Jason K. Firth, C.E.T.

Instrumentation, Control, and Automation

3d printers again...

Jan 162018

Yesterday, I had a revelation about my new printer. I was pretty happy with the prints I was getting (happy to be getting any prints at all, in fact) but the quality wasn't quite where I wanted it.

 

I ran a check of the extruder calibration and found it substantially out. I asked for 100mm, but got 57mm instead. 

 

I was already looking at calibrating the extruder, so I switched to the Marlin AC branch. That branch contains the latest developer patches.

 

Along the way, I had to move my config changes to the new firmware, so I had a deeper look. One change I made is to reduce the "slow" speed while calibrating. The stock settings shook the whole thing. I also increased the number of calibration points and changed the calibration routine to take each measurement 3 times.

 

One of the additions to the marlin-ac was automatic bed levelling. I assumed the auto calibration took care of levelling, but it seems that's a different feature.

 

Someone in the flsun Facebook page suggested that my "delta kossel" and the "mini kossel" I keep reading about might be the same printer. It does seem plausible on second thought. However, it means that the example config is just completely wrong.

 

The other thing is that the flsun YouTube page appears to call the delta kossel and mini kossel different things. It's difficult to figure out whether the two are the same or not.

This speaks to a fundamental of maintenance: defining your equipment. Giving it consistent naming, giving it a unique identifying number that functions within a system. For a company with perhaps 9 different products, this ought to be trivial. Perhaps a digit for product category (3d printers), one for product type (delta kossel), one for the subcategory (mini/standard/jumbo), a digit for model number, and a digit for revision number. "3ks1a" - easy. Then everyone can search for "3ks1a" and find Information directly relating to that printer.

In industrial automation, the ISA 5.1 standard defines similar naming. In industries around the world, this convention is used to name instruments in an immediately identifiable fashion.

Let's look at a typical designation:

66-FIT-123

The 66 part of the above is area number. Very few plants are monolithic. Most consist of a certain number of defined areas with defined functions. These areas often have a single number associated with them. If 66 were for a certain power boiler, for example, anyone in that plant would immediately recognise that the instrument existed in that power boiler.

The second part, "FIT" above, is a standardized designation based on the ISA 5.1 standard. In this case, the first letter tells us the process variable. In this case, "Flow". Other common process variables are Temperature, Pressure, Analytical, or Density. Each represented by the first letter of the word. The second letter above is "Indicating". It is a modifier telling us that the instrument has a display. Finally, the last letter is "Transmitter". This speaks to the function of the device. Often you'll see Switches, Valves, or Elements. Sometimes you'll see a Y, which indicates "special function relay"

Finally, the number "123" above represents the unique loop number. Every loop in the area will have a unique number, making it trivial to look for loop sheets, wires in a junction box, or PLC code.

In terms of the name you'd give it, I prefer following a few general rules.

1. Name for humans. This means naming things using natural language, and in a way that people can read. I've seen colons, dashes, And underscores in names. There's no need for that. I've also seen things named something nobody calls something. Either correct your name, or change what people call the thing.

2. Name precisely. Calling stuff pump #1 is tempting, but makes things too difficult when trying to refer to something. "Boiler #10 feed water pump #2" tells someone everything they need to know about that device. Calling the printer the "Delta Kossel" is too broad. Every printer of this type is a "Delta Kossel", and it appears the company has multiple kossel style printers.

3. Name consistently. Create a nomenclature or taxonomy and follow it. Don't refer to the same device with six different names. In this case, the "Delta Kossel" and "Mini Kossel" might be different things. If they are, that's fine. If they're not, that's a major failure of naming.

 

Anyway, I'm done playing with the printer until next weekend. Looking forward to the next steps. I'll keep everyone updated.

 

Thanks for reading!

3d printer, day 2.

Jan 132018

I'm Jason Firth.

I apologize in advance for the photos. No idea why they came out so bad.

Last time, I talked a bit about setting up my new 3d printer, an FLSUN Delta Kossel. The first day consisted of fighting with the firmware that was set up without any limits, and with some seriously wonky default settings.

I was able to complete my first 3d print, a ring from thingiverse, and then moved onto my second 3d print, a ball valve I designed:

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Unfortunately, it didn't print very well, and after printing successfully once, I wasn't able to get it to print at all again.

I still had a few problems. The head wanted to dig into the bed. I tried to tape some magazine stock to the bed to protect the head and I tried to calibrate the bed that way, but that was a pretty poor solution. What I discovered is that there were a few problems with what I was trying.

The unit came with leveling springs, and the instructions on YouTube suggested I install them. This turned out to be a bad idea, because the nozzle contains a spring as well,and the two were fighting each other. I took out the spring, and because I'm concerned about the heated bed touching a bunch of plastic, I took one of the spare square bolts and used it as a spacer:

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Next, I wasn't happy with the auto calibration. The entire unit shook dramatically as it auto calibrated because of the huge amount of force needed to overcome the spring. I looked at the head and realized I didn't have *one* adjustment, I had *two*. The silver set screw that set where the button releases, and the black set screw that set the spring tension:

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I realized I'd have to calibrate the nozzle before I could run a printer calibration.

First, I loosened the silver screw until I heard the switch click, then I tightened it slowly until I heard it click again. I pressed the nozzle to prove the switch was actuating properly, because a couple times I just tightened it until I heard it click again but it didn't reset with nozzle movement.

Second, I loosened the black set screw until the switch opened, then tightened it back up until I heard the switch close again.

After calibrating the print head, I was getting much better calibrations that didn't shake the unit so badly.

Finally, to deal with the print head jamming itself into the print bed, I discovered a setting called Z-offset. I was able to change the z-offset from the unit faceplate.

First I went to the control menu:

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Then the motion menu:

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and Finally set the Z-offset:

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I figured out the z-offset by setting my height (I used the faceplate in the prepare menu, but you could easily use Repetier to do it from your computer) lower and lower, until I couldn't slide a piece of paper under the nozzle anymore. I set the Z-offset to the number of mm.

The final improvement I made was to place a fan near the bed. The unit has a fan built onto the nozzle, but this didn't seem like a bad idea.

I was finally able to consistently make successful prints. Early on, I designed and built these clips so we can screw our undercabinet lighting to the cabinets:

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And by the end of the day I had printed a spool holder I designed:

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I was really happy how this one turned out. Not so happy about how the picture turned out, mind you. No promises how it will hold up once I place a 1kg spool on it instead of the smaller provided spool.

A few things I've discovered in a day of printing:

Don't waste time trying to save material. A 1kg spool of filament has about 330m of filament. All the designs I've been printing use less than 10m of filament.

You see a lot of prints that look like they're really substantial, but they might not be. The prints might be completely hollow inside. The above print has a 5% infill, so very little inside.

Shell thickness is your friend. I printed a tube with a 0.5mm shell thickness, and it was a great demo, but very quickly broke. I printed with 1mm shell thickness, and everything was much more substantial and is holding up much better. Given the choice between infill and shell thickness, I'll choose shell thickness every time.

I didn't need a raft or anything once I had the printer well calibrated. Suddenly the bottoms of my print were good by themselves.

Even though professional designers using molded plastic might use voids to conserve material, that seems to be a really bad idea here. I created an earlier spool holder that used a thick column with voids, and it was a really complicated print -- it was constantly retracting and spooling out and ended up being really messy.

Today's prints pushed the limits of a 40mm radius print bed, so I spent some time doing some tests. I figure I can safely print to 70mm without the print head or arms contacting anything, so I increased the print radius to 70mm in the marlin source code and re-uploaded.

I had a calibration error I couldn't figure out -- my Y axis was off, but only my Y axis. A post on the marlin forums suggested moving to the latest, so I moved to the nightly and re-uploaded. That worked perfectly. After upgrading, the printer calibrated happily and I'm ready for more printing tomorrow.

Because I don't want someone like me to have to deal with the annoyance that was my first day, I took the configuration headers and submitted them to the marlin project for entry into the examples file.

3d printing

Jan 092018

I'm Jason Firth.

This year I wanted to go on a bit of an adventure, so I got a couple of toys. One is the Oculus Rift VR system, the other is the FLSUN delta kossel 3d printer with a heated bed. I purchased both from Amazon Canada with Prime shipping.

The Oculus is more a consumer entertainment device, so let's talk about the 3d printer. It's a consumer device, but it's interesting enough on it's own.

I had never done anything with 3d printing before this weekend. It's been on my wish list for years, but I didn't feel I was quite ready until recently. This journey is still therefore fresh, I am not coming into this after I've learned everything there is to learn.

On Friday night, I got off the plane from work and found the printer box waiting for me. I couldn't wait, I immediately ripped it open and started reviewing the contents. The printer arrives completely disassembled.

Being a proud tradesman, I decided early on that I wanted the wiring to be built and wired in a neat and workmanlike manner as much as is physically possible. This turned out to be more difficult than I'd hoped later -- most of the wires attached are far too long, and a couple were just a little too short for a good install. In retrospect, I likely would have built it differently knowing what I know now. In particular, I would have planned from the beginning to have an electrical box on the side and run the extruder wires directly through it. But I'm getting ahead of myself.

The box allegedly came with instructions, but I found the written directions disjointed and incomplete. The best bet was following the videos on YouTube. The video was essential to putting the printer together, but as time went in the level of detail started to slip. Eventually they stopped telling us which screw sizes to use and when it came time to wire the board it just said to look at the wiring diagram.

If you follow their directions perfectly, you'll end up with a rats nest of wires. There's very little mention of routing the wires except for the end stop switches, and the instructions assume you'll jam the box on the table under the heated floor. I ended up pulling apart some of the printer after assembling to route the cables in the aluminium rails.

The kit comes with virtually everything you'll need to build the printer. The bolts are all metric and I didn't realize they'd done that until I'd made it part way through. It was a pleasant surprise.

I purchased a 6x6x6 electrical box from home Depot and 2 strain relief connectors. In retrospect. I needed 4 strain relief connectors: 1 for the wires from under the heated bed, one for the wires from the extruder and the 12vdc power, one for the USB cable, and one for the pair of ribbon cables going to the display. I'm reasonably happy with the result on the outside, but inside the box is a rats nest of wires because some of the wires are too short.

I had a premonition once the wires were connected and plugged the 12v power supply into the wall for a smoke test. Blue Sparks immediately started sizzling and flashing from the power supply! I quickly unplugged the supplyand discovered that the screw terminals on the supply had not been soldered down. Gives me reason to question that QA sticker. Sort of a big detail to miss. I soldered the screw terminals in and after that was getting 12.00vdc on my meter. Good enough!

There are numerous extra parts not shown in the video. Fans, heat sinks, and much more. I'm happy to have parts, but I'm concerned that I'm hurting something by not installing these parts. Before I do major printing, I intend to install at least the heat sinks.

Before I got the printer, I started reading and chose tinkercad as my first 3d modelling program. It's very simple, which I feel I need at this point. I designed a simple ball valve as my first print. I'm hoping to eventually 3d print stuff like this. Tinkercad is easy to use, web based software from Autodesk. Once you're happy with your object, you can Immediately export it as a file the 3d printer software stack can understand.

The board contains an atmel microcontroller, and is programmed using the Arduino software. The firmware it comes with is called "Marlin", and 99% of the work is already done. That last 1% is a doozie.

There is a buzzer, a knob, and a button on the front panel. The buzzer does what you'd expect, the knob is used to control the units interface (spin it left and right and press to select), and the third button immediately resets everything. I treated that third button like an emergency stop, and I needed it a lot at first.

I downloaded the latest Marlin source code and used the example configuration for the flsun 3d kossel mini. All the configuration is in 2 files, a configuration header and an advanced configuration header. You've got to tweak them in the Arduino software before you start.

There's a #define that allows you to access the calibration menu from the faceplate. I uncommented that early because it made it easier doing all the cal tests that I ended up doing.

The example configuration for the kossel mini in Marlin 1.1.18 was dangerously wrong for my printer. The more immediate problem is that the delta radius was substantially off. This meant that the print surface was extremely convex. In the middle of the print surface, I would be touching the print surface with the print head, but at +50 or -50 on the x or y plane I could fit my finger beneath the print head. I measured the radius from the print head to the pivot point on the side rail of one of the arms, and I think I found a number somewhat like 135mm. The number was very different from what the config had by default. With this massive error, the printer could not auto calibrate. The second problem was the delta height was too low. It was set for 250 or so. This caused it to try to find the bed level in the middle of the air. I set it to 318 and the height calibration worked, somewhat. More on the height later. Finally, the printable radius was set to 110. This is the dangerous part. The printer simply cannot move like that. Ultimately, I might be able to set this to 50-55, but after getting burned a couple times jamming my print head outside the print area and jamming the e-stop, I set it to 40 for now. The second number that was causing the calibration to catastrophically fail is the cal radius. It was set to something like 90, Which is simply outside the range of this printer. I set it to 36.

All this took time to figure out -- about a day, After setting these values and uploading the resulting firmware, I was finally able to get the machine to complete an auto calibration cycle.

There's still one problem: the bed height is coming up too low. My reading suggests that the problem is the spring dampeners on the bed. The nozzle has a spring and a limit switch, so when the nozzle touches the bed it is supposed to push the nozzle up and actuate the switch while calibrating. With springs on the bed, the bed bounces back as well, causing inaccuracy on the calibration because the bed moves down. I've been able to print by manually decreasing the bed height, but the inaccurate calibration has also caused inaccurate measurements on the bed level. As a result, the nozzle digs in on one side and floats on the other. I used thick magazine paper as my bed material to reduce damage to the head if it does dig in for my first 2 prints. When I get home I'm going to mount the bed solidly to the frame to eliminate the vibration error. Seeing what masking tape does on a heated bed, I purchased some kaptan tape for future prints.

Out of the box, there's nothing to hold the reel of filament. Once I have the printer working reliably, one of the first things I want to print is a reel holder. In the meantime, I noticed that the rails are wide enough to hold a jeweler's screwdriver, so I am hanging the reel off a jeweler's screwdriver for now.

The software stack the printer uses on windows is called Repetier-host. You can download .STL files from thingiverse and directly open it in Repetier. From there you choose print location and size, then send the print to software called a "slicer" which turns the 3d model into instructions the printer can print, called g-code. From there, the slicer can directly give the instructions to the printer over USB, or it can save the g-code file to an SD card. You can then directly place the SD card into the printer and print using the front panel.

I had to fiddle with a couple settings. First, I had to set the printer surface to be circular, and I had to fiddle with the slicer, telling it my filament size, extruder size (.3 it seems), and a couple other options.

Having done all this, I finally successfully printed something!

That said, it was more dumb luck than anything. I successfully printed a little ring for my wife, then I printed the valve I designed, but after that I was having issues getting the bed to stay down.

I discovered 3 things: first, the aforementioned bed springs being a problem. Second, the extruder temperature was too low causing the bed to have problems adhering. Third (paradoxically), once the filament left the extruder, it stayed too hot for to long, so the prints melted into a mess that looked like a wax sculpture of what I wanted melting in a hot car in the sun.

For a first attempt, I'm pretty happy. If it was easy, it wouldn't be nearly as fun.

I'll keep you posted. Thanks for reading!

Unacceptable.

Oct 232017

I'm Jason Firth.

 

I'm not normally the sort to comment on current news stories (apparently I'm making a habit of it, though). I would rather my blog not become overtly political, and personally I think the idea of 'picking sides' in partisan nonsense is a great way to lose friends and make enemies.

 

However, when it comes to the stories coming out about Harvey Weinstein's reprehensible behaviour, I'm willing to make an exception.

 

In years past, I wrote about the environment women in technology and the trades might find themselves in. When I said "it won't be fair", I was referring to more passive behaviours I saw: looks that weren't appropriate for the workplace, comments behind people's backs and behind closed doors that weren't the most professional. What I was absolutely NOT referring to is overt sexual harassment or sexual assault in the workplace.

 

I want to be crystal clear: Overt sexual harassment or sexual assault is not acceptable in the workplace, period. There is no "Oh, work your way through it" in such situations -- such a person should face the legal and practical consequences of their actions, and nobody -- male or female -- has any reason to work under such conditions. It is against the law for a supervisor or manager to sexually harass a worker under any and all circumstances. There is no excuse.

In fact, in Ontario, "wanting it" isn't a defense. If a supervisor or manager is making advances against workers, that's unlawful harassment under the occupational health and safety act. Speak up. If that supervisor won't listen, then another will. We have a legal duty to.

Thanks for reading.

Do not pass go, do not collect $200.

Aug 292017

I'm Jason Firth.

I don't make it a habit of commenting on local news stories, but this one really got under my skin: A car dealership demanded additional money from a customer after the sale concluded, and when the purchaser refused to comply, they remotely disabled the vehicle.

A consumer rights organization spoke to consumer rights law, but let's call a spade a spade here: this is a criminal act. Someone should be going to jail over this.

Perhaps you think I'm being melodramatic about this, but hear me out. This dealer accessed computer equipment they had sold -- equipment they no longer owned and were not authorized to access. They did so for the express purpose of following up on a threat they'd made: "either pay us, or we will hack and disable your vehicle."

This is exactly the modus operandi of the WannaCry hackers. They took over systems they did not own, and issued an ultimatum: pay us or lose access to these systems we do not own.

Besides the thinnest veneer of respectability, there is no difference between the two.

Well, there is one difference, but it is without distinction for legal purposes: whereas the WannaCry hackers had to force their way into systems, the auto dealership left a bomb in the car they once owned.

On a few occasions, disgruntled former employees have used old usernames and passwords to get into the systems of former employers. It's still very illegal and the fact that they had a username and password does not mean they are magically authorized to enter systems for which they no longer have reason to enter.

Both the WannaCry hackers and disgruntled former employees would go to jail for their crimes. The responsible people at this dealership ought to as well.

In the grand scheme of things, this should also be a warning to those of us who are in charge of digital systems: if a car dealership can commit extortion, if they can use a trap well laid to demand more money, then so can former employees. It's important then to make sure you revoke permissions immediately when people leave the company, and do routine audits to find hidden bombs before they can turn into a threat down the line.

 

Thanks for reading!

 

Blue skies, green Fields

Aug 242017

I'm Jason firth.

One commonality I notice when people ask me to help solve a problem is that quite often they explicitly limit solutions to "what sort of control systems can we install?" Type queries.

I immediately force myself to ignore the question as presented, because of the limits it puts on the creativity we can use to solve problems.

Occasionally, we can introduce a new and innovative control system to solve a problem, but just as often, we need to take a step back and re-examine the problem. Sometimes we can solve a problem by providing more data to operators, or by making it easier to follow procedure using their current user interface. Sometimes we need to inform rather than control. Sometimes we need to analyze in a new way. Sometimes it's a maintenance problem and fixing a chronic problem will help. Sometimes there's no problem at all and things must be operated on a certain way for safety or operational reasons.

By looking at problems outside of their ostensible technical scope, we can see the systems involved. We can ask questions we might not have asked otherwise: systems involve processes, equipment, operators, procedures, user interfaces, and control systems. Sometimes the answer comes from looking at the whole picture rather than a small piece.

Looking at problems this way also provides new opportunities. A few years back, I was asked to investigate problems with a certain Historian in gathering process critical data. What I discovered was that we were asking the historian to do something incompatible with its design. Historians consist of dozens of working parts, all of which need to function for data to be saved and retrieved. Instead of fighting the historian to conform, we created a new system which consisted of a single simple program with one purpose. Instead of requiring dozens of systems to work, suddenly we only needed two: retrieval and storage. Once we created this new system, we were able to extend it to automatically produce files for regulatory reporting -- an unexpected boon which saved the site time and increased accuracy.

This provides new opportunities for a shop. Many people want their shop to limit its influence to "what control systems can we install", but by looking at a strategy which embraces increased responsibility and increased work in service to other groups, new opportunities arise, because it's all connected.

Everyone wants to find a new and innovative and cool control system, but sometimes you need to step back from that well trodden lot, and look at the areas nobody is looking, where there are blue skies and green fields, waiting for someone.

Thanks for reading!

The next road

Aug 192017

I'm Jason Firth.

It's been a long while since I updated, because I've been transitioning into a new role: planning and supervising the instrument shop, and supervising the gas fitters.

The transition from front line worker to front line supervision has meant a whole new set of challenges, and a whole new viewpoint.

As a worker, road blocks are a nuciance. "They really ought to make this easier", I'd say. We'd all say it. Now, navigating those road blocks and keeping workers away from them is a big part of my raison d'etre. The more I can keep my guys working on jobs, the better job I'm doing.

There's a lot of road blocks out there, too. From inception, the question of whether work should even be completed ought to be answered by supervision and management before a worker is ever even close to being assigned the job.

In maintenance planning, there's a lot of processes that should exist and be followed to ensure the job is properly vetted. For corrective work, risk analysis can help justify work. For preventative maintenance, a methodology like Reliability Centred Maintenance can define and justify which work shall be done. For proactive maintenance, there are a number of failure mode analysis tools which can help dictate what work should be done in response to different unmanaged failures.

Following processes like these can help on two fronts: it helps ensure that front line workers aren't wasting their time on work that is going to be immediately vetoed, and it helps ensure that supervision and management have their finger on the pulse of exactly what is going on and why. Besides that, it ensures that appropriate documentation to support work exists so you can go back as part of a living program and see how your assumptions worked out.

Next up are planning road blocks. Ideally, you should have all the parts kitted for the job, you should have all the steps identified, correctly documented, and permits pre prepared as much as possible. If you can schedule the job as well and coordinate with operations to get the equipment in question, that's another major roadblock that front-line folks won't have to deal with.

During execution, your best people will have their better nature working against them. People will want help with their personal priorities, but the problem is if you're focusing on everything, you're focusing on nothing. It's important to keep your people on the task at hand. For those who have personal priorities, they need to enter their work into whatever work management process you have.

Looking at the big picture, the work management process is your most important tool. See the work, prioritize it, plan it, schedule it, execute it. This requires teamwork not just amongst your team, but amongst your site.

The "hey buddy system" is any time where someone sidetracks the work management process and tried to get their work done through side channels. This is sometimes appropriate for high criticality work, but usually it isn't appropriate. Every job that gets done on the "hey buddy system" is another job that went through the proper channels that got delayed. When someone successfully gets their job done this way, it reduces the credibility of the process, and increases the number of "hey buddy" jobs done.

This is the easiest roadblock for great workers to hit: the traffic jam. A hundred uncontrolled jobs hit at once, and in trying to keep everyone happy by focusing on all these jobs, none but the simplest jobs get done.

If I'm doing my job right, then everyone should win: the workers should be less stressed out because they can focus just on doing the work safely. Operations should have the right work happening at the right time. Supervision and management can complete their due diligence in preparing work, and a system of continuous improvement should help make the process consistently smoother.

To be honest, although I took the career track change for professional reasons, the reason I get out of bed in the morning (and one of the big reasons I applied for the job) is knowing how difficult life is on the front line when you don't have someone there willing to handle these problems.

As for a different perspective, You get to peek out from the front line and see (or even steer) the path ahead. Changing from being a passive observer of what's coming down the line, you can become an active participant.

I'm sure I'll have plenty more to say in the future, but this is what I've learned so far in my crash course on supervision.

Thanks for reading!

All you need to know about PID controller

Feb 272017

27 Feb 2017

I'm Jason Firth.

 

I recently commissioned this article explaining the function of a PID controller by freelance writer Sophia O'Connor. It's one of a few pieces I've commissioned recently. It's partially a test to see how well commissioning freelancers can work, and partially a public service to get some stuff written about some basic concepts. Enjoy!

 

A proportional integral derivative (PID) controller is an instrument that is used mainly in the industrial control applications. PID controller involves three controllers i.e. p-controller, D-controller and I-controller. All these controllers are combined in a way that they produce a control signal. The main purpose of using a PID controller is to control the speed, temperature, pressure, flow and other variables that needs to be processed. It can be installed near the control regulation devices. Moreover, a PID controller is monitored through an SCADA system.

Working of a PID controller:

As explained above, a PID controller involves the working of three different controllers that are combined together to perform different tasks. The main purpose of installing a PID controller is to control the operations. Although a simple machine with the ON and OFF option can be easily used for this purpose. However, when it comes to something complex, the only thing that can be used is the PID controller. It will provide with the maximum opportunity to control the overall system.

A PID controller is responsible for the controlling of the output. Moreover, the desired output can also be achieved with the help of this. The three basic controls have their own working in the PID controller, they all work together to achieve a common goal. The working of these controls is explained below:

Functions of the Proportional controller:

P-controller is responsible for providing the output that is required. The output that is achieved is proportional to the current error value. The main working of a P-controller involves the comparison of the desired set point with the actual value or the value that is achieved through the feedback process. So, if the error value of this controller is zero, the output value of the controller is also zero. Moreover, this type of controller requires a manual resetting every time.

Functions of the Derivative controller:

The requirement of the controlling system involves the prediction of the future behaviour as well. This will not be done with the I-controller. D-controller is the one that will solve this problem. The output value of this controller is dependent on the rate of change of error with the time. It works as a kick start for the output system hence increasing its system response.

Functions of the integral controller:

There are certain limitations with the p-controller that are fulfilled with the help of I-controller. It is needed in this controller system because it will provide with necessary actions that are required for the elimination of the steady state error. It is responsible for integrating the error for a period of time so that the error value reaches to zero value.

 

All of these controller works together to form a perfect controller that can be used in the process control application.

 

 

Thanks for reading!

What does success look like?

Jan 012017

Jan 1st, 2017

I'm Jason Firth.

 

I recently wrapped up a fairly major project, which I spoke of earlier: Implementing a large software package for 2 sites.

The story of this project can be seen as a tale of two cities, or of two different groups with fundamentally different requirements, and importantly fundamentally different ideas of what success looks like.

In one city, we have the 10,000km view. From this viewpoint, the project was a huge success. We successfully designed the project, successfully trained all the users, successfully deployed the software on time and under budget, and our metrics look great -- thousands of work orders created, thousands closed, as large increase in the number of active users of the software, and we can all pat ourselves on the back for a job well done.

In another city, we have the close up view. From this viewpoint, the project was much less successful. The design was clunky and complicated, the training was incomplete and in some cases meaninglesss, the go-live day was a mess which never really got cleaned up, time and budget are irrelevant because of the former, as are metrics. Congratulations on foisting a broken system on a bunch of unwilling users, who are upset that we've taken their original tools away from them!

 

Let's look at another project.

Implementing a new control system, the spec comes back from engineering. We followed the spec completely, successfully implemented it, documented it, and patted ourselves on the back.

The problem? The specs were for a control system that wasn't going to work. After being implemented, the system was never put into service for any appreciable amount of time, because it didn't correctly control the process.

 

So, which viewpoint is correct?

Both. It all depends on how you define success. That's why it's important to define success properly to encompass both viewpoints: Both the micro and the macro. Is the project successful as a project, as something with a beginning, middle and end, with a budget and concrete goals? Is it successfull as an ongoing operation afterwards, will it actually be used, is it acceptably free of defects, does it actually do the intended job? Is it structurally good, is there ongoing documentation and training, continuous improvement set up in the systems at the facility you're at?

 

If you're able to succeed on the micro level, and at the macro level, then you've got something that's going to make you look good over time.

Thanks for reading!