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How do 3 axis robots you can buy for 100$ (3D printers) have a static accuracy of 0.05mm? It's not control theory, but mechanics and steppers.
Yes but they're not robot arms so it's not as fascinating. The length of the arm amplifies error so if you made a "mechanics and steppers" arm with the same positional accuracy as a printer, the motors would have to be much more precise or if you geared them down, the backlash extremely low like an industrial robot arm.
How do 3 axis robots you can buy for 100$ (3D printers) have a static accuracy of 0.05mm? It's not control theory, but mechanics and steppers.
I'm curious what would be the best way to replicate an x/y (optionally z) system with 0.05mm or lower accuracy? Without sacrificing speed of course.
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. https://electroimpact.com/Products/Robots/AchievingAccuracy
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. https://electroimpact.com/Products/Robots/AchievingAccuracy
Of what use are the primary encoders then?
Great, but that robot isn't doing an actual task? I sort of struggle to see how getting good positioning accuracy from a high backlash system under zero load can have a useful application. Maybe just lack of imagination on my part. There is this trend that says make and buy bad hardware, the software will solve it. I haven't noticed that paying off. Tesla using webcams for self driving is an example. Boeing designing…
You have oversimplified the Boeing one: their goal was to create an efficient plane to compete with Airbus without needing the expense and delays of a new type certification. To do this they needed bigger engines on the same frame, which in turn needed to be mounted further forward affecting flight characteristics and requiring retraining. Retraining would be a sales killer so they hacked on some software systems to…
Boeing’s argument is that an MCAS trim runaway is able to be addressed by the (memory item) Trim Runaway checklist and the crew of ET302 correctly used the STAB TRIM CUTOUT on that checklist during their attempt to save the flight. They then undid that action, in order to manually command nose-up trim (also reasonable under the circumstances, though contrary to the checklist), then stopped commanding nose-up trim while leaving the trim runaway checklist item reverted, allowing MCAS to continue the trim runaway that they’d previously correctly stopped by following basic 737 training. Then the flight was lost.
Boeing did wrong here, but their argument was that if a 737 pilot correctly executed the emergency checklist that is drilled into them during initial type training and in recurrent training, they’d be able to overcome that emergency. That falls into at least the probably technically correct category to me.
(The yoke displacement method to disconnect the autopilot was not part of the emergency checklist for stab trim runaway.)
Earlier quoted context omitted.
Of what use are the primary encoders then?
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.
https://electroimpact.com/Company/PatentFiles/US8989898B2.pd...
Earlier quoted context omitted.
Or, in the case of the 737Max, to trigger a chain of events that proved lethal to hundreds to people. That’s the secondary use of the AOA sensor in combination with the FC software that they implemented. It would have been relatively easy to integrate the AOA input with other sensors to eliminate this problem, but it would have invited a deeper look at the hazards of their design decisions. Bean counters bathing in b…
> Bean counters bathing in blood, all the way down. No resource is infinite and money is an important constraint in any engineering project. Engineering is all about making compromises. Good engineering is making the right compromises: especially when life and death decisions are being made. Casually blaming "bean counters" is a distracting fantasy available to anyone that doesn't have to make real-world decisions. U…
Bean counters bathing in blood, all the way down.
The forward mounting of the engine nacelles could have been countered with a small adjustment of the sweep or the surface area of the horizontal stabiliser, instead of the faulty flight control software solution, keeping the aircraft an aerodynamically safe aircraft as had been earlier generations. But that would have been a de-facto admission that the fundamental aerodynamic characteristics of the aircraft as certified were changed by the forward mounted nacelles.
They chose to monkeypatch the flight control system instead of making a minor change that would have produced the inherently safe aerodynamic characteristics that the aircraft was certified with.
They did this to avoid the delay and cost that would have resulted if they had been required to prove the aircraft design was still airworthy. There’s a reason that new designs must be certified to be used in passenger transport. They tried to work around the fact that the 737 max is a substantially new aircraft by monkeypatching the FCS to compensate for a potentially dangerous aerodynamic flaw that was introduced by the new location of the engines.
They chose to produce a more profitable but potentially dangerous aircraft instead of letting the engineers do their job and make the aircraft stable with the new engines. Regulators were also complicit in the regulatory evasion. Hundreds died as a direct result of this malfeasance.
Bean counters bathing in blood, all the way down.
With direct drive (no gear box), do we still need the secondary encoder?