Skip to main content
19 events
when toggle format what by license comment
Feb 9, 2020 at 8:02 history bumped CommunityBot This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
Sep 28, 2019 at 16:01 history bumped CommunityBot This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
Aug 27, 2019 at 10:30 answer added hooskworks timeline score: 1
Aug 27, 2019 at 10:01 history bumped CommunityBot This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
Apr 25, 2019 at 20:51 comment added KalleMP I also feel this is a strange question. Some need is hidden from us or you are looking for error or noise in the least likely places. Your encoder output can be made surprisingly accurate if you sample the encoder pulses with a very high time resolution. Noise component would then be slot edge errors, motor angular jitter or optical sensor noise. Over a full revolution these should be possible to average out to near zero. If you have other concerns we need more information.
Apr 25, 2019 at 17:03 history bumped CommunityBot This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
Feb 12, 2019 at 19:00 comment added Scott Seidman How can an encoder be anything but accurate. If there are X counts per revolution, if you count to X, you've gone 1.0000 revolutions.
Feb 12, 2019 at 18:55 answer added sstobbe timeline score: 0
Feb 12, 2019 at 18:38 comment added Ale..chenski Strange request. Optical wheel encoder IS the MOST accurate sensor of rotation speed (except laser-based methods). Based on pulse forming, there should be no any "measurement noise", unless your MCU has a badly screwed software.
Feb 12, 2019 at 16:38 comment added Chu Measure the back-emf during the PWM off-periods, using an ADC. Back-emf is proportional to angular velocity.
Feb 12, 2019 at 16:12 history edited JYelton CC BY-SA 4.0
Added datasheet link
Feb 12, 2019 at 15:58 comment added user503842 hey guys, thx for your comments! I want to determine the accuracy, not the precision. Actually, I want to estimate the optical wheel encoder's measurement noise. To do so, I figured I would measure the encoder's output and compare it against what the velocity should be given a certain PWM-signal. I could then plot the results (measured velocity - real velocity). They should be Gaussian distributed with 0 mean. And the variance would be my measurement noise. @Chu: can you elaborate on your idea?
Feb 12, 2019 at 15:22 comment added Chu Depends what you mean by 'exact'. You can calibrate the motor angular velocity against back-emf (assuming you're driving the motor with PWM). This can then be used in a closed-loop speed control configuration.
Feb 12, 2019 at 14:51 comment added frarugi87 The easier way is to calculate the "precision" of the wheel encoder given the nominal values and uncertainties, not characterize your system
Feb 12, 2019 at 14:45 comment added Hearth There is no way to calculate the exact angular velocity of the motor. There are too many unknowns.
Feb 12, 2019 at 14:44 history edited Hearth CC BY-SA 4.0
typo in title
Feb 12, 2019 at 14:29 comment added uglyoldbob A strobe light and some way of marking can provide a way of checking angular velocity
Feb 12, 2019 at 14:23 comment added Elliot Alderson It is impossible with current technology to measure the exact angular velocity, so you need to be more specific about what you really need. Also, the words precision and accuracy do not mean the same thing, so think about the difference and reflect on what it is you are trying to accomplish.
Feb 12, 2019 at 14:18 history asked user503842 CC BY-SA 4.0