I hope the votes continue to go up. He’s a smart guy that doesn’t try to make everything complicated to make himself seem smarter. He explains the shit the way a lot of people can understand. Keep it up uncle bumble fuck
Meanwhile in Kentucky, a local barber in my area just got arrested for selling drugs. Blew my mind. I've been his customer for years. I had no idea he was a barber.
My company makes an ultra-precision wind direction sensor using a resolver. One of the advantages is no brushes or wipers to introduce friction - the wind vane has to move easily in order to respond precisely at low wind speeds. Cool!
Those MOFO springs still give me the willies. I used to do design and manufacture of lifting and lowering equip for TV and film studio, and that sort o shit. We used to use pairs and quads of the big fuckers for the small pantograph hangers we made. We would often do batches of 100 or more of the fuckers. And it was usually Joe Toss here who got lumbered with the pain in the arse "power end" (not actually powered as such just the springs) winding and installing the springs. Ya get damn good at it. But that's the problem. Ya get complacent, start thinking about other things or just chatting shit and and BANG, one of the cunts comes snaking out at 100 miles an hour, and them edges tend to be mighty fuckin' sharp to be whipping around. Fun times.
Same lol, happened just yesterday. Since I already understood transformers well enough, I hit him with a few carefully selected questions to try and make him explain things in a better way for the rest of the class
I don't get some professors. It should be relatively straightforward to explain the basic principle of operation of something like a transformer, even to a mechanical engineering student, but they just ... can't.
Used to use resolvers in satellite antenna control systems on systems designed in the early 90's (still selling now!). You can get 15 or 16 bit resolution out of them if you treat them nice and connect them to a Resolver to Digital Convertor chips. (Expensive though!) They are great for use with long cables and resistant to noise pick-up too. We also used them in pairs with precision gearboxes to provide coarse & fine ranges, combined in software for 18 or 19 bit resolution. This can give you 0.0006 degree step sizes.
Resolvers are excited by a sine wave of 400 to 1000 hertz. The outs will also be sine waves with sine / cosine relationship rotated by the mechanical angle.
A cool thing about resolvers is you can connect two back to back with a common AC supply, and one will follow the shaft position of the other. This was often used in olden times for things like aircraft instrumentation to transfer position information from one place to another
Secrecy aside, this is my favorite BOLTR. interesting product. well explained concepts. Now I'm wondering what other unlisted videos i've missed at the end of ANY AvE video thinking it was a link to a video I've seen
Thank You! I'm all about the technical. I work for myself in technicals all day long & I went to college for Avionics. Stuff like this keeps me abreast of what is going on in other fields. PS if you like tube tech check out Mr Carlsons Lab.
Awesome information! The battery powered 3 yard "scooptrams" at my previous employer had very high performance electric motors. Generally speaking the resolver was the most common failure on the electric motor. Swap them out and recalibrate, good to go again. In one instance I can remember on a Sunday evening our "Batmen" as in battery technicians were calibrating a machine with the help of the manufacturers head techie while he was on approach to LAX. The flight attendants were politely asking him to power down his laptop. What an age we live in!
That spring is called a mainspring! They're not that nasty to get out, ones in windup clocks are made from THICK spring steel. You unwind it from the center, and use your thumb to make sure it only comes out a half turn at a time. Hard to explain in writing, but you just alternate left and right thumb, and it works its way out. Now, winding it back in, is a massive pain in the ass..... Source: Clock and Watchmaker
Definitely works for a watch spring. Might work for a clock spring. But for this beast you'll need some 200 pound gorilla's thumbs, and hide behind a blast door while he's at it.
Nah, the spring here is made from thin metal, it stores all the energy from many winds, while a thicker spring gets more energy from less winds. Most clock mainsprings are 15-20 thou thickness, but you basically just unravel it, and the only part that takes muscle is getting the first loop in.
Yeah, but what does it do? I guess it keeps 'back tension' on something so that if there's a gear involved it will eliminate any slop... but with a spring that large they're looking to do that over several revolutions. Am I even remotely close?
Excellent explanation of a synchro resolver. They were used frequently in aerospace for their extreme reliability and accuracy. They can also drive an indicator directly.
Why aren't all teachers like this bloke? I'd never heard of an industrial resolver before seeing this in my subscription list. Now I know what they are for, how they work, and what to do with any that I come upon. Thanks, AvE!
Couple of things to point out: 1) To find what the measurement resolution on the Bridgeport would be, you need to divide the distance travelled during a single rotation of the lead screw by the resolution of the encoder. e.g. If it moved 1mm per revolution and the the encoder/resolver had 100 steps then your resolution would be 10um per measured step (1/100 mm) 2) Also absolute encoders exist, the optical ones have a number of rings with lines on them. The rings are designed such that each combination of lines only exists at a single orientation so you know at exactly what angle the encoder is at without needing to know the angle that it was previously at.
Resolvers and Synchros were extensively used in aircraft navigation equipment and auto-pilot systems from the 1970s onwards. They were used to determine and control the position of shafts and flying controls within the aircraft systems. (ex RAF Navigation systems engineer) :) Btw you could still use this to produce more than enough accuracy on your 48" milling table by having it operate multi-turn. It is not restricted to just providing output for one rotation. If you did this then you would also need another encoder (like a potentiometer) to give you a rough position and then just use the resolver output to measure the fine position. I remember back in the day with one analogue type aircraft altimeter (clock faced ones) that the resolver would do one turn for every 12,500 feet that it indicated. There was an additional course potentiometer which could be read to tell you which segment you were in ie 0-12,500ft or 12,500 to 25,000ft or 25,000 to 37,500ft etc etc :) funny how you remember all this shit lol
I used to build electric motors at my old job. We made one for GE Aviation that used a resolver. The motor was meant to operate flaps on a fuel tanker jet's refueling boom, to aim it at the fighter jets "special place" for aerial penetration. We used 400Hz sinusoidal AC for those resolvers. Hooking the Sine and Cosine outputs to a Scope and overlaying the two signals is pretty cool, cause it looks like you can see the waves rotating, even though it's a flat image.
New subscriber here, completely fascinated by your hilarity, I've literally watched every video you've ever posted, its taken me 2 weeks but I've watched them all, keepem choochin along, this channel is skookum as frig!
Hi Uncle BF, My job as a lead maintenance mechanic means I'm always trying to explain electrical, hydraulic, and mechanical concepts to the trainees. I love the idea of transformer as gear reduction, brilliant! I will be using that one. As well as the whole explanation of the difference between encoder and resolver. Thanks, Boney Snatches
It has basically one spool that gives the x-axis and one the gives the y-axis, some sine+cosine and you get the angle. Which means that the measured _angle_ doesn't have a linear precision, it will be more precise when one of the axes is near zero and less when X_value=Y_value OR X_value=-Y_value. I'm just thinking: this would make for a good exam or exercise for a mechanical engineering faculty
That was really weird, I saw this like earlier this week and went huh... I don't remember this, figured I must have watched it before and didn't but now its back with a fresh upload date...
A few thoughts regarding the waveforms on the scope. 1) it'd be good to have the primary on a third channel and trigger off of that so the waveforms don't move around as much. 2) I'm not sure you're connected to the secondaries quite right. When one channel passes through zero, the other should remain around its maximum, but we're seeing the yellow trace isn't at its max when the blue goes through zero. 3) if you could sort out getting the correct secondaries, then if your scope has an x-y plotting mode, that would be a great way to look at the encoder output: you'll get a line on the screen, the angle of which direct reflects the angle of the resolver.
Oh man! Your explanation of a transformer and resolver was amazing. I'm not sure how you make it any easier to understand than that. I will be sharing this video a lot to explain that exact concept. Well done!
ive never heard electrical engineering explained explained so thoroughly using the the term "thinga-ma-jig" you're a special creature, well played my friend.
As far as I know encoders have no problem reading absolute position. My understanding is that they use a kind of rotating barcode giving a distinct output for each 'position', and can use perhaps 11 bits or more (based on one particular high end encoder I know of) giving 2048 readings of position, and on startup the particular combination of 'light and dark' in the encoder will give position. I do know for certain that at least some high end (read CNC machine tool grade) servomotors use encoders rather than resolvers.
Very interesting! One thing to note, though: there are absolute position rotary encoders. They use multiple sensors and usually use Gray codes to eliminate slight sensor misalignment, but they have a fixed resolution that is determined by the number of sensors built into the encoder. I believe the device here is often called a quadrature encoder and the resolution is mostly only limited by the input signal and external ADCs: more expensive but more better!
I've been an avid watcher of your vids for a couple of years now and all I can say is that I still have no fecking clue what you are talking about half the time. When I say about half the time, I mean all the time. All I'd like to say is that you, sir, are an educator. Fill every school, college and Uni with copies of you and the world would be a far better adjusted shit heap than it currently is. In my work I need to be able to communicate with folks who run the entire spectrum of intellectual/educational levels and if I were able to do what you do in the way that you do it, then my work would be so much easier and I would be more successful. Keep doing what you do and do so well. The world is a better place with you in it. Take it easy and stay safe matey.
CNC field service here. I can't stop watching your videos! I felt like I was in a classroom on this one but by the end of the lightbulb went off ha ha! Good stuff thanks
A lot of microcontrollers prefer budgeting for having a fancy DAC to a dedicated ADC, so their ADC operations are done with a few comparison operations on the input with iteratively incremented DAC outputs. Not the most efficient, timewise, but you get as much resolution on the ADC as you can have on your DAC, for one piece of hardware.
AvE i am truely amazed at your engineering knowledge and skill. I wish i had just a portion of your knowledge. I never had any formal training but years of what i call backyard experience. I have got by and at times done a few things that even surprised myself. So watching you is trueeducation for me thanks for sharing your knowledge with us.
I am astounded by how you can take something relatively unknown and deduce exactly what it is. To watch the process of discovery and almost see the lightbulbs go off above your head is something I could watch all day! I feel like I have learnt so much since watching your channel I just want to say thank you for Sharing.
Also the combination of high intelligence and the inner mentality of a 10 year old letting out barking spiders and getting into general fuckery is not only probably highly dangerous but fucking funny!
Resolvers can also be parallel connected: you ecite the coils in both, turning one resolver will result in the other one turning the same. (It's used for indicators and remote actuation.)
In response to some of the comments below. I've been bumbling around as a mechanic for 20 years heavy industrial mechanic that is. And I love this channel I've learned some neat tricks that I've used at work once in awhile. I only subscribe to 2 channels and this is one of them. And this is my favorite channel to watch on the throne. A higher compliment I can not bestow. I find the general attitude of the channel awesome laid back hey let's tear schitt up and learn something keep up the good work. And some of the comments are f$&/info hilarious. Great channel please don't ever stop.
AvE, I've got a couple of questions about your ADC math. 1: since we're looking at 2 coils and subsequently 2 data points wouldn't we be multiplying our possible digital values instead of adding them? 1024*1024 = 1,048,576 instead of 1024+1024=2048? 2: since we're dealing with bidirectional voltage inputs would we effectively double our usable bits or would we be borrowing one bit to deal with the +/- sign? Thanks man! Keep up the amazing work!
Resolvers are also used in modern cars with electric power steering - which is the majority of cars made in the last 5 years (trucks are still using hydraulic power steering because of power needed to turn those large wheels). Resolvers are also used on electric cars in their drive motors. You did an excellent job explaining how they work in very basic terms both pictorially and with the oscilloscope.
Absolute encoders will give the shaft position. They use multiple optical gaps and a disk with 2, 4, 8, etc divisions per revolution. The field type that you have is going to be more rugged, long term, especially if there is vibration or electrical noise. I pulled an optical rotary encoder out of a rolling mill once which had been pumped full of crap because the seal failed. A field type would have just kept working. The input signal is an ac signal, so it uses filters to isolate the signal from noise.
As an engineering technician just starting my career, I can truly say I wish I knew you personally to share your wisdom of material science and industrial enginerd'ing. your patreon page was being slow a few days ago, I shall check it again.
You can have a digital resolver as well, using either switches or slits, patterned in Gray Code. That is probably harder to manufacture than just magnetic coils, as you need a switch/sensor for each bit, but it would be much much easier to read (no ADC needed). I suspect that magnetic one is supposed to be run on sine wave input. You will get a more proportional ratio, input/output, if you drive it with a sine wave.
WOW! Thank you again for another incredibly informative vijeo!!!! I am not too savy on this type of stuff -so I will watch this one many times again!! However, because of your skoochum vijeo, once again I just happily received an advanced course in both mechanical engineering and electronics. And I'm lovin' it! But yes...my brain-pixies do hurt a bit at the moment!!!...so I'll re-watch, process the information, and get my brain to skootch with your information. Thanks professor! Always GREAT stuff AvE!!!!!! THANK YOU!!!!
Who ever invented this resolver is an an actual genius. Im sat here at uni studying aerospace engineering and watching this(not at the same time). Brilliant
To read angle resolver they seldom use just A/D and do the math inside a processor. They now have a variety of IC's that provide a precision SINE wave to the primary of the resolver and read the sine and cosine. Very seldom are resolvers driven with a square wave. Most are not just 10 bit. Most are either 12 bit or 16 bit resolution with a digital output. The best way to grasp the shaft position on a scope is to set the scope to vector XY display and use the drive signal to gate the intensity to blank 1/2 of the resulting line. The 1/2 line on the scope is a ray directly showing the shaft angle. This analog vector is precise. This type of resolver is sometimes referred to as a 4 quadrant resolver when it is converted to vector amplitudes and polarity. Another way to display the result on a scope is to use the drive signal to integrate the signal and use the zero crossing of the integrated signal (sine peak detection) to operate a pair of S&H slicers. The two voltages are DC analog vectors of the shaft position, which when displayed on a vector scope display produces a dot that circles the 0,0 center coordinate. Most of the time this DC S&H, and A/D, And conversion is completed inside 1 custom chip instead of using discrete parts. A typical one chip solution for 16 bits is the RD-19230 IC. To eliminate brushes, most precision resolvers rotate the primary on the shaft and is driven by a rotary transformer with the primary and secondary coaxially on the shaft and shell. Then the secondaries are as mentioned a 2 phase winding on the stator.
Im an automation engineer and It's been a while since I've seen a resolver. Great explanation of how it works 👍. This technology is super old school and now days you would use an absolute encoder.
Seems like the kind of part that would report back to the computer in an airliner on flap/rudder angles, etc- and with the VERY strong tensioner built in, maybe even landing gear.
I like the analog A.C. Synchro. Has the same features as far a positioning memory, but has an A.C. voltage output. I think the Synchros are way more sensitive. Cool stuff Ave.
When you use 2 10-bit ADCs together like that, you end up with a resolution of 20 bits (because you multiply the two values together, not add). That means you get 2^20 or about a million different positioning values. That makes it even more accurate.
A resolver is an older method of determining the location of the robot arm, which is then used to either hold its motors, or to determine which direction to move the motor to reach a particular location. most modern robots actually use encoders with battery backups because they are much cheaper and easier to put into a robot. the absolute resolver is still relevant technology, but its not used much any more.
Now that this video showed me how to make things aerospace grade, it seems many of my tools have been made aerospace grade considering they've flown around the room after I busted a knuckle. Good tip.
Compared to encoders, resolvers have the advantage of being less susceptible to vibration and contamination. Can also be used in a submerged environment. Tamagawa Seiki also makes resolvers for the Prius that are installed inside of the crankcase. They are a cool company and have a really amazing automated production facility.
So, I'm curious. If you had one Coulomb per second squared going through a one Henry inductor, would it create one Ohm of reactance? Guessing yes, because that would make sense with the way SI units are defined
Same method they used to use in old analog automotive gauges - sine/cosine coil. Varying the voltages on each coil would position the needle on the gauge. Caveat is that there is a 180 degree ambiguity with a sine-cosine coil like that drawn on the table.
Hello AvE, resolvers like this are driven by sine wave. The two pickup coils have a voltage whose phase relative to the excitation and each other gives the angle. Clever software can calculate the angle or multiple manufacturers (Ti, Analog, Tamagawa and so on) sell decoder chips which give position as well as velocity. Great vid though!
They are also absolute encoders (what you referenced was incremental) that know position upon power up as well. They are more money, but work just like an incremental but have unique outputs for each position (resolution specified with $$ spent) they have the added benefit of being digital in their very design so no adc needed.
If you use a resolver as the feedback for a servo you do have to have a way to home it. Since that won't be locked into just one rotation. On power loss the servo won't know it's location either. So absolute for what you plan on using it for, but not always an absolute position indication.
Thanks for posting the video. Awesome straight forward explanation. Answered allot of questions I had as to how these worked. BTW I've got a skookum as frig Ave t shirt. When people ask what that means, my answer is if I have to explain you wouldn't understand.
Small tip: on that Rigol Oscilloscope you can change the font size of the measurement functions like the Vrms that you used here. (It's somwhere in the "Display" menu if i recall correctly) Might make it easier to read/film.
Using this on the Bridgeport would work great! You did not take into consideration the circumference of your gear. The smaller the gear, the less linear travel you would have per rotation increasing your accuracy. With that being said, you would loose your ability for the machine to know the startup location because you would have many times in your travel that would give any given value. This could easily be overcome by integrating a homing function with a limiting switch. If you really wanted to be tricky, and you wanted to maintain your startup location, you could gang 2 of these units together. If you had one that returned a very corse interval and one with a fine interval you could compair the 2 outputs to get a ferry accurate reading.
Where I worked we had a Cincinnati with resolvers on the servo motors and glass scales for each axis. It would repeat position to within .00005 inch. yes that's half a tenth.
Wouldn't it be easier to integrate say a variable resistor to the unit to act as a counter for more than 360 degrees? Maybe even a linear resistor with a contact on a fine thread? The variable would be good to say 2 inches per step, with the resolver getting around 1000th inch per step? I'm not in this field, just spitballing lol
For the idea of using that on the bridge port. Could you put that gear that is on the resolver onto a rack gear, then get the 2048 steps over the circumference instead of the full travel? Granted you would need some sort of counter for multiple rotations. But if that was digital, that would be relative, with location inside that rotation being absolute. My two sents. Keep up the skookum vidjayos.
Chris Hurlbut I figured the same thing, gear it so it's 2048 steps over 1 inch instead of the full 45"? Or half an inch for even more accuracy? At what point do you draw the line? At what point is it essentially useless to be more accurate?
I was thinking the same. It appears to be about a 4" disk that you could connect to. So, roughly 12" circumference meaning 4 turns for the full travel which gets you to about 5 mil tolerance. Not a clue if that's good enough for the ole' Bridgeport but sounds good to me!
A resolver is a type of rotary electrical transformer used for measuring degrees of rotation. It is considered an analog device, and has digital counterparts such as the digital resolver, rotary (or pulse) encoder. en.wikipedia.org/wiki/Resolver_(electrical) Gotta love Gargle :)
Crazy when you consider most cars use hall effect, VR or even wiper-based rotary sensors for positioning information. These would be way better for throttle position, crank speed, cam phase etc. The Maserati 3200 is quite well known for throttle potentiometer failures in the pedal and throttle body - they're wiper based. Maserati want you to replace the whole throttle body at a cost of something stupid like £1-1.5k but men in sheds will convert to hall effect for a couple hundred.
You can get absolute positional rotary encoders too, different to quadrature encoders, they tell you an absolute angle as gray code which is easily converted to binary, however they can't give you precision like this thing
So for people who didn't get that awesome and simple explanation: this little thing can make robot that can show you middle finger in perfect angle of 90° and hide it fast enough so you will not see it.
10:57 Since the voltage induced in the rotating coil varies according to the cosine of its angle to the stationary coil, angular resolution will be much finer near 0* (parallel) and much coarser around ±90* (perpendicular), assuming the A-to-D is linear with voltage.
Chances are the reference coil will be a different resistance than the sin and cosine coils (which will be equal). Used to use them to know fuel valve position and for variable geometry on gas turbines
Would love to say something witty but all I got is a big "thank you", both for the introduction to a resolver (never heard of it before) and the great explanation of how it works. BTW, regarding what you said at 5:14, what is the difference between 0 and 360 degrees? Love the channel, thanks again.
Encoders CAN be absolute value using Gray code: (from Wikipedia): "Optical absolute encoders The optical encoder's disc is made of glass or plastic with transparent and opaque areas. A light source and photo detector array reads the optical pattern that results from the disc's position at any one time.[5] The Gray code is often used. This code can be read by a controlling device, such as a microprocessor or microcontroller to determine the angle of the shaft."
idk what math you did but on a milling machine with a 4 threads per inch lead screw, that means 4 full turns per inch, so 1440 degrees per inch. You said at 10 bits you get roughly 0.2 degrees, thus 1440 -> 1 0.2 -> x x = 0.2*1/1440 = 0.0001 inches That's a tenth - 2.5 micron, I doubt most milling machines even have that much precision, so I'd say about good enough. Plus you can just gear it down, a 2.5:1 ratio would get you to 1 micron, and those are dry air seal tolerances, you don't see that everyday with traditional machining. Thanks for the vadjeo!
I think that got pinched from the LIGO array over at Hanford, WASHINGTON. How are they gonna detect gravitational waves without that??? I want another neutron star collision report!
Have you had an increase in unsubs since your last video?
Naw, only culled a few dozen weirdos. *sad face*
Nope! Up 13k
AvE because 99% of you subcribers don't suck of pewdiepie or vlogers.
+Stratton Schippers
Nope, he is on the upswing according to socialblade 13% more subs 33% more views
I hope the votes continue to go up. He’s a smart guy that doesn’t try to make everything complicated to make himself seem smarter. He explains the shit the way a lot of people can understand. Keep it up uncle bumble fuck
Meanwhile in Kentucky, a local barber in my area just got arrested for selling drugs. Blew my mind. I've been his customer for years. I had no idea he was a barber.
My company makes an ultra-precision wind direction sensor using a resolver. One of the advantages is no brushes or wipers to introduce friction - the wind vane has to move easily in order to respond precisely at low wind speeds. Cool!
"It flew, now it's aerospace grade"
Well played, sir.
Those MOFO springs still give me the willies.
I used to do design and manufacture of lifting and lowering equip for TV and film studio, and that sort o shit. We used to use pairs and quads of the big fuckers for the small pantograph hangers we made. We would often do batches of 100 or more of the fuckers. And it was usually Joe Toss here who got lumbered with the pain in the arse "power end" (not actually powered as such just the springs) winding and installing the springs. Ya get damn good at it. But that's the problem. Ya get complacent, start thinking about other things or just chatting shit and and BANG, one of the cunts comes snaking out at 100 miles an hour, and them edges tend to be mighty fuckin' sharp to be whipping around.
Fun times.
cunting right. the buggers.
My professor spent 20 minutes poorly explaining transformers today, and AvE spent 20 seconds... Why can't everyone be as beautiful as you?
I had the same professor!
Same lol, happened just yesterday. Since I already understood transformers well enough, I hit him with a few carefully selected questions to try and make him explain things in a better way for the rest of the class
I don't get some professors. It should be relatively straightforward to explain the basic principle of operation of something like a transformer, even to a mechanical engineering student, but they just ... can't.
Same here. Those electric pixies can be extra confusing when explained by a professor.
Zoidberg227 yeah, does getting a PhD in Electrical Engineering mean you loose the ability to talk to regular people?
Used to use resolvers in satellite antenna control systems on systems designed in the early 90's (still selling now!). You can get 15 or 16 bit resolution out of them if you treat them nice and connect them to a Resolver to Digital Convertor chips. (Expensive though!) They are great for use with long cables and resistant to noise pick-up too. We also used them in pairs with precision gearboxes to provide coarse & fine ranges, combined in software for 18 or 19 bit resolution. This can give you 0.0006 degree step sizes.
They take impact, heat alot better than encoders also. We have alot of them where i work.
Resolvers are excited by a sine wave of 400 to 1000 hertz. The outs will also be sine waves with sine / cosine relationship rotated by the mechanical angle.
A cool thing about resolvers is you can connect two back to back with a common AC supply, and one will follow the shaft position of the other. This was often used in olden times for things like aircraft instrumentation to transfer position information from one place to another
Secrecy aside, this is my favorite BOLTR. interesting product. well explained concepts.
Now I'm wondering what other unlisted videos i've missed at the end of ANY AvE video thinking it was a link to a video I've seen
nearly fell of my chair when DAvECAD magically transformed to AvECAD :-) ill note that one down in my AvEEBlog
Waited 10 minutes only to see AvE draw a squiggly swastika on his bench top.
Was not disappointed.
Super secret unlisted BOLTR?! I feel like I'm somehow rubbing danglers with the mighty AvE.
keep it in your vice young man
Secret video! What are you trying to hide?
HEY: Shhhhh....
This was in my notifications. And I already saw it a while back. Unless I'm missing something.
Unlisted pixies and schmoo! What foreign land have I landed in, eh?
Thank You! I'm all about the technical. I work for myself in technicals all day long & I went to college for Avionics. Stuff like this keeps me abreast of what is going on in other fields. PS if you like tube tech check out Mr Carlsons Lab.
3 new ave videos in 1 day, holy shit!
John Possum fuckengland
In my head, that was read to the "Olivia Newton John - Physical", I will hear that now EVERY time I hear the word Technical.
Frozen wasteland of Hoth.
Awesome information! The battery powered 3 yard "scooptrams" at my previous employer had very high performance electric motors. Generally speaking the resolver was the most common failure on the electric motor. Swap them out and recalibrate, good to go again. In one instance I can remember on a Sunday evening our "Batmen" as in battery technicians were calibrating a machine with the help of the manufacturers head techie while he was on approach to LAX. The flight attendants were politely asking him to power down his laptop. What an age we live in!
I might add the mine was in Northeastern Ontario. Calibrating an electric motor a mile underground from an airplane over a mile high >4500 km away...
This is where we find out that AvE and Dave are the same person. They're actually both played by the greatest actor on earth: Fred Savage.
How do I miss this one. I've watched all of them
tony Hern me too wtf?
Right. And why did it have so little views
Because it's unlisted for some reason.
I think Ave is forcing us to watch his vacation videos to the end in order to get the "secret link" videos
Same here. How many other BOLTR are we missing out on
That spring is called a mainspring! They're not that nasty to get out, ones in windup clocks are made from THICK spring steel. You unwind it from the center, and use your thumb to make sure it only comes out a half turn at a time. Hard to explain in writing, but you just alternate left and right thumb, and it works its way out.
Now, winding it back in, is a massive pain in the ass.....
Source: Clock and Watchmaker
Definitely works for a watch spring. Might work for a clock spring. But for this beast you'll need some 200 pound gorilla's thumbs, and hide behind a blast door while he's at it.
Nah, the spring here is made from thin metal, it stores all the energy from many winds, while a thicker spring gets more energy from less winds. Most clock mainsprings are 15-20 thou thickness, but you basically just unravel it, and the only part that takes muscle is getting the first loop in.
Yeah, but what does it do? I guess it keeps 'back tension' on something so that if there's a gear involved it will eliminate any slop... but with a spring that large they're looking to do that over several revolutions. Am I even remotely close?
Excellent explanation of a synchro resolver. They were used frequently in aerospace for their extreme reliability and accuracy. They can also drive an indicator directly.
Why aren't all teachers like this bloke? I'd never heard of an industrial resolver before seeing this in my subscription list. Now I know what they are for, how they work, and what to do with any that I come upon. Thanks, AvE!
Yes sir I walked into the kitchen slipped turned my head and damn, the microwave exploded into a million pieces 😂
Couple of things to point out:
1)
To find what the measurement resolution on the Bridgeport would be, you need to divide the distance travelled during a single rotation of the lead screw by the resolution of the encoder.
e.g. If it moved 1mm per revolution and the the encoder/resolver had 100 steps then your resolution would be 10um per measured step (1/100 mm)
2)
Also absolute encoders exist, the optical ones have a number of rings with lines on them. The rings are designed such that each combination of lines only exists at a single orientation so you know at exactly what angle the encoder is at without needing to know the angle that it was previously at.
I always saw you as a sage. when you started calculating with both hands in the screen, you turned into a goddamn wizard. Blessed be, bro.
Resolvers and Synchros were extensively used in aircraft navigation equipment and auto-pilot systems from the 1970s onwards. They were used to determine and control the position of shafts and flying controls within the aircraft systems. (ex RAF Navigation systems engineer) :)
Btw you could still use this to produce more than enough accuracy on your 48" milling table by having it operate multi-turn. It is not restricted to just providing output for one rotation. If you did this then you would also need another encoder (like a potentiometer) to give you a rough position and then just use the resolver output to measure the fine position. I remember back in the day with one analogue type aircraft altimeter (clock faced ones) that the resolver would do one turn for every 12,500 feet that it indicated. There was an additional course potentiometer which could be read to tell you which segment you were in ie 0-12,500ft or 12,500 to 25,000ft or 25,000 to 37,500ft etc etc :) funny how you remember all this shit lol
I used to build electric motors at my old job. We made one for GE Aviation that used a resolver. The motor was meant to operate flaps on a fuel tanker jet's refueling boom, to aim it at the fighter jets "special place" for aerial penetration. We used 400Hz sinusoidal AC for those resolvers. Hooking the Sine and Cosine outputs to a Scope and overlaying the two signals is pretty cool, cause it looks like you can see the waves rotating, even though it's a flat image.
New subscriber here, completely fascinated by your hilarity, I've literally watched every video you've ever posted, its taken me 2 weeks but I've watched them all, keepem choochin along, this channel is skookum as frig!
Hi Uncle BF,
My job as a lead maintenance mechanic means I'm always trying to explain electrical, hydraulic, and mechanical concepts to the trainees.
I love the idea of transformer as gear reduction, brilliant! I will be using that one. As well as the whole explanation of the difference between encoder and resolver.
Thanks,
Boney Snatches
Weird I was just rewatching part of this last night. As its been on patreon for ages
x9x9x9x9x9 Yeah, I was just thinking I've seen this... That's cause I helped pay for it!
x9x9x9x9x9
>it flew, now it's aerospace grade
Why I love this channel.
It has basically one spool that gives the x-axis and one the gives the y-axis, some sine+cosine and you get the angle.
Which means that the measured _angle_ doesn't have a linear precision, it will be more precise when one of the axes is near zero and less when X_value=Y_value OR X_value=-Y_value.
I'm just thinking: this would make for a good exam or exercise for a mechanical engineering faculty
That was really weird, I saw this like earlier this week and went huh... I don't remember this, figured I must have watched it before and didn't but now its back with a fresh upload date...
A few thoughts regarding the waveforms on the scope.
1) it'd be good to have the primary on a third channel and trigger off of that so the waveforms don't move around as much.
2) I'm not sure you're connected to the secondaries quite right. When one channel passes through zero, the other should remain around its maximum, but we're seeing the yellow trace isn't at its max when the blue goes through zero.
3) if you could sort out getting the correct secondaries, then if your scope has an x-y plotting mode, that would be a great way to look at the encoder output: you'll get a line on the screen, the angle of which direct reflects the angle of the resolver.
Oh man! Your explanation of a transformer and resolver was amazing. I'm not sure how you make it any easier to understand than that. I will be sharing this video a lot to explain that exact concept. Well done!
ive never heard electrical engineering explained explained so thoroughly using the the term "thinga-ma-jig" you're a special creature, well played my friend.
As far as I know encoders have no problem reading absolute position. My understanding is that they use a kind of rotating barcode giving a distinct output for each 'position', and can use perhaps 11 bits or more (based on one particular high end encoder I know of) giving 2048 readings of position, and on startup the particular combination of 'light and dark' in the encoder will give position. I do know for certain that at least some high end (read CNC machine tool grade) servomotors use encoders rather than resolvers.
Very interesting! One thing to note, though: there are absolute position rotary encoders. They use multiple sensors and usually use Gray codes to eliminate slight sensor misalignment, but they have a fixed resolution that is determined by the number of sensors built into the encoder. I believe the device here is often called a quadrature encoder and the resolution is mostly only limited by the input signal and external ADCs: more expensive but more better!
I've been an avid watcher of your vids for a couple of years now and all I can say is that I still have no fecking clue what you are talking about half the time. When I say about half the time, I mean all the time.
All I'd like to say is that you, sir, are an educator. Fill every school, college and Uni with copies of you and the world would be a far better adjusted shit heap than it currently is. In my work I need to be able to communicate with folks who run the entire spectrum of intellectual/educational levels and if I were able to do what you do in the way that you do it, then my work would be so much easier and I would be more successful.
Keep doing what you do and do so well. The world is a better place with you in it.
Take it easy and stay safe matey.
I normally only have a slight idea wtf you're talking about but damn am I addicted to these videos!
The DAvE cad gag was great. Love seeing youtubers reference eachothers great content.
CNC field service here. I can't stop watching your videos! I felt like I was in a classroom on this one but by the end of the lightbulb went off ha ha! Good stuff thanks
A lot of microcontrollers prefer budgeting for having a fancy DAC to a dedicated ADC, so their ADC operations are done with a few comparison operations on the input with iteratively incremented DAC outputs. Not the most efficient, timewise, but you get as much resolution on the ADC as you can have on your DAC, for one piece of hardware.
AvE i am truely amazed at your engineering knowledge and skill. I wish i had just a portion of your knowledge. I never had any formal training but years of what i call backyard experience. I have got by and at times done a few things that even surprised myself. So watching you is trueeducation for me thanks for sharing your knowledge with us.
Quick point - when checking unknown wires into a black box with an ohmmeter remember to also check in reverse because lots of components have a bias.
I am astounded by how you can take something relatively unknown and deduce exactly what it is.
To watch the process of discovery and almost see the lightbulbs go off above your head is something I could watch all day!
I feel like I have learnt so much since watching your channel I just want to say thank you for Sharing.
Also the combination of high intelligence and the inner mentality of a 10 year old letting out barking spiders and getting into general fuckery is not only probably highly dangerous but fucking funny!
Resolvers can also be parallel connected: you ecite the coils in both, turning one resolver will result in the other one turning the same. (It's used for indicators and remote actuation.)
In response to some of the comments below. I've been bumbling around as a mechanic for 20 years heavy industrial mechanic that is. And I love this channel I've learned some neat tricks that I've used at work once in awhile. I only subscribe to 2 channels and this is one of them. And this is my favorite channel to watch on the throne. A higher compliment I can not bestow. I find the general attitude of the channel awesome laid back hey let's tear schitt up and learn something keep up the good work. And some of the comments are f$&/info hilarious. Great channel please don't ever stop.
AvE, I've got a couple of questions about your ADC math. 1: since we're looking at 2 coils and subsequently 2 data points wouldn't we be multiplying our possible digital values instead of adding them? 1024*1024 = 1,048,576 instead of 1024+1024=2048? 2: since we're dealing with bidirectional voltage inputs would we effectively double our usable bits or would we be borrowing one bit to deal with the +/- sign?
Thanks man! Keep up the amazing work!
Resolvers are also used in modern cars with electric power steering - which is the majority of cars made in the last 5 years (trucks are still using hydraulic power steering because of power needed to turn those large wheels). Resolvers are also used on electric cars in their drive motors. You did an excellent job explaining how they work in very basic terms both pictorially and with the oscilloscope.
Absolute encoders will give the shaft position. They use multiple optical gaps and a disk with 2, 4, 8, etc divisions per revolution. The field type that you have is going to be more rugged, long term, especially if there is vibration or electrical noise. I pulled an optical rotary encoder out of a rolling mill once which had been pumped full of crap because the seal failed. A field type would have just kept working. The input signal is an ac signal, so it uses filters to isolate the signal from noise.
Many lolz to the DAvECad/ AvEcad reference.
As an engineering technician just starting my career, I can truly say I wish I knew you personally to share your wisdom of material science and industrial enginerd'ing. your patreon page was being slow a few days ago, I shall check it again.
You can have a digital resolver as well, using either switches or slits, patterned in Gray Code. That is probably harder to manufacture than just magnetic coils, as you need a switch/sensor for each bit, but it would be much much easier to read (no ADC needed).
I suspect that magnetic one is supposed to be run on sine wave input. You will get a more proportional ratio, input/output, if you drive it with a sine wave.
WOW!
Thank you again for another incredibly informative vijeo!!!!
I am not too savy on this type of stuff -so I will watch this one many times again!!
However, because of your skoochum vijeo, once again I just happily received an advanced course in both mechanical engineering and electronics. And I'm lovin' it! But yes...my brain-pixies do hurt a bit at the moment!!!...so I'll re-watch, process the information, and get my brain to skootch with your information.
Thanks professor!
Always GREAT stuff AvE!!!!!!
THANK YOU!!!!
Who ever invented this resolver is an an actual genius. Im sat here at uni studying aerospace engineering and watching this(not at the same time). Brilliant
To read angle resolver they seldom use just A/D and do the math inside a processor. They now have a variety of IC's that provide a precision SINE wave to the primary of the resolver and read the sine and cosine. Very seldom are resolvers driven with a square wave. Most are not just 10 bit. Most are either 12 bit or 16 bit resolution with a digital output. The best way to grasp the shaft position on a scope is to set the scope to vector XY display and use the drive signal to gate the intensity to blank 1/2 of the resulting line. The 1/2 line on the scope is a ray directly showing the shaft angle. This analog vector is precise. This type of resolver is sometimes referred to as a 4 quadrant resolver when it is converted to vector amplitudes and polarity. Another way to display the result on a scope is to use the drive signal to integrate the signal and use the zero crossing of the integrated signal (sine peak detection) to operate a pair of S&H slicers. The two voltages are DC analog vectors of the shaft position, which when displayed on a vector scope display produces a dot that circles the 0,0 center coordinate. Most of the time this DC S&H, and A/D, And conversion is completed inside 1 custom chip instead of using discrete parts. A typical one chip solution for 16 bits is the RD-19230 IC. To eliminate brushes, most precision resolvers rotate the primary on the shaft and is driven by a rotary transformer with the primary and secondary coaxially on the shaft and shell. Then the secondaries are as mentioned a 2 phase winding on the stator.
AvE, they have absolute encoders these days. Multiple bits of gray code and what have you.
Im an automation engineer and It's been a while since I've seen a resolver. Great explanation of how it works 👍. This technology is super old school and now days you would use an absolute encoder.
No, it depends on the usage, Resolvers are still current.
Seems like the kind of part that would report back to the computer in an airliner on flap/rudder angles, etc- and with the VERY strong tensioner built in, maybe even landing gear.
I like the analog A.C. Synchro. Has the same features as far a positioning memory, but has an A.C. voltage output. I think the Synchros are way more sensitive. Cool stuff Ave.
When you use 2 10-bit ADCs together like that, you end up with a resolution of 20 bits (because you multiply the two values together, not add). That means you get 2^20 or about a million different positioning values. That makes it even more accurate.
I sent my brother a pic of my new Cockfordollie shirt, He sends me back a pic of his Release the Schmoo shirt. DANGIT he beat me!
A resolver is an older method of determining the location of the robot arm, which is then used to either hold its motors, or to determine which direction to move the motor to reach a particular location. most modern robots actually use encoders with battery backups because they are much cheaper and easier to put into a robot. the absolute resolver is still relevant technology, but its not used much any more.
Now that this video showed me how to make things aerospace grade, it seems many of my tools have been made aerospace grade considering they've flown around the room after I busted a knuckle. Good tip.
Compared to encoders, resolvers have the advantage of being less susceptible to vibration and contamination. Can also be used in a submerged environment. Tamagawa Seiki also makes resolvers for the Prius that are installed inside of the crankcase. They are a cool company and have a really amazing automated production facility.
You teach better than some of my college professors... And i have learned so much from your vgo's! Thank You!
current = electron flow
current flow = electron flow flow
Respectfully,
Department of Redundancy Department
Isn't "Current flow" the flow you are getting at the moment ?
One Coulomb per second squared.
So, I'm curious. If you had one Coulomb per second squared going through a one Henry inductor, would it create one Ohm of reactance? Guessing yes, because that would make sense with the way SI units are defined
Something something ATM machine.
James Ellis that’s the current current flow
Great explanation of transformers for those of us still confused by light bulbs!
I must have taken an extra tab and fell down the rabbit hole to end up here.
Wow that was greatness !!!. awesome demo of a resolver.
Describing the electrickery LEGOs in terms of mechanical devices is exactly the sort of thing that makes it all click in my brain.
Same method they used to use in old analog automotive gauges - sine/cosine coil. Varying the voltages on each coil would position the needle on the gauge. Caveat is that there is a 180 degree ambiguity with a sine-cosine coil like that drawn on the table.
Hello AvE, resolvers like this are driven by sine wave. The two pickup coils have a voltage whose phase relative to the excitation and each other gives the angle. Clever software can calculate the angle or multiple manufacturers (Ti, Analog, Tamagawa and so on) sell decoder chips which give position as well as velocity.
Great vid though!
They are also absolute encoders (what you referenced was incremental) that know position upon power up as well. They are more money, but work just like an incremental but have unique outputs for each position (resolution specified with $$ spent) they have the added benefit of being digital in their very design so no adc needed.
Awesome description for this laymen. Really cool!
If you use a resolver as the feedback for a servo you do have to have a way to home it. Since that won't be locked into just one rotation. On power loss the servo won't know it's location either. So absolute for what you plan on using it for, but not always an absolute position indication.
Thanks for posting the video. Awesome straight forward explanation. Answered allot of questions I had as to how these worked. BTW I've got a skookum as frig Ave t shirt. When people ask what that means, my answer is if I have to explain you wouldn't understand.
Small tip: on that Rigol Oscilloscope you can change the font size of the measurement functions like the Vrms that you used here. (It's somwhere in the "Display" menu if i recall correctly) Might make it easier to read/film.
Using this on the Bridgeport would work great! You did not take into consideration the circumference of your gear. The smaller the gear, the less linear travel you would have per rotation increasing your accuracy. With that being said, you would loose your ability for the machine to know the startup location because you would have many times in your travel that would give any given value. This could easily be overcome by integrating a homing function with a limiting switch. If you really wanted to be tricky, and you wanted to maintain your startup location, you could gang 2 of these units together. If you had one that returned a very corse interval and one with a fine interval you could compair the 2 outputs to get a ferry accurate reading.
Alex Grimes I believe Fadal cnc machines were equipped with resolvers.
Where I worked we had a Cincinnati with resolvers on the servo motors and glass scales for each axis. It would repeat position to within .00005 inch. yes that's half a tenth.
Wouldn't it be easier to integrate say a variable resistor to the unit to act as a counter for more than 360 degrees? Maybe even a linear resistor with a contact on a fine thread? The variable would be good to say 2 inches per step, with the resolver getting around 1000th inch per step? I'm not in this field, just spitballing lol
You can get absolute encoders which use coded disk to provide absolute position. We use them in our automatic satellite pointing earth stations.
For the idea of using that on the bridge port. Could you put that gear that is on the resolver onto a rack gear, then get the 2048 steps over the circumference instead of the full travel? Granted you would need some sort of counter for multiple rotations. But if that was digital, that would be relative, with location inside that rotation being absolute. My two sents.
Keep up the skookum vidjayos.
Chris Hurlbut I figured the same thing, gear it so it's 2048 steps over 1 inch instead of the full 45"? Or half an inch for even more accuracy? At what point do you draw the line? At what point is it essentially useless to be more accurate?
I was thinking the same. It appears to be about a 4" disk that you could connect to. So, roughly 12" circumference meaning 4 turns for the full travel which gets you to about 5 mil tolerance. Not a clue if that's good enough for the ole' Bridgeport but sounds good to me!
"There it flew, it's aerospace grade aluminum". That's one of the funniest things I've heard right next to the "Saskatchewan socket set".
A resolver is a type of rotary electrical transformer used for measuring degrees of rotation. It is considered an analog device, and has digital counterparts such as the digital resolver, rotary (or pulse) encoder. en.wikipedia.org/wiki/Resolver_(electrical) Gotta love Gargle :)
I suspect that the big "watch spring" is wound up to remove / reduce backlash in any gear chains involved in the assembly.
Crazy when you consider most cars use hall effect, VR or even wiper-based rotary sensors for positioning information. These would be way better for throttle position, crank speed, cam phase etc. The Maserati 3200 is quite well known for throttle potentiometer failures in the pedal and throttle body - they're wiper based. Maserati want you to replace the whole throttle body at a cost of something stupid like £1-1.5k but men in sheds will convert to hall effect for a couple hundred.
Well I am glad this popped up on my UA-cam feed even if it is a year old. This thing is awesome. I had no idea this existed
You can get absolute positional rotary encoders too, different to quadrature encoders, they tell you an absolute angle as gray code which is easily converted to binary, however they can't give you precision like this thing
So for people who didn't get that awesome and simple explanation: this little thing can make robot that can show you middle finger in perfect angle of 90° and hide it fast enough so you will not see it.
10:57 Since the voltage induced in the rotating coil varies according to the cosine of its angle to the stationary coil, angular resolution will be much finer near 0* (parallel) and much coarser around ±90* (perpendicular), assuming the A-to-D is linear with voltage.
Chances are the reference coil will be a different resistance than the sin and cosine coils (which will be equal). Used to use them to know fuel valve position and for variable geometry on gas turbines
Would love to say something witty but all I got is a big "thank you", both for the introduction to a resolver (never heard of it before) and the great explanation of how it works. BTW, regarding what you said at 5:14, what is the difference between 0 and 360 degrees? Love the channel, thanks again.
Holy shit that's what 1024 PPR actually means! You're damn good at explaining electrical thingies to mechanical people.
Excellent description of how a resolver works. Thanks for that.
Encoders CAN be absolute value using Gray code: (from Wikipedia): "Optical absolute encoders
The optical encoder's disc is made of glass or plastic with transparent and opaque areas. A light source and photo detector array reads the optical pattern that results from the disc's position at any one time.[5] The Gray code is often used. This code can be read by a controlling device, such as a microprocessor or microcontroller to determine the angle of the shaft."
Literally the only explanation of a transformer that made sense to me! Thanks a million, eh!
You should see if you can find an old FM Tachometer. I really like your example of what a transformer does. Very good analogies.
the resolution of the resolver for use on the bridgeport is 2048 pulses per turn of the handle, not over the 48 inches of travel of the machine.
idk what math you did but on a milling machine with a 4 threads per inch lead screw, that means 4 full turns per inch, so 1440 degrees per inch. You said at 10 bits you get roughly 0.2 degrees, thus
1440 -> 1
0.2 -> x
x = 0.2*1/1440 = 0.0001 inches
That's a tenth - 2.5 micron, I doubt most milling machines even have that much precision, so I'd say about good enough. Plus you can just gear it down, a 2.5:1 ratio would get you to 1 micron, and those are dry air seal tolerances, you don't see that everyday with traditional machining. Thanks for the vadjeo!
I think that got pinched from the LIGO array over at Hanford, WASHINGTON. How are they gonna detect gravitational waves without that??? I want another neutron star collision report!
Transformer Torque Converter analogy just blew my mind a little bit. (@ 06:35)