There are larger industrial robots that use secondary encoders to improve "out of the box" accuracy for more demanding tasks. The secondary joint feedback is paired with a kinematic model of the robot structure/mechanics to accurately predict where the robot tool point actually is.
It lets you see the position of the motor's shaft. That's used in some motor control algorithms, even if the motor's position isn't exactly the joint's position.
If I’m not mistaken, one encoder measures the position and force applied by the motor, while the other encoder measure the position of the slack of the business end of the robot.
How is that patent even a thing from 2009? Position feedback in robots is WAY older than that. I have textbooks at least a decade older than that patent describing that very system, so I wouldn't be surprised if it falls over at the first prior use claim it encounters.
How in the world can a company get a patent on math and basic techniques that have been around for decades before the patent was even filed? I can understand materials, unique “first come” algos, brand new mechanics, but there nothing novel in that patent. There’s nothing novel about having secondary (or tertiary or ….)feedback for a system
Legit question: if I replicate a patent for a personal non profit use, is this infringement? Perhaps it is because I'm benefiting from the intelectual property.
In the USA there's an exemption for research use of patents, specifically for "amusement, to satisfy idle curiosity, or for strictly philosophical inquiry." https://en.wikipedia.org/wiki/Research_exemption
!> Yes, replicating a patented invention, even for personal, non-profit use, is technically considered patent infringement. A patent grants the inventor the exclusive right to make, use, sell, and distribute the patented invention for a certain period (usually 20 years from the filing date).
What part of the patent in your opinion infringed by the youtube video?
Robot arms have existed long before 2015. And a lot of them use some combination of encoders. The term "secondary feedback" by itself without clarification doesn't really mean anything specific, and in terms used by the patent I would call this more of adding primary/primary feedback system.
The part that the patent seems to repeat is having secondary position sensor attached to the mechanical joint of robot (I assume as opposed to encoders already builtin into the servo drive), although patentability of even that seems somewhat questionable in 2015. I am not that good at reading patents, so maybe I am missing the actually relevant/novel part of that patent.
In the video both encoders are builtin the servo, instead of attached to the arm itself, even more the extra angle sensor introduced by author is attached directly to motor before the gearbox and it's slop which is complete opposite of what the patent tries to claim. The angle servo attached to output shaft after gearbox is what all hobby servos have.
If you go through the actual claims of patent most of them are not applicable to the video. 1) "system for large-scale assembly operations, ... secondary feedback mounted to joint ...". Not suitable for large scale asembly operations, no feedback attach to joint, both feedback systems are built in the hacked servos and can't measure any slop within the joint itself or servo to joint connection. 2) angular accuracy of 0.05 arcminutes - very unlikely 4) system of claim 1 wherein the manufacturing assembly is an aerospace assembly - no aerospace assembly making here, 5) 6rotary axis and 1 linear axis - no linear axis, 6) secondary feedback system is optical encoder -> questionable whether the optical angle sensor attached before gearbox matches the definition of "secondary encoder" as described by rest of the patent, also optical encoders is typically used for describing relative postion/angle sensor based on bunch of slits and counting pulses instead of analog amplitude measurement which gives absolute position. Typically I wouldn't bother with minute differences in classification of how the angle sensor is implemented, but since patent explicitly lists very specific sensor technologies I guess it matters. Otherwise they could just claim that there is an angle sensor/encoder. 7) secondary feedback system is inductive encoder - no inductive encoders here, 8) magnetic encoder - no magnetic encoders, 9) secondary feedback system is resolver - no resolver here (as in analog angle sensor based on ac coupling change depending on angle between two parts to directly generate the sin/cos of angle), 10) "system for acurate large scale-manufacturing assembly operations, ... >3 axis robot arm, with end tool, secondary feedback mounted on rotary joint" - this just more or less restates claim 1 only this time mentioning >=3 instead of >= 6 axis for some reason and mentions an end tool. Is ballpoint pen an end tool for large-scale manufacturing operations? Also the secondary feedback thing discussed before.
BLDC motors require electronic commutation. The motor controller must read the current angle of the motor so that it knows which phases U V W to enable via six MOSFETs.
An ESC can cheat by reading out the back EMF but this only works once the motor has started spinning, such as in a drone, but in a robot arm that is supposed to hold its position.
Shane Wighton's story of getting hired at Formlabs is interesting.
He wanted to work for the company and didn't have a way in. He built a better version of their slicing software over a long weekend and sent it to the Formlabs team. He was hired very quickly after they saw it.
I would recommend Citizenfour if you haven't seen it. It's a documentary where you essentially see Snowden leak the documents from his Hong Kong hotel room. It's amazing the footage exists.
Any suggestions for a mechanical engineer who has some coding aptitude and wants to switch careers? I'm self taught and have mostly worked on hobby projects. I have some professional controls experience programming automated machinery (PLC). My lack of formal CS training seems like a real barrier to jumping into a full-time software role.
It's true, you might be able to find a slow career move where your roles take on more and more code until eventually pure programming rolls trust your experience. However if you're looking for a faster move look into night classes, if possible. You can get a computer science degree for much cheaper in a couple years of just doing night classes along with your work. It can be hard to balance all that but career changes are usually difficult to navigate. I wish you luck!
As a long time CAD user I was surprised to learn that a CAD kernel exists as a concept and that the same kernel is licensed and used in competing CAD packages.
Solidworks, Siemens NX, and OnShape all use the Parasolid kernel.
Inventor and Fusion360 use the ShapeManager kernel.
Zeloof's father runs a sheet metal fabrication shop that makes components for other manufacturers. They do excellent work, I've worked with them in the past. I'm guessing his father knows engineers in all sorts of industries.
The common term is "pneumatics" and the components are prevalent in all automation and manufacturing. The air required is typically compressed on site.
Pneumatic actuators are relatively inexpensive, have a binary state that is easy to control, and offer a high power density.
The air in industrial pneumatic systems is filtered and dried, which would prevent these issues.
Pneumatic systems often use small orifices and valves to control the air flow which would be quickly clogged by any debris, so cleanliness is important.
An aside: PID control was, back in the day, mostly implemented in pneumatic control systems (using a set of levers, bellows springs and nozzles). Pneumatic control systems were (and still are) used a LOT in industrial control systems where e.g. flammable environments where electrical equipment is too much of a risk.
If anyone is interested in factory automation I'm working on a site to catalog different processes. A good design can often be recycled into a similar machine.
I'm trying to design a vibratory bowl feeder that I can 3D print. Designing features to align or reject parts is a bit of a dark art and it's requiring a few more iterations than expected.
https://electroimpact.com/Products/Robots/AchievingAccuracy