Yaskawa
eLearning
Hello this is Matt Pelletier and let's look at a Motion Control System Overview
and learn some of the terminology.
This is especially useful if you are new to the motion industry.
So, first let's look at the components of a motion-control system.
The most important component in many aspects being that of the load and what we call,
in this case, a ball screw, a belt, any type of mechanical system.
But the load can't move by itself.
We have to have a motor and servo motor, in many cases, but the servo motor also
can't move by itself it has to be driven through a drive. The servo drive is often
referred to as the amplifier or amp and Yaskawa has a name that we'll put on the
front of ours called Servo Pack.
So these terms are synonymous in the motion world you'll often hear the word
servo and the servo can be referring to the motor, the motor and drive,
sometimes together or separate and one common, you might call it mistake, is to call this
drive the controller and in a sense it is controlling the motor, but the
controller or the logical controller, the PLC, is a separate system and so I'll
call this the controller. The drive just takes a command and makes the motor move
as commanded. The controller is what makes the decisions and decides what
that command should be. Now and over the years different manufacturers have done
things to combine the controller and drive into one package or to combine
the drive and motor into one package.
Yaskawa has done this, we've got an MP 2600iec puts the controller together in
one package with the drive. But really no matter how you look at it,
we still have these distinct components whether they're in the same package or not.
And finally, here the user interface we'll call the HMI the Human Machine Interface
and that could be a nice panel like this or it could simply be switches and indicator lamps.
And then this HMI is used to access and perhaps change
different parameters in the controller so that the controller, it can change the
way it commands motion to the drive and hence to the load.
So let's start by looking at the controller because the controller
selection often determines the setup and configuration of the drive system.
The controller selection can be based on the programming environment and that's one
of the reasons that Yaskawa has moved to the IEC platform.
It's an international standard programming environment.
Communication is also important as there may be a communication to other systems,
EtherNet device net,
Modbus are some examples. The IEC series has a lot of communication here through
both Mechatrolink and EtherNet and the controller used also affects the servo
control features specifically the tuning algorithms and then the type of command
that sent from the controller to the amplifier. Again, using the case here of
the IEC controller we would be using the amplifiers in position mode so that we
can take advantage of the Sigma-5's advanced tuning algorithms and other
types of controllers may use speed, position or torque command and then
different levels of the Sigma-5 amplifiers tuning algorithms would be available.
Controllers also dictate the number of servo axes one drive motor and
load is considered to be an axis and of course price is important.
Customer specification, sometimes just dictates which controller will be used
and the manufacturer reputation, the other non-technical criteria.
Some of the controllers that Yaskawa offers are the MP2000iec family.
That's down here...we have the MP2300Siec
and the 2310iec which has a little more built in IO capacity and the MP2600iec
which is the one I was mentioning that's part of the amplifier all-in-one package.
There's also the MP2000 family. It uses a programming platform and a different
operating system but also very powerful and is capable of a very high axis count
in the case of the MP2200 here, up to 256 axes, 256 servo motors can be controlled by this controller.
But Yaskawa also make Sigma-5 amplifiers that are compatible with
the third party vendors such as Galil, Delta Tau, Omron and others and so
whether it's network amplifiers or analog pulse amplifiers like we're showing here
the Sigma-5 can interface with just about any type of host controller
including motion controllers, CNCs, indexers, PLCs - you name it we've got an
amplifier that will interface with that controller.
And here we are showing example of a controller, Torque Control mode
CNC controllers are many and varied, but in general, they send a speed command
and so we call it speed control.
And the most simple type of controller is often found in PLC's
where they're just send position command to the controller
this is very similar to a stepper motor or as it shows here, a stepper card commanding a servo.
So, with all these controllers - torque, position, speed, we could always do
positioning as a system, the question or the difference
is just what type of command is being sent between controller and amplifier.
A separate type of Sigma-5 amplifier is the Mechatrolink-II.
That's an open network interface.
And Yaskawa uses that with our IEC and MP2000 series controllers.
Other third-party controllers such as Omron
also make controllers to run servos using this network.
This Mechatrolink network can also support
IO Modules and an example of those is the Phoenix bus coupler
so you can use any of the Phoenix IO on the Mechatrolink network as well.
Let's look next at the motor technology.
Yaskawa offers three types of motor technology.
Rotary, Linear motors and Direct Drive motors. Rotary is the typical servomotor.
When you think of a servomotor, I think of this rotary type and linear motors
include two types; one type is the pre-built pre-engineered SigmaTrac
where you just take the whole thing, ordered to length and plug in the cables and it runs.
Well, we also sell component-level linear motors.
Three types of linear motors; Coreless, Flat Iron Core and T-Type Iron Core,
where you got the magnet track sold in lengths and then the moving coil you build
up the system custom or perhaps even mounted straight to the machine.
And the third type of motor technology offered at Yaskawa - it's called Direct Drive and it's
especially designed with these mounting holes to mount a rotary table
so you can have a pretty large, very large diameter rotary table on one of
these small motors and the motors don't go very fast, just about 500 RPM is the
fastest one - 300 to 500 RPM is about as fast as they go, but they really have
high torque and high inertia and so very good for rotary table applications they
have a very high resolution encoder.
So those work out really well and you don't have to have any additional gear
boxes or other mechanical components as you would if you use the typical rotary motor.
Of all the motor technologies out there why a servomotor?
Why not an AC induction motor? Why not a simple universal
motor like you have a power tool?
Well, servo motors are the most powerful for their size you the most torque and speed
out of a servo motor compared to other technologies.
Servo motors also have very fast response
so if you try to turn the shaft of a motor that's well-tuned, a servo motor
it's going to respond and hold that position very tightly and also when you
make it move it stops, starts, changes speed very quickly we're talking
milliseconds of change time not seconds.
And so this really lends itself well to the motion industry where we're trying
to do a motion repeatedly and shave off the few milliseconds here, a few
milliseconds there, to get the most output possible. With a servomotor, you always
have to have an encoder on the back and that means you always need the amplifier
you don't run servomotors off the line power at constant speed, you need to have
the servo drive and so because of this you always have a higher cost especially
compared to an induction motor with a VFD system.
The amplifiers don't really cost any more for servo versus a VFDs but the motor is definitely more
expensive so you get what you pay for - a millisecond response in a very small package.
Different options available and many of the servo motors offered by Yaskawa
First of all, is the voltage for Sigma-5. We have either the 200 volt motor or 400 volt motor.
That doesn't mean that you can't run on a 100 volts
it's just that the motor will run on 200 volt and there are a 100 volt
amplifiers that run the tunable motors. Another option are holding breaks and
that adds a piece to the end of the motor and allows the motor to hold its
position even with the servo is off and you don't have any power, especially good
for vertical loads where the load could fall if it doesn't have something holding the shaft.
A motor seal is when you have a shaft seal so that chips
and pieces of material, cutting fluid etc. have no chance then of getting into the
motor from the shaft side.
The motor is very well sealed from the outside but from the shaft that
is a an entry point, unless you have the additional seal installed over the shaft.
And so that's something you have to have installed at the factory - the shaft seal.
The absolute encoder is our standard option now with Sigma-5.
An absolute encoder means that you don't have to "home" more than one time
per install, once you've "homed" the motor and have that position that gets
communicated up to the controller and the controller always knows where the
motor is and even if the power is off the battery to the encoder is never off
and the encoder will effectively stay on at all times and you'll always know
then if the shaft is moved even with the machine power off.
Keyway is on the shaft itself.
It's a little cut out, a little notch cut out of the shaft
and then when you install the servo motor, and couple it to the machine
there's a mating Keyway and that does a lot to really ensure that the shaft
cannot slip relative to the load. So Keyway is an option
and if you don't need the Keyway most of the time you can have a shaft with
the Keyway anyway, it doesn't bother if using this compression type of coupling.
There are many performance specifications related to the servo motor
and just a few of them here is an overview I'm going to list.
The first is Torque, or in the case of a linear motor, Force and that's how hard the
shaft can turn. In the case of this motor more torque means more foot-pounds.
Think of a wrench and you know the amount of torque you can torque down a nut
depends on how long the wrench is and how strong you are, and so by the same token
you have a servomotor has torque and so there's a measure for that of how hard
that shaft can turn. In the case of a linear motor that's just straight linear force.
When you think of a motor, you think of it turning
and that is a speed measured in RPM, revolutions per minute, of the shaft
and just get a ballpark idea of how fast servo motors go, the Sigma-5 motors
can go as fast as 6,000 RPM on the G series is one that has a more torque but
less speed and those max out at around 3,000 RPM and a third very important
specification for servo motors is the moment of inertia and that's typically
referred to by the letter "J" for inertia and "M" here for motor, inertia of the motor,
and moment of inertia is a measure of how difficult it is to accelerate the
motor from stop to its mass and its dimensions so a general trend here is
the greater the radius of the rotor inside, the spinning part, the greater the
inertia will be and then also the heavier that spinning part is the
greater the inertia will be. So the equations of dynamics and physics are
used to determine the moment of inertia of the rotor and the moment of inertia
is a very key measurement in the sizing of servos
we like to look at the comparison of the load's moment of inertia and the motor's
moment of inertia and try to keep that within a certain range for certain types
of applications that are very demanding.
This concludes the Motion Control System Overview