Forum: Math and Science
08-10-2013, 00:10
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
I re-ran my script once for each of MATLAB's ODE solvers (http://www.mathworks.com/help/matlab/ref/ode45.html), adjusting the tolerances as necessary to get a reasonable solve time.
Every solver...
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Forum: Math and Science
07-10-2013, 22:28
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
Makes sense.
I never bothered to do any accuracy analysis, so that's probably the case.
After lowering the tolerances and calculating bounds for the error (total error should be less than 1e-7), I...
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Forum: Math and Science
07-10-2013, 21:22
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
Question 6 solution:
Position: ( -3.7271, -4.0749)
Distance: 60.8613
Code (slightly modified from my last script):
% Set up various useful functions that don't require integration to...
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Forum: Math and Science
07-10-2013, 21:07
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
True (except for the last part -- I don't think Simpson's integration would slow it down for equivalent accuracy, but I haven't tried it, so I don't know).
Having used MATLAB a bit, I think...
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Forum: Math and Science
07-10-2013, 20:39
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
It took one or two seconds (MATLAB isn't terribly fast). It was entirely numerical, performing a numerical integration (for angle) inside another numerical integration (to get position).
Where it...
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Forum: Math and Science
07-10-2013, 19:55
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
I've refactored my code to be much faster (using basic manual Euler integration instead of MATLAB's integral() function) and plotted the robot's position for problem 5. The plot is attached.
Here is...
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Forum: Math and Science
07-10-2013, 19:01
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
X position: -5.9443 ft
Y position: -9.1103 ft
Distance: 129.5972 ft
MATLAB:
rotate_CW = @(t) 1.5*sin(t/2.5);
angle = @(t) 5*pi/12 - integral(rotate_CW, 0, t, 'ArrayValued', true);
forward = @(t)...
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Forum: Math and Science
04-10-2013, 22:17
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
I think he's just reporting the angular orientation of the robot. Since the angular rate does not depend on the location (in the XY plane), it is still facing 15 degrees clockwise from the Y axis.
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Forum: Math and Science
04-10-2013, 18:14
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Replies: 37
Views: 2,820
Re: calculating position using follower wheels
Speed = sqrt(4^2+5^2), which approximately equals 6.4 ft/s
6.4 ft/s * 3 sec = 19.2 feet (circumference of the circle).
Thus the radius is 19.2 feet / (2*pi), or approximately 3.06 feet
EDIT:...
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Forum: Math and Science
04-10-2013, 18:07
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Replies: 37
Views: 2,820
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Forum: General Forum
01-09-2013, 00:55
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Replies: 25
Views: 3,793
Re: Drivers Control
2008: This was before my year, but in 2008, 957 used a steering wheel and two beige kit joysticks. The robot had ackermann steering, so the steering wheel controlled the angle of the front wheels....
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Forum: General Forum
15-08-2013, 23:41
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Replies: 4
Views: 1,599
Re: Choose your own control-system adventure
1. Radio connection reliability -- this is a fairly difficult thing to achieve in FRC's atmosphere, and it often (in my experience) makes the difference between a fun event and a frustrating one.
2....
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Forum: Extra Discussion
12-08-2013, 23:41
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Replies: 19
Views: 3,956
Re: pic: Crazy Web Filter
This happened to me in middle school. I forget what site it was, but it was a legitimate site (something like Wolfram MathWorld).
My school, however, used the "Bess" filter -- according to...
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Forum: General Forum
09-08-2013, 12:11
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Replies: 207
Views: 40,046
Re: NI Week Athena Announcement and Q&A Panel
Thank you -- I saw the whitepaper, but that didn't mention anything specific about the kernel itself. The NI community post is much more informative.
I'm glad to hear it's PREEMPT_RT -- in my...
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Forum: General Forum
09-08-2013, 11:55
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Replies: 207
Views: 40,046
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Forum: General Forum
26-05-2013, 22:11
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Replies: 50
Views: 5,594
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Forum: General Forum
26-05-2013, 19:08
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Replies: 50
Views: 5,594
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Forum: Programming
06-04-2013, 15:07
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Replies: 64
Views: 5,777
Re: Which Linux distributions do you use?
Just to be 100% clear:
For the reasons explained by rbmj above, this command is perfectly safe.
The output file, /mnt/sdb1/MBR.img is a normal file -- it is not a device node, and does not control...
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Forum: CAN
24-03-2013, 13:10
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Replies: 6
Views: 1,825
Re: CAN vs. PWM
Team 957 used PWM witth Talons for reliability and performance.
If it were not for our rookie programming team, we would not have been afraid to utilize CAN with the new IFI Jaguars if we had any...
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Forum: Programming
23-03-2013, 12:26
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Replies: 64
Views: 5,777
Re: Which Linux distributions do you use?
This is probably beating a dead horse by now, but I'll add that I'm currently on Mint (Xfce, but I'm eyeing Cinnamon).
Additionally, my last year as a student programmer, I did all my work on Gentoo.
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Forum: FIRST Tech Challenge
16-03-2013, 14:53
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Replies: 2
Views: 1,012
Re: [FTC]: Braking NXT Motors Using RobotC
Note: I am not familiar with the FTC setup, so I cannot tell you anything about your code -- hopefully someone with FTC experience can chime in.
Motor braking won't actually stop a motor. It will...
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Forum: NI LabVIEW
26-02-2013, 20:09
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Replies: 29
Views: 5,459
Re: PID vs Bang-Bang for Shooter Consistency
Ether, thank you for this info -- this information would be very useful for deciding whether to use this rate determination functionality or numerical differentiation in calculating an encoder's...
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Forum: Programming
12-02-2013, 21:40
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Replies: 5
Views: 1,265
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Forum: General Forum
30-01-2013, 22:52
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Replies: 2
Views: 1,254
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Forum: Programming
26-01-2013, 16:49
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Replies: 12
Views: 1,014
Re: What control laws are you using?
Team 254 did a MIMO controller two years ago. They utilized state space techniques, but I'm not aware if they used pole-placement, LQR, or something else to design their controllers.
There's a...
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Pro safety tip: put a string through coil springs that is tied off securely on the robot frame. This will help prevent the spring from jumping out and killing an inspector if it snaps. - Ninja_Bait [more] 
