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Anton Abaya
01-16-2002, 04:26 PM
After taking a poll, it seems a lot of the teams who browse Chiefdelphi are going to be building dual transmission robot. I guess I would define this as a robot that can shift gears (low to high).

http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=1697

Now with this information, can someone post what they have done in the past? I'm particularly interested in "on-the-fly" gear switching mechanisms using spur gears or a built gear box. But post anything and everything you're willing to share.

As always, I am grateful for your help.

-anton

Wayne Doenges
01-16-2002, 04:56 PM
Last year we used drill motors for propulsion. We used servos to shift gears. The problem is you had to be standing still to shift. We had a spring go from the servo arm to the shift lever. The spring acted as a servo saver and wouldn't stall the servo. When the servo arm would swing left/right the spring would pull on the shifter. It worked pretty well.

Wayne Doenges

s_alaniz
01-17-2002, 08:50 AM
Anton,
If you're willing to build your own shifting transmission, I suggest you look at a moped/minibike transmission, they do auto shifting AND RC car transmissions. We are attempting to develop shifting but as yet all our ideas are unproven



Best Wishes


Steve Alaniz

"Ted, I think the microwave just exploded your soup" - Sally Forth
" Once agin, technology turns on it's masters." - "Ted Forth"

BillCloyes
01-17-2002, 09:14 AM
Originally posted by Wayne Doenges
Last year we used drill motors for propulsion. We used servos to shift gears. The problem is you had to be standing still to shift. We had a spring go from the servo arm to the shift lever. The spring acted as a servo saver and wouldn't stall the servo. When the servo arm would swing left/right the spring would pull on the shifter. It worked pretty well.

Wayne Doenges

Could you post some pictures for this spring lever.

team222badbrad
01-17-2002, 09:47 AM
Maybe I will be nice for once and give you a picture of our shifters!

Matt Reiland
01-17-2002, 01:06 PM
See if someone has a picture of the HOT BOT from last year they had a trick shifting mechanism using little air cylinders. I don't know if they used it but it looked really cool

Matt

Mike Rush
01-17-2002, 09:10 PM
Why shift? Why not a continuously variable transmission? Any thoughts?

Anton Abaya
01-17-2002, 09:21 PM
like using belts similar to the insides of a drill press? lots of friction perhaps? i dunno.

CaptainPlaid
01-18-2002, 09:29 AM
It is also possible to shift both drill motors with one servo. We did this on Big MO two years ago. However you still have to stop to shift. On-the-fly shifting is the way to go. By the way, HotBots shifting did work last year. Now if only there was pictures. :) ;)

thedillybar
01-18-2002, 07:37 PM
Our team is going to try to shift on the fly by having 2 sets of drive wheels that are always spinning (one set for high gear, one set for low gear) and putting the high gear wheels down with a pneumatic. I am skeptical of it but only time will tell.

Dr.Bot
01-20-2002, 07:48 AM
A transmissiom would be cool - anyome thought of using something smple like a bicycle chain dereiler? This would be failry easy if using one drive wheel - harder if two drive wheels -
you'd need a differential - really hard if using a 4 wheel drive.

The drill press stacked pulleys are really the same thing has the
typical bicycle gear cluster, and I have seen designs for 'infinately variable speed transmissions based on two parabolic cylinders and a drive wheel.

Remember automatic transmissions work because of fluidic coupling - ie they are clutch less. Manual transmission rely on the
very sophisticated feedback system of a human mind to match the
speed of the motor to the speed rnage of the wheels.

So while I see that some of you suoer sophisticated teams will want to be both super fast and have super torque, think about all those gears and sprokets and things getting strewn all over the competition floor. What is the problem you are trying to solve? Is a multi-speed transmission the only way to do it?

Jon Lawton
01-20-2002, 03:21 PM
Originally posted by Mike Rush
Why shift? Why not a continuously variable transmission? Any thoughts?

Personally, I love this idea to bits! Being from the "Computer Science" side of the force, I'm not exactly sure what the best way is to make one of these contraptions. I think other teams have done it with varing degrees of sucuess? Could those teams who have made CVTs please tell us about them? Pictures too! Thanks! :)

schitnis
01-20-2002, 04:21 PM
One idea which we had, but we did not use it, was that there be a cradle for the chain on the gear. then, a high torque, low speed motor was taken and made to pull this cradle left and right and make the chain go from gear to gear. We did not consider this design because a bike chain is required to be used. It is same like a multi speed bike. Need presicision work

Works in moton and while standing !!!

Regards
schtnis
Team 915

Jeff Waegelin
01-20-2002, 06:09 PM
We did consider building a CVT, but we decided against it. We came up with a much better idea, and it is simpler and easier to build. I won't tell you what it is our how it works, but anyone going to Cleveland or Chicago will get a chance to see our secret drive system in action and on display. I bet you all can't wait to see...

Marc P.
01-20-2002, 08:44 PM
Originally posted by thedillybar
Our team is going to try to shift on the fly by having 2 sets of drive wheels that are always spinning (one set for high gear, one set for low gear) and putting the high gear wheels down with a pneumatic. I am skeptical of it but only time will tell.


We are doing essentially the same thing, Fast and Slow wheels, powered by the same drill motors, but to conserve space only skid plates will be used in conjunction with the fast wheels.

Paul Copioli
01-21-2002, 08:38 AM
Hey Jeff,

you wouldn't happen to be spinning the ring gear of a planetary gear set, would you?


-Paul

ateene
01-21-2002, 10:03 AM
We were considering a dual motor CVT using planetary gears and had the basic design, but didn't have time or expertise to engineer all the details. Maybe next year.

Here is a link that describes the basic idea. http://www.solomontechnologies.com/articles/design1.htm

Andres

Keithicus
01-21-2002, 12:35 PM
Paul,

A student on our team suggested spinning the ring gear of a planetary gear set. He argued that in low gear you would realize the benefit of the drive motor and the motor spinning the ring working together to give you high torque, while in high gear you would get increased speed with both motors working together.

I didnt believe this to be true, however. I agree that in one case you do get both working together to give you high torque, but its not a true transmission (since there is no gearing going on), so in the high gear both motors are not in fact working together.

Your thoughts?

Keith Sevcik
Mentor, #920

Paul Copioli
01-21-2002, 02:24 PM
Keith,

We are, in fact spinning the ring gear this year. I am not divulging how many motors/type (at least, not yet), but we are using the spinning ring gear transmission. The student on your team is right and wrong about the motors working together.

They actually don't work together. If you simply coupled the output of 2 motors together, you would get more torque, but at a fixed gear ratio. What the spinning ring gear gives you is variable gear ratio. Simply put, if you spin the ring gear and the sun gear in the same direction, you get a low gear ratio (fast output speed). If you spin the ring gear in the opposite direction, you get a high gear ratio (low speed output). The motors do not at all work together! The ONLY thing the ring gear motor does is spin the ring gear and react to the loads of the sun gear motor (input motor). This means of transmission is inefficient, because the ring gear motor has to react to forces normally taken out by locking the ring gear against the housing; but it is very effective in varying the gear ratio.

Bottom line is that we thought it was of value, but have spent a year and a half perfecting it and making it work.

-Paul

Keithicus
01-21-2002, 02:45 PM
Thanks Paul, you've helped to end a long standing controversy. I was trying to attack the problem from a static approach but encountered quite a bit of difficulty and was reluctant to dive into the dynamic problem. But yeah, i figured it was something like that.

Eugene
01-21-2002, 03:11 PM
Hey! I'm that student Keith is talking about, and I'm really glad that my idea was at least worth making, as I'm learning from you guys. Unfortunately we only have one engineer (Keith), and no money and time to develop such a sophisticated transmission, so I came up with a much simpler design for a dual speed transmission. I would really appreciate if after building is done if you could share you knowledge, so I could truly understand this design.

Eugene

Paul Copioli
01-21-2002, 03:54 PM
Hey Eugene,

Actually, we plan to release ALL the detail and assembly drawings right after the ship date. We did all the files in SolidWorks, and it has a free viewer that everyone can use. The viewer can be downloaded from www.solidworks.com.

I will put a zip file together with all the assembly models, part models, and detail drawings. If you download the viewer, you will be able to view and print all of the files.


-Paul

P.S. We will be at Chicago, Ypsilanti (MI), and the Championship.
If you are going to any one of these, just stop on by.

Ken Leung
01-21-2002, 05:07 PM
Fortunately there are the chiaphua's in the kit this year, that have a really close maximum power output to the drill motors... So matching speed torque curve won't be too hard to do. Gear them down to the same slope, and electronically lower one of them to match the y-intercept, if that's necessary at all. I guess the curves don't have to match exactly. I wonder how close they have to be.

Would've been hard to do with drills and fisher price last year. Guess you got lucky this year... Unless you knew something in advance before we do. ;) Looking forward to see this working. I hope you don't mind me introducing this design in the Technical newsletter.

Eugene
01-21-2002, 05:53 PM
To Paul Copioli:

Hopefully our team will get enough money to get to champs, so if that is the case, I would be very glad to stop by and talk with you guys.


To Ken Leung:

If you remember me talking about a mysterious way of changing speed without switching gears, then this is what I was talking about. Really sucks that I will not get chance to build it, but I'm still hoping that our current design will be sufficient to draw some attention to the robot.

Eugene

PMGRACER
01-21-2002, 10:08 PM
Originally posted by Anton Abaya
After taking a poll, it seems a lot of the teams who browse Chiefdelphi are going to be building dual transmission robot. I guess I would define this as a robot that can shift gears (low to high).

http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=1697

Now with this information, can someone post what they have done in the past? I'm particularly interested in "on-the-fly" gear switching mechanisms using spur gears or a built gear box. But post anything and everything you're willing to share.

As always, I am grateful for your help.

-anton Team 27 is using an"air" shifter on the trans, just like my Camaro. We are also using 2 Taco motors and two hole shooter motors. We like big torque, Kinda like the torque the 471 in my Camaro makes. Better yet, Don't be suprised if you see our bot' show up with a fire breathin' Big Block Chevy stuffed between the frame rails!!!:D

JHBurch
01-22-2002, 04:37 PM
Lots of drawing details are available in the following white paper.

http://www.chiefdelphi.com/forums/papers.php?s=&action=downloadpaper&paperid=21

This is also a stop-before-you-change design, but it's not too hard to automate the code to stop, change, and go again without the driver having to let up on the joysticks. Here's the code we used to do it last year:

'---------- Gear Change --------------------------------------------------------

if (p1_wheel > 57) then next_option
servo_gear = LowGear 'p1_wheel button setup for lo_gear

next_option:

if (p1_wheel <= 200) then GCnext7:
servo_gear = HighGear 'p1_wheel button setup for hi_gear
GCnext7:

if (servo_gear_old = servo_gear) then no_change:

for k = 1 to 50 'Stops main drive base
Serout USERCPU, OUTBAUD, [255, 255, 127, relayA, 127, relayB, 127, 127, 127, 127, 127, 127, servo_gear_old, servo_gear_old+GearOff, 127, 127, BSRollPWM, 127, BSArmPWM, 127]
next

for k = 1 to 50 'Changes gear with the servo drive
Serout USERCPU, OUTBAUD, [255, 255, 127, relayA, 127, relayB, 127, 127, 127, 127, 127, 127, servo_gear, servo_gear+GearOff, 127, 127, BSRollPWM, 127, BSArmPWM, 127]
next

for k = 0 to 128 'Ramp Speed up
Serout USERCPU, OUTBAUD, [255, 255, 127+(k/8), relayA, 127, relayB, 127+(k/8), 127, 127, 127, 127, 127, servo_gear, servo_gear+GearOff, 127, 127, BSRollPWM, 127, BSArmPWM, 127]
next

for k = 0 to 100 'Stop again
Serout USERCPU, OUTBAUD, [255, 255, 127, relayA, 127, relayB, 127, 127, 127, 127, 127, 127, servo_gear, servo_gear+GearOff, 127, 127, BSRollPWM, 127, BSArmPWM, 127]
next

no_change:

servo_gear_old = servo_gear

kacz100
01-22-2002, 08:49 PM
Am I alone in thinking that if you have to stop and shift that another robot could come up to you and push you with almost no resistance? Or is everyone content with their design and willing to take the chance?