View Full Version : FRC Blogged-Kit of Parts Drive System Option
Steven Donow
25-09-2013, 10:55
http://www.usfirst.org/roboticsprograms/frc/blog-Kit-of-Parts-Drive-System-Option-2014
Please see the update below on the Kit of Parts Drive System Option from Kate and Collin, the Kit of Parts team:
For the 2013 FRC season, veteran teams had the option to opt out of receiving the Kit of Parts Drive System and instead receive a $450 Product Donation Voucher to AndyMark. Nearly 700 teams took advantage of this option. In the 2013 KOP Survey, 83% of teams who knew that it was an option said it improved the KOP experience. (Unfortunately, 10% of teams said they didn’t know it was an option. We need to work on that!)
Given the positive reception last season, the option will again be available for 2014! Veteran teams can choose to receive a Product Donation Voucher (PDV) from AndyMark instead of the KOP Drive System at Kickoff. Rookie teams will automatically receive the KOP Drive System.
The PDV will again be worth $450 and can be used on AndyMark parts. To accommodate orders and lead times, the option to opt out of the KOP Drive System for the PDV will be available ONLY from 10/3 to noon eastern on 10/17. During that time, the option to receive the PDV in place of the KOP Drive System will be found in the “What’s New” section on the right side bar of the TIMS main screen.
NOTE: If teams do not choose to opt out of the KOP Drive System in favor of the PDV by 10/17, they will be assigned the ‘default’ option of receiving the KOP Drive System as part of their Kickoff Kit.
To help you make your decision, we can give you some general information about this year’s KOP Drive System. It will look very different from those of the past and the two major variations include the following:
The C-Base is gone. In its place is a redesigned frame using sheet metal and extrusion designed to make it easier to attach superstructures to the drive base.
It is still a six-wheel belt drive robot, with an estimated final drive speed of about 10.5 feet per second. But, with the new design, we’ve changed to a direct driven center wheel powered by ToughBox Mini gearboxes.
The KOP Drive System can still be set up as a six-wheel drive “long robot”, but the redesign also now allows a six-wheel drive “wide” robot out-of-the-box. We are excited to continue to increase the competitive level of the KOP Drive System while continuing to give teams the opportunity to make the Kit of Parts as valuable as possible. We thank AndyMark and Gates Corporation for their support in creating this possibility.
Interesting to see that the new kitbot is a sheetmetal structure.
Interesting, I wonder if this is any indication on next years game.
Looks interesting though...
Akash Rastogi
25-09-2013, 11:18
Excited to see what the new kit frame looks like. Making superstructure attachment easier might make more teams want to stick to the kitbot.
Nice work AM!
AllenGregoryIV
25-09-2013, 11:30
I'm guessing the standard 12.75:1 toughbox mini with 6" wheels. That's 10.9fps unloaded and 8.83fps with standard JVN loads.
I really do wish they would give a bit more information. I always like having a KOP drive to build so my team can be trained to help rookies. If I know it was simple enough to not need it I would rather have the voucher.
Giving a direct drive system to teams is very interesting.
D.Allred
25-09-2013, 12:01
I'm guessing the standard 12.75:1 toughbox mini with 6" wheels. That's 10.9fps unloaded and 8.83fps with standard JVN loads.
10.7:1 looks like the correct option.
Anyway, I'm interested to see a sheet metal chassis that is long or wide out of the box.
AdamHeard
25-09-2013, 12:03
Interesting to see that the new kitbot is a sheetmetal structure.
Curious what they mean by this, as the KOP drive (ever since it's inception in 2005) has always been sheet metal :cool:
ttldomination
25-09-2013, 12:18
I am actually really interested to see the new design of the kitbot.
To that end, I'm wondering what will be the pricepoint for the frame and such. Is the $450 the dollar equivalent of a new kitbot?
- Sunny G.
I wonder if the direct driven wheel means we'll be getting a WCD kitbot this year. My gut tells me yes. I hope it's true, if not for the advantages of WCD then for the sheer coolness of it.
Thad House
25-09-2013, 13:10
I think even though it is a direct driven center, I think it will still be a dead axle system. I don't think FIRST would make the kit chassis not have an outer frame member because that outer member is very helpful for both mounting structure and mounting bumbers, and I dont think they want rookies having to worry about how to mount things without that outer member.
Lil' Lavery
25-09-2013, 13:24
I just hope it's revealed prior to October 3rd (or 17th at the very latest).
ttldomination
25-09-2013, 13:44
I just hope it's revealed prior to October 3rd (or 17th at the very latest).
Yeah, I'm wishing for this, but I don't think we're going to see it anytime soon.
The speculation about the game with be insane. At the very least, it would throw some hints about frame sizing and such.
- Sunny G.
Jon Stratis
25-09-2013, 13:57
Yeah, I'm wishing for this, but I don't think we're going to see it anytime soon.
The speculation about the game with be insane. At the very least, it would throw some hints about frame sizing and such.
- Sunny G.
They could reveal it without giving away any frame size hints. For example, put it together at the largest dimensions the frame possibly can go (something like 30x30), so it's ridiculously oversized for our purposes. Then just include a small note that says something like "This shows the maximum for each dimension possible with the KoP frame. This does not reflect legal robot dimensions for the 2014 season." Just about anyone who has been around for any length of time will realize that you'll have to cut a few members shorter to fit into the legal dimensions, and which members are chosen will define if you have a wide or long bot.
AllenGregoryIV
25-09-2013, 14:03
They could reveal it without giving away any frame size hints. For example, put it together at the largest dimensions the frame possibly can go (something like 30x30), so it's ridiculously oversized for our purposes. Then just include a small note that says something like "This shows the maximum for each dimension possible with the KoP frame. This does not reflect legal robot dimensions for the 2014 season." Just about anyone who has been around for any length of time will realize that you'll have to cut a few members shorter to fit into the legal dimensions, and which members are chosen will define if you have a wide or long bot.
Most recent KOP frames have been marked with a small hole for the cut line to the smaller dimension. I would assume this one would have the same feature. Posting a picture to this community would lead to us probably figuring it out. The better question is why does anyone care about releasing frame size 3 months early. For about 8 years we knew frame size and it was never an issue.
Ben Martin
25-09-2013, 14:45
We always appreciate AM's efforts, and given the information provided, there is a very good chance we'll pick the chassis option over the PDV again. Getting a frame on day 1 where we don't have to do much fabrication and every part is aligned correctly is hard to pass up. Gates' belt system is also awesome. We have ran it through 7 competitions with no issues, and we will happily use it again.
A couple requests, if Andy/others are watching, which I'm sure you all have probably considered:
1) Making the length/width ratio a little less this year in the long configuration to improve turning
2) Making the drive shaft of the center wheel hex if possible, so interfacing a VEXPro transmission is easier and the system comes together without keys.
I smell modular robot systems...
Easy attachment of "superstructures" means easy removal of superstructers.
I smell modular robot systems...
Easy attachment of "superstructures" means easy removal of superstructers.
Not if you weld, epoxy, or shrink-fit them on :)
jvriezen
25-09-2013, 16:35
I'm disappointed in the CD community. This was the first game hint. We now know that the robot rules will allow rectangular framed robots that needn't be square. Surely someone can take that information along with choices of phrasing in the blog post and make logical inferences to conclude that this year is a water game.
I'm disappointed in the CD community. This was the first game hint. We now know that the robot rules will allow rectangular framed robots that needn't be square. Surely someone can take that information along with choices of phrasing in the blog post and make logical inferences to conclude that this year is a water game.
Probably the reason for more sheet metal and extrusion instead of the c-channel is because it's now going to be easier to waterproof; instead of the old, obsolete, leaky c-channel system.
I also do want to see it before we have to make a decision. Since our machining capabilities are still uncertain, it would be nice to know what the drive was and how customizable it is, before deciding either way (I just want to put colsons and 6 cim gearboxes on it :D )
Andrew Lawrence
25-09-2013, 16:54
Curious what they mean by this, as the KOP drive (ever since it's inception in 2005) has always been sheet metal :cool:
If it ain't broke, don't fix it.
Lil' Lavery
25-09-2013, 16:54
I'm disappointed in the CD community. This was the first game hint. We now know that the robot rules will allow rectangular framed robots that needn't be square. Surely someone can take that information along with choices of phrasing in the blog post and make logical inferences to conclude that this year is a water game.
The previous kitbot frame had been referred to as being made from "c channel" as opposed to "sheet metal" like the upcoming one. Based on that, we know that things beginning with the letter c ("c channel," "carpet") are out and five letter words ("sheet," "metal," "water") are in.
Bam, water game.
CENTURION
25-09-2013, 16:55
Curious what they mean by this, as the KOP drive (ever since it's inception in 2005) has always been sheet metal :cool:
The KOP drive so far has been extruded aluminum C-channel, not sheet metal.
I have a feeling this new drivetrain is going to look eerily similar to the VexPro DIAD Chassis (www.vexrobotics.com/2013-drive-in-a-day.html)
Akash Rastogi
25-09-2013, 16:59
The KOP drive so far has been extruded aluminum C-channel, not sheet metal.
I have a feeling this new drivetrain is going to look eerily similar to the VexPro DIAD Chassis (www.vexrobotics.com/2013-drive-in-a-day.html)
Actually, Adam is correct. It is bent 5052-H32 sheet metal. Not extruded. The corner connectors are the extruded parts.
CENTURION
25-09-2013, 17:12
Actually, Adam is correct. It is bent 5052-H32 sheet metal. Not extruded. The corner connectors are the extruded parts.
Really? Interesting, I'll have to take a closer look at that C-channel next time I'm at the buildsite.
Great to hear that the kit bot is getting an upgrade - I'm very curious to see what it looks like. Hopefully it's possible to put in 2 speed gearboxes with slight modifications.
I like the C-Base frame (we've used it in some fashion for 3 straight years). But I'm excited to see improvements. In my opinion, the biggest drawbacks of C-Base are as follows:
1) Not setup for direct drive
2) Track width not maximized: wheel treads are at best about 2" from the outside of the frame perimeter
3) Limited electronics room: belly pan area too narrow / wheel channels too wide
It's fantastic to hear that this is a direct drive ready frame. On items 2 and 3, I think there's a decent chance we'll see a bit of an improvement with Corner Connect (http://www.andymark.com/product-p/am-0212.htm) presumably going away. If wheels can be 0.5" closer to the outsides and wheel channels can be 1" narrower, I'll be a pretty happy guy.
I'm guessing the standard 12.75:1 toughbox mini with 6" wheels. That's 10.9fps unloaded and 8.83fps with standard JVN loads.
For students with inquiring minds...
In the spreadsheet, the 8.83 number is calculated directly from the 10.9 number by multiplying by a "Speed Loss Constant" (default is 81%).
This constant is not computed within the spreadsheet from user-entered info about physical loads and motive forces in the drivetrain: you get the same 8.83 answer from the spreadsheet if you change the number of motors, stall torque of motors, the mass of the robot, or gearbox/drivetrain friction.
The best way to determine what value you should use for the "Speed Loss Constant" for your drivetrain is to build the drivetrain and measure its top speed, then divide that by the theoretical unloaded speed.
Perhaps they wanted to make it easier to attach superstructures because this year's superstructures will need a lot of structural support to do some heavy lifting? I'm calling stacking game.
Wild speculations about what this means about the game.
First big assumption: You can build a competitive robot using the KOP chassis as designed.
Second implied assumption 6 in wheels based on stated speed.
Third implied assumption direct drive places the gear box center line on the wheel.
So with a 3" high nano box & 6" wheels, you have 1.5" ground clearance at the center of the robot. 8" wheels give you 2.5" of ground clearance in the center of the robot.
Leads to Big assumption based on this is no big obstacles the robot has to go over.
Wheels & stated speed also implies no water game. Again. Sorry guys.
One limitation of a direct drive box is the difficulty of changing ratios.
Really? Interesting, I'll have to take a closer look at that C-channel next time I'm at the buildsite.
If you look on Andymark's web site, you find the drawing it is made from.
So it is true that it is made from sheet stock. In modeling terms & usage I think of them as more of a shape though.
In a previous lifetime I use to have I beams occasionally made from plate metal. Once they were made, people called I beams & would look at you funny if you called them plate.
Second implied assumption 6 in wheels based on stated speed.
(snip)
One limitation of a direct drive box is the difficulty of changing ratios.
It could be 6" wheels with 12.76:1 gearing or maybe 4" wheels with the 8.46:1 gearing option.
If it's 6" wheels, the gearbox options give the options of switching to 13 ft/s or 16 ft/s, at least.
It's too bad Toughboxes aren't setup with a 50:12 initial stage instead of 50:14. Then we'd also have the option of switching the first stage to 50:11 or 48:14 for a bunch more options.
Calvin Hartley
26-09-2013, 12:45
Not if you weld, epoxy, or shrink-fit them on :)
Use velcro. Bam, removable. :rolleyes:
s_forbes
26-09-2013, 13:20
Maybe AM made it easier to attach super structures because teams typically need to attach super structures? Nothing can be implied with these kit frame details other than the robots will most likely be allowed to have wheels.
We loved the kit frame last year, it's great to see some improvements are being implemented. I'm hoping the transmissions are easier to get into than they were on the previous iteration, that's what gave us the biggest setbacks.
Maybe AM made it easier to attach super structures because teams typically need to attach super structures?but...but...reality without wild suppositions is so much less convivial! ;)
This is silly. Obviously, the point is that all robots will have to be both long- and wide- simultaneously. In fact, they'll have to be entirely symmetrical, because we're landing on the field like this (http://www.youtube.com/watch?v=7G75kQm7pSE)* [/sarcastic wild supposition]
*Mars Pathfinder 40g "bounce" landing, if you don't want to click.
It could be 6" wheels with 12.76:1 gearing or maybe 4" wheels with the 8.46:1 gearing option.
If it's 6" wheels, the gearbox options give the options of switching to 13 ft/s or 16 ft/s, at least.
It's too bad Toughboxes aren't setup with a 50:12 initial stage instead of 50:14. Then we'd also have the option of switching the first stage to 50:11 or 48:14 for a bunch more options.
If its 6" wheels, with the 10.71:1 ratio configuration, JVN's calculator drops out 10.51fps as the max speed.
If its 6" wheels, with the 10.71:1 ratio configuration, JVN's calculator drops out 10.51fps as the max speed
How do you know what "Speed Loss Constant" to use?
I don't. I just assumed the 81% isn't wildly out to lunch. I'm also guessing that HQ/AM in saying "10.5fps" did some kind of calculation using commonly available tools -- likely JVN's calculator.
Does anyone know where the 81% number came from?
Does anyone know where the 81% number came from?
Two stages of gearing, each 90% efficient -- .90 * .90 = .81
Two stages of gearing, each 90% efficient -- .90 * .90 = .81
Are you sure that's not just a coincidence?
The "Speed Loss Constant" in cell I5 is independent of the gearing in cells C12 thru D15, or the Drivetrain Efficiency in cell J5.
.
If its 6" wheels, with the 10.71:1 ratio configuration, JVN's calculator drops out 10.51fps as the max speed.
Looking at the blog again, I see that they're calling that an "estimated final drive speed," so I shouldn't have been looking at maximum theoretical speeds.
As an extra piece of information, last year they said this about the 2013 kit drive:
The 2013 gearbox is a ToughBox Mini with 10.71:1 reduction. The estimated final drive speed is about 10 feet per second.
That drive had a 42:39 timing belt reduction, so the ratio was 11.53:1. If they used the 0.81 factor last year, they'd get around 9.75 ft/s, which they might have rounded up to 10 ft/s. Based on that I'd agree that they're very likely doing 6" wheels with 10.71:1 gearboxes. If not, they're estimating the speed differently this year.
This constant is not computed within the spreadsheet from user-entered info about physical loads and motive forces in the drivetrain: you get the same 8.83 answer from the spreadsheet if you change the number of motors, stall torque of motors, the mass of the robot, or gearbox/drivetrain friction
Also worth noting: in the real world, the % of "speed loss" is not constant when changing gear ratios either:
Team 1678 did some testing earlier this year on a bot with a 2-speed gearbox. The "Speed Loss Constant" was 92% in low gear and 72% in high gear.
Also worth noting: in the real world, the % of "speed loss" is not constant when changing gear ratios either:
Team 1678 did some testing earlier this year on a bot with a 2-speed gearbox. The "Speed Loss Constant" was 92% in low gear and 72% in high gear.
Ether is correct on most accounts. Keep in mind that JVN's "speed loss constant" comes after a "drivetrain efficiency" (i.e. losses from gearing), therefore the 81% number cannot be attributed to gearbox losses. The testing we did earlier this year found the overall speed loss from the theoretical free speed of the motors. The numbers we found make intuitive sense, given that motor resistance, friction, rolling resistance, and air drag all tend to increase as speed increases.
My conclusion now is the same as it was then: test your drivetrain instead of blowing smoke from your behind about the theoretical speed you think you'll get.
Keep in mind that JVN's "speed loss constant" comes after a "drivetrain efficiency" (i.e. losses from gearing), therefore the 81% number cannot be attributed to gearbox losses.
The Speed Loss Constant does not come "after" the drivetrain efficiency (at least not in the 2013 version). It is completely independent. See below:
The testing we did earlier this year found the overall speed loss from the theoretical free speed of the motors.
^^This is exactly what the "Speed Loss Constant" in the JVN spreadsheet is.
My conclusion now is the same as it was then: test your drivetrain instead of blowing smoke from your behind about the theoretical speed you think you'll get.
I love test data too.
But I still think it may be possible to develop a physics-based model that will reasonably predict overall drivetrain performance -- including not only top speed but also time to reach a desired speed, time to reach a desired distance, and accel, speed, distance, motor amps, motor volts, and Coulomb consumption versus time -- based on a priori estimates of a limited number of parameters .
BBray_T1296
28-09-2013, 20:05
Wild speculations about what this means about the game.
First big assumption: You can build a competitive robot using the KOP chassis as designed.
Second implied assumption 6 in wheels based on stated speed.
Third implied assumption direct drive places the gear box center line on the wheel.
So with a 3" high nano box & 6" wheels, you have 1.5" ground clearance at the center of the robot. 8" wheels give you 2.5" of ground clearance in the center of the robot.
Leads to Big assumption based on this is no big obstacles the robot has to go over.
Wheels & stated speed also implies no water game. Again. Sorry guys.
What if the water is only 1" deep?
What if the water is only 1" deep?
Then that drastically reduces the coefficient of friction between the wheels and the playing surface, reducing the robot's ability to accelerate to the maximum drive speed, and possibly making it impossible to accelerate to 10 ft/s within the length of the playing field. However, they never said that the robot would be able to achieve that speed on the field. That was just the estimated speed. ::rtm::
I'm hoping that the dimensions are increased this year. The dimensions last year severely limited what teams could design (although it meant less clutter on the field). The fact that they somehow fit 6 wheels in a wide configuration makes me hopeful the dimensions are increased this year.
Has anyone tried modifying last year's wide 4-wheel KOP drive base in a 6 wheel base, keeping the same dimensions? This could answer the question of dimensions; if it's unfeasible or useless, then chances are that the dimensions could have been increased for next year.
Kernaghan
29-09-2013, 20:59
Just some ideas.
"Belt drive robot" - "direct driven center wheel"
Unless andymark has aquired new belts, there are currently only two sizes. The 20.47in belts are not large enough to accommodate 6in wheels or larger(and I imagine they might be using their new 6in HiGrip (http://www.andymark.com/product-p/am-0940a.htm) anyway). Because it is a direct driven center wheel, the outside wheels are the pulley center distance away from the middle wheel(minus the 1/8in center drop). Inferring we are using the current pulleys and the 31.5in belts, the center distance is about 11.5in.
Soooooooooooooo
(11.5in * 2) + (3in(HiGrip radius) * 2)
= 29in
Possibility the new drive train is at least 29 inches in length.
z_beeblebrox
05-10-2013, 13:16
Will it be possible for teams to buy a second kitbot for a practice robot?
Historically, its been available from AndyMark after kickoff.
Steven Donow
05-10-2013, 13:21
Will it be possible for teams to buy a second kitbot for a practice robot?
Andymark usually puts the kitbot on sale sometime within (http://www.andymark.com/product-p/am-2239.htm) the first (http://www.andymark.com/product-p/am-0958.htm) week after kickoff
MikeBrock
05-10-2013, 14:04
I wish we had more information to base our decision off of. I'm generally not a fan of the kitbot, but if it has some new improvements, it would be a great option.
Akash Rastogi
05-10-2013, 14:14
I'm hoping that the dimensions are increased this year. The dimensions last year severely limited what teams could design (although it meant less clutter on the field). The fact that they somehow fit 6 wheels in a wide configuration makes me hopeful the dimensions are increased this year.
I liked the new dimensions. The new limitations were really cool and forced kids and mentors to think harder and iterate more. It also made transportation easier, made more room on the field, and I felt it made everything a bit more fun.
I hope the new dimensions stay.
I liked the new dimensions. The new limitations were really cool and forced kids and mentors to think harder and iterate more. It also made transportation easier, made more room on the field, and I felt it made everything a bit more fun.
I hope the new dimensions stay.
Agreed. Seeing the little robots beside the 2012 and earlier robots really showed me how inefficient teams were with their space.
Chris is me
05-10-2013, 17:31
Does anyone know where the 81% number came from?
If I remember correctly, I once read a really, really old CD thread that said 81% was determined by taking one of 229's drive bases, running it to top speed, and measuring that speed. Ratio of that top speed to actual speed became the default "speed loss constant". I'm sure this number is somewhat correlated with efficiency, wheel size, tread type, etc etc. For most practical purposes it's "good enough".
Efficiency in JVN's calculator is used to calculate motor loading, not speed.
If I remember correctly, I once read a really, really old CD thread that said 81% was determined by taking one of 229's drive bases, running it to top speed, and measuring that speed. Ratio of that top speed to actual speed became the default "speed loss constant".
I seem to recall reading that somewhere too, but I wasn't sure.
I'm sure this number is somewhat correlated with efficiency, wheel size, tread type, etc etc.
It's a lot more than "somewhat". In the real world, the top-speed to theoretical-speed ratio is correlated with playing surface, wheel type (e.g. pneumatic or solid) and tread type, chain vs belt, chain or belt tension, wheel alignment, wheel runout, torque-dependent friction in the gearbox and drivetrain, and speed-dependent friction factors such as large airfoils.
For most practical purposes it's "good enough".
It's quite useful as a rule of thumb. Whether or not it's good enough depends on what you're using it for. Students need to understand the limitations.
Efficiency in JVN's calculator is used to calculate motor loading, not speed.
That is true. In a physics-based model, the torque-dependent friction (gearbox "efficiency") would affect top speed.
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