Nutating stepping motor consists of an output rotating gear and a nutating gear. A flueric logic circuit controls the nutating motor. The complete system constitutes a reliable, open loop actuator system with inherently high output stiffness, reasonable slewing speeds and small step size

Dustin, M. O.

Griffin, W. S.

Wallhagen, R. E.

English

NASA Technical Reports Server

August 1970	 Brief 70-10332 
NASA TECH BRIEF	 LA  4P' 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Flueric-Controller Pneumatic Stepping Motor System 
A novel pneumatic nutating stepping motor was de-
veloped during a research effort on flueric controls for 
propulsion and power systems. The nutating motor, 
Figure 1, consists of an output gear which is free to 
rotate only, and a nutating gear that is free to nutate 
or wobble only. The nutating gear is actuated by eight 
bellows around its periphery. When four adjacent bel-
lows are pressurized, the nutating gear is tilted into 
contact with the rotating gear. Sequencing the bellows' 
pressurization pattern causes the nutating gear to nu-
tate. Since the nutating gear has 181 teeth, and the out-
put gear 180 teeth, the output gear is forced to rotate 
2° for each nutation of the input gear. 
A flueric logic circuit, Figure 2, composed of 24 
flueric amplifiers was developed to control the nutat-
ing motor. The purpose of the logic circuit is to store 
the actuator bellows' pressurization pattern and to 
sequence it in either a forward or backward direction, 
depending on the direction of the input command 
pulses. Forward pulses enter the circuit at eight loca-
tions marked T f , and backward pulses enter the cir-
cuit at eight locations, T h . The outputs labeled A A 
to D D actuate power amplifiers which, in turn, pro-
vide high pressure and flow to the eight bellows of the 
nutating motor. The heavy lines in Figure 2 indicate 
the signal lines which would be pressurized when bel-
lows A, B, C, and D are pressurized. The application 
of one forward pulse to the eight T 1
 ports would ad-
vance the pattern to A, B, C, and D. 
An integrated version of the logic circuit was de-
veloped in which the entire flueric circuit was con-
tained in a solid block 2 in. x 2 in. x 3 in. The block 
was composed of copper laminates fused together by 
diffusion bonding. 
Test results indicate that the flueric circuit could 
drive the nutating motor at a speed of almost300 steps
Bellows
Gimbal 
Ring 
Outpu
Output Gear 
N utat i ng 
Gear 
Inlet Port 
to Bellows 
Figure 1. Pneumatic Stepping Motor Actuator 
(or 75° of output shaft rotation) per second. The out-
put torque at zero speed was approximately 80 in-lb. 
The complete system constitutes a reliable, open 
loop actuator system with inherently high output stiff-
ness, reasonable slewing speeds and small step size: 
Although the stepping motor uses more air than an 
equivalent piston actuator driven by a flapper valve, 
this high air use might be accepted for some applica-
tions in order to gain simplicity, reliability and high 
output stiffness. 
References: 
1. NASA-TN-D-4495, "A Breadboard Flueric-Con-
trolled Pneumatic Stepping Motor System," by 
William S. Griffin, 1968. 
2. NASA-TN-D-5155, "Design and Performance of 
Two Integrated Circuits for Fluidic-Controller Pneu-
Dynan 
-	
.	 (continued overical) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
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 owned.rights.
https://ntrs.nasa.gov/search.jsp?R=19700000320 2020-03-17T00:19:54+00:00Z
Passive AND 
Elements 
Central Bistable 
Amplifiers with 
4-Input Bistable 
Amplifiers 
Passive AND 
Elements
A.A; B,B; CC; D,D; Counting-Circuit Outputs (to Control Ports 
of Power Amplifier) 
T f Forward Timing-Pulse Input Ports 
Tb Backward Timing-Pulse Input Ports 
Time Delay Line 
Figure 2. Flueric Logic Circuit 
matic Stepping Motor System," by Miles 0. Dustin 
and Robert E. Wallhagen, 1969. 
Notes: 
1. The following documentation may be obtained 
from:
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.65) 
Reference: 
NASA-TM-X-52250 (N67-11333), Devel-
opment of High Speed Flueric Logic 
Circuitry for a Novel Pneumatic Stepping 
Motor
2. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B70-10332 
Patent status: 
No patent action is contemplated by NASA.

Source: W. S. Griffin, M. 0. Dustin

and R. E. Wallhagen
Lewis Research Center

(LEW-1105 1) 
Brief 70-10332	 Category 02


Flueric-controller pneumatic stepping motor system

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