Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Remote control system
Reexamination Certificate
2001-10-23
2003-05-13
Nguyen, Thu (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Remote control system
C244S075100
Reexamination Certificate
active
06564124
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device for controlling steering signals for a radio-controlled model helicopter.
Helicopters can make a flight by rotating the main rotor, with the wings (blades) thereof adjusted to a certain attack angle, thus producing a lift. The steering is performed to four-axis control directions including roll, pitch, collective pitch, and yaw. The roll axis, the pitch axis, the collective axis, and the yaw axis are controlled by adjusting the rotor pitch angle of the rotating plane of the main rotor of a helicopter. For this control, a swash plate, which is disposed coaxially on the rotating shaft of the main rotor and of which the three axes have the degree of freedom, is controlled by means of servomechanisms.
FIG. 5
shows the principle of the control (here, the main rotor is not shown). The forward and backward control, shown in FIG.
5
(
a
), is called pitch control (often referred to as elevator control). The rightward and leftward control, shown in FIG.
5
(
b
), is called roll control (referred to as aileron control). The ascent and descent control, shown in FIG.
5
(
c
), is called collective pitch control. In flight, the helicopter can travel in a desired direction by combining the above-mentioned controls.
In order to fly the body forward (in the direction of the arrow A), shown in FIG.
5
(
a
), the servomechanism (not shown) controls the swash plate
12
disposed coaxially on the rotating shaft
11
of the main rotor to tilt the body in the direction of the arrow (a). In order to advance the body backward, the swash plate
12
is tilt in the reverse direction. The swash plate
12
is tilted in the opposite direction to fly the body backward.
In order to fly the body leftward (in the direction of the arrow B), shown in FIG.
5
(
b
), the servomechanism (not shown) controls the swash plate
12
to tilt the body in the direction of the arrow (b).
In order to fly the body upward (in the direction of the arrow C), shown in FIG.
5
(
c
), the servomechanism (not shown) controls the swash plate
12
to tilt the body in the direction of the arrow (c).
In the conventional roll, pitch, and corrective pitch steering method for the model helicopter steering device, independent mechanisms control the swash plate. However, recently, the so-called swash mixing method where three steering elements are mixed to steer a helicopter has been broadly used.
FIG. 6
is a cross-sectional view illustrating the swash plate
12
called a 120° swash plate.
FIG. 7
is a perspective view illustrating the swash plate
12
called a 120° swash plate.
The swash plate
12
, which controls the main rotor (not shown), is formed of a lower plate
13
a
and an upper plate
13
b
. The plates
13
a
and
13
b
are tiltably mounted on the rotating shaft
11
. The lower plate
13
a
can be vertically slid on the rotating shaft
11
of the main rotor
11
a
and does not depend on the rotation of the rotor
11
. The upper plate
13
b
, which rotates in harmony with the rotating shaft
11
, is mounted coaxially together with the rotating axis
11
and the lower plate
13
a
.
The main control rods
16
a
,
16
b
,
16
c
, and
16
d
are faced oppositely to and linked perpendicularly to each other on the circumference of the upper plate
13
b
. The other end of each rod extends to the main rotor
11
a
. The swash plate control rods
15
a
,
15
b
, and
15
c
are linked on the outer circumference of the lower plate
13
a
at intervals of 120°. The pitch servomechanism
14
a
, the collective pitch servomechanism
14
b
, and the roll servomechanism
14
c
are directly linked to the other ends of the swash plate control rods
15
a
,
15
b
, and
15
c
, respectively. Moreover, the control device is prepared that cooperatively operates the three servomechanisms in accordance with a collective pitch control amount and cooperatively operates the three servomechanisms in accordance with a roll control amount or pitch control amount. The control device selectively operates cooperatively the three servomechanisms through the electrical mixing process.
In the roll manipulation, for example, the right and left direction control of the body is performed as follows. That is, the collective pitch servomechanism
14
b
is moved by the same amount in the direction opposite to the moving direction of the roll servomechanism
14
c
. The swash plate control rods
15
b
and
15
c
are vertically moved to rotate on the axes (Y, Y) (
FIG. 6
) as center. Thus, the lower plate
13
a
and the upper plate
13
b
are tilted. By controlling the main control rods
16
a
to
16
d
, the pitch angle of a blade of the main rotor
11
a
is changed.
In the pitch manipulation, the operation amount is controlled to ½ in the direction opposite to the movement of the pitch servomechanism
14
a
to operate the roll servomechanism
14
c
and the collective pitch servomechanism
14
b
. The swash plate control rods
15
a
to
15
c
are vertically moved to rotate on the axes (X, X) (
FIG. 6
) as center. Thus, the lower plate
13
a
and the upper plate
13
b
are tilted and the main control rods
16
a
to
16
d
are controlled. The pitch angle of the blade of the main rotor
11
a
is changed so that the forward and backward movements of the body are controlled.
In the collective pitch manipulation, all the three servomechanisms
14
a
to
14
c
are controlled in a similar manner to operate vertically. Thus, the swash plate control rods
15
a
to
15
c
are traveled vertically by the same amount. The lower plate
13
a
and the upper plate
13
b
are vertically moved in parallel on the circumference of the driving shaft
11
, with the plates
13
a
and
13
b
maintained to the original tilt. Thus, when the main control rods
16
a
to
16
d
move vertically, the pitch angle of the blade of the main rotor
11
a
changes. As a result, the upward and downward movement of the body is controlled.
11
a
is controlled in accordance with the collective pitch control amount. In the roll control, the right and left tilt angles of the main rotor are changed in accordance with the roll control amount. In the pitch control, the front and back tilt angles of the main rotor are changed in accordance with the pitch control amount.
As described above, the plural mixing manipulations allow the swash plate
12
to be controlled.
The direct swash control has the advantage in which the looseness is small because the mechanism is simple and the mechanical linkage allows direct connection to the servomechanism.
However, the direct swash control requires that two or more servomechanisms operate for each axis manipulation. This complicates the control method. The following problems to be solved occur to subject the operation of the servomechanism to the mixing control.
Firstly, since the servo control signals transmitted from the transmitter is converted into a serial pulse sequence, time shifts occur when the servo control signals respectively reach the servomechanisms at the body of a helicopter. This causes a response difference in the servo operation for each axis, thus resulting in an axial interference.
Secondary, when there is a difference between servo operation velocities of the axes, the axial interference occurs in manipulation.
Thirdly, in the pitch control, the roll servomechanism and the collective pitch servomechanism can move by ½ of the moving angle of the pitch servomechanism. This operation causes the time difference between servo operations, thus resulting in an axial interference.
Finally, the servomechanism generally moves circularly to implement the control operation. For control, pivots, arranged in a disk pattern, are linked to the pivots of the swash plate. The collective pitch manipulation causes three servomechanisms to move at the same time, thus offsetting the pivot points. If the roll or pitch manipulation is carried out at the offset point, a difference occurs between the movement of the swash plate in the ascent direction and the movement of the swash plate in the descent direction.
Futaba Corporation
Nguyen Thu
LandOfFree
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