Subject:
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Re: "Servo" Driver for NQC
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 1 Feb 2002 00:17:57 GMT
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Viewed:
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943 times
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"Dick Swan" <dickswan@sbcglobal.net> wrote in message
news:GqsAv4.GL1@lugnet.com...
> This is a long post. It covers the following:
<snip>
Dick, let me first say thank you for the post. I've implemented some of your
suggestions and my robot has gone from unuseable to operating as I had hoped
it would. I may even be able to speed it up a bit, without sacrificing
performance or reliability.
> If you replace the loop with the following you should get be able to get
> much finer control with a loop that takes about 10.5 msecs to execute. • Loop
> should have three instructions only for statments on [3], [4] and [5].
> You'll get much shorter pulses -- 3.5 msec on; 7 msec brake.
> [1] while (true)
> [2] {
> [3] ON;
> [4] BRAKE;
> [5] if ((rotation Sensor != value)
> [6] break;
> [7] }
This has worked wonderfully. Eliminating the wait statements has reduced any
visible jitter in the deceleration portion of my servo task.
> Above timings assuming only a single task is executing. If you're running
> more than one simultaneous task, then expect even longer delays since
> running tasks are scheduled round robin with a "timeslice" of one opcode.
I am running three simultanous servo tasks for controlling axis positioning.
Therefore I can assume my performance would only get better with a reduced
number of pseudo-servo axes.
Thank you again for your very helpful suggestions and answering many
questions I have had for a long time!
Iain
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Message is in Reply To:
 | | Re: "Servo" Driver for NQC
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| This is a long post. It covers the following: 1. How the "WAIT x 10 msec" opcode is implemented and its inherent inaccuracy for low delays. And suggests an alternative code implementation 2. How RCX motor PWM is implemented. And the implication that (...) (23 years ago, 31-Jan-02, to lugnet.robotics)
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