Our last few postings talked about the “torque mode” operational theory that we added to our “Hybrid” drive. Prior to that we added “variable current mode” and “position makeup”
If you haven’t read about those drive enhancements, I suggest that you go back and pick up on those threads to catch up and get a good understanding as to how they work.
Why, you ask? Because these enhancements blend the servo technologies with the stepper technologies and we came up with what we call “hMTechnology.”
This technology allows a stepper motor to operate without stalling and without missing any steps. It also allows us to make the stepper motor act like a torque motor. These enhancements will allow us to use steppers in applications that they couldn’t participate in before, so “hMTechnology” has opened up new opportunities.
If you go way back in our postings you’ll see that the simplicity of a stepper system makes it one of the most cost effective motion control solutions, but stepper systems can’t meet all motion control requirements.
If they did, servos and all the other motor technologies would have gone away. All these technologies have an appropriate place in the motion control spectrum. The enhancements that the “hMT” brings to the application table allow us to use a potentially less expensive solution in applications that we couldn’t take part in previously. If you’ve read this far, and you were of the mind set that you avoided steppers because they can stall, reviewing these postings might encourage you to at least try it, or at least consider it in an application and see if it is a cost effective solution for you.
Rather than incorporating the “variable current mode,” the “position make up” and the “torque modes” into a standard stepper drive, which would take us quite a while to design and debug and then it would get us into patent infringement issues, we could just purchase the commercially available “Hybrid Motor Technology” and take advantage of the Novanta IMS’s design and the cost effective integrated motor-driver design that helps reduces the electronic-cabinet-mounting footprint.
Some points to consider when applying this technology are related to how the “position make up” takes place. For example: In the Liberty* MDrive, the speed of the “position make up” can be performed at one of two speeds. Step insertion can be at a specified speed or it can be set at the maximum speed the load will allow. There is no acceleration or deceleration applied to “position make up”, therefore it could be abrupt and at high speed. Make up steps could be interleaved during the slew portion of a move or made up during the deceleration portion. Make up could also take place at the end of the move profile.
Aggressive move profiles may present no opportunities to make up missed steps during the move profile. The missed steps would be inserted at the end of move which can affect the overall move time.
So what does this all mean?
We’ll get to see what it all means in our next posting.
*Previously Lexium
