Subject:
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Re: NXTway DS powered by LEJOS OSEK
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 3 Aug 2007 03:01:12 GMT
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Viewed:
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4338 times
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Hi Dick,
At first, I really appreciate your comment because I live out of the NXT core
community, so feedback from the experts are valuable for me!
> 1. AFAIK, the RobotC firmware is the only available NXT firmware that
>
> reduces the lag time between changes in analog sensor value and
> when they are received and processed by the ARM firmware. There are
> several tricks in the ROBOTC firmware to reduce the 2-msec update
> interval.
I do not intend to compete with RobotC. I know some of the folks have developed
high speed real-time application in RobotC such as NXTway-G.
I have a good analogy about ANSI C(LEJOS OSEK) and RobotC.
LEJOS OSEK is a racing car (very high-performance, but only racing driver
can drive) and RobotC is a high-performance passenger car which has safety
systems like Airbag,ABS, ESP...)
> 2. Writing user programs using a 1-msec update interval require an
> operating system or virtual machine that ensures all user tasks
> are capable of executing every msec. I think some of the various NXT
> firmware implementation have a maximum time slice duration larger than
> 1-msec!
LEJOS OSEK natively executes user application program, so task latency is
very small and then, almost no time slice duration in comparison with other
VM based firmware. LEJOS OSEK uses an OSEK RTOS which was developed for
real automotive control systems, so it is very fast and stable.
> 3. NXT motor encoders are processed directly on the NXT ARM's CPU.
> Fortunately, they do not have the lag times described above for
> analog sensors.
This is the reason why 1msec periodical task execution was required for NXTway
DS. (even analog sensor values remain same, motor encoders value may be varied
every 1 msec). NXTway DS control algorithm is different from PID. NXTway DS
estimates its physical dynamics during run-time to control the both of body
angle and position.
Thanks again.
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Message has 1 Reply:
 | | Re: NXTway DS powered by LEJOS OSEK
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| Takashi, Could you (or one of the other LEJOS developers) do me a favor? A few months back, I created a page that lists different types of NXT software, including an early version of LEJOS: (URL) like to update it with info about the latest version, (...) (17 years ago, 3-Aug-07, to lugnet.robotics)
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Message is in Reply To:
| | RE: NXTway DS powered by LEJOS OSEK
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| (...) A 1-msec scanning rate should be achievable with several of the interpretative virtual machine environments for the NXT. I can confirm that ROBOTC can easily execute at this rate for a PID loop with error based on difference between two (...) (17 years ago, 2-Aug-07, to lugnet.robotics)
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