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Author Topic: Closed Loop Stepper Compared with Open Loop Stepper  (Read 26839 times)

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Closed Loop Stepper Compared with Open Loop Stepper
« on: May 29, 2012, 02:14:27 AM »
Traditional open loop stepper systems operate in open loop providing position control without feedback. When stepper motors move loads in open loop, a potential loss of synchronization called "Stall" or "Loss of Steps", between commanded steps and actual steps may occur. In the past, this has been solved by adding a feedback device such as an optical encoder and feedback the "current" position for monitoring or verification. But this implementation can only "alarm" position loss and can't correct it at the end of the move. When an application requires real-time closed-loop performance throughout the move, engineers are forced to choose much higher cost and complexity of servo systems. But in many applications, because traditional servo systems lack of high torque feature of stepper systems, expensive planetary gearboxes have to be added to achieve desired torque.

Leadshine closed loop stepper is named as hybrid servo system (www.leadshine.com/ProductList.aspx?Type=36), by implementing high resolution encoders to update the motor position every 25 micro-seconds, closed loop stepper drives ensure control real-time position accuracy without lose of steps in open loop stepper system.

Different from the constant current output of open loop stepper systems, output current in closed loop stepper systems is optimized and changes based on moved loads. Therefore, closed loop stepper systems generate higher torques, lower motor heating, lower vibration, and lower noise than open-loop stepper systems.

When compared with brushless or brush servo systems, cost for closed loop stepper systems are much lower. In addition, much higher torque, simple tuning and configuration, no overshooting, and no hunting also make closed loop stepper systems better solutions over servo systems in many low to middle applications.

Visit website www.leadshine.com to get more product information.
Re: Closed Loop Stepper Compared with Open Loop Stepper
« Reply #1 on: January 27, 2015, 01:39:16 PM »
Hello,
i just installed a pair of ES-P32320 kits as my X and Y axis and nema 34 with an 808 as a z. what mach settings in motor tuning are appropriate. these are replacing open loop steppers and the settings i have vastly different to get them to move. the leadshine's are installed at stock factory recommended dipswiches. ~2000 steps/inch old open steppers @ 1/2 steps bipolar parallel and ~40000 steps/inch with leadshines.

what did i miss? it works awesome. maybe i should just not worry about it but this detail i cant reconcile. ???
just getting the hang of it
Re: Closed Loop Stepper Compared with Open Loop Stepper
« Reply #2 on: February 23, 2015, 07:28:19 PM »
what did i miss? it works awesome. maybe i should just not worry about it but this detail i cant reconcile. ???

Hello Jstites,

Did you get the bugs worked out on this?  Did you get the help you needed here or from Leadshine?
I would like to do exactly what you did with my Taig mill.  Would you be willing to share exactly what you purchased from Leadshine?
Thanks for any info you are willing to share.

Pete
Re: Closed Loop Stepper Compared with Open Loop Stepper
« Reply #3 on: February 24, 2015, 03:09:06 PM »
Hi Pete,

i did get a response from Leadshine, it was about to how to correctly calculate the steps/inch and not really a diagnostic approach. in the software set up for the leadshine i thought i read that the minimum step pulse time was 5ms and i think mine is set there but ill have to double triple check that..... my old set up got hot and was noisy. not that that's bad, just smooth, cool and swift is definite positive upgrade.

i dealt with this fellow named chris and he was easy to coordinate and verify that the kit was correct for my application. came in about a grand for the motors, drivers, power, interconnects, and motor/encoder wires. i built a case and re wired everything.

i need to steal a few hours from the rest of my lifes draws and tinker with it. ill have to get back to you for a complete fix.

how do we post pics....?
just getting the hang of it
Re: Closed Loop Stepper Compared with Open Loop Stepper
« Reply #4 on: February 24, 2015, 03:11:39 PM »
ah i think i found it

this my home mill. a Grizzly a G0463
http://www.grizzly.com/products/Mill-Drill/G0463
just getting the hang of it