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 Robotics / RCX / NQC / 1711
1710  |  1712
Subject: 
Re: Motor Speed Control
Newsgroups: 
lugnet.robotics.rcx.nqc
Date: 
Tue, 30 Nov 2004 09:14:33 GMT
Viewed: 
5356 times
  
Hello Iain,

Has anyone done something at all similar to this?  I'm aiming at geting
smooth, slow motor speed.

You should definitely try Dick Swan's 10x firmware
(http://news.lugnet.com/robotics/?n=22989). Among other goodies (interpretation
speed for example ;o), it features more power levels (128 instead of 8), and a
flag to modify behavior of PWM motor control. Standard LEGO firmware powers
motor during n ms then floats it during (8-n) ms. The problem with this control
is that lightly loaded motors reach almost full speed even at low power levels.

Dick's firmware can replace this float period by a break period. This way you
achieve a true speed control, where unloaded speed is directly proportional to
power level (This remains true with a linear load. Of course if you want to get
constant speed with load variation you still need to add a closed loop
regulation!).

I experimented this, it works extremely well (minor problem: some noise in the
motors, similar to Spybot that uses the same regulation, but much less annoying
because frequency is lower. Might also wear your motors prematurely but I don't
think so).

Philo



Message has 1 Reply:
  Re: Motor Speed Control
 
(...) I've been using a power/brake method (instead of power/float) for quite some time in BrickOS. That was one of the first big steps in getting my Legway to work. ( (URL) ) It allows you to program a robot to make smooth turns (slow, instead of (...) (20 years ago, 30-Nov-04, to lugnet.robotics.rcx.nqc)

Message is in Reply To:
  Motor Speed Control
 
Hi, I'm trying to do a basic test setup to code a compact speed control module for the 9V gearmotor. I've mounted an encoder (rotation sensor) directly to the gearmotor shaft. In my code, I'd like to set a variable (speedDesired) and have the motor (...) (20 years ago, 30-Nov-04, to lugnet.robotics.rcx.nqc)

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