RE: hybrid stepper/servo system

I talked to the company (Bearing Engineers) this morning about their Servo motor controller and motor package. If my understanding is correct, each controller will control one size 17, or one size 23, or one size 34 motor. The resolution of the size 34 servo motors they offer is 2000 line quadature (8000 steps per 360 degree rev), and 1000 line (4000 steps per 360 degree rev) for the other motors they offer. The size 34 motor is rated at 200 OZ. The size 17 is rated at 18 OZ. Peak torque is higher. They offer two different size 23 motors.

The controller accepts step and direction signals and requires about 11 MA of sink on a five volt signal and the controller has internal pullups. The Power Supply is external (as an option) and should be 24V to 75 VDC and 75VDC is recommended. The controller also has two limit switch inputs, and can operate from an additional signal on the interface to limit the motor current for hard home landings (not used often) if you want to drive into a wall.

It is necessary to calibrate the Controllers and motors using an oscilloscope and they sell the Calibration software and cables with the first Motor and Driver you purchase for around $1421.00 10 foot cables are $75.00 (included with the calibration package and first motor), so to put this in perspective, if you want 3 axis of size 34 for 200 OZ motion control and a resolution of 8000 steps per rev, You will probably pay $1421.00 for the first Controller / Motor / Cable / Special Calibration cables and documentation, then $1100.00 plus $75.00 time two for two additional Controllers / Size 34 Motors and ten foot motor cables. Once you have the calibration kit, each added axis for Size 34 is $1175.00 Size 23 is $900 + $75.00 and I didn't get the cost for Size 17, but the Size 23 is the bottom end.

I do not have the complete specifications, and I am sure that other features are offered beyond the highlights described. They seem to be very willing to answer any questions and provide any necessary assistance.

David Howland


-----Original Message-----
From: CG [SMTP:cnk@...]
Sent: Thursday, September 30, 1999 1:46 PM
To: CAD_CAM_EDM_DRO@onelist.com
Subject: [CAD_CAM_EDM_DRO] hybrid stepper/servo system

From: "CG" <cnk@...>

Dave -

I just ran across a company called Bearing Engineers
http://supersite.net/semin2/bearinge/home.htm (see the Press Releases)
that sells an impressive step/direction controlled servo system. What does
everybody think about this approach for a low-cost servo system? It's all
digital and they make some big claims as far as following errors and
performance. I think they're doing something fancy with "sinewave vector
commutation" or the like, but even the step/direction approach for
plain-vanilla servos sounds like it could have alot of potential with a fast
enough steprate.

Carlos Guillermo



David Howland <dhowland@...> wrote:

>
> The diamond in the pile of possibilities (on my front) may be
> open loop stepper motor programs, driven through a higher speed
> interface into a black box which turns a DC motor and encoder
> into a higher performance stepper motor (a hybrid). This may be
> realized, if surplus DC servo motors offer more bang for the buck
> and can be identified and used easily. Some surplus servo motors
> are neither easy to identify, or appropriate for this use.
>

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