rusEFI display

Hardware inside and outside of the ECU
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kb1gtt
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rusEFI display

Post by kb1gtt »

I've been thinking of making a display. The hacked RX8 CAN bus display is a great thing, but has limited availability, and can be hard to install in a vehicle that doesn't have friendly dash mounting points. I also see a need for other applications. For example, you buy a used car and you are stuck with a speedometer only dash. Wouldn't it be nice to upgrade that to get more gauges with out having to break the bank, or with out having to do a major modification to the car?

So I propose the CoCO display (Cluster or Cluster Overlay). Basically you put this display over your existing display, or you mount it as your display. It's fairly easy to modify, as you can cut a different piece for your primary shape, which allows you to install it in pretty much any application. The draft below is about 5.5in X 14.5in X 1.5in (140mm X 370mm X 36mm)
Untitled.png
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This is a needle style back-light gauges which should be visible in day light or no light. The needles are self-light with RBG LED's so you can change the color of the needle if required. The LCD allows various things like check engine light, or diagnostics messages. The CoCO display includes accelerometer/gyro, CAN interface and USB interface. There are 8 needles which allows for RPM, Tach, Temp, Boost, Voltage, oil pressure, and 2 others. The cluster is clear plexi-glass with gauges painted on from the back side. After the gauges are painted on, then the entire back is painted with black lacquer. For night time the gauges are light by edge lighting.

I see an application being done like this.
1. Obtain the DXF or PDF of the display.
2. Print out or draw the pattern on a piece of cardboard that's about 1/8 inch thick.
3. Either verify the design will work, or make a new outline. You have been provided the initial DXF, so you can fairly easily make a new outline.
4. Get plexi cut, with luck you can simple buy an existing shape.
5. Get components, then bolt together using only a Phillips #1 screw driver.
6. If you have rusEFI, connect 4 wire ribbon cable between the display and the rusEFI board.
7. Configure gauges (min max ect).
8. Watch gauges wiggle around as the engine RPM changes.

The basic collection of parts is like this
1x Polycarb panel $TBD
8x RC micro servo's TowerPro SG90's about $2.50 each
16x McMastercarr servo screws 91772A265 $3.10 for 100
8x Servo needle lighting PCB's $TBD
6x McMastercarr discovery screws 91772A078 $4.49 for 100
1x USB micro to panel-mount adapter $5
1x STM32F429I-DISC1 $29
1x Discovery adapter PCB with Accelerometer and CAN $TBD
1x Adafruit part number 894 White LED's on a wire $5

Does anyone have any thoughts about this? I'm dubbing with it bit by bit now. Comments now might make the first draft even better. I'm kind of thinking 3D printed needled would be a good thing.
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Re: rusEFI display

Post by AndreyB »

kb1gtt wrote:Does anyone have any thoughts about this?
I think I need a 'how to control a servo for dummies' thread so that I can try to control the serve which I have with as little brain activity as possible :)
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Re: rusEFI display

Post by abecedarian »

russian wrote:
kb1gtt wrote:Does anyone have any thoughts about this?
I think I need a 'how to control a servo for dummies' thread so that I can try to control the serve which I have with as little brain activity as possible :)
Servo's are pretty easy. Just send a PWM signal at the right frequency and they move.

What we have here, though, might be a failure to communicate!

8 servo's = 8 independent PWM signals. So, most likely, the dash would need an MCU of its own and data sent to it by the ECU... sounds familiar, no?
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Re: rusEFI display

Post by kb1gtt »

3D PDF added to the first post of this thread.

Can people with out official adobe reader's view a 3D PDF? I haven't found a 3rd party that can do it yet, and I'd like to know if there is one that can.

Yes this cluster is very similar to any modern OEM dash. However this is low cost and customize-able. While OEM's are closed source and specifically designed for a certain dash.

This picture pretty much explains how a RC servo works. The SG90 is 0 to 5V friendly. Would probably work with 3.3V as well.
Image
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Re: rusEFI display

Post by abecedarian »

Looking around at various sites and it seems those servos are rated 4v-6v; 3v3 might not be enough to drive them. Also, they suggest 400-2400ms pulse width.
Since the board will require external power anyways, might as well let it take 12v from the vehicle and regulate down as needed.

Might want to consider VFD type display since LCD are sensitive to temperature.
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Re: rusEFI display

Post by DaWaN »

I kinda like the idea, but I am not sure I am fond of the servos. They are not particular fast: Operating speed: 0.1 s/60 degree and probably noisy too.
The size seems reasonable, but it would be nice if the dials would be flatter than 30 mm.
Now I am not aware of any ubiquitous small steppers, so that is a difficulty.
Driving stepper motors would be fairly easy with a couple of SN754410's.

The 32F429IDISCOVERY delivers unbeatable value, so it is a great base.

I have been thinking of a similar project, but I was thinking more of a small additional display and not replacing the stock gauge cluster.
Personally I would love a display which is the same size as a single DIN car stereo. For this project I already bought the screens which fit in this size (2x 2,2" QVGA screens).
The idea of a cover for the stock cluster is a good one, you do not want to replace the standard warning lights and fuel gauge and such..

Looking at existing products (race dashboards) I think all of them use digital displays with some additional LEDs. From experience I can tell some bright diffuse LEDs are great for reading RPMs when racing.
The display is always tricky to read, but ordinary LCDs with fixed digits (something like this) is best in my opinion.
Does somebody know a non-OEM cluster with dials? It would be interesting to have a look at it.
Maybe buying some cheap stepper motor dials from eBay and tear them down? Something like these: Click here

I think this product can be more successful if it is compatible with 3rd party ECUs and/or remapped OEM ECUs.
With this in mind I was thinking of the following features for my display:
Datalogging with SD card (when using the dash with an OEM ECU it is nice to have datalogging features)
Accelerometer / gyro for datalogging
Tachometer output (some old tachometers require a signal from a distributor or something alike, so a coil on the board to provide this would be nice)
Some spare analog / digital inputs to replace extra gauges (preferred to use the ECU for reading sensors, but maybe not for all dials)
kb1gtt wrote: Can people with out official adobe reader's view a 3D PDF? I haven't found a 3rd party that can do tit yet, and I'd like to know if there is one that can.
When reviewing mechanical designs I always prefer the eDrawings viewer, which can be found here:
http://www.edrawingsviewer.com/
Export tools are available for all common CAD tools.

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Re: rusEFI display

Post by kb1gtt »

Great feedback and good links. i wasn't able to find such low cost stepper style gauges.

The SG90 is limited to 180 degree's, which I'm not crazy about. I'd prefer 270 degrees of motion. However SG90 is low cost and a good starting point. I guess the goal is to fail fast and fail cheap. If it doesn't completely fail, we can find better servos easy enough, you just have to toss $ at it. If these end up noisy, it's generally because of poor assembly / craftsmanship. AKA bad POT or a bad solder joint internally.Remote Control (RC) vehicles are very sensitive to noise and other such accuracy issues. I think they should be good visually. I guess time will tell. With some luck I'll get to build it before too long but life keeps getting in the way. Rumble groan moan, 3 tinny little inches of snow and a worn out snow blower drive belt gobbled up an entire day.

Hmmm, .3 seconds for 180 of travel, that's seems kind of yuck. I have experience with the MG995, which has a slower spec. The MG995 seems faster than that. Perhaps they spec that speed with some kind of a load or inertia connected to it. Also you can make them go faster if you increase the voltage. I guess we'll have to see how fast that is in reality. Here's a video of how fast they should be able to move Gut feel tells me they will be OK. How fast can 7 segment display update?

About how often the pulse should be sent, I would say we should plan that people can see 30 frames per second (movies are 29.blahFPS), so we should send an update pulse at least once ever 33mS. Faster is OK, but I would say we should send no slower than that.

Hmmm, if we assume at least 1k steps for 180 degrees of rotation from a stepper, to get a similar speed as the servo, it would require over 3k pules per second. I don't think steppers move that fast, they typically can't sustain the internal BEMF fields with the inertia of the magnetic core. However perhaps a small enough stepper can do it. I think steppers will have a similar angular rate.

I generally don't look directly at the gauges, they are generally in the peripheral vision. I like needle gauges for this purpose, as you don't have full video processing out there. I can't decode digital gauges in my peripheral vision. I tend to think the digital displays have become popular not because they are superior, but because they don't require craftsmanship to assembly. You can generally setup a machine to built them very cost effectively with a very high build quality. Kind of like why we have digital watches instead of fine Swiss watches.

One of the things I like about servo's is that when you are in steady state, you don't draw power. Steppers will require the firmware to remember to turn off a stepper to prevent current draw. If you don't you'll likely generate a fair bit of heat in the cluster. Also if the stepper gets moved accidentally, it has to be homed before it's again correct. Servo's can handle slight bumps with out loosing accuracy. For lost cost purposes, I left it such that you can touch the needles. If you use a stepper, you really need to put a window in-front of the needles such that you can't bump them. Then you have to keep a light needle such that vibration won't cause it to move when it's not powered.

I did draw this up in Solidworks, so e-drawing is an option. I plan to post the source files eventually. If people seem interested in trying it themselves or modify it, I'll post the files sooner rather than later. If someone is having trouble viewing the 3D PDF, then let me know and I'll post the e-drawing.

Now that I have the physical stuff drafted, I'm starting the electrical design stuff.
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Re: rusEFI display

Post by puff »

I didn't get why you are reinventing the bicycle
http://guy.carpenter.id.au/gaugette/2012/05/25/buyers-guide/
http://guy.carpenter.id.au/gaugette/2012/02/16/using-the-switecx25-library/

all in all I recommend you just look through the Guy's site.

here's an old video of mine (the needle is dodgy cause my math is too bad - I seem to have found that bug, but need to test it once again)
[video][/video]

I doubt the DIY panel will be as attractive and good looking as the factory-made.
As for me, I am thinking of keeping the original design, while using these steppers for tacho, fuel-level, temperature and speedo gauges.
the odometer thing will be tricky…
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Re: rusEFI display

Post by kb1gtt »

A search on Ebay for "cluster steppers" produces several results for reasonably low $. I tend to like closed loop systems, but I understand steppers are what is commonly used. I would guess that's largely because of simplicity of design.

It looks like you have a discovery with rusEFI on the PC. Do you mind if I ask what you have for hardware? I wonder what you are using to drive the stepper. Such small steppers can probably use some interesting circuits. I'd bet you can use the GPIO and use the ESD rail diodes to snub the spikes. I'm curious if you've tried that, or if you are doing something different for the hardware part of the driver.

Also how did you physically connect the stepper wires? I ask as I can offer some suggestions on how to keep the stepper working well. The short version is that it's common with a stepper that if you get a .1 ohm or .01 ohm connection in the stepper leads, that it can cause hundreds of volts internal to the stepper, which can cause an over-voltage and burnt traces internal to the stepper.

Perhaps we should choose a common set of hardware such that we can share the effort. If you have interest in sharing the effort, let me know. I'm not really tied to the servo thing, I was just doing it as it was low cost, simple-enough, and close loop. I could be convinced to follow the common path. I like the lower profile of the steppers.

Also I see it like re-inventing the wheel, not the bike. If I considered it a bike, then we'd have the elusive problem of a bike shed color :)
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Re: rusEFI display

Post by puff »

the stepper is driven directly by gpio pins of mega8. even no snubber diodes. used some olimex 5 inch length jumper wires for that purpose. could have used any thin wires with equal success. can't get what hundreds of volts you are talking about. mega was powered from the '5 v' pin of the discovery board. if i remember it correctly, it even worked from the 3.3v pin, but becamesomewhat lazier.
however, i don't think that it would be safe to drive it directly from discovery. just check the datasheets. i believe, i should better use snubber diodes. there are some driver chips whiih could be use wih small power 3.3v microcontrollers.
all in all, i'd better buy the used rx8 cluster for 30$ if it provides all of the needed signals...

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Re: rusEFI display

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Re: rusEFI display

Post by puff »

jobbers! I got 6 pcs of those steppers for $15 delivered from ebay. 3d printed needle is poo. got mine cut from a cd cover - took me just couple of minutes.

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Re: rusEFI display

Post by kb1gtt »

Migrated from here, http://rusefi.com/forum/viewtopic.php?f=13&t=1122&p=21256#p21256

These displays can be handy, but for almost $700 that's perhaps less desirable. There is a thread around here where @russian used an existing CAN dash obtained from a salvage yard. Then connected it to Frankenso's CAN interface and got it to move needles, etc. See gauges noted at 42 seconds in this video.
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Re: rusEFI display

Post by RustyGargoyle »

kb1gtt wrote:Migrated from here, http://rusefi.com/forum/viewtopic.php?f=13&t=1122&p=21256#p21256

These displays can be handy, but for almost $700 that's perhaps less desirable. There is a thread around here where @russian used an existing CAN dash obtained from a salvage yard. Then connected it to Frankenso's CAN interface and got it to move needles, etc. See gauges noted at 42 seconds in this video.
Yeah, I was thinking the same thing! $700 is insane, That is a turbo or nitrous setup easily :lol:

And I really like the aesthetics of the display. Reminds me of an s2000 cluster. Or a cluster of a 80s vintage vehicle.

Image


I wanna say the racepak uses some sort of graphic LCD, maybe? but its so crisp I doubt it.

Image

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Re: rusEFI display

Post by kb1gtt »

Oh, yeah I haven't mentioned it yet, because I haven't gotten it posted to the repository yet. I have a Chibios / uGFX firmware working for the STM32F429 discovery board. uGFX is really handy for the graphics. I was planning to get it doing something that's kind of interesting before posting the code. However if someone is interested I can post it and let others dig into it. I'm going really slow, and can allow others to take it from where I'm at and start running faster than I am.
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Re: rusEFI display

Post by stefanst »

I'm fairly sure the racepak is a custom LCD. That's why it's so crisp.

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Re: rusEFI display

Post by RustyGargoyle »

Yeah it looks really good in pictures I cant imagine how good it looks in real life, maybe at night.

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Re: rusEFI display

Post by kb1gtt »

I'm a fan or real needles for things like speed and tach, you can see this in any light. Then I'm a fan of LCD for less critical things like odometer, warning codes, etc. I see that e-ink displays have come down in price. Those are handy as they can be easily seen in day light. However the refresh rates are blah.
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Re: rusEFI display

Post by Abricos »

VW TFT dashboard
[video][/video]

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Re: rusEFI display

Post by AndreyB »

Have a random TowerPro MG995 servo from an old box. It has a 10 pin connector and a funny colored pigtail - red, blue, violet. Any ideas which one could be which?
Would it work from USB 5v or would I need proper external 5v?
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Re: rusEFI display

Post by kb1gtt »

I recognize that. It's an OpenServo. I must have given that you you some time ago. That one is very special compared to normal servo's. It likely has full rotation, and it has I2C communications instead of your normal servo pulses. It was a MG995, but now it's an OpenServo in a cheap package. I would suggest putting that to the side for now.
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Re: rusEFI display

Post by puff »

not so cool actually :D (my remark to github feaure request)
what's cool is that we have CAN support)

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Re: rusEFI display

Post by AndreyB »

OK, I've got SG90 working but that's only 180 sweep.

Do we have anything similar size with 270 or more degrees?

Google says https://www.amazon.com/DFRobot-Metal-Geared-Standard-DSS-M15S/dp/B018E2K56E or https://www.amazon.com/LewanSoul-LD-3015MG-Standard-Digital-Control/dp/B073F4TRSK

Would these allow me to attach a 3D printed 8 inch needle? Do we have compatible 8 inch needles for sale on eBay?
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Re: rusEFI display

Post by stefanst »

I'm a bit late to the party and it has probably already been covered, but why not use a cheapo Amazon/Ebay gauge like these?
https://www.amazon.com/NCElec-Universal-Backlit-Tachometer-Gasoline/dp/B01M6D0IRJ/ref=sr_1_5?ie=UTF8&qid=1521338835&sr=8-5&keywords=rpm+gauge
All you need to do is feed a frequency for rpm or speed gauges. Others can be controlled by PWM. Or you can print custom scales for rpm gauges and then control everything with a frequency output.
I'm not a fan of RC servos. Their position-repeat is terribly inaccurate and it gets even worse with temperature changes. I tried to use them as reliable actuators on a home project and ended up using steppers instead.

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Re: rusEFI display

Post by kb1gtt »

Cool. Do you have a video, showing wiring?

Try over and under driving the input. The spec is 1mS to 2mS pulses. Try pulses down to 0.5mS and up to 2.5mS. That will commonly provide extra range. However the extra is commonly to ensure that manufacturing tolerances are meet, and are commonly not guaranteed, but you can commonly get extra out of it.

Keep in mind that if you have control over the needles range of scale, you don't need to have a linear scale. AKA why would you need 0 to 30 MPH on your race car? You could change your full range to be 30 to 70 MPH, then you get more resolution. As well you could make 10 degrees of rotation be 0 to 30 MPH, then the top 170 degrees of rotation could be 30 to 70 MPH.

Also keep in mind that these servos have different categories. See the list noted below for ServoCity. The SG90 is micro. However Nano and submirco are also an option.
https://www.servocity.com/servos/hitec-servos

The DSS-M15S and LD-3015MG is standard sized servo, so it would be physically larger than the SG90, resulting in more physical depth. However they are still fairly short, so probably not a real issue for most people. As well they appear to be 5V to 7.2V, so they might not work with 3V signals.

I see this Nano has 225 degrees, but costs much more than the SG90. As well I see it specifically specifies it's 3V compatible.
https://www.servocity.com/hs-35hd-servo

This has 203 degrees
https://www.servocity.com/hitec-hs-55-servo

If you're patient, you can commonly find the range of angle in this database.
https://servodatabase.com/advanced-search

Beware that a 360 degree servo typically does not have the positioning POT and typically the command signal is direction and how fast, not a specific position.

The SG90 is commonly purchased for around $2 each, and it can be directly driven by 5V or 3.3V logic. Most of these Nano or Submirco servos can be directly driven by 3.3V. As well they have many many many off the shelf options which allow them to be configured into any dash you may desire, with minimal tools. They have many many many supply sources, while fly by night cheap ebay devices tend to change or disappear over time. Using RC servos is low cost and you have many options. This is why RC people use them, they offer many features for low dollar. Can you make your ebay needle 2 inches longer if you wanted it longer? Have you been able to buy that ebay gauge for the last 30 years? Will you be able to buy it in 30 years? The RC hobby industry has been doing this for some 30 years and is likely to still have the same stuff for the next 30 years.
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Re: rusEFI display

Post by puff »

Those amazon kits, I bet, are based on stepper motors, rather than on servos.
So far, I haven't seen any dashboard with a servo.

After successful experience with rx7 cluster (controlled by can!) and willing to keep the original look and feel of my stock dashboard, I came to the following plan:
blue-pill board (stm32f103) + can driver + AX1201728SG quad driver chip (equivalent to the X12.017 or VID6606) + four switec motors + 2 TIC33 indicators. That would be the new guts for my old good dashboard. Probably, the trickest part would be not to mistake in dimensions (to properly align those TIC33 pinouts + a stepper to the dial face, plus all those fittings and vertical dimensions) - but that promises a lot of fun!

What frightens me a bit is when I look into the stock-produced dashboard, there are too many electonic components, but they have some other circuits - to control and power up all those leds - which are not necessary in my case.

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Re: rusEFI display

Post by kb1gtt »

For more rotational angle, you typically need a "360 servo" or a "multi-turn servo". Of course sales people often call a continuous rotation servo a 360 servo, so finding a 360 vs continuous rotation is not easy. Typically "Sail Winch servo's" are multi-turn servo's. The below is 2.5 turns. So you get more than 360 degrees of rotation.

https://www.ebay.com/i/323111492692?chn=ps&dispItem=1
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Re: rusEFI display

Post by ZHoob2004 »

https://www.adafruit.com/product/2424

This is going back to the stepper vs servo debate, but these steppers are really cheap because of their use in GM instrument clusters, and are already used in an automotive application. They're marginally more complex to drive than a servo, but are very compact, very cheap, fairly quick, and fairly precise.

Adafruit is basically the highest price you can find for these, but I linked them because of the nice animation showing the sweep of the gauge.

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Re: rusEFI display

Post by puff »

yeah. it seems I got 6 of them for 10 or 20 us dollars. building my version of cluster. just 4 gauges and a fuel low lamp.

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Re: rusEFI display

Post by kb1gtt »

I would love to see someone put out a stepper based design. If someone did I would offer advice and what ever guidance I can to help make the design stronger. However the design I would push would not use steppers. Here are some of the reasons why.

Keep in mind other costs that come with steppers. The automotive steppers require 4 pins per motor and each pin needs to drive significant amps. The first post shows 8 needles plus an LCD screen. I do not know the amps required for the stepper, but lets call it 40mA. At 8 needles, that's 320mA which is typically far more than a MCU can drive from it's IO pins. While you could drive one stepper, or perhaps even two steppers from an arduino, I don't think you'll get all the needles you typically want. You'll either need multiple MCU chips or some form of an external driver to drive these needles. It is also likely that you cannot drive this many needles off the discoveries 100mA supply that is also providing the power to the LCD screen. As well if you plan to use an PCB to ease your motor connections, then you're adding cost to the PCB to get 8X4=32 connects. Granted adding $2 power supply, isn't a huge cost, as well adding an external driver chip isn't a huge cost, and adding a PCB to mount these parts on, is also not a huge cost. Those costs and complications are starting to add up.

Also keep in mind that small ohms in the connector between the inductive stepper motors and the capacative power supply, create a circuit which is commonly known as a tank circuit. A tank circuit commonly causes voltage spikes which damage the electronics.

Servo's require far less amps from the STM chip, as they include there own power drivers internally. The communication signals from the STM around 1mA each or less. As well if you make a PCB about the size of you thumb nail you can easy the assembly for small money. They are just so flexible and require such small amounts of effort to implement. As when you have a lack of quality control on the electrical connections, servo's are far less likely to damage other electronics.

Was I able to find these automotive steppers 30 years ago? Will I be able to find them 30 years from now?

Any how, those are some reasons why I'm designing with servo's instead of steppers. I understand steppers are commonly faster responses. However I think the servo's are fast enough.
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