Building a motorized cable workout system

Hi @inst-tech,

  Thanks for your input.

  Sorry, I confess to not being familiar with the product you reference, so I am not clear if it would be particularly appropriate. I think this application requires the motor to actually be turned by the user's muscle power ... the motor is required to offer a programmable controlled resistance to this turning force. This is not a situation that I have any experience, and hence I suggested starting with a scaled model.

It appears @tasan is intending to contact the commercial company offering a product with at least some of the capabilities required, so at this stage it is probably appropriate to wait for further information.

Best wishes, Dave

@davee Hi Dave.. This is just information for you since you stated you weren't familiar with thies type s of motors.. We used them on our paper machine for tension control of the paper sheet as it was 330 inches wide and traveling @ 3450 fpm!.. At near the bottom of the article is a short video demonstration of how the torque motor works.....Very interesting..

https://blog.orientalmotor.com/the-right-motor-for-tension-control

Kind regards,

LouisR

@inst-tech For a couple of years I worked in the cold rolled steel business (steel to make cars from) and the newer mills were 60" wide, the older 48". I don't know at what speed the steel went through any of the mills, but it was pretty fast except for the galvanize mill.

That was 60+ years ago so I have no memory of the motors, but they were probably very different than today. The oldest machines were still on 25 cycle, we had a dedicated power line from Niagara Falls Ont to Hamilton Ont. The MG set was about 12 ft tall and if memory serves 25,000 HP.

In the case of steel, the tension was generally maintained by each motor running faster than the preceding motor. Since they were making the steel thinner as it went through the individual rollers, the motors had to go faster as the steel got longer. My oldest mill was a 5 stand cold mill, the electronic modern (mostly down) was a 4-stand. I was responsible for at least 4 other mills, some only one machine some more but simpler.

That job was my last shift work job and then I joined IBM. Discrete transistor logic!

Sorry for the nostalgia.

@inst-tech That is a great demo of what I was referring to although I named it differently. I am sure it works very differently today to create the drag than what we did over 50 years ago.

Posted by: @zander

↑

@inst-tech That is a great demo of what I was referring to although I named it differently. I am sure it works very differently today to create the drag than what we did over 50 years ago.

@zander, Indeed, the demo was pretty impressive!  I also found an article that shows how torque motors are used in various application on a paper machine.

https://www.tappi.org/content/events/07place/papers/whiteside.pdf

take care my friend,

regards,

LouisR

@inst-tech Excellent document. I am fairly certain my oldest equipment was not so sophisticated, but the newer equipment would have been. I have toured a newspaper line and saw the various rollers with loops before and after with the printing in the middle, but that was while I was in College because I was a reporter at school and when I handed in an article to the local paper they gave me the entire tour but it was just me, not a group as usual.

When I worked for the steel company, I don't remember any high-speed mills that had the loops, but the galvanize mill did. It was quite slow as the main loop was immersed in the liquid and had to stay in contact for a while.

Hi Louis @inst-tech,

   Thanks for the extra info on 'torque motors'. Obviously, I am not intending to build the machine this thread is about, but I am always interested to know how things work, even if I never even see one in my lifetime.

A few seconds Googling suggested that torque motors are, in many ways, similar to stepper motors, in that they have many poles, static windings, and with suitable electrical drive, can be aligned to any static angle.

However, Google did not offer an instant answer to my 'torque motor versus stepper motor' question, so I spent a few minutes more looking, and formed the following, probably greatly flawed, overview. (Please remember this was only a few minutes searching, not a comprehensive survey, and I do not profess any expertise in this area.)

Of course, there are differences, such as the torque motors, maybe marketed as a 'kit' of active parts, not including frame and bearings; maybe used in a 'spindle-less' arrangement with a large diameter stator and rotor; 'kit parts' may include orientation sensors and driver electronics for interfacing to computer control, and so on. Of course, other manufacturers may also produce complete 'framed' motors. I suspect the windings may be arranged for a three-phase style instead of the two windings style often seen on stepper motors, but again I did not survey the market, so this might not be a general case.

Clearly, the large stator and rotor would enhance its ability to carry large currents and encompass many poles, which would be required for high torque, and/or precision positioning and control. It also probably helps to make very precise mechanical arrangements, providing the hosting machine is built to the highest standard.

Overall, this suggests to me that stepper motors with appropriate electrical drivers, and torque motors with appropriate electrical drivers, could have much in common when considering the computer control and interface requirements and capabilities. Similarly, they seem to be aiming to provide a similar type of precision controlled motion, including accurate static positioning. The differences seem to be more a case of optimising for the specific application. Vastly oversimplifying, stepper motors seemed to be optimised towards lower cost, lower torque, lower custom mechanical design and fabrication cost and complexity, whilst the torque motors offered higher specifications in these areas, but possibly at higher cost and the need for very high precision and/or strength mechanics.

Please feel free to correct any misapprehensions on my part.

Best wishes, Dave

@davee You said

 torque motors, maybe marketed as a 'kit' of active parts

I think the motors referred to by Louis(@inst-tech) are not kits. Neither are any of those shown in his videos and links. Perhaps you meant something else?

HOWEVER, I think there is sufficient similarity to a stepper that a motivated individual could do some experiments and write a paper that describes how a stepper plus circuitry could be used as a torque motor at least at the hobbyist level. I am NOT that individual.

Posted by: @davee

↑

Hi Louis @inst-tech,

   Thanks for the extra info on 'torque motors'. Obviously, I am not intending to build the machine this thread is about, but I am always interested to know how things work, even if I never even see one in my lifetime.

A few seconds Googling suggested that torque motors are, in many ways, similar to stepper motors, in that they have many poles, static windings, and with suitable electrical drive, can be aligned to any static angle.

However, Google did not offer an instant answer to my 'torque motor versus stepper motor' question, so I spent a few minutes more looking, and formed the following, probably greatly flawed, overview. (Please remember this was only a few minutes searching, not a comprehensive survey, and I do not profess any expertise in this area.)

Of course, there are differences, such as the torque motors, maybe marketed as a 'kit' of active parts, not including frame and bearings; maybe used in a 'spindle-less' arrangement with a large diameter stator and rotor; 'kit parts' may include orientation sensors and driver electronics for interfacing to computer control, and so on. Of course, other manufacturers may also produce complete 'framed' motors. I suspect the windings may be arranged for a three-phase style instead of the two windings style often seen on stepper motors, but again I did not survey the market, so this might not be a general case.

Clearly, the large stator and rotor would enhance its ability to carry large currents and encompass many poles, which would be required for high torque, and/or precision positioning and control. It also probably helps to make very precise mechanical arrangements, providing the hosting machine is built to the highest standard.

Overall, this suggests to me that stepper motors with appropriate electrical drivers, and torque motors with appropriate electrical drivers, could have much in common when considering the computer control and interface requirements and capabilities. Similarly, they seem to be aiming to provide a similar type of precision controlled motion, including accurate static positioning. The differences seem to be more a case of optimising for the specific application. Vastly oversimplifying, stepper motors seemed to be optimised towards lower cost, lower torque, lower custom mechanical design and fabrication cost and complexity, whilst the torque motors offered higher specifications in these areas, but possibly at higher cost and the need for very high precision and/or strength mechanics.

Please feel free to correct any misapprehensions on my part.

Best wishes, Dave

@davee,  Indeed Dave, Your right on target..The Torque motors are used for high end industrial precision applications as noted in my link to the article i furnished you with. My only experience with them was in the Paper mill where I worked for almost 30 years.. The Winders, Rewinders, Press section, dryer section and calipers rolls all need tension control, and the equipment is very sophisticated ... This link will give you some idea of just how complex it is...lol

https://library.e.abb.com/public/8bdb5394c88ec3e4c12577d6003dabaa/Brochure_PMC800_ABBs_control_solution_for_paper_machine_drives_EN_FINAL_021110.pdf

I kinda thought you'd be interested in it, even if you never see one the rest of your days... 😉

Regards,

LouisR