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EQDrive and other options

eq ATM equipment mount
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#1 Space99

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Posted 21 November 2017 - 03:54 AM

Hi everyone,

 

I'd like to start a discussion re drive options of a EQ mount.... new or old....  I hope this is OK by the mods...   smile.gif

 

Noticed Valentine's add  https://www.cloudyni...-40kg-and-more/

 

I'd do like this kit... I'm in the design stage of a big EQ mount ( in a  permanent observatory.)

 

I think it would be beneficial for all of us if we get all the info/education what we can get about this and alternative systems.

The original EQMOD is 'stuck' with the 705:1 gear ratio .... this 'interface' is free from that, and it does not use a 'micro-step'  ...  drive the stepper as a 'synchronous' motor.... direct drive the worm without 'jitter'   ??

 

Also, options for us on a budget, is a 2nd hand Gemini 1,  AstroEQ  https://www.astroeq....k/tutorials.php   and Synta's EQ6 go-to upgrade kit with steppers (stuck with overall gear 705:1)

 

Not sure how this will compare to a servo based system, like Sidereal Technology Servo Control. I'm on a budget, so it's about 1:2 cost difference...  can't use EQMOD and a servo motor is way more expensive.

And noisier (with the transfer gears)!

 

If you are using any of these system, I'd like to hear your opinion.

 

ps: I'm interested in buying one of the systems, and have no financial or personal interest in any of the vendors.

 

Kind Regards to all,

Mick


Edited by Space99, 21 November 2017 - 04:06 AM.


#2 orlyandico

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Posted 21 November 2017 - 05:15 AM

I can't speak to EQDrive, but I bought a Littlefoot Elegance Photo (LFEP) for over $700 a few years ago.  It was one of the best stand-alone GoTo controllers back then for stepper motors and I thought I got a good deal.

 

Bad move. The guy designing them (Rajiva) decided to close shop and now I have a boat anchor.

 

For this reason, I would highly suggest something like OnStep which is open-source, so even if Howard stops working on it, the source code is out there and people can continue developing it.


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#3 burdij

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Posted 21 November 2017 - 03:13 PM

Could you use AstroEQ. It is usable with any size steppers, just depending on which drivers you use and allows a number of drive gear ratios to be accommodated. It does use microstepping to achieve a compromise between fine control and fast slewing. ASCOM is supported.

 

Here is the link: https://www.astroeq.co.uk

 

I have built a version of this for an EQ-5 mount which integrated well with Stellarium and Cartes du Ciel. Haven't tested the SGP yet, though.


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#4 benula

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Posted 21 November 2017 - 04:34 PM

Here's another vote for OnStep.



#5 astrokor

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Posted 22 November 2017 - 02:56 AM

I am the founder of the EQDrive project.
In the beginning the project was like the others, based on the motor drivers STEP/DIR.

 

The study showed that such control is not softstart and not flexible. And we developed a control algorithm similar to synchronous motors. We got control over the parameters of the stepping motor without a closed loop.

Currently the project, is not open sources, but is now available as DIY.
http://www.eqdrive.com.ua/?page_id=969
Sorry so far only Russian language. :(

 

In the near future I plan to open the source of the project.

 

Best regards,
Ruslan Korop.


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#6 Space99

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Posted 22 November 2017 - 03:13 AM

I am the founder of the EQDrive project.
In the beginning the project was like the others, based on the motor drivers STEP/DIR.

 

The study showed that such control is not softstart and not flexible. And we developed a control algorithm similar to synchronous motors. We got control over the parameters of the stepping motor without a closed loop.

Currently the project, is not open sources, but is now available as DIY.
http://www.eqdrive.com.ua/?page_id=969
Sorry so far only Russian language. frown.gif

 

In the near future I plan to open the source of the project.

 

Best regards,
Ruslan Korop.

Thanks Ruslan,

and welcome to CN :) 

 

Glad you join in and explain how it works.

 

In your opinion open loop, like the stepper driver you have with EQMOD, how would it compare to a servo based software like Sitech or Gemini?

 

I do like the stepper for the reason of low transfer gearing... less noise and backlash. The simplicity of the electronics is a bonus too. However, it's an open loop and you drive it like a 'synchronous' motor ... so how is the pointing accuracy compare to the servo based systems?

 

Thanks,

Mick


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#7 astrokor

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Posted 22 November 2017 - 03:52 AM

Sitech is a good integrated development. It supports many configurable parameters. I am guided by this development.

 

Yes, the stepping motor and the synchronous motor mode were chosen as an alternative to the servo motor.

 

Of course, an open loop does not give absolute accuracy. The next step is a closed loop with stepper motors and encoders. But, the EQDrive system gives a smooth move in comparison with the microstep mode and guiding solves the problem of an open loop.

 

Ruslan



#8 Space99

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Posted 24 January 2018 - 04:50 AM

Hello everyone,

 

I restart this discussion, because finally I have the worm gears (had a bit of difficulty to get them).

 

Ruslan, I like to ask your opinion: is your system can drive this direct couple the steppers to the worm? A 7.1" worm 252:1 for DEC and 11" 359:1 for RA.

I do like the idea of direct drive to eliminate noise and backlash.

 

This kit suppose to be for big eq mount: 

 https://www.ebay.com...5.c100005.m1851

 

ps. ebay say it's not available till late Jan!!

 

Because your design  not using micro-steps, direct drive shouldn't induce jitter me think ... may be not enough torque? So a spur or pulley gear of 3:1 or 4:1 recommended?

 

Any advice appreciated   bow.gif

 

Thanks,

Mick

Attached Thumbnails

  • 20180123_195103-11111.jpg

Edited by Space99, 24 January 2018 - 05:03 AM.


#9 astrokor

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Posted 01 February 2018 - 01:53 AM

I am now working on the production of a small batch is the new version EQDrive.
Yes, this kit is suitable for large mounts, there is a man from Korea who installed an EQDrive for 500mm Cassegrain on a fork eq mount.

 

We use a gear ratio of 1:2-1: 3.

 

I now conduct experiments with low ratio, and this is very good.
There was also an experiment on installing the camera directly on the axis of the motor, is a example a tracker with a direct drive.

 

I will prepare, with time, a more complete report on the results of the experiment with a low ratio with EQDrive TCS.

 

Ruslan.


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#10 Space99

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Posted 01 February 2018 - 03:57 AM

Thanks Ruslan, sent you a PM

 

What is the difference in the new version?

 

Mick



#11 astrokor

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Posted 01 February 2018 - 04:37 AM

EQDrive Standard4
This is the same as Standard 3.
Maximum current 2A
Input Voltage 10...28V

 

Differences:
Optimized pcb design,
Version with Limits, Home or Position sensors.
Version with DC/DC Step Up to 30V at an input voltage of 10-28V

 

Ruslan


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#12 rdw4176

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Posted 01 February 2018 - 02:02 PM

Thanks Ruslan for sharing the info about Standard4, I am already using std3 with a GP mount and looking forward to std4 for my NJP mount, let us know once it is available!



#13 pterodyne

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Posted 01 March 2018 - 10:28 AM

Im working on an ATM EQ mount. It is 200:1 harmonic drive reduction on both axis, and 4:1 HDT3M pulley reduction off NEMA23 steppers.  TMC2130 Drivers using Onstep.  Currently Im sourcing all the parts for Onstep, which is a great project.   For reference, I also have a converted Titan with Sitech Servo 2, and a CG5 with AstroEQ.

 

Anyhow, Ruslan, can you give me more info about the synchronous stepper mode you are discussing?  Sounds very Interesting, but I don't understand.  I have pretty good knowledge of how microstepping works, and for Onstep I was planning on using the newer style drivers TMC2130 in SPI mode which from what I read are far superior to the older style chopper drivers.  How do you calculate resolution?  With microstepping you include the uStep into the gearing to calculate.

 

I originally was going to go with AstroEQ, but it requires that the power be turned on BEFORE the USB is plugged in, or the microcontroller can lock up.  This is a problem in a remote observatory because I have a single relay for the Pier, and I don't want to figure out how to sequence the Power first, then connect usb.  This is why I chose Onstep, but I don't want to commit because I need to make sure the ASCOM driver is really good and functions to specification. (BTW, I don't just leave all the equipment on because the whole observatory is off grid on solar/battery.).  I use ACP, MaximDL, and Focusmax.

 

This brings me to EQDrive, I have followed this project for a while, and have seen the kits on Ebay.  I assumed it was similar if not identical to either a real synscan controller or astroeq.  This apparently was wrong.

 

Ruslan, thanks for any info, and I love the possibility of closed loop with stepper, and the inclusion of limit/home switches. My titan has a Gurley encoder for use with the Sitech Servo 2 on the RA axis, it is very effective.  Would the encoders work with EQMOD?  I think the EQ8 works with eqmod but the encoders are not used. For that matter, are there any functions you have implemented that cause problems or are ignored by EQMOD? Things like limit switches, Alt/Az modes and Equatorial fork (No meridian flip)?

 

Sorry for the long post!  Im planning the mechanical aspects right now, and building parts at eMachineshop (online machine shop).  My hope is to have 40Kg without counterweight. Basically this is a Chronos with steppers instead of servos.  The chronos also used 2 stage harmonic drive (2 interleaved long period errors), mine will be single stage harmonic drive with a small timing pulley reduction, and as such, hopefully one slow periodic error.

 

Thanks.  Ramble over.

 

Bryan Ramsey



#14 astrokor

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Posted 01 March 2018 - 01:52 PM

Thanks for your feedback.

 

EQDrive does not have microsteps. Or rather there is a discretes, of course.

I studied the drivers of the Trinamic, but for free control of the motor they did not fit. In EQDrive I used the Texas Instruments drivers DRV8813.

 

The synchronous algorithm. In short:

The two table is calculated using a sin cos functions;
For motion, a vector is started at the required speed;
The vector pointer determines the currents in the motor coils;

 

The table has a length of about 2000 values ​​with a resolution of 12 bits.
This determines the discrete, but I will note this is not a microsteps. And I already have ideas how to improve and this parameter. :)

I already have a stand ready and wait for the clear sky (is now much snow). I want to make a qualitative assessment of the EQDrive controler in direct drive to a worm.

 

Ruslan


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#15 astrokor

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Posted 01 March 2018 - 03:23 PM

...We are now working on a closed loop and sensors. EQMOD was chosen for a quick start, but with it we are limited in functionality for example such mode as Alt/Az. But we are working on our Ascome driver and also there is a possibility to add the protocol Meade LX200. This future.



#16 LarsMalmgren

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Posted 21 March 2018 - 12:04 PM

Hello Ruslan,

 

You show no handcontrol on your web-site but imply that a "SynScan console" can be use with the EQDrive Standard 3.

Do you mean that a SynScan handcontroller is to be used with the EQDrive ??

 

Do you suppert other kind of handcontrollers?

Meade #497, Celestron etc ?

 

In order to upgrade a mount that already have motors, i guess that one would need to take the motor controller boards out and connect EQDrive directly to the motors, right ?

 

On your web-site you mention "Speed of a gidirovaniye" in relation to the ACC port.

What is "gidirovaniye" ?    Guide speed?

 

You have 2 different pin layouts on the ACC port.

Why is that, i don't quite understand?

 

 

Thanks



#17 astrokor

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Posted 23 March 2018 - 05:01 AM

Yes, SynScan can be used in connection with EQDrive. Do not support others controller. We are developing a controller, it is more functional for EQDrive.

 

 

In order to upgrade a mount that already have motors, i guess that one would need to take the motor controller boards out and connect EQDrive directly to the motors, right ?

right

 

ACC we use in two modes
1) ST-4 port
2) simple 5 buttons console (DIY).

 

Ruslan


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#18 LarsMalmgren

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Posted 23 March 2018 - 09:27 AM

Thank you, Ruslan!

 

Very interesting product indeed!



#19 rdw4176

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Posted 18 June 2018 - 12:34 AM

EQDrive Standard4
This is the same as Standard 3.
Maximum current 2A
Input Voltage 10...28V

 

Differences:
Optimized pcb design,
Version with Limits, Home or Position sensors.
Version with DC/DC Step Up to 30V at an input voltage of 10-28V

 

Ruslan

Ruslan, I see that EqDrive STANDARD 3N has been released, is it Standard4?

How to configure "Limits, Home or Position sensors"?

thanks



#20 netwolf

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Posted 22 June 2018 - 10:19 AM

Does eqdrive have an alt/az support? Can it be used on an alt/az mount. 



#21 555aaa

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Posted 22 June 2018 - 02:21 PM

I noticed the thread title says "and other options." I have a drive system that will work on arbitrarily large mounts because it uses industrial servo control electronics. The current build of the code is written around the Faulhaber servo drive but I am working on the CANopen protocol version, which is an open standard for industrial drives. There is a build thread over in the ATM forum; you can message me for more details. This drive currently is running a Meade 16" telescope on  custom made offset equatorial mount which is used for asteroid photometry and astrometry.

 

https://www.cloudyni...r-meade-16-acf/


Edited by 555aaa, 22 June 2018 - 02:23 PM.



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