slipknot loop can also be made a bit larger or smaller to fine tune the length, but I believe doing that will require rope reinspection

2017-02-27
Chris Rininger6:33 PM

I just realized meetings are early this week & I cannot attend... We currently don't have a final set of ropes. @Cruz Strom @Conrad Weiss @Samantha Rosen Since you have experience, will you please make sure there are at least 3 ropes ready for the weekend? Thanks

Chris Rininger6:33 PM

If not enough monkey's fist knots can be tied, another option is just a small bowline loop at the top that will go through the two davit fingers and then wrap around the outside of each davit finger before securing the pin.

2017-02-28
Chris Rininger8:59 PM

@Cruz Strom @Conrad Weiss @Samantha Rosen They did a stress test on the rope tonight, letting the motor continue to run for several seconds at the top of the climb putting additional strain on the rope, and the rope broke. So we need the rope at the top to be stronger to mitigate that kind of scenario. Here's what I propose: Let's do a 3-strand braid of the same paracord at the top of the rope (from the bottom of the stopper knot down 30 inches), and also let's use the new 750 paracord (in coach's room). That would practically quadruple the strength of the rope at the top of the climb compared to the single 550 paracord. Cruz, do you think it would work to tie the monkey's fist with the 3-strand braid? Might only need one knot instead of 3 nested ones. Any other ideas?

Cruz Strom9:02 PM

Do you mean make a monkey's fist out of a braided rope"

Chris Rininger9:02 PM

Yes, wondering if you think it would work

Chris Rininger9:03 PM

Or we could just use a tight loop instead of a stopper knot as I've mentioned before or some other stopper knot

Chris Rininger9:04 PM

clarification: when I say braid I mean braid the paracord

Chris Rininger9:05 PM

so there are 3 strands instead of 1

Cruz Strom9:08 PM

I will pick up the paracord tomorrow and try to work on the braid at lunch.

Cruz Strom9:11 PM

Should I cut 2 pieces of rope off and use those 2 and the main section to tie it?

Chris Rininger9:14 PM

If you have other ideas from your experience fire away - this seemed like a fairly minimal change to the overall rope design. Could also use a different stronger rope at the top, but we would need to acquire it, etc.

Cruz Strom9:35 PM

I will try the braid. I just don't want to cut the rope too long or too short.

Chris Rininger9:49 PM

Maybe we should just go with a small bowline - would be strong enough, and no problem with predicting length (just not as cool :))

Will Hobbs9:56 PM

Cruz can you tie one rope with then new 750 pound test rope and a monkeys fist for tommorow?

Will Hobbs9:57 PM

We can also try the braid with a bowline if we think it is necessary

Cruz Strom10:01 PM

I should be able to. The monkey's fist would be best and I will try to make it tomorrow.

Chris Rininger10:19 PM

Most importantly, did anybody get a video of the fall and crash?

2017-03-01
Paul Vibrans7:13 AM

Where along its length did the rope break?

Cruz Strom7:24 AM

I think that it broke at the top because they stress tested it at the top.

Chris Rininger7:26 AM

At one of the knots up top

Chris Rininger7:36 AM

One thing that would be a good idea before marking the resettable slipknot on the new rope: spend a couple minutes tweaking the rope length with the robot. Have the rope swing and the robot approach, and then determine what length best results in the rope coming to rest centered in front of the robot. Do this a few times without actually climbing. And then mark the slipknot on one of the ropes. That length becomes the baseline. In the first couple matches this weekend observe closely the same thing with the rope & robot on the actual field and adjust as needed. I have used measurements to date to determine rope length, but I think this would be better.

Kaedric Holt7:40 AM

It broke at a knot that won't be there in competition, The connection to the back up system.

Paul Vibrans7:58 AM

A knot reduces the strength of rope by half.

Paul Vibrans8:07 AM

Someone should contact NET Systems on Day Road to see what kind of Spectra rope they have that might work. They once had 12 strand braid in small sizes that was much stronger than nylon and could be spliced easily.

Paul Vibrans8:15 AM

Paracord is stretchy. Spectra is not stretchy. Paracord is better for shock loads.

Chris Rininger8:47 AM

Agree spectra is very strong but I have heard knots come untied more easily with spectra than other types of rope, so using it will mean checking knots regularly. Not a deal breaker, but something to keep in mind. If there is a local source it is worth trying.

Paul Vibrans9:09 AM

NET Systems on Bainbridge Island might donate a 1 pound spool of 1/8" inch Spectra if you ask. If John Adams in sales has not retired, he is the person to contact.

Paul Vibrans9:12 AM

I have spliced 12 strand Spectra with great success in a very high load application. It was 3/16" diameter however. I regularly loaded it to 1000 pounds.

Terry Shields11:55 AM

I am heading to NET Systems on Day Road right now (noontime). I will let the team know what I find out shortly.

Terry Shields1:13 PM

I have 4 pieces of 1/8" Spectra, each piece is 12 foot long. Donated by NET Systems. I will bring them to school this afternoon -- I'll be there by 3:30.
Paul, John Adams has retired from NET Systems. The gentleman that helped me today is Xzalivar White (yes, I spelled his first name correctly).
His only request is to send him a picture of the Spartonics robot. It would be great to also show the robot climbing on the cord.
1/8 inch Spectra comes in 600 ft. spools. Price is approx. 30 cents per ft. Luckily they had a few pieces laying around so we did not have to get involved with their production inventory.

Terry Shields1:15 PM

This is the business card for Xzalivar White at NET Systems.

Enrique Chee1:16 PM

Thanks Terry !

Clio Batali1:53 PM

Thanks, Terry! We'll be sure to get some photos/videos for him.

Paul Vibrans3:21 PM

A fid is needed for splicing. NETS may loan one or give the dimensions for Cruz to make one from rod.

2017-03-04
Paul Vibrans3:23 PM

I missed the first match. Did the robot climb?

Rose Bandrowski3:24 PM

Yes we've climbed each time (I'm pretty sure)

Chris Rininger3:28 PM

I we are 3 for 3 on climbs. There's some concern about misalignment & risk of bearings failing I heard, but I think they'll figure it out.

Paul Vibrans4:01 PM

Do you know which bearings are troubling ?

Alex Larson Freeman4:28 PM

The bearing next to the break on the Velcro drum had popped out earlier, we glued it back in with loctite red

Alex Larson Freeman4:28 PM

It was only partially out so the climber was still functional

Paul Vibrans5:18 PM

That is a brake. Your English grade just went down. Otherwise, great job. When can I expect to see a pressure of 30?

Paul Vibrans7:19 PM

What happened in that last match that the robot didn't climb?

Kaedric Holt7:32 PM

Just didn't have time, no malfunction of the climber that I know of.

Chris Rininger9:04 PM

I heard a ball got into the drivetrain causing lack of control

Kaedric Holt10:14 PM

Is that what happened? Didn't know about that.

2017-03-05
Chris Rininger12:38 AM

@Cruz Strom: I think we should switch to sewn thread to mark the reset point on the slipknot rather than sharpie because an inspector could interpret rule I-04 D to mean sharpie marks are illegal. One of the Q&A's asked if it ok to color the rope to help visibility, and the answer was no because of I-04-D. I think it is a safe play to go with thread. https://frc-qa.firstinspires.org/manual/rule/I/04 https://frc-qa.firstinspires.org/search?query=rope%20color.

Enrique Chee6:03 AM

Thanks Chris

Cruz Strom6:45 AM

I will bring a needle and thread

Chris Rininger11:35 PM

Next match, different inspector... I still think the thread slipknot mark instead of sharpie is a safe play...

Chris Rininger11:36 PM

Hey! Climber (& rope) contributors: thank you for doing the work to make it happen!

2017-03-06
Chris Rininger9:57 PM

On the topic of replace climber velcro. The stuff that is on there now is nice and "grabby" because of how it has been gnarled up in my opinion. Plus it is REALLY stuck on there from what I can tell. Maybe instead of a full replace we could measure in an inch from each end of the drum, cut with a utility knife & remove those outer bands, and then just add a fresh 1-inch band of velcro on each end of the drum.

Will Hobbs9:57 PM

That would work

Will Hobbs9:58 PM

Thanks for the idea

Chris Rininger10:03 PM

potential timesaver: if you have 1-inch masking tape just put a couple wraps of it on each end, and then use that as the guide for cutting

2017-03-09
Cruz Strom8:48 PM

I just thought of another needed fix on the climber. If we have time, in between the left side of the fold-down part of the climber and the bracket mounted to the frame, we need to put a spacer. We just need something there to hold the climber fold-out part to the right. Currently, we have a ziptie which works because there is not enough pressure to break it but it is a temporary fix and we will need something more permanent. If the ziptie breaks, the climber will slide a spacers distance to the left and after a few climbs, the bolt head on the right will wear down and the right side of the climber would come off the worn down bolt head and would put all of the weight on the motor hex. If that happens, the weight of the robot will bend the motor hex and could drop the robot.

2017-03-10
Chris Rininger11:23 AM

Good catch Cruz. Another thing I thought of on the rope. When marking the resettable slipknot with thread instead of sharpie, let's sew it loosely into the sheath of the paracord only in order to avoid creating a weak point in the rope.

Chris Rininger1:22 PM

another thought: just use another overhand knot above the loop to mark the reset point

Cruz Strom3:07 PM

That is what I was thinking about doing

Paul Vibrans9:17 PM

An overhand knot weakens the rope.

Cruz Strom10:17 PM

So we should just sew loosely.

2017-03-26
Paul Vibrans10:18 PM

I checked the existing climber design and the tapered shaft connections are in the proper orientation. The taper on the sprocket shaft is just too shallow and tightening the brake pulls the taper through the drive flange a little more each time. We need a new shaft and a new sprocket and the tapered bore of the drive flange needs to be changed to match the new shaft. I believe the sprocket is in inventory as it is the same type as on the climber motor. The bearing next to the brake will need to be changed from cylindrical bore to hex bore. I have drawings.

2017-03-27
Bo Baird6:57 AM

So when we come into the shop what should we prepare? Hex bearing, new sprocket, metal stock for new drive shaft...

Bo Baird6:57 AM

Anything else?

Paul Vibrans9:39 AM

We need to make a new shaft and remanufacture the drive flange. The old shaft can't be saved. I will bring materials on Wednesday.

Chris Rininger10:43 AM

Watching other climbers, it seems clear others are using more aggressive gear ratios to climb faster... Faster climb could mean finishing a climb in time or allowing for more time before climb for other activities. Would it be work trying at Cheney, given our decent positioning in the PNW? And then if it didn't work out could switch back to 35:1?

Lucas Rininger10:52 AM

The majority of climbers use 775 pros, which are far faster than a CIM to begin with. I've seen climbers from other teams that use 775 pros at about a 50:1 reduction, which I assume would result in a higher rpm after reduction than a CIM at 35:1. Without switching motors, I don't know how much lower we can go on our reduction

Lucas Rininger10:52 AM

Have any calculations been made to figure out the torque we need to climb?

Do we currently use a dual-speed setting for the climbing motor? A slower speed to latch on to the rope, and faster to climb? If not, we may need to implement that if we go to a faster climb rate, as it may be more difficult for the velcro to attach while the take-up spool is spinning too quickly.

Chris Rininger10:55 AM

I also think we could save a little time by making the slipknot loop smaller (maybe cut size in half) - I think we have a bit more slack via the loop than we probably need. Our original climbs with robot used a rope with a smaller loop. A couple wraps should be enough for the drum to take the load, and I think we have enough rope in the slipknot loop for more like 4 wraps.

Chris Rininger10:59 AM

@Riyadth Al-Kazily It would be good to know if we're climbing at full power - I remember testing at 80 or 90%. Folks with all these potential tweaks I'm just look for ways to cut a few seconds that could be otherwise utilized. If there is consensus it's too risk, no problem - just some ideas.

Will Hobbs11:06 AM

I agree that we should try to get a faster climb

Will Hobbs11:06 AM

I think we should try to stick with the cim but change the gear ratio

Climber software sets motor voltage to 90% by default, but it looks like it can be overridden on the smart dashboard

I see there is also a "slow" mode from a separate button that sets the motor voltage to half of the smart dashboard value (45% default for slow mode)

These values could easily be changed in the software, but I would recommend designing the hardware to use 100% for the main climb.

One thing to keep in mind is how easily we can stop when we get to the top of the rope. Faster climb means we're more likely to crash into the touch pad and break the rope (or something else).

Paul Vibrans1:44 PM

How much does the robot really weigh?

Lucas Rininger1:46 PM

~95 lbs as far as I know

Will Hobbs1:51 PM

At the last inspection we weighed somewhere between 95 and 100 pounds

With or without the battery?

Will Hobbs2:26 PM

Without

And how much does the battery weigh? Important, as we probably will be climbing with a battery :-)

Jack Chapman2:47 PM

Did that weight also include the bumpers?

Cruz Strom3:18 PM

I think that when we replace the part on the climber, we will be able to climb at the speed that we were able to before. Which means we could shoot after the ropes drop and then climb.

Cruz Strom5:02 PM

With that fact, I think that we will be fine without changing the motor or the gear ratio.

Will Hobbs5:03 PM

I would like to be able to climb faster

Will Hobbs5:03 PM

Even compared to when the climber was new

Cruz Strom5:03 PM

Good point

2017-03-28
Cruz Strom9:00 PM

If we change the motor or gear ratio, we need to make sure to be able to mount it to the same bracket or manufacture a new bracket.

Paul Vibrans9:05 PM

The gear doesn't change size, it just gets some new internals.

Chris Rininger9:27 PM

Copying Paul's message from Driving Team channel: Paul Vibrans [9:02 PM]
I reviewed my climber calculations and it looks like our time to climb can be reduced by about 2.5 seconds if we change the climber gear ratio from 35:1 to 25:1. The motor current goes up to 25A from 20A at 11 volts supply. Margin on stalling remains, particularly after the new parts are installed in the brake assembly. Is changing the gear ratio worth doing?

I'm not sure we have the gear kits for 25:1. I think we have 3:1, 4:1, 5:1, 7:1, and 10:1, but I don't think we have two 5:1. So we might need to choose from 20:1, 21:1, and 28:1.

2017-03-29
Paul Vibrans8:12 AM

Using a 21:1 gear will raise the motor current to about 30A and cause more voltage drop. Using a 28:1 gear makes no great improvement over what we have. If we can't do 25:1 I suggest going to 21:1 and if that tends to stall out or miss the rope, going to 28:1 rather than all of the way back to 35:1.

Paul Vibrans9:14 PM

I just checked the climber at 10 volts and 40 amps with a 21:1 gear. It climbs in 5.2 seconds with some torque margin, according to the calculations. I recommend changing the climber gear to 21:1 in Cheney.

2017-04-06
Cruz Strom1:10 PM

Had the climber been put back together?

Chris Rininger1:29 PM

Yes, it is performing well :+1:

Binnur Alkazily6:47 PM

@Chris Rininger then why are we not climbing? Can't tell the issue from the videos

Lucas Rininger6:57 PM

In our last match, we got stuck on the gear peg. Generally, when we don't climb we didn't have time because we were going for an objective that grants us a bonus r.p.

2017-04-13
Chris Rininger7:23 AM

Did anyone do a really close inspection of the rope? Any plan to create a fresh rope to use?

Cruz Strom7:30 AM

The last 2 ropes were starting to go out of shape and get all chunked up so we made 3 new ones for worlds. One of the last 2 is still functional and will be used for a few matches before it will be switched out.

2017-10-25
John Sachs5:40 PM

@John Sachs has left the channel

Jon Coonan5:54 PM

@Jon Coonan archived the channel