A device to be used with an aircraft simulator to apply positive and negative g forces to the pilot's arm is described. An arm harness fits around the arm which the pilot uses to operate the throttle. The device allows the harness to track intentional arm movements without exerting any restraining forces, and at the same time, applies g forces to to the pilots arm which are recorded by the aircraft simulator computer

Ashworth, B. R.

Merrill, J. T., IV

English

NASA Technical Reports Server

REPLY TO
ATTN OF: GP
NATIONAL AERONAUTICS AND SPACE A D M I N I S T R A T I O N
WASHINGTON, D.C. 20546
AUG 1974
TO: KSI/Scientific & Technical Information Division
Attn: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General
Counsel for Patent Matters
SUBJECT: Announcement of NASA-Owned U.S. Patents in STAR
In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided:
U.S. Patent No.
 : J,
Government or
Corporate Employee
Supplementary Corporate
Source (if applicable)
NASA Patent Case No.
(r I
NOTE - If this patent covers an invention made by a corporeite
employee of a NASA Contractor, the following is applicable:
YES '/ NO
Pursuant to Section 305(a) of the National Aeronautics and
Space Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
inventor (author) appears at the heading of column No. 1 of
the Specification, following the words "...with respect to
an invention of ..."
Bonnie L. Woerner
Enclosure
https://ntrs.nasa.gov/search.jsp?R=19740022484 2020-03-17T15:17:24+00:00Z
United States Patent
Ashworth et al.
[ i i ] 3,824,707
[45] July 23, 1974
[54] APPARATUS FOR APPLYING SIMULATOR
G-FORCES TO AN ARM OF AN AIRCRAFT
SIMULATOR PILOT
[75] Inventors: Billy R. Ashworth, Newport News;
John T. Merrill, IV, Yorktown, both
of Va.
[73] Assignee: The United States of America as
represented by the Administrator of
the National Aeronautics and Space
Administration, Washington, D.C.
[22] Filed: June 9, 1972
[21] Appl. No.: 261,183
[52] U.S. Cl 35/12 E
[51] Int. Cl G09b 9/00
[58] Field of Search 35/12 S, 12 E, 12 W, 12 D,
35/12G, 12 P; 244/83 D
[56] References Cited
UNITED STATES PATENTS
2,521,680 9/1950
2,851,795 9/1958
2,860,423 11/1958
Amtmann 35/12 R
Sherman 35/12 S
Dehmel 35/12 S
3,220,121 11/1965 Cutler 35/12 S
3,529,365 9/1970 Shelley 35/12 S
Primary Examiner—Robert W. Michell
Assistant Examiner—Vance Y. Hum
Attorney, Agent, or Firm—Howard J. Osborn; William
H. King; John R. Manning
[57] . ABSTRACT
This invention is a device to be used with an aircraft
simulator to apply positive and negative g-forces to
the pilot's arm. An arm harness fits around the the pi-
lot's arm that he uses to operate the throttle. The de-
vice allows the harness to track intentional arm move-
ments without exerting any restraining forces and at
the same time applies through the harness g-forces to
the pilot's arm that are computed by the aircraft simu-
lator computer.
The invention described herein was made by
employees of the United States Government and may
be manufactured and used by or for the government
for governmental purposes without the payment of
any royalties thereon or therefor.
8 Claims, 3 Drawing Figures
24
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 s
 "U cKAFT SWULAIOB PILOT
: (NASA) 4 p
N7U-30597
Onclas
00/11 54551,
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PATENTED JUL23I974 3,824,707
12
FIG. 1 „.
15
D
14
13
25 29
27
32
FIG. 2
31
26 30
21
20
21
23
-5V 30
FIG. 3
3,824,707
APPARATUS FOR APPLYING SIMULATOR
G-FORCES TO AN ARM OF AN AIRCRAFT
SIMULATOR PILOT
BACKGROUND OF THE INVENTION
The invention relates generally to simulators and
more specifically concerns a device for applying com-
puted g-forces to a pilot's arm as he operates an aircraft
simulator.
A pilot of an aircraft depends on "seat-of-the-pants
feel" for control of the aircraft. That is, as the aircraft
is being flown the pilot is subjected to g-forces that in-
fluence his movements in controlling the aircraft. In the
past, the primary method used to supply the g-forces in
aircraft simulators was to make the cockpits of the sim-
ulators movable. The main disadvantage of the mov-
able cockpit is that the movement of the cockpit has a
limited range which limits the effectiveness of the simu-
lator. In addition, a large additional cost is added to the
simulator when the cockpit is movable. Also, it is not
easily adaptable for use with a visual scene in the simu-
lator. The reason for this is that the cockpit moves rela-
tive to the scene unless the scene is made to move in
unison with the cockpit.
It is the primary purpose of this invention to provide
a simple, inexpensive device for applying computed g-
forces to the arm of a simulator pilot for the purpose
of simulating the feel of a pilot in a real aircraft.
SUMMARY OF THE INVENTION
The device that constitutes part of this invention is
mounted on a movable cart that is attached to the
throttle for movement therewith in the horizontal di-
rection. The cart is level and moves on bearings to pres-
ent negligible force to the throttle movement. The in-
vention includes an arm harness for attaching to the
simulator pilot's arm that controls the throttle. Signals
representing computed values of g-forces are applied
from the simulator computer to the device which con-
verts these signals into forces that are applied through
the arm harness to the pilot's arm. The device also al-
lows the harness to track intentional arm movement in
the vertical direction by the pilot without exerting any
restraining forces with or without g-forces being ap-
plied to the pilot's arm through the harness. The cart
allows the pilot to move his arm in the horizontal direc-
tion without exerting any restraining force. Hence, any
intentional arm movement will be tracked with no
change in g-force.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram showing how horizon-
tal movement of the pilot's arm is accomplished;
FIG. 2 is a schematic diagram of the mechanical
components that enable the g-forces to be applied to
the pilot's arm and that enable the pilot to move his
arm in the vertical direction; and
FIG. 3 is a schematic diagram of the electrical com-
ponents that enable the g-forces to be applied to the pi-
lot's arm and that enable the pilot to move his arm in
the vertical direction.
DETAILED DESCRIPTION OF THE INVENTION
Turning now to the embodiment of the invention se-
lected for illustration in the drawings the number 11 in
FIG. 1 designates a cart that is mounted for movement
10
1 5
20
25
35
40
45
50
..
65
along a rail 12 in a horizontal direction. The throttle 13
of the aircraft simulator' is attached to cart 11 by any
suitable means 14 such that when the pilot of the simu-
lator moves the throttle back and forth, cart 11 will
move along rail 12. A device 15j which is disclosed in
detail in FIGS. 2 and 3, is attached to cart 11 so that
it moves with cart 11. This device 15 applies g-forces
to the pilot's arm and enables him to move his arm in
the vertical direction without exerting any restraining
force.
The mechanical components of device 15 as shown
in FIG. 2 includes an arm harness 20 which is approxi-
mately 6 inches long and fits on the pilot's arm about
one inch above the wrist. The arm harness is elasticized
to fit snugly on the pilot's arm. A three-wire support 21
is on each side of arm harness 20 to allow some rota-
tional motion of the pilot's arm as well as providing
more uniform forces. A cable 22 is attached to each of
the three wire supports 21 and wrapped around a sys-
tem of pulleys 23, 24, 25 and 26. Each of the pulleys
is attached to cart 11 such that it will rotate relative to
the cart. Cable 22 has preload springs 27 and 28, which
can be rubber cords, for maintaining tension in the
cable to avoid deadband in the system. The spring con-
stant and amount of preload depends on the amount of
force desired at the arm harness. Cable 22 is also at-
tached to strain gages 29 and 30, and to the shaft 31 of
a torque motor 32.
As shown in FIG. 3, strain gages 29 and 30 are simple
bridge-type gages the outputs of which are applied to
differential amplifiers 35 and 36, respectively. Differ-
ential amplifier 35 produces a positive output and dif-
ferential amplifier 36 produces a negative output. The
output of amplifier 35 is connected through a summing
resistor 37 to input A of a differential amplifier 39, and
the output of amplifier 36 is connected through a sum-
ming resistor 38 to input A of amplifier 39. The analog
signals from the aircraft simulator computer represent-
ing the g-forces to be applied to the pilot's arm are ap-
plied to a terminal 40. These signals are applied to a po-
tentiometer 41 the slider of which is connected through
a resistor 42 to the input B of differential amplifier 39.
The output of amplifier 39 is connected through a
power amplifier 43 to torque motor 32.
In the operation of this invention, the computed g-
force signals are applied to terminal 40 from the air-
craft simulator computer. These g-force signals are ap-
plied through the slider of potentiometer 41, resistor
42, and amplifiers 39 and 43 to torque motor 32. The
resulting torque produced by motor 32 are applied
through cable 22 to apply forces to the pilot's arm
through arm harness 20. The torque applied through
cable 22 cause strain gages 29 and 30 to produce sig-
nals that are applied through resistors 37 and 38 to dif-
ferential amplifier 39 to balance the system.
Whenever the pilot operates the throttle 13 his arm
has both a horizontal movement and a vertical move-
ment. The horizontal movement is taken care of by the
movement of cart 11 along rail 12. The vertical move-
ment, either up or down, is taken care of by the device
in FIGS. 2 and 3 as follows. Assume that no g-force sig-
nal is applied to terminal 40 and assume that the pilot
moves his arm up. Then amplifier 36 will increase its
output due to the increased tension on strain gage 30
and amplifier 35 will decrease its output. Since ampli-
fier 36 has a negative output and amplifier 35 has a pos-
itive output, point A becomes negative with respect to
3,824,707
point B and motor 32 turns clockwise. Consequently,
motor 32 moves the arm harness up to assume the new
neutral position. Since motor 32 begins to turn as soon
as the pilot starts his arm moving upward, the arm har-
ness does not offer any resistance to the pilot's arm
movement. If the pilot moves his arm down, point A be-
comes positive with respect to point B, motor 32 turns
counterclockwise and the arm harness follows the pi-
lot's movement. If g-force signals are applied to termi-
nal 40 the corresponding g-forces will be applied
through the arm harness to the pilot's arm and at the
same time the arm harness will follow the intentional
movement of the pilot's arm as described above.
The advantages of this invention are that it provides
a simple, inexpensive means for applying simulated g-
forces to a pilot's arm as he controls an aircraft simula-
tor thereby providing a "seat-of-the-pants feel" for
controlling the aircraft simulator. :•
It is to be understood that the form of the invention
herewith shown and described is to be taken as a pre-
ferred embodiment. Various changes may be made
without departing from the spirit and scope of the in-
vention as described in the subjoined claims. For exam-
ple, the pulley arrangement could be different from
that shown and different electrical components could
be substituted for those shown. Even though this inven-
tion is described as being used by the pilot as he oper-
ates the throttle of the aircraft simulator, it is obvious
that it could be used with other control mechanisms
such as the stick. Consequently, the claims in this appli-
cation should not be limited to use with a throttle.
What is claimed is:
1. A device for applying simulator g-forces to the arm
of an aircraft simulator pilot, g-forces being repre-
sented by input electrical signals, and for allowing a
pilot to move his arm either up or down without exert-
ing any restraining forces comprising:
an arm harness which is adapted to fit around a pi-
lot's arm;
a system of pulleys fixed relative to said pilot;
cable means attached to each side of said arm har-
ness for forming a closed loop that is engaged with
said system of pulleys such that a pilot can move his
arm up or down;
torque motor means engaging said closed loop cable
means for exerting forces on said arm harness re-
lated to all electrical signals applied to said torque
motor means;
a first strain gage in said closed loop cable means be-
tween one side of said arm harness and said motor
means;
. a second strain gage in said closed loop cable means
between the other side of said arm harness and said
motor means;
each of said strain gages producing an electrical sig-
nal proportional to the strain in said cable at the lo-
cation of the strain gage with the signal produced
by the second strain gage being negative with re-
spect to the signal produced by the first strain gage;
means for summing the electrical signals produced by
said first and second strain gages; and
means for applying to said torque motor means a sig-
nal representing the difference between said
summed electrical signals and said input electrical
signals whereby any time the input electrical sig-
nals changes the g-forces applied to a pilot's arm
changes and any movement in the vertical direc-
tion will be followed by said torque motor means
such that no restraining force is exerted by the arm
harness.
5 2. A device according to claim 1 including a cart
means attached to a control mechanism of the aircraft
simulator and mounted for movement in a horizontal
direction with said device fixed with respect to said cart
whereby a pilot's arm can move in both a horizontal
10 and a vertical direction as he operates the control
mechanism.
3. Apparatus for applying simulated g-forces to the
arm of an aircraft simulator pilot, g-forces being repre-
sented by input electrical signals, and for allowing the
15 pilot to move his arm horizontally and vertically as he
operates a control mechanism of an aircraft simulator
without exerting any restraining forces comprising:
cart means attached to the control mechanism of a
aircraft simulator and mounted to move in a hori-
20
 zontal direction as the control mechanism is oper-
ated;
an arm harness mounted on said cart means which is
adapted to fit around a pilot's arm that he uses to
operate the control mechanism; and
means mounted on said cart means and attached to
said arm harness receiving said electrical signals for
applying g-forces to the arm of a pilot through said
arm harness and for allowing a pilot to move his
arm vertically as he operates the control mecha-
nism of the simulator without exerting any restrain-
ing forces on the pilot's arm whereby a feel is de-
veloped for a pilot that enables him to better con-
trol the aircraft simulator.
4. Apparatus according to claim 3 wherein said
means for applying g-forces to the arm of a pilot in-
cludes cable means attached to opposite sides of said
arm harness to form a closed loop.
5. Apparatus according to claim 4 wherein said
.„ means for applying g-forces to the arm of a pilot in-
cludes a system of pulleys with said closed loop of said
cable means fitted into the pulleys of said system of pul-
leys to support said arm harness.
6. Apparatus according to claim 5 wherein said
45 means for applying g-forces to the arm of a pilot in-
cludes a torque motor with its shaft attached to said
cable means to turn said closed loop in said system of
pulleys.
7. Apparatus according to claim 6 wherein said
50 means for applying g-forces to the arm of a pilot in-
cludes a first strain gage located in said closed loop
cable means between said shaft and one side of said
arm harness and a second strain gage located in said
closed loop cable means between said shaft, and the
55 other side of said arm harness each of said strain gages
producing an electrical signal proportional to the ten-
sion in said cable at its location the electrical signal of
the second strain gage being negative with respect to
the electrical signal of the first strain gage.
60 8. Apparatus according to claim 7 wherein said
means for applying g-forces to the arm of a pilot in-
cludes means for summing the signals produced by said
first and second strain gages, means for obtaining the
difference between said summed signals and said input
65 electrical signals and means for applying the resulting
difference signals to said torque motor.
25
30
35


Apparatus for applying simulator g-forces to an arm of an aircraft simulator pilot

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