Control.com - Nerds in Control

Hello all,

I am a EE, but I'm new to industrial controls.

I am building a 2 axis flight simulator, and am using AC servo motors. I'm trying to buy the motors and drives as cheaply as possible, so I am looking on Ebay and other surplus sites.

I have bought an emerson MGM-4120-CBNS 5hp AC brushless servo motor with gear reducer down to 60rpm. I have been looking for a drive to work with it, but so far I'm not having any luck. I was told that the Emerson EN-214 will work, but I can't find one surplus. Emerson's site also doesn't seem to have information on a lot of the other drive models I see on Ebay, so it's difficult to determine what will work with this motor.

Is is recommended to use a different brand of drive? I have seen a few others that will handle the horsepower, but are different brands.

Thanks in advance,
Rick

If this is the typical permanent magnet servo with hall switch commutation and incremental encoder, you can use just about any drive for brushless motors. Copley controls makes some good drives.

You don't mention the motion controller you are using. If you use something like Galil, Delta Tau, Elmo, you can get a programmable controller and Drive unit in one. Depending on what you are doing this might make sense.

The motor specs from Emerson state that it uses neodymium magnets (I'm assuming that's a permanent magnet design.) 2048 lines per rev. incremental encoder, and low-inertia.

As I understand it, I can use either a position controller, or just a standard controller which accepts a voltage input for the motor speed, as well as a direction line, enable line, and brake line. I was considering using only the simple controller (amplifier) and building my own device to accept the encoder feedback and use PID algorithms to generate the motor outputs.

One other question: If I use the position controller, will these typically control the position for only one revolution? In my application, the flight simulator will be mounted on a gimbal, so it will be able to have unlimited rotation, but the controls will be concerned with the position of the cockpit, not just the speed. Do you all think that one of these controllers will handle that, or will I need to make something else?

Thanks for the help,
Rick

It is good that the motor has an incremental encoder. If it has UVW channels, even better.

Look at the Copley Controls digital drives, such as the Xenus. They have software that makes the motor setup relatively easy. They also have the option of built in position control (single axis). Or you can tune them up in velocity mode and use you own position controller. Galil makes a reasonably priced multi-axis position controller.

For more advanced control (and more $$$), the Delta Tau Geo PMAC drives have decent motor setup software and very capable multi-axis control. They have excellent features for three dimensional coordinate system control, both cartesian and non-cartesian. These controls have a bit of a learning curve however.

Most position controllers track the motor position over multiple turns, until the position register overflows. Some have a modulo mode, that makes controlling a single turn device easier.

Bill

Some drives can be configured for other motors, but many cannot. A-B Ultra 100, many Baldor, and Kollmorgen ServoStar can, but it is not easy. The type of feedback is critical, usually encoder or resolver. An analog brushless drive like Copley, AMC, or Glentek might be the easiest, there is less software involved. If you have an encoder with hall channels, the analog drives are fairly straightforward, but you still have phasing and tuning issues.

Most drives will handle "foreign" motors if you have the data for the motor and they are reasonably compatible. This has been better as of late with motors becoming more "standard". I see all kinds of mix and match. There are still some drives and motors that are made for each other.

Regards
cww

I think that you need 2-axis motion controller for axes synchronization and analog servo amps with six-step commutation by Halls. Suggested above Galil motion controller with dual build-in servo amp (or external Elmo analog servo amp) would be cheaper vs. others.