Direct drive electromechanical system is composed of brushless dc torque motor, offset-tooth magnetic sensor that derives position and rate information directly from output shaft, and rotary power transformer that transfers electrical power from external source to proper load. System has high servo loop stiffness and minimum power consumption

Veillette, L. J.

English

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Comparator	
Digital 
Logic 
Sensor
Signal
Processor
Sensor 
Rotor 
Secondary 
V
Output 
Shaft 
Stator 
N N 
Rotor 
September 1970	 rief 70-10346 
RM. 1.313 
KSC HQS. 
N,
 
-: ---- 	 -- - -	 -	 - - 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the National Technical Information Service, Springfield, 
Virginia 22151. Requests for individual copies or questions relating to the Tech Brief progam may be directed to the Tech-
nology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
_i_- _	 - .•-:;	 ...	 .ii-. 
Electronically Controlled Motor Drive System Has Ultra-high 
Reliability and Long Lifetime 
Controller	 Sensor Stator 
.)irectiOfl Rate	 t1i
Motor 
I I	 "-"rmature 
Command 
Generator	
Difference 
Signal ki Amplifiers
Control
Signal
Processor 
Offset-Tooth Magnetic 
Sensor	 Rotary Power and Load Transformer 
A direct drive electromechanical system shown 
in the figure has the exceptional performance features 
of ultra-high reliability and long lifetime. No gears or 
sliding contact elements are used and only low speed 
bearings are required. The mechanical components of 
the system include a brushless dc torque motor which 
replaces the conventional brush-type motor, an offset-
tooth magnetic sensor that derives position and rate 
nformation directly from the output shaft, and a
rotary power transformer that transfers electrical 
power (without the use of brushes) from an external 
source to the proper load. Digital and linear integrated 
circuits process the shaft position and rate signals and 
generate the logic functions which control the shaft 
rotation. 
The design properties of high servo loop stiffness, 
minimum power consumption,and the capability of 
operating indefinitely at low angular rates enable 
(coiitinucd 0' erteal) 
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Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately ownedrights.
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the system to be utilized in a wide variety of industrial 
applications which require precise part location, such 
as graphic plotters and automated machine tools. 
Manufacturers and designers of process control sys-
tems which employ servo positioners would have spe-
cial interest in this synchronous and dc drive system. 
Technical performance highlights of the electro-
mechanical components include a stall torque of 90 in. 
-oz. developed by the motor which weighs only 4.3 
lb. The rotary power transformer, weighing only 2.3 lb 
handles 500 watts of power (at about 97% efficiency) 
and operates at 10 kHz. Development work is in prog-
ress to increase the stability, maximize the servo loop 
stiffness and reduce the overall system complexity.
Note: 
Requests for further information may be directed to: 
• Technology Utilization Officer 
Goddard Space Flight Center 
Code 207.1 
Greenbelt, Maryland 20771 
Reference: TSP70- 10346 
Patent status: 
No patent action is contemplated by NASA. 
Source: L. J. Veillette 
Goddard Space Flight Center 
(G SC- 10065) 
Brief 70-10346	 Category 02


Electronically controlled motor drive system has ultra-high reliability and long lifetime

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