Stepper Motors vs. Servo Motors - A ClearPath Demonstration
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- เผยแพร่เมื่อ 30 ส.ค. 2016
- Have you ever wondered what the differences are between a stepper motor and a servo motor? Do you ever get frustrated with your stepper motor losing steps, but hesitate buying a servo motor because you think they are too expensive or complicated? With this video, learn the differences between servo motors and stepper motors when it comes to power, price, and performance.
Teknic wants your feedback. Like this video? Give it a thumbs up! Be sure to comment with any questions about motion control and let us know what you did or did not like about the video.
For more information on Teknic ClearPath servos, subscribe to our channel and visit Teknic's website.
Teknic TH-cam Channel: / @teknicinc
Teknic Website: www.teknic.com/
In this video, Teknic compares the power, price, and performance advantages and disadvantages of both servos and steppers. The video then shows how the new, all-in-one ClearPath servo motors bridge the gap between cost and performance.
In this demonstration, you can also find general examples of applications where you would use a stepper or a servo. Teknic discusses how to properly compare steppers and servos and how to calculate power from a torque-speed curve.
Toward the end of the video, there is a demonstration of the differences in performance (speed, smoothness, accuracy, noise, etc.) between a stepper motor and a servo motor. There are also differences between tuning, noise resistance, setup, and more. - วิทยาศาสตร์และเทคโนโลยี
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I have used 2 of Clearpath's most powerful NEMA 34 mount servos for a project I did about a year ago and can tell you that although this smells of the typical biased "vs" type reviews that manufacturers make, Clearpath makes QUALITY servos and there's no BS to what he's pitching. My servos are almost dangerously-powerful and quick and extremely capable. Will easily buy again when it comes time to get a CNC router :)
Thanks Jesse Silver. We greatly appreciate your comments.
Our #1 goal for our videos is education. We try to impart knowledge by using facts and examples that are easy to understand. We appreciate your business and wish you much success.
Tom T
Meaningful comparison. Thanks for the effort
Thank you for the useful comparison.
Oh my god! 😲 Super fast, almost completely silent, more reliable AND cheaper?! 🤯
Is this for real?! 😳
Hi Aerox,
If you need at least 30 watts of shaft power and an industrial quality motor and drive, ClearPath is a great solution for many motion control applications.
Some have expressed the sentiment that it seems too good to be true. That’s why we decided to offer a long, money-back guarantee (90 days, and the motor can be returned with any amount of reasonable wear and tear). This gives people ample time to fully evaluate ClearPath’s performance.
If you have a current application, give it a try, risk-free. And please don’t hesitate to call us if you need any help choosing the best model.
Erik M. - Teknic Servo Systems Engineer
@@TeknicInc Thanks for answering me! 🙂 I'm still trying to learn the basics of electronics at the moment, so as for now I should probably stick to something smaller 😅 But my plans for future projects are definitelly going to require your products! So I'll come back later when I have enough experience to handle more power! 😊👍
It's nice that you show how to compute the power given a speed-torque curve. I echo the comment that someone else says that feedback to stepper motor drives is readily available to drive PID control loops. The Schneider M-drive stepper motor and the Oriental Motor Alpha-Step products (not the model shown in the video) referenced in someway during the video have a closed loop PID control loop. Leadshine also has a similar product. I've used all three of these products. I understand the comparing similarly priced products, but perhaps just a mention that steppers can also have servo control loops (for more cost) or the make-model and configuration would help with transparency of the demonstration.
I was one of the original folks to write to your support group when the ClearPath was announced. Unfortunately, I was not able to use them at the time because I needed either continuous following error reporting or duplicated encoder signals. I asked on your video today if the -SC model has the ability to report these in software. Unfortunately, that video appears to have been removed. If the -SC has this support, I certainly would order one for testing.
Finally, I would say that steppers still have a purpose in applications there any dither must be avoided such as some optics setups.
Thank you
Thank you for your feedback. Teknic servos have proprietary AntiHunt™ technology that virtually eliminates hunting while at rest. That being said, a $50 stepper motor still provides some value when all you need is a $50 stepper motor for your application. The historical high price barrier of servos has been addressed by the ClearPath integrated servo motors and has opened up many new markets and applications. When comparing smoothness of motion, quietness of operation, power density and efficiency of energy usage, the benefits of the ClearPath integrated motors vs stepper motors become readily apparent the first time you use them.
I'm impress with the low noise and high power!!!
Hi Alexandre, thanks for the feedback! Stay tuned as we continue to develop new videos.
Kevin S
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Hi i really like your stuff and i would like to make some questions!Well a stepper motor rotates in steps,the frequency of steps define acceleration or velocity,am i right?When it comes for a servo to replace a stepper motor,what kind of control is applied to servo,is it speed profiles or something like small position changes with the frequency change desired position again define speed and accel like steppers do??Which is the smallest possible step angle for a servo compared to stepper,if the servo shaft encoder provide 1000 pulses per rotation,is it possible to step one encoder pulse or it needs more pulses and why(maybe the cascaded PID loop tracks the error in a smaller scale than the smallest step of the servo)??I would appreciate any advise!!
These are some good questions. The ClearPath SD models take in step and direction signals like most stepper motors do. Teknic designed the SD model this way so that a user could drop in a ClearPath SD servo as a replacement for a stepper motor without having to change the software on his/her step and direction controller. So, a user would program these motion profiles into the CNC controller and then send these profiles to ClearPath's drive through step and direction pulses. You are correct that the frequency of these step pulses defines velocity; the rate of change of the pulse frequency defines the acceleration.
A big difference between a typical stepper motor and ClearPath SD is that ClearPath SD is closed-loop. The encoder inside of ClearPath is constantly sending feedback to the internal drive which continuously makes torque adjustments to closely follow the commanded step and direction signals. This is why ClearPath will not stall or lose steps like a stepper. The encoder and drive firmware ensure that the motor achieves its commanded position unless there is physical obstacle that ClearPath cannot overcome, or if the motor is undersized for the application.
NEMA 23 and 34 ClearPath motors all have a 12,800 count per revolution encoder for feedback, but depending on the model, the “input resolution” (i.e. how many step pulses correspond to a command for one motor revolution) ranges from 800 to 6,400 pulses per revolution. The "regular, R" version allows for 800 pulses/rev to command to. The "enhanced, E" version allows for 6,400 cts/rev to command to. You can choose the input resolution (pulses per shaft resolution) in ClearPath's MSP software. Please see more about this input resolution and the specific degrees of rotation per count in the ClearPath User Manual: www.teknic.com/files/downloads/clearpath_user_manual.pdf
Finally, ClearPath uses a PIV compensator as opposed to a PID version (the "V" term denotes an embedded velocity loop as opposed to the "D" or derivative term within PID). It also uses multi-derivative feedforward gains to reduce tracking errors (preemptively, before they even occur) based on the motion command. Designing a PIV compensator is more difficult than designing a PID, which is why the PID is much more common, but it is higher performance, and the tuning is not iterative like PID tuning. This makes tuning much easier and more deterministic whether the tuning is done manually or by ClearPath’s auto-tuning algorithm.
Thanks for the information!!Something last to ask about PIV.What is a typical frequency of the PIV loop and is it relative to speed,or constant?
You should talk about wiring though, I use stepper motors with 4 wires (requires homing and verification of the "steps per mm) but it's 4 wires nonetheless. How is it wires compared to a similar stepper without an encoder? If the control is built into the back of the motor, can it emulate the 4 wire connections and actually be a drop in motor replacement that similar just needs quick config and a separate connection for power?
Hi Kevin Delaney,
It sounds like you have a separate stepper motor and stepper drive (similar to the stepper motors we demonstrated in this video), and the 4 wires are the phase wires connecting the drive to the motor. When using a ClearPath motor, you don’t need to wire the two together since the servo motor and drive are a single package; i.e. you'd be replacing both the stepper motor and drive with a single integrated servo system.
We designed the ClearPath SD motors to be as close to a drop-in upgrade as possible for a stepper motor and drive system (we demonstrate the SD-series in this video). ClearPath SD motors take in the same Step & Direction signals typically sent to stepper drives (the electrical inputs are rated for 5-24 Vdc), and often times use the same DC bus power as well.
We've created a number of videos, wiring diagrams, and technical documentation showing how to use these ClearPath SD motors. You can find that information here on our website (www.teknic.com/products/clearpath-brushless-dc-servo-motors/model-support-sd-dc/).
If you have any other questions, feel free to contact us directly at support@teknic.com.
Best regards,
Matt C. - Teknic Servo Systems Engineer
Got a pair of these beauties on my red sail clone laser cutter. I got to say that I was not super impressed with the auto tuning but after manually tuning them they work much faster than my previous step motors. They are about as good at low speeds but as I go beyond 100 rpms they are the clear winner. They also allow for stupid fast acceleration which to me is even more valuable as it minimizes over burning associated with slow cutting speeds. I wish the auto tuning allowed you to set machine specific parameters like the intended maximum speeds and acceleration. While the auto tuning does wonders for the higher rpms one can achieve significantly better results by specifically tuning for your intended use.
Hi Abraham, thank you for your feedback. We wrestled with how much data we should ask users to provide to the autotuner. Providing more data about the mechanics and application, if accurate, definitely makes the autotuner’s job easier. One feature to help optimize the tuning for different applications is the “fine tuning” slider located under "Setup" and "Fine Tuning". (A lot of people don’t notice this tool-we may have to make it more prominent in the UI.) The slider allows you to trade off stiffness and disturbance rejection for quieter motion (especially at the lower speeds). If you have already manually optimized your tuning, you won’t need this slider, but for future applications, you might find it helpful.
Teknic Inc you truly have a killer package here. The more I use them and learn the more I appreciate how great they are compared to steper motors.
With your knowledge depth sir, would you recommend this for a robotic arm or stepper motor ?
Hi Skitnado, Either choice may work depending on the physical design and application goals. A servo may be the better choice if you're looking for faster and smoother motion. However, if you don't require a great amount of power, the stepper motor might be more cost effective. The choice will be dependent on many specific design factors.
Best regards,
Bridgette G.
I'm on the fence in choosing the clearpath sdsk over a closed loop this one:
www.omc-stepperonline.com/closed-loop-stepper-kit/ye-series-1-axis-closed-loop-stepper-cnc-kit-2-0-nm-283-28oz-in-nema-23-motor-and-driver.html
I can't find any videos comparing servo vs closed loop.
What are the advantages of the servo over closed loop?
Thanks
Hello Jungle,
Thanks for watching the video, and for your excellent question.
Adding an encoder to a stepper motor makes it a closed loop design, but there remains fundamental structural differences between a closed loop stepper motor and a closed loop servo motor. Teknic makes drives that control closed loop stepper motors as well as servo drives, so we have experience with both technologies. There is merit to both technologies and the best choice depends on your application requirements.
Perhaps the two most common criteria used to compare closed loop stepper motors and servo motors is price and performance. Stepper motors are significantly cheaper to manufacture and the system you referenced seems to be consistent with this low price point (~$80 ea). On the other hand, the physical properties of servo motors enable smooth, dynamic performance and power density that steppers fundamentally cannot match. So the optimal choice (stepper vs. servo) is often driven by the trade off between price and performance.
That said, there is one fundamental challenge with nearly all closed loop systems, regardless of the motor technology. This critical topic is electrical noise immunity - frequently a topic that gets ignored until it's too late. Virtually all closed loop motors need shielded, twisted pair cabling for the feedback device. Additionally, the wiring installation must be carefully followed using a detailed electrical installation guide. If any installation steps are missed or if the system degrades over time, the system will become susceptible to noise-related failures. On the other hand, the ClearPath integrated motors are designed to eliminate noise issues based on design architecture like optical isolation. In fact, ClearPath motors are often used on plasma tables with 50+ foot long control cables that are neither shielded or twisted pair and with no noise related issues.
So your decision may be as simple as the allowable budget for your machine. If the decision is more about robustness, improved performance, and factory-direct support, the ClearPath motor is worth a closer look. After purchasing a ClearPath motor, you have 90 days to evaluate the performance of the motors. If your machine doesn't need the added benefits that the ClearPath provides, you can return the motors for a full refund (minus shipping).
If you have any additional questions, please contact us at www.teknic.com/contact or give us a call M-F between 8AM and 6PM EST at 585-784-7454.
We look forward to hearing from you.
Best regards,
Tom T - Teknic Servo Systems Engineer
@@TeknicInc Thanks Tony, I placed an order last Monday and was shipped today, so I should hopefully get them on Friday :)
I've a laser cutter machine that I think will really benefit from the clearpath servos. My only concern is the "enable" signal, my current leadshine stepper motor drivers do not use that signal, and as far as I can see my motion controler (Ruida) does not have an output for the enable signal. Is there a way to bypass the enable signal at all?
Hi Abraham- For safety reasons, it is not possible to by pass the enable because this is what allows the motor coils to be energized and de-energized at will. Without enabling the motor, you will not be able to command ClearPath to move. However, the enable doesn't have to be connected to your controller. You can wire the enable up to a simple switch. You can enable and disable the motor through a mechanical switch and when the motor is enabled, send commands to the other inputs through your controller. Just be sure that the switch is rater for 5-24VDC logic power.
Already ordered! found both 5V and 24V 500 ma logic signals on my laser cutter controller. I'll be adding some before and after videos of my machine once they arrive.
holy wow that noise
hi is it possible to get 5000 mms with servo motor, for laser engraving machine only engrave not cutting
Hi Roland,
Our fastest ClearPath motors have a top rotary speed of 6,000 RPM. Your specific mechanics will determine whether that rotary speed will allow you to reach a linear speed of 5,000 mm/s.
If you'd like to discuss your application more to see whether 5,000 mm/s is an attainable top speed, please feel free to contact us at support@teknic.com.
-Ian R, Teknic Servo Systems Engineer
servos are, in some ways, better than the stepper.servos are useful in hobby electronics.i suggest servos for robotics beginners but steppers do have a lot more importance in the current world like printers.therefore i suggest to even learn about steppers too.
Hi Abuthahir-Thanks for your feedback! I agree with your comments. For motor sizes smaller than NEMA 23 (like what would be used in a desktop printer or other table top applications), steppers often make more sense because they are relatively inexpensive compared to servos at that size (NEMA 14 and smaller). This video compares industrial servo motors vs. stepper motors in the NEMA 23 and larger sizes. For hobby electronics (such as RC cars or planes), servos actuators are typically used, but those are much different from the servo motors in this video.
They talk about stepper drivers, but what about servo drivers?
Hi robertoviana514,
Teknic's ClearPath motors are fully-integrated meaning the brushless servo motor, digital servo drive, and incremental encoder are all integrated into one package. While this video primarily compares the differences between ClearPath motors and stepper motors, the ClearPath SD series can replace both stepper motors and other digital servos. Due to the fully-integrated nature of the product, ClearPath would replace both the motors and drives in a system.
Teknic's ClearPath Overview video discusses all three series of ClearPath and the different types of motors/drives that they can replace: th-cam.com/video/rA6yrZrxuPs/w-d-xo.html
There's also more information about the ClearPath motors on the Teknic website: teknic.com/products/clearpath-brushless-dc-servo-motors/clearpath-servos/
If you have any additional questions, please feel free to submit a contact request on Teknic's website at teknic.com/contact/ or give us a call at 585-784-7454.
Aimee F. - Teknic Applications Engineer
@@TeknicIncthe power supply is included with the servo?.
Hi @@elsunshine9976 ,
A separate (24-75VDC) supply is required to run the NEMA 23 and NEMA 34 frame size ClearPath motors (the power supply is not included with the servo). Larger frame size ClearPath motors (NEMA 56, 143, and IEC D100) can be directly powered from a range of AC input voltages.
Please feel free to submit a contact request on Teknic’s website at teknic.com/contact/ or give us a call at 585-784-7454 if you have any further questions.
Aimee F. - Teknic Applications Engineer
@@TeknicInc do you guys have WhatsApp??
Hi @@elsunshine9976
Teknic does not use WhatsApp. We’ve tried similar apps in the past, but the limitations when discussing technical products far outweighed the “click convenience" benefit.
The best way to get effective support from Teknic is by using the contact request forum on the website (teknic.com/contact/) or by calling us at 585-784-7454.
Aimee F. - Teknic Engineer
You make mismatch with the concepts!!!! Servo motor is ANY motor with FEEDBACK.
If you put feedback on a stepper motor, it will be ALSO a servo motor.
BLDC motor with feedback is also servo motor. Asynchronous AC motor with feedback is also servo.
In this video, its not correct to compare servo BLDC with stepper WITHOUT feedback, they are in different classes.
Thank you for your comment. You're correct that technically any motor that uses feedback to control torque, velocity, and/or position could (and probably should) be termed a "servo motor". However, our experience is that most commonly, when people use the term "servo motor", they're referring to a servo controlled BLDC motor and when people use the term "stepper motor", they're referring to an open loop stepper motor. (Comment continues...)
Usually when an encoder is added to a stepper system, it's for the purpose of checking for lost steps after the move is finished. It's possible to continuously servo control a stepper motor (we can do this with our Meridian product line), however, the high inductance and detent torque of a stepper motor makes it a poor choice for servo control (so we only recommend the stepper option with Meridian when it's required for size or cost reasons). The stepper motor's historical strength is that it can be run open loop, and, as we state in the video, in lower power applications (that can use a NEMA17 size motor or smaller), the stepper motor will usually be less expensive.
Although it's correct for you to say that a servo controlled BLDC is in a "different class" than a stepper without feedback, we think it's a fair comparison because the pricing is similar and the two types of motors are often used in similar applications. Additionally, a stepper motor with an encoder paired with a stepper drive with encoder inputs, would be more expensive than a ClearPath servo system without the performance benefits of a BLDC servo system, so we didn't think it would be a helpful comparison.