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#211
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Re: NEW 2009 Control System Released
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Keep in mind that the cRIO is an embedded system. VA Tech did use Lab View on their DARPA urban challenge robot but the image processing, navigation, obstacle avoidance, etc. was performed on a pair of quad core servers. The cRIO was relegated to the break, throttle, and steering control functions that are pretty much what we have been doing with the current control system for years. I’m not saying that you can’t do a lot more with 64MB of RAM and a 32 bit processor but you still might actually have to worry about the efficiency of the implementation. You will always find yourself in a resource constrained situation if you are in a competitive real-world situation. I'm sure that the game designers will make sure of that soon enough. |
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#212
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Re: NEW 2009 Control System Released
I believe the point is that the controllers for the FLL (NXT), FTC (an NXT-ish device), and FRC competitions are all programmable with LabVIEW or a LabVIEW-derivative, so that students can more easily build upon prior experience as they "graduate" from program to program.
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#213
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Re: NEW 2009 Control System Released
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-Danny |
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#214
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Re: NEW 2009 Control System Released
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#215
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Re: NEW 2009 Control System Released
I agree these seem to be common concerns, so I'll put in my 2c.
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1. The old system and the new system teach different skillsets. Which one is more important is a matter of opinion. 2. If you want to teach both skillsets, just buy a PIC on your own and interface it with the cRIO. That's a lot easier than building a custom board with a PowerPC running VxWorks and interfacing it with a PIC. So if your goal is to build a robot, the cRIO is clearly better (there's a reason they send 32-bit processors running VxWorks to mars and not PICs). If your goal is to teach, the cRIO gives you more opportunities to do that. Quote:
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IMHO I think everything except for the cost is a non-issue. |
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#216
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Re: NEW 2009 Control System Released
Jay,
My big concern is that with current system we could have many kids on a vex system in preparing for FRC. You could proto-type what you wanted to do on vex. But the new system you don't have that link to the two systems other than a labview similiarity. I am sure it will all work out. Plus most of us will not get the crio system until Jan 2009 because of cost and there is a lot to prepare for in understanding crio. Should be an interesting year. |
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#217
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Re: NEW 2009 Control System Released
This was sent out tonight...
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#218
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Re: NEW 2009 Control System Released
Previously with the PIC, "system programmers" had the advantage and "application programmers" who wanted all that h/w stuff hidden were at a disadvantage. The advent of WPILIB and EasyC closed some of that gap, but still the plaform was more systems programmer friendly.
The platform was kinda backwards, often requiring a lot of systems knowledge before you could become an applications programmer. This typically meant new programmers were at a disadvantage. The new platform is more the norm/inverse of that. The entry level for all is as applications programmers using the API of the RT/OS either within kernel tasks or RTPs (real time process). If you want to be a systems programmer, the entry costs in terms of time, effort, and knowledge just increased. But that is usually how it is. The new platform should align better with both sets of folks. The WPILIB will be just another library/plugin option on top of the RT/OS that provides an API to access the pins, PWMs, etc. that we're familiar with on the PIC. Having the source may or may not help much unless the NI drivers for the modules have the source included in the cRIO kit also. But this library will be *the* method of accessing DIO, ADC, PWM, and relays for almost all but a few teams. For example, lets say the device special file for the digital io module was /tyDIO and pins 0-15 were /tyDIO/0 .. /tyDIO/15. Then WPILIB would need to do something like the following to read an input pin. Code:
fd = open( "/tyDIO/0", O_RW, 0 ); // open DIO driver for NI module, pin 0
bytes_read = read( fd, &byte, 1 ); // read value of pin 0
close(fd); // close device
** this is pure swag -- there are several ways of doing this, but this is the
most direct but again depends on the device naming scheme for the
modules and its subparts.
The biggest problem I'm having wrapping my head around is the sheer size of the API and doc set for VxWorks along with a lack of information on what the NI driver/library interfaces look like. But all in good time... |
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#219
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Re: NEW 2009 Control System Released
The NI I/O model depends on the HW target, but in this case the FPGA and the PPC use a memory mapped register set. Instead of the driver kit seen above, you'd see something equivalent to an
NI_RIO_PEEK(FPGARef, address, &result); The FPGARef is the result of an early Open that loads and/or connects to an FPGA image. Then because some of the access would be difficult, there is a layer that supports critical section exclusion and provides cleaner C datatypes. This layer of C++ objects is generated with the FPGA image, and that is what WPI will link against. Greg McKaskle |
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#220
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Re: NEW 2009 Control System Released
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Having said that, an OO language does make it much nicer, especially if it supports STL classes. Last edited by steveg : 24-04-2008 at 03:00. |
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#221
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Re: NEW 2009 Control System Released
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#222
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Re: NEW 2009 Control System Released
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My guesses on what the links should be based upon the above descriptions... You can begin reviewing the training material already available online at: * Tutorial: Getting Started with the New Control System * Slideshare: Training sessions from the 2008 Championship * Tutorial: Program the New Controller with NI LabVIEW * Tutorial: C / C++ Programming for the 2009 FRC Control System Last edited by dcbrown : 24-04-2008 at 16:20. Reason: link back |
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#223
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Re: NEW 2009 Control System Released
There has been a lot of discussion about the new controller in this thread, especially on the software/programming side. (I will leave software to the experts ) I however, have an opinion similar to Mark McLeod's above. What the new controller and interface represent is a nightmare for rookie teams and those with little or no electrical mentorship. In comparing with the present controller where single point failures are reduced to an absolute minimum, the future contoller has multiple power supplies (I count five min.), negative power on the case, multiple interfaces and multiple connections between the RC and the outboard hardware. Diagnosing a failure in the controller will be next to impossible for anyone that is not skilled in in this black art. Rookie teams will be especially vulnerable to failure and damage of the control system.
We need to put ourselves in the shoes of a rookie team to see what they go through. As an inspector and mentor who regularly visits rookie teams, I can tell you that many rookies can't get a motor connected properly without guidance. To add this level of complexity will doom many rookies from participating once registered or from enjoying their first year's experience. Although, a lot of thought has gone into the interface boards and connector design, there is just too many places for something to go wrong. As Mark has pointed out, the power supply wiring is just one place that things can go horribly wrong. Power distro is another area of concern. As I have pointed out in lectures for many years, the battery is capable of supplying 600+ amps and the power distro needs to be able to withstand that current. In addition, the design must take into account the voltage drop across the distro panel as far as power supply droop and noise is concerned. At what voltage does the DC-DC power supply drop out? I can tell you that the battery terminal voltage regularly drops to 4 volts (for short pulses) under load. Add a game that requires pushing and you will find teams with six motor drives drawing the battery down below 8 volts a regular occurence. These same teams will (and have in the past) depleted a battery in less than two minutes. Although weight is not an issue for most rookies, it is more than considerable for experienced teams that weigh in at 120 lbs. Added together with the multiple modules teams are likely to want, the control system, DC-DC power supply and interface boards will likely produce a system that weighs in excess of 5 lbs. A considerable mass that will need secure mounting. Finally, a delivery date of kickoff is too late (see above). When asked, I stated I need it next week. FIRST, if you are listening, please consider giving some teams prototype systems now so we can break them. Give us the chance to work out problems and solve them before the 2009 season starts. |
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#224
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Re: NEW 2009 Control System Released
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So NI_RIO_PEEK and NI_RIO_POKE (assumption) would work within kernel applications/tasks, but what about RTPs? Since opens are not traditionally shared across the RTP/kernel interface could RTPs do their own open on the FPGA image or will this type of macro call only work inside the kernel? Is there a technical architecture overview document for the FPGA and NI I/O modules - essentially similar to VxWorks component API manuals? Trying to find any real tech information on this platform has been particularly frustrating. Especially since this is NOT a new platform. I don't need to know the particulars of how the FPGA/IO interface will be set up for FRC, but it would help immensely to know what a typical engineer recieves in terms of documentation, software templates, and information when they buy an cRIO IO module. |
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#225
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Re: NEW 2009 Control System Released
Excellent comments Al.
Our team has consistently helped hurting teams, and they are not all rookies, many are below 1000 in team number. It takes a deep rich team to have the skills for the mechanical, pneumatics, electrical, programming and sensors. Much less PR and fund raising skills. Even at championships 1/3 of the teams couldn't drive forward to get the 4 points. Many teams we helped had electrical shorts or bad connected cables. Robotics, especially one that takes such abuse game after game is a complex challenge. To me the biggest programming problem of teams is that the hardware is usually not done until shipping day, thus the programmers usually don't get the machine until that day or at competition. I do hope they will allow a few teams (like 1902) to have the processor ahead of time if they have the commitment to help others. Our fear is that with a new system in competition there will be many problems and even the experienced teams will be scrambling to make it happen and will not be able to help others. FIRST is committed to the kids and their future. I have high confidence they will do what is right and in the end this will work better for the kids. As a much older kid I am excited about a new toy and to be able to learn more myself. |
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