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#16
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Re: The 2009 Control System Q&A Thread
First, some quick background. I love NI hardware, but really don't like LabView. At my Co-Op we used a whole bunch of your hardware (M-Card, 8-port serial card, 4 axis motion control card, can bus module, VBAI) to build a testing robot and ran it from Visual Basic in Windows XP.
I really like the ease of using calls to the CVI libraries... will the same CVI calls be available in the Wind River C environment? Also, I don't know how much of your (awesome) vision system you're including, but do you know if we'll be getting vision assistant or VBAI? If you can pick... I find VBAI much easier to use and more powerful, and it's very easy to load up an inspection with a CVI call. How much resolution do the PWM outputs have? What frequency do they output at? ![]() Thanks, -q Last edited by Qbranch : 29-04-2008 at 07:57. |
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#17
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I'll focus on the HW answers (Greg can snag the SW):
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Last edited by crake : 03-05-2008 at 04:37. Reason: Updating the 9403 update rate |
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#18
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Re: The 2009 Control System Q&A Thread
Regarding the 150lb weight limit, I certainly hope that a 120 lb robot + 15 lb bumpers + 13ish lb battery doesn't "weigh a good deal more than 150 pounds".
A few years back, we learned that not all SLA batteries are created equal. There are mass differences between samples and we found out that robot weight changed substantially depending on which battery was installed during inspection. So... for consistency, we now weigh robots without the 12V SLA battery installed. Russ Beavis Chief Inspector |
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#19
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Re: The 2009 Control System Q&A Thread
I'm not sure I understand the answer. I'm not looking for the toolchain or C tools, but rather just the documentation of the API for what currently ships with cRIO in terms of cRIO's version of VxWorks and the special FPGA interface. Since the C programming interface is not currently customer visible, my interpretation of the above is "Not currently available, will be created and shipped with the H/W"?
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#20
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Re: The 2009 Control System Q&A Thread
Your interpretation is correct. The C interface for the FPGA are not released yet.
Greg McKaskle |
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#21
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Re: The 2009 Control System Q&A Thread
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I'm not positive about the licensing of the visions stuff. I think that Vision Assistant will be in the kit. Greg McKaskle |
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#22
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Re: The 2009 Control System Q&A Thread
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I'm still confused as this is (may be) an answer to only half the original question? The other half had to do with the VxWorks API as supported on cRIO. RTPs, for example, are not available in the VxWorks port on cRIO. It would be very useful to know which set of components of the VxWorks API that are NOT in the cRIO. I think the answer is the same, "information not currently available, will ship with h/w"? Thanks for the clarification. |
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#23
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Re: The 2009 Control System Q&A Thread
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I would expect such OS documentation will ship with the final product, and hopefully you won't be subject to working directly with the OS but through heavily tested interfaces such as the WPILib. -Danny |
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#24
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Re: The 2009 Control System Q&A Thread
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If working in the C/C++ environment, I'm not sure how you wouldn't end up working with the OS since you need to at least create tasks and schedule them... I seriously doubt the WPILIB will package up the necessary routines to create/schedule/prioritize kernel tasks, do data stream logging i/o, etc. which is already available within the OS API. The duplication effort would not seem to add value -- but anything is possible. Last edited by dcbrown : 30-04-2008 at 16:49. |
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#25
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Re: The 2009 Control System Q&A Thread
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But then again, anything is possible. -Danny |
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#26
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Re: The 2009 Control System Q&A Thread
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Currently there are between 250-300[*] different component libraries within VxWorks kernel each with a average of 8-10 interface calls... device drivers as being supplied by WPILIB represent 5% or less of that total API call interface. I just don't see the WPILIB providing all the templates needed to hide the other 95% of the operating system interface so C/C++ programmers don't have to call any OS functionality. For example, I doubt that the WPILIB will provide a callable inertial navigation system (INS) whereby you can customize at the call interface specifying how many sonar, IR, quad encorders, gyros, accelerometers, GTS, and other specific sensors exist on your particular robot. To implement your own INS, you will need to use various services of the operating system plus the drivers supplied by WPILIB. [*] from "VxWorks, KERNEL API REFERENCE Volume 1: Libraries"; some of these are undoubtedly not implemented in the cRIO port of VxWorks, but most should be there. Last edited by dcbrown : 01-05-2008 at 10:04. |
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#27
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Re: The 2009 Control System Q&A Thread
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Now, the 9403 has an update rate of 7us. Given that we have to vary our pulse by 1ms for a "full" range of control, that gives us about 143 counts of resolution over the full range. As opposed to the 255 counts on the IFI RC. (Presuming the IFI pulse work out to exactly 255 for 1-2ms variation) When you add in the Victor's deadband and only 97 output steps, you end up with an effective resolution of 54 output steps with the cRIO/9403/Victor combination. I realize that we're not doing rocketry control systems here, for the most part anyways, but effectively halving our output resolution annoys me, as one or two counts can definitely affect how straight your robot's driving. Especially considering this is the Control System of Tomorrow and the motor control system now seems to be less capable than the Control System of Yesterday. I think following in NASCAR's Car of Tomorrow footsteps is taking the Overdrive theme just a bit too far. Last edited by Kevin Sevcik : 02-05-2008 at 00:15. Reason: Having my post clobbered is kinda weird.... |
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#28
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Re: The 2009 Control System Q&A Thread
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#29
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Re: The 2009 Control System Q&A Thread
That's not quite what I was saying. The 9403's update rate (which really is 6.625us if you want to be precise) was well known and understood when the module was selected. Also the selection process included detailed performance profiling of various motor controllers when used with the 9403.
Last edited by crake : 03-05-2008 at 04:06. Reason: Fixed update rate |
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#30
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Re: The 2009 Control System Q&A Thread
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' wouldn't have worked with any higher of a minimum ouotput power. You can (even with the 3% throttle and resolution available now) still see our 2008 robot shimmy as it's dynamic braking to enter an interpolated arc motion (just check out any videos on TBA of our autonomous, especially Midwest and Archemedes).You know, if they try hard enough, I bet they can get this new control system to be just as good as the old one (that cost way less than half of the new one)! *whimpers* Why, oh why couldn't we have just upgraded to the PIC32 (80MIPS) or even the Querk controller... ![]() -q ![]() |
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