Re: Open source low cost servomotor controller
The purpose of open source is to aid rapid development by allowing a collective of developers to work on a project and to encourage development
Yes, but that is just your view of open source. It may not be everyone elses'.
At the end of the day it is HIS project to do with as he pleases, but as the files are all available
Precisely.
If macdowswr wishes to run HIS project under slightly different 'rules' from what you want, that is his perogative. He has generously made the sources available in the format he uses. That is 'open source'.
What I want to see is a report on how his completed PCBs work with a real load. If they pass that test - and the SW successfully handles various fault conditions, then it's all pretty amazing stuff.
As an aside: these modern digital MOSFET drives with uP cores give a performance which older CNC machines could only dream of achieving. These drives (by M) are not single chip drives for tin-can steppers: they are way, way beyond that. The idea that they have to be made available at $50 a pop is a bit humerous: they can replace older drive systems costing $10k or more.
My 2c.
Cheers
Roger
Re: Open source low cost servomotor controller
Quote:
Originally Posted by
RCaffin
The purpose of open source is to aid rapid development by allowing a collective of developers to work on a project and to encourage development
Yes, but that is just your view of open source. It may not be everyone elses'.
At the end of the day it is HIS project to do with as he pleases, but as the files are all available
Precisely.
If macdowswr wishes to run HIS project under slightly different 'rules' from what you want, that is his perogative. He has generously made the sources available in the format he uses. That is 'open source'.
What I want to see is a report on how his completed PCBs work with a real load. If they pass that test - and the SW successfully handles various fault conditions, then it's all pretty amazing stuff.
As an aside: these modern digital MOSFET drives with uP cores give a performance which older CNC machines could only dream of achieving. These drives (by M) are not single chip drives for tin-can steppers: they are way, way beyond that. The idea that they have to be made available at $50 a pop is a bit humerous: they can replace older drive systems costing $10k or more.
My 2c.
Cheers
Roger
At least a reply worth responding to.
Yes it's his project and he's the only real developer involved in it and mostly for the reasons I stated.
I'm in no rush, I have all the time in the world, if he abandons it I'm sure I can commission someone to finish it for me.
This driver will never replace an expensive servo system without increasing the voltage and current capabilities to handle significantly higher loads and larger motors and to think otherwise is foolishness.
This is a hobby product with some light commercial/industrial small machine applications but I wouldn't expect it to drive a CAT30 size machine when the power requirement is 2KW+ per axis and just slinging the 400lbs dry table around requires more power than an outrunner can provide.
I look at some of these 500W and 1KW outrunner BLDC motors and the peak current exceeds 50A that it's just not possible to see the rated power from the motor when the current is just not available from the drive and the efficiency of an outrunner isn't very high so don't htink input power equals output power cause it's not even close.
The way that some of these outrunner motors are rated is so far from reality that it's hard not to laugh, not one actually came close to the rated HP on a dyno and from what I can only imagine they did to get the power was, they have calculated the HP based on the voltage and current consumption which is no where near reality.
I've never seen a modern servo system costing $10K, our Okuma 8050 drive system costs $2700.00 and $1600.00 of this cost is the motor cost, we bought an extra to have in stock in case of a failure to reduce down time as advised by Okuma but our older 7040 machine the motors alone are $3500.00 and physically twice the size.
During development, cost is important, as a hobbyist you can't afford to go through $100.00 in fets on a weekly basis to work out a current saturation problem or burn up a $100.00 board trying to get the code right and trying to do it with one board is nothing shy of a waste of time cause your gonna blow one at some time during development.
Access to good quality BLDC motors designed for servo applications and not converting an outrunner reduces the risk of thermal overloading and I'm lucky to have a source of servo drives that meet this specific application for basically the same cost so I'm one step ahead of the game when the product is finally completed.
The OP picked his software and manufacturing sources and these alone are the largest contributors to the lack of willing developers to join in, unless he's offering them free boards as an incentive most look at the cost to be involved and find it unreasonable and move on.
The OP seems knowledgeable, I've tried to engage him in a conversation to work on a side project of a single axis SMT32F1 driver by providing the hardware for free and I didn't even get a courtesy reply so I'm not expecting anything miraculous from him.
I'm looking at his code base and reducing and adjusting it as required for a single axis application (STMCube software is useful to a point), PCBA production cost $31.00/pc, 25 board being produced as I write and I'll send a couple off to some interested developers so having a single axis solution in the interim will be available to me as I wait for the 2-axis, 3-axis and 4-axis drivers to be completed by the OP.
Re: Open source low cost servomotor controller
Quote:
Originally Posted by
websrvr
I'm content letting you be the sole developer, if and when you give up and it's incomplete, I'll pay someone to finish it, I think it's a great project with unlimited potential and I have a million and one uses for it.
Nice of you to whinge about others responses but man you can't see just how rude in someone else's thread you are?
If all the aspects are so bad, and the design is so poor, and the hardware is laughable, and you expect it will fail dismally anyway, why on earth aren't you taking the source and forking it yourself?
And if/when you get the boards done, and they're not so outrageously high in cost, I might consider buying some!
cheers, Ian
Re: Open source low cost servomotor controller
Yeah, those tiny outrunner motors look real cute, and probably go great for 5 minutes on an RC plane with a LOT of air flow. Don't think I would try using one on a CNC though.
a CAT30 size machine when the power requirement is 2KW+ per axis
Dunno about the 2kW. My machine runs a BT30 spindle, and the motors are rated at only 300 W (XYZ) and 500 W (spindle). Ah, but the motors are Baldor industrial DC motors or equivalent, and they are rated for 24/7 at full power. And yeah, they are a lot heavier than a tiny outrunner. BIG lumps of machined cast iron I think.
The power rating is a bit deceptive too: I miscalculated when peck drilling some titanium and suddenly noticed I was putting about 2 kW into the 500 W motor for short periods (a few seconds each). Oh well - oops. No damage. Bottom line for me: show me the 6 hour rating. That is meaningful on a CNC.
as a hobbyist you can't afford to go through $100.00 in fets on a weekly basis
Been there, done that, but not as a hobbyist. :) :) Ended up with a large jam jar of blown TO220 FETS. That was before they put the intrinsic reverse diodes into the packages. The switching transients were murder.
Let us wait and see. Nothing like the enthusiasm of a start-up.
Cheers
Roger
Re: Open source low cost servomotor controller
Quote:
Originally Posted by
aarggh
Nice of you to whinge about others responses but man you can't see just how rude in someone else's thread you are?
If all the aspects are so bad, and the design is so poor, and the hardware is laughable, and you expect it will fail dismally anyway, why on earth aren't you taking the source and forking it yourself?
And if/when you get the boards done, and they're not so outrageously high in cost, I might consider buying some!
cheers, Ian
I offered the OP an opportunity to produce boards at 1/2 the current cost, he rejected the offer so if you want to complain about the price complain to him, it was his decision to use an expensive solution and beyond my control.
It would help if you could read english, then you would see I praise the concept, the design and the efforts of the OP but unfortunately that where it ends and you can't seem to grasp what I'm talking about and clearly an example of someone looking for their five minutes in the lime-light as you try to make something out of nothing.
Why you insist on fabricating and twisting what I say to mean anything more than what I have stated is a common problem you seem to have repeatedly made and it's a good reason that you should refrain from involving yourself in matters way above your comprehension level, now I'm going back to just ignoring you.
Quote:
Originally Posted by
RCaffin
Yeah, those tiny outrunner motors look real cute, and probably go great for 5 minutes on an RC plane with a LOT of air flow. Don't think I would try using one on a CNC though.
a CAT30 size machine when the power requirement is 2KW+ per axis
Dunno about the 2kW. My machine runs a BT30 spindle, and the motors are rated at only 300 W (XYZ) and 500 W (spindle). Ah, but the motors are Baldor industrial DC motors or equivalent, and they are rated for 24/7 at full power. And yeah, they are a lot heavier than a tiny outrunner. BIG lumps of machined cast iron I think.
The power rating is a bit deceptive too: I miscalculated when peck drilling some titanium and suddenly noticed I was putting about 2 kW into the 500 W motor for short periods (a few seconds each). Oh well - oops. No damage. Bottom line for me: show me the 6 hour rating. That is meaningful on a CNC.
as a hobbyist you can't afford to go through $100.00 in fets on a weekly basis
Been there, done that, but not as a hobbyist. :) :) Ended up with a large jam jar of blown TO220 FETS. That was before they put the intrinsic reverse diodes into the packages. The switching transients were murder.
Let us wait and see. Nothing like the enthusiasm of a start-up.
Cheers
Roger
Hard-rail machines require massive inertia motors and a CAT30 Okuma 6030 with a 400lbs table or our CAT40 Okuma 7040 with a table weighing in at over 600lbs, 500W wouldn't move it but our new Okuma 8050 with linear rails and medium inertia motprs is over-powered and 500W would probably move it but most likely not at reasonable speeds.
I've set aside a small budget for 75 motors and have 25 coming now as I start to build some frame around them, I'm thinking travels such as 16 x 12 x 16 in R8 / BT20 size tooling would make for a decent size hobby mill, I've got three BT20 ATC spindles already assembled and will be starting to assemble the 2HP output power 12,000RPM asynchronous servo spindle motors to drive them in the next month or two based on an existing design that has been in use for a couple of years now so I'm confident it's more than suitable for this application.
While I've mostly used steel and cast iron in frame construction, I might try my hand at a cast-able material platform in either a true polymer or real epoxy based with multi-sized aggregate and not that crappy (non real) epoxy which is polyester resin based or perhaps something along the lines of epucrete which is a polymer based concrete type material currently used in machine.beds by some machine manufacturers but may be not cost prohibitive as I'm still looking into it.
There's also some other concrete type material being used to cast countertops with which look promising and I'm talking with a local factory that produces some impressive looking countertops who is willing to consider a side line of casting small and medium sized machine frames if the materials holds up to some abusive vibration testing and some environment testing for durability and longevity.
One reason for considering a cast-able material is low production cost, the only real cost is in the mold itself and precision is only in certain surfaces like rail seats and column perches, everything non relevant is purely comsmetic, 15 or 20 gallons of casting material would be less than $250.00 including the cost of the inserts and once set, no post machining is required, all precision is done in key surfaces in the mold and the molds are designed so that the key surfaces can be calibrated so it does have some excellent inexpensive frame potential in quantity productions to swallow the cost of the mold but I am willing to produce the first mold at my own expense in a machine size suitable for most home/hobby applications with a proposed travel of 16 x 12 x 16.
We have access to some equipment at a nearby shop that has a large Nacamura-Tome 3080L composite lathe, I don't care what anyone says, a 24in 6-jaw power chuck is massive by any standard and with a 6.5in thru-hole makes larger material easier to manage, it looks like it's made of black granite and installation was done in a morning by simply pouring 4 puddles of concrete, setting the lathe on the puddles and leveling it before the concrete set and then powered up and ready for use the next morning, of course this particular shop has some impressively large toys and it's always a treat to go over and ogle some of the modern technology used in mold, stamp and die making equipment such as frame-less articulating arm milling machines that can machine in any 3D spatial position of the work area with extreme precision and Ezzel, a local grinding shop that does some insane precision grinding makes the hardest job look easy so I have some perks being in the industry.
Re: Open source low cost servomotor controller
our new Okuma 8050 with linear rails and medium inertia motors is over-powered and 500W would probably move it but most likely not at reasonable speeds.
I should have mentioned that my machine uses linear bearings everywhere. That does make it easy to move.
In fact, what was almost rather frightening was the time I stripped off the X axis ball nut and tilted the whole machine slightly. The carriage went flying at just a few degrees off horizontal. Serious oops moment there!
Speed - well, more power => more acceleration. Very true. But my machine is a 'hobby' machine: even though I do some production work (for sale), I am not dependant on it for a living. It is fast enough. A nice BT30 spindle, up to 3,500 RPM. It does a nice finish on Al and steel.
cheers
Roger
Re: Open source low cost servomotor controller
Quote:
Originally Posted by
RCaffin
our new Okuma 8050 with linear rails and medium inertia motors is over-powered and 500W would probably move it but most likely not at reasonable speeds.
I should have mentioned that my machine uses linear bearings everywhere. That does make it easy to move.
In fact, what was almost rather frightening was the time I stripped off the X axis ball nut and tilted the whole machine slightly. The carriage went flying at just a few degrees off horizontal. Serious oops moment there!
Speed - well, more power => more acceleration. Very true. But my machine is a 'hobby' machine: even though I do some production work (for sale), I am not dependant on it for a living. It is fast enough. A nice BT30 spindle, up to 3,500 RPM. It does a nice finish on Al and steel.
cheers
Roger
I've been manipulated into accepting the following concept, there is little difference from a machine for hobby use and a machine for commercial/production use, I should expect the same performance, repeatability, precision and power based on the platform size.
I would never build a wooden router or power one with a dremel or porter-cable wood router or a cheap water cooled china high speed ER20 spindle, if the spindle is not designed to be air cooled and used continuously and properly power rated such as actual output of 24,000RPM 3.0KW then the spindle is considered garbage just like those cheap china 24,000RPM water cooled spindle rated at 3.0KW, but are 220V/10A and really only outputs 1.43KW and for mills it better be an S1 rated 2.2KW (3HP) output (220V/12.75A) 100-10,000RPM asynchronous servo spindle motor driving a BT20 or R8 spindle or an S1 rated 3.0KW (4HP) output (220V/17.25A) 100-10,000RPM asynchronous servo spindle motor driving a BT30 spindle and these are considered my bare minimum power requirement if I expect to do some real work.
Yes I can make a machine that moves along with 100W DC servo motors but if I can't cut stainless at reasonable feeds because it stalls an axis then I've made a wrong choice in axis motion power and need to make a new choice immediately.
The cost of 220V AC servos with drivers is pretty cheap now, 750W motor and drivers can be had for about $300.00 new and 16in travel, 1/2in DIA 0.100in pitch ballscrews are about $150.00 and provide 300IPM rapids and 100IPM cut speeds so a small mill with sufficient power to cost steel and aluminum shouldn't be expensive but a 500W BLDC servo and driver should be doable for half the cost and still be within the axis motion power requirement.
If a 1in DIA 0.200in pitch ballscrew is employed then I would expect nothing less than 750W using a 2:1 reducer and still see 300IPM rapids and 150IPM cutting speeds without stalling an axis and yes, 300IPM rapids on 16in of axis travel looks fast, using 1.5KW motors and no gear reducer gives you 600IPM of rapids and 300IPM of cut speed without stalling and becomes mandatory when large mass comes into play like moving and stopping 400lbs tables.
Re: Open source low cost servomotor controller
Macdowswe,
You are doing a most awesome job regardless of the rumors the guy from the sunshine state is spreading.
Got to get back to the bakery now.
JoeyB
Re: Open source low cost servomotor controller
I've been manipulated into accepting the following concept, there is little difference from a machine for hobby use and a machine for commercial/production use, I should expect the same performance, repeatability, precision and power based on the platform size.
Dunno about 'manipulated', but I will go along with the demand for quality.
Perhaps one should back off slightly and treat the area as being not one monolithic beast but several overlapping markets.
There is the cheap Chinese wood router market for hobbyists. If someone wants such a machine for a few k$, fair enough. It's a hobby. Treat as such.
There is the cheap Chinese 'router claiming to be a mill' market, which is where a lot of the problems arise. I'll pass on that one.
There is the not so cheap hobby mill, which can range up to - $10K maybe? Your call.
Thene there is the serious hobby and light machine shop market. Easily up to $15k.
The last two should be able to handle hard aluminium and, I would hope, steel. I would expect tolerances down to 0.01 mm for the more serious machines, with resolution well below that.
The motor powers I quoted allow me to machine steel, SS and titanium accurately. Dunno about the speeds: I work in metric, but my machine and expectations are maybe lower than yours. That's OK: I am more concerned with quality than speed. My machine meets my requirements for quality. Cutters for steel and Ti are a bit more expensive if I want them to last.
Cheers
Roger
Re: Open source low cost servomotor controller
I am excited to let you know that the time has finally come for the alpha stage of the ODrive project!
Alpha release
This consists of two components, the alpha software release and the manufacturing run for ODrive v3.2.
The alpha release will include all the core features of the board, and allow go-to commands sent over USB, as well as step/direction interfacing. You can check which features will be included in the release on the roadmap.
ODrive v3.2
The new design is ready, and can be reviewed on github. The design will go to production on Monday the 17th of April, and you can get in on the production run here.
https://static1.squarespace.com/stat...G?format=2500w
More info
If you want to read more about it, you can check out the blog post.
Re: Open source low cost servomotor controller
Wow that demo video is mad!
When does the 3/4 axis come out? ;-)
cheers, Ian
Re: Open source low cost servomotor controller
Hey Ian, Thanks!
The plan is to make v4 3-axis. But it will be at least half a year until v4 is ready. But you can just use two v3's connected over CAN to get a 4 axis setup.
Cheers,
Oskar
Re: Open source low cost servomotor controller
Hi,
Just wanted to let you guys know that there is an ODrive community getting started over at https://discourse.odriverobotics.com, with some discussion that you might find interesting.
Cheers!
Re: Open source low cost servomotor controller
Hey guys, long time no post. Thought I'd show off the new demo video:
https://www.youtube.com/watch?v=FUh36RUHzdU
Re: Open source low cost servomotor controller
Looks awesome!
Great stuff!
cheers, Ian
Re: Open source low cost servomotor controller
It's pretty cool what you're doing.
I quickly brought myself up to speed by skimming through the posts and trying to skim more quickly through the fight parts, although I admit I was rooting for one or two people (won't say who).
I was actually flying electric RC planes earlier today.
macdowswe,
First of all, very awesome, I wish I had your skill set sir.
A couple of questions for you (or anyone who knows)
The demo video (post #139), very nice, how long have you been able to continuously run that machine for? What acceleration values are you using? Looking for inches per second squared or meters per second squared or G's, something like that.
I had a look through this document you posted in a previous post:
https://docs.google.com/spreadsheets...H4Y/edit#gid=0
Is the torque in Nm (column H) valid across the entire speed range? If not, is there a torque vs speed graph? Also, do you know what the rotor inertia is for the different motors?
I ask, because I'm thinking of doing the math using some different gear reducers to predict the performance of larger, heavier machines using ball screws or rack and pinion including inertial effects. For example, calculating the maximum linear acceleration at different speeds (In mach 3 for example, you can only enter one acceleration value and you are stuck with that one value up to your top speed), the cutting force available at different speeds using a constant acceleration value, etc.
Also, not quite sure what you are doing for a power supply? Earlier there was some talk of using batteries to help out during peak demand? I can use up a 4 cell lipo in 7 minutes, but it takes 45 minutes to recharge, and that's just for one motor.