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(...) Dave- Where are you getting that 1250 rpm upper limit from? While I haven't counted exactly yet, I'm dropping only 20 counts out of every thousand at ~15,000 rpm. I had assumed this was mainly gear slop, since it only appears to occur while (...) (25 years ago, 7-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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Using a Futaba 9ZAP radio with a built in optical tachometer and the two bladed LEGO prop I got 380 rpm for the gearhead motor and 4320 rpm for the older nongeared motor. Of course this was done with a battery box and brand new batteries so I am (...) (25 years ago, 7-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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My memory is a bit fuzzy here since it was a while back, but according to my notes... * sensors are sampled every 3ms * rotation sensor is a quadrature encoder with a 4:1 gearing in front of it (one rotation of the axle yields 16 "ticks"). * sensor (...) (25 years ago, 7-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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(...) Oh! Math mistake on my part... 16 instead of 4. Hmm... the ~15K was an off the top of the head estimate, which would go down to ~4K if divided by four again like it should be :) I'll have exact numbers some time today. Like I said, it is (...) (25 years ago, 7-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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(...) You could get close using the differential as an adder. The ratio of speeds above is about 11:1 (its 11.3:1, but lets keep things as integers). That is a prime number, and we know there aren't any lego gear options that give you an 11:1, so (...) (25 years ago, 7-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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(...) Assuming those numbers are correct (I've been too slack to actually look up the tooth counts), I'll give further clarification on my earlier post. I'm using a combination of three 40:8 combos, giving me an effective ratio of 125:1. The gearing (...) (25 years ago, 7-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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Well, this took me a while, but it appears that the rotation sensor is reliably counting at nearly 2500 rpm. Here are the numbers: ~650 ticks per second. This count is not quite constant, but the error is within 5 percent. The way it is geared, this (...) (25 years ago, 13-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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In article (...) 650 ticks per second works out to about 1.5 ms per tick. I didn't think the RCX sampled inputs that fast - I thought it was 3.0 ms per sample. If so, this would mean that the RCX is capable of adding 2 to the rotation value during a (...) (25 years ago, 13-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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(...) Nope-it's not. I use LegOS, and that only adds 1- I know that particular section of code inside and out. Therefore, it must be the sampling time. Or a really egregious error on my part. (...) <snips much code> (...) Yes, but at this speed, you (...) (25 years ago, 13-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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In article (...) I don't know anything about legOS - perhaps it has its own sensor sampling code. I was looking through the standard Lego firmware to determine the 1250 rpm number, and I verified it with a few experiments, but again using standard (...) (25 years ago, 14-Jul-99, to lugnet.robotics)
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| | Re: What is RPM of Gear Motor???
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(...) Ah! I thought the 3 ms you were referring to was a function of the hardware, not the software- I thought it might have something to do with the A-to-D in the chip. FYI, in legOS, the rotation sensor can technically be sampled as often as the (...) (25 years ago, 14-Jul-99, to lugnet.robotics)
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