Aeronautics and astronautics – Aircraft control – Pilot operated
Reexamination Certificate
1999-12-16
2001-07-10
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Aircraft control
Pilot operated
C244S194000, C318S564000, C701S004000
Reexamination Certificate
active
06257529
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a duplicate type servo actuator apparatus which causes an operation unit to be displaced on the basis of an input signal, and also to an aircraft control apparatus which uses such a duplicate type servo actuator apparatus.
2. Description of the Related Art
In an aircraft such as a helicopter, a servo actuation system of a hydraulic, electric or electrohydraulic type is used in a control system, a stability augmentation system (SAS), and an automatic flight control system (AFCS).
Such a servo actuation system is provided with various countermeasures against hardover. In a system of the mechanical hydraulic type, duplicate spools of a hydraulic control valve and the like are used to realize multiplication of the mechanical and hydraulic systems. In a system of the electric or electrohydraulic type are employed the following countermeasures: 1) the maximum operation amount is restricted so as to exist within such a range that the flight safety is not critically affected even when a hardover occurs; and 2) the system is multiplied to be redundantly managed so that the probability of occurrence of hardover is suppressed to an allowable value or less.
As the performance and function of aircraft such as a helicopter are made higher, mechatronics systems are more frequently used. Therefore, it has been studied that a system is highly multiplied to expand an operable range while the maximum operation amount is not limited too much. In particular, triple or quadruple multiplication of a Fly-By-Wire control system, SAS, AFCS or the like realizes the following: a) the probability of function loss (including hardover) suppressed to 10
−9
times/hour in commercial planes or 10
−7
times/hour in military planes; b) specification of the probability of function loss (including hardover) corresponding to the failure influence request level (e.g., 10
−5
times/hour); and c) a failure influence suppression (fail passive, fail soft, fail safe) and separation from a failure system.
As higher redundancy is made by multiplication of a system, higher the flight safety is improved. However, such multiplication causes the system to be complicated and increased in size, and cost.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a servo actuator apparatus and an aircraft control apparatus, in which anti-hardover or hardover-degree suppression can be realized with a simple configuration thereof.
The invention provides a servo actuator apparatus comprising:
a first actuator for relatively displacing a first operation unit relatively with respect to a first body unit on the basis of an input signal E
1
;
a first position sensor for detecting a position of the first operation unit with respect to the first body unit and outputting a detection signal D
1
;
a second actuator for displacing a second operation unit relatively to respect to a second body unit on the basis of an input signal E
2
;
a second position sensor for detecting a position of the second operation unit with respect to the second body unit and outputting a detection signal D
2
;
a first difference calculation unit for subtracting the detection signal D
2
of the second position sensor from an external command signal C
1
, and outputting the input signal E
1
; and
a second difference calculation unit for subtracting the detection signal D
1
of the first position sensor from an external command signal C
2
, and outputting the input signal E
2
,
wherein a positive displacement direction of the first operation unit is reverse and series to a positive displacement direction of the second operation unit, and the first and second body units are integrally movable.
According to the invention, the first actuator operates on the basis of the input signal E
1
obtained by subtracting the detection signal D
2
of the second position sensor from the command signal C
1
, and the second actuator operates on the basis of the input signal E
2
obtained by subtracting the detection signal D
1
of the first position sensor from the command signal C
2
. The first body unit of the first actuator and the second body unit of the second actuator are integrally movable, and the positive displacement direction of the first operation unit is set to be reverse and series to that of the second operation unit. Therefore, the total displacement amount Q of the first and second operation units is proportional to the total of the command signals C
1
and C
2
. The positive displacement direction of the respective operation units means an operation direction in the case where the command signal is increased in a positive direction.
Herein a first system of the first actuator and the command signal C
1
and a second system of the second actuator and the command signal C
2
have the same functions and performances in a double configuration, namely a duplicate redundant system.
First, the basic operation (the operation in a normal operation state in which no failure occurs) of the invention will be described. The external command signals C
1
and C
2
have basically identical values, and respectively serve as a displacement amount (operation amount) by which the actuator apparatus is to be moved in response to a command. Accordingly when the operation amount of the first actuator based on C
1
is simply added to that of the second actuator based on C
2
, the operation amount of the whole of the servo actuation system reaches to twice the required amount. Therefore, the operation command of the first actuator is switched to E
1
obtained by subtracting D
2
from C
1
, and that of the second actuator is switched to E
2
obtained by subtracting D
1
from C
2
, so that the operation amount E of the whole of the servo actuation system is calculated as E=E
1
+E
2
=(C
1
−D
2
)+(C
2
−D
1
)=(C
1
+C
2
)−(D
1
+D
2
). Furthermore, since (D
1
+D
2
) during a time period from the start of the operation of the servo actuation system to the end of the operation is equal to C
1
(or C
2
having an equivalent value), the servo actuation system eventually operates in accordance with the command signal C
1
(or C
2
).
Consequently, the first and second operation units are displaced in proportion to the increments of the command signals C
1
and C
2
. As a result, the actuator apparatus operates in the same manner as a signal actuator.
Next, assuming that any portion of the first system including the first actuator fails and the operation of the first actuator falls in hardover, the detection signal D
1
obtained by detecting the actual operation of the first actuator has a value in which a deviation due to the hardover is added to (or subtracted from) the value during the normal operation. The detection signal D
1
is corrected with respect to the command signal C
2
of the second actuator in the direction opposite to the deviation direction, resulting in (C
2
−D
1
). Accordingly, the second actuator operates while correcting in real time the deviation (hardover amount) of the operation of the first actuator. To the contrary, when the second actuator falls in hardover, the first actuator operates in the same manner as the second actuator described above.
In this way, the first and second actuators can monitor each other while the actuators are always maintained in the operation state, and, when one of the actuators falls in hardover, the other actuator can correct the hardover in real time. As a result, a duplication system can be realized without requiring a complex mechanism such as a complicated fault detection mechanism, or a mechanism for switching over the first and second actuators.
The servo actuator apparatus of the invention can be applied to all kinds of servo actuation systems such as a control system of aircraft including a helicopter or a fixed wing aircraft, and construction machinery, and others.
In the invention it is preferable that differential circuits are respectively interposed between the se
Kubo Yoshiharu
Tomio Takeshi
Advanced Technology Institute of Commuter-Helicopter, Ltd.
Dinh Tien
Jordan Charles T.
Wenderoth , Lind & Ponack, L.L.P.
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