System for coupling control columns

The present invention relates to a system for coupling at least two control columns (2A, 2B) of a control device (DC) of a machine, especially an aircraft. The coupling system includes for each of the columns (2A, 2B), at least one operating member (13A, 13B, 14A, 14B) capable of making the column (2A, 2B) tilt about an axis, and a calculation unit (CAL) receiving information relating to the position of tilt of the columns (2A, 2B) and generating, when at least one of the columns (2A, 2B) is operated, tilt commands which are transmitted to the operating member (13A, 13B, 14A, 14B) of the other column (2A, 2B).

The present invention relates to a system for coupling at least two control 
columns of a control device of a machine. 
Although not exclusively, it is more particularly applicable to control 
devices for aircraft and will be described hereafter more particularly 
with reference to an application of this kind, it being clearly understood 
that this must not in any way restrict the scope of the invention. 
It is known that many machines, such as airplanes, helicopters, battle 
tanks, civil engineering work plants, etc., have a series of controlled 
elements that can be operated from one or other of two twin command 
stations, controlled by two separate operators (known as the driver and 
co-driver in the case of land vehicles and as the pilot and co-pilot in 
the case of airborne vehicles) each equipped with a control column 
articulated so that it can be tilted about at least one axis of tilting. 
Various solutions for coupling control columns are known. 
A first series of known solutions recommends the use of mechanical systems 
such as those described, for example, in the documents U.S. Pat. No. 
5,137,234 and WO-95/03212. 
However, such mechanical coupling solutions have a great many drawbacks, 
especially as regards the mass, size and maintenance. 
Another kind of solution is described in the document EP-0 384 806, which 
discloses a control column which has an electric motor but on the one hand 
allows the creation of a force sensation and, on the other hand, when two 
columns of this type are associated with one another, allows the tilting 
of one column to be mimicked by the other. 
An electrical coupling system of this kind, which makes it possible to 
overcome some of the drawbacks of mechanical coupling, does however have a 
major drawback, namely the fact that a breakdown in said electrical system 
means that force sensation, and particularly the re-centering of the 
control columns to a neutral position when these columns are not being 
operated is lost. A drawback of this kind would not be acceptable without 
special precautions, particularly for a civil transport airplane. 
So, to use a solution of this kind, for example, on a civil transport 
airplane would lead to the imposition of a great many stipulations, as 
regards said coupling system and especially the amount of redundancy and 
the reliability of the elements making it, so that the safety of said 
airplane is not affected. 
The purpose of the present invention is to overcome these drawbacks. The 
invention relates to a system for coupling at least two control columns 
which can be produced simply and with a small size and can form 
particularly effective coupling, with the possibility for easy 
deactivation. 
To achieve this, according to the invention, said system for electrically 
coupling at least two control columns of a control device of a machine, 
said control columns being intended to be operated by separate operators 
and each being mounted so that it can tilt about at least one axis of 
tilting, said electrical coupling system comprising: 
for each of said control columns, at least one tilt sensor delivering an 
electrical signal that is a function of the amplitude of tilting of said 
control column about its axis of tilting on either side of a neutral 
position; 
for each of said control columns, at least one operating member capable of 
acting, in accordance with commands received electrically, on said control 
column; and 
calculation means receiving the electrical signals generated by said tilt 
sensors and capable of sending electrically, on the basis of said 
electrical signals, on the one hand, commands to control members of the 
machine and, on the other hand, commands to said operating members, 
is noteworthy in that, for each of said control columns there is also at 
least one mechanical or hydraulic means generating resistance to tilting 
when said control column is tilted, the amount of resistance being a 
function of the amplitude of said tilting, so as to produce a force 
sensation function, in that said calculation means can be activated and 
deactivated for generating the commands for said operating members, in 
that said operating members are commanded only when said calculation means 
are activated, and in that the commands for one operating member 
associated with one of said control columns always depend on the tilted 
position of the other control column so that the force sensation function 
and the function of coupling the control columns are separate, the force 
sensation function being achieved purely mechanically by the action of 
said mechanical or hydraulic means and the coupling function being 
achieved electrically by the action of said operating members. 
Thus, by virtue of the invention a particularly effective "active" coupling 
system as specified hereinbelow is obtained. 
In addition, said coupling system can easily be deactivated either manually 
by one of the operators or automatically by an appropriate device, 
especially by deactivating said calculation unit. 
Furthermore, in the event of a breakdown in the coupling system in 
accordance with the invention, which work electrically, the force 
sensation created by said mechanical or hydraulic means that generate 
resistance to tilting is maintained, because said mechanical means are 
independent of said coupling system, unlike the known and aforementioned 
solution in document EP-0 384 806. Also, the coupling system in accordance 
with the invention can be produced simply with few redundancies. 
Advantageously, when just one of said control columns is operated, in a 
first position of tilting, the operating member (for example an electric 
motor or a geared motor unit), of the other control column is commanded to 
bring this operating member into a second position of tilting, the 
amplitude of tilting of which is equal to the amplitude of tilting of said 
first tilted position, multiplied by a determined coefficient. 
Furthermore, when said control columns are operated simultaneously, the 
present invention can be implemented in two different alternative ways. 
In a first alternative, each operating member is commanded so that a 
resistance to the tilting, with a value that is a function of the 
amplitude of tilting of the other control column is generated in the 
associated control column. Thus, although the control columns can be 
tilted independently, the operators are informed, by the resistance to 
tilting, of any simultaneous operation. 
In a second alternative, said operating members are commanded in such a way 
as to bring said control columns into identical positions of tilting, the 
amplitude of tilting of which is a function of the respective forces 
applied by the operators to said control columns, which makes it possible 
to obtain identical controlled tilting. 
In this second alternative, the coupling system in accordance with the 
invention preferably comprises, for each of said control columns at least 
one load sensor capable of measuring the force applied by one operator to 
said control column, and said coupling system is deactivated when the 
force applied to one of said control columns exceeds a predefined value. 
According to the invention, said calculation unit receives information 
relating to the position of tilt of the control columns, in a first 
alternative directly from said tilt sensors and, in a second alternative, 
from said central unit. 
In the latter case, the calculation unit is preferably incorporated into 
said central unit. 
Furthermore, the coupling system in accordance with the invention may also 
have a damping function. 
For this, in a first embodiment, said coupling system has at least one 
speed sensor associated with one of said control columns and capable of 
measuring the rate of tilt of said control column; and the operating 
member associated with said control column is commanded, when it tilts, in 
such a way as to generate resistance to tilting, the value of this 
resistance being a function of the rate of tilt measured by said speed 
sensor. 
In a second embodiment, at least one independent damping means, for example 
a hydraulic damper, associated with one of said control columns is 
provided. 
Of course, it is also envisageable to achieve damping by using said 
aforementioned first and second embodiments simultaneously. 
It will be noted that the coupling system can also be applied to a machine, 
especially an aircraft, that can be controlled by an automatic pilot. 
In this case, according to the invention, said coupling system comprises: 
in a first alternative, priority-action means which keep the control 
columns in a determined set position, for example a neutral position, when 
said machine is being controlled by said automatic pilot; and 
in a second alternative, means which, when said machine is being controlled 
by said automatic pilot, make said control columns follow the tilting with 
amplitude that corresponds to said control.

The coupling system 1 in accordance with the invention is depicted 
diagrammatically in FIGS. 1 and 2, in two different embodiments 
respectively, is intended for coupling control columns 2A and 2B of a 
control device DC of a machine, in this case an aircraft, for example a 
civil transport airplane. 
In a known way, said control columns 2A and 2B are produced in the form of 
grips that can be operated by hand, by the aircraft pilot and co-pilot 
respectively. 
For the pitch and roll control of said aircraft, said control columns 2A 
and 2B which when in the neutral position or position of rest are oriented 
longitudinally along an axis Z--Z, can be maneuvered: 
on the one hand, forward and back, as indicated by a double-headed arrow F, 
so as to tilt about a transverse axis X--X which allows the pitching of 
the aircraft to be controlled; and 
on the other hand, to the right and to the left, as indicated by a 
double-headed arrow E, so as to tilt about a longitudinal axis Y--Y, which 
allows the rolling of the aircraft to be controlled. 
It will be noted that said control device DC comprises identical elements 
associated respectively with said control columns 2A and 2B described 
hereinabove. To simplify the description, the elements which are identical 
will be denoted by the same number, followed either by the letter A or by 
the letter B, according to whether said elements are associated with the 
column 2A or with the column 2B. 
As is known, said control device DC comprises, in addition to said control 
columns 2A and 2B: 
a mechanism 3A or 3B comprising an articulation, for example a ball joint 
or cardan joint, allowing said control column 2A or 2B to tilt about its 
axes of tilt X--X and Y--Y; 
a tilt sensor 4A or 4B detecting, by means of a link rod 5A or 5B, the 
tilting of the control column 2A or 2B about the axis X--X to either side 
of the position of rest along Z--Z, and delivering an electrical signal 
which is a function of the amplitude of said tilting; 
a tilt sensor 6A or 6B detecting, by means of a link rod 7A or 7B, the 
tilting of the control column 2A or 2B about the axis Y--Y, to either side 
of the position of rest along Z--Z, and delivering an electrical signal 
which is a function of the amplitude of said tilting; 
mechanical means 8A or 8B generating resistance to tilting, when said 
control column 2A or 2B is tilted about the axis X--X; 
mechanical means 9A or 9B generating resistance to tilting, when said 
control column 2A or 2B is tilted about the axis Y--Y, it being possible 
for said mechanical means 8A, 8B, 9A and 9B to be produced for example, in 
the form of spring links, leaf springs or sprung scissor stays; and 
a central unit UC connected by links 10A, 10B, 11A and 11B to the sensors 
4A, 4B, 6A and 6B respectively, that receive the electrical signals 
generated by said sensors 4A, 4B, 6A and 6B, and which on the basis of 
these electrical signals calculates commands for the control members, for 
example the control surfaces, not depicted, of the aircraft, and 
transmitting said commands to said control members via a link 12. 
The coupling system 1 in accordance with the invention is applied to said 
control device DC of a known type, described earlier. 
According to the invention, said coupling system 1 comprises: 
for each of said control columns 2A or 2B, operating members 13A and 14A or 
13B and 14B capable of making said control column 2A or 2B respectively 
tilt about the axes of tilting X--X and Y--Y depending on the tilt 
commands received electrically; and 
a calculation unit CAL, capable of being activated and deactivated, 
receiving information relating to the position of tilt of said control 
columns 2A and 2B and generating, when activated, when at least one of 
said control columns 2A and 2B is operated (tilted), tilt commands which 
are transmitted electrically to the operating members of the other control 
column 2A and 2B. 
According to the invention, said operating members 13A, 13B, 14A and 14B, 
which are controlled by the calculation unit CAL, via links 15A, 15B, 16A 
and 16B respectively, may each be produced in the form: 
of a geared motor unit; or 
of an electric motor without gearing. 
As is known, said operating members 13A, 13B, 14A and 14B are controlled by 
means of electronic regulation, of the usual type, not depicted. 
In the embodiments depicted in FIGS. 1 and 2, said calculation unit CAL, 
produced in the form of a separate unit, receives the information relating 
to the position of tilt of the control columns 2A and 2B from the central 
unit UC via a link 17. 
Said calculation unit CAL may, however, be produced in a different way, in 
particular: 
it may be incorporated into the central unit UC; or 
it may be connected directly to the sensors 4A, 4B, 6A and 6B and therefore 
be independent of said central unit UC. 
It will be noted that the calculation unit CAL, and therefore the coupling 
system 1, may be deactivated: 
either manually, by one of the operators; 
or automatically, via a means, not depicted, for example depending on the 
value of measured parameters. 
Thus, the coupling system 1 can be activated either just for some phases of 
the flight, or for the entire flight. 
According to the invention, said calculation unit CAL, in the embodiment of 
FIG. 1, controls the operating members 13A, 13B, 14A and 14B in such a way 
that: 
when just one of said control columns 2A or 2B is tilted about an axis of 
tilting X--X or Y--Y into a first tilted position, the operating member of 
the other control column, relative to the same axis of tilting, is 
commanded so as to bring this column into a second position of tilting, 
the amplitude of tilting of which is equal to the amplitude of tilting of 
said first tilted position, multiplied by a coefficient; and 
when both control columns 2A and 2B are tilted simultaneously, each 
operating member is commanded so as to generate in the associated control 
column a resistance to tilting, the value of which is a function of the 
amplitude of tilting of the other control column. 
According to the invention, when just one column is operated or tilted, 
said coefficient may: 
be equal to 1, so as to obtain faithful mimicking by the control column 
that is not operated; 
be less than 1, so that the control column that is not operated follows the 
movement of the control column that is operated, but with a smaller 
amplitude of tilting; or 
be greater than 1, so as to obtain mimicking with a greater amplitude of 
tilting. 
In another embodiment, as depicted in FIG. 2, the calculation unit CAL 
commands the operating members 13A, 13B, 14A and 14B in such a way that: 
when just one of said control columns 2A or 2B is operated, the command is 
identical to the command in the embodiment of FIG. 1; 
when both control columns 2A and 2B are operated simultaneously, the 
operating members 13A, 13B, 14A and 14B are commanded in such a way as to 
bring said control columns 2A and 2B into identical positions of tilt, 
where the amplitude of tilting depends on the respective forces applied by 
the operators to said control columns 2A and 2B. 
In this case, said coupling system 1 additionally comprises load sensors 
18A and 18B associated respectively with the control columns 2A and 2B and 
capable of measuring the force applied by an operator to the corresponding 
control column and of transmitting said measurements to the central unit 
UC via links 19A and 19B respectively. 
According to the invention, in this case, said coupling system 1 is 
deactivated when the force applied to one of said control columns 2A or 2B 
and measured by the associated load sensor 18A and 18B exceeds a 
predefined value. 
Thus, by virtue of the invention, a particularly effective "active" 
coupling system is obtained. 
What is more, in the event of a breakdown in said coupling system 1 which 
works electrically, the force sensation created by the mechanical means 
8A, 8B, 9A and 9B which are independent of the calculation unit CAL and of 
the operating members 13A, 13B, 14A and 14B is maintained. 
The coupling system 1 may also have a damping function. 
To achieve this: 
said system 1 comprises speed sensors capable of measuring the rate of tilt 
of the control columns 2A and 2B about the axes X--X and Y--Y. The sensors 
4A, 4B, 6A and 6B may perform this function; and 
the calculation unit CAL, when at least one of said control columns 2A or 
2B is tilted about an axis X--X or Y--Y, commands the corresponding 
operating member 13A, 13B, 14A or 14B in such a way as to generate a 
resistance to tilting, the value of this being a function of the measured 
rate of tilting. This embodiment allows a complex damping function to be 
produced. 
This damping function may, however, also be employed by an independent 
damping means, for example a hydraulic or friction damper of the usual 
type like the known damping means 20A, 20B, 21A and 21B depicted in FIGS. 
1 and 2. 
Of course, in a specific embodiment, said damping function may be provided 
in part by the calculation unit CAL and at least one operating member and 
one speed sensor, and in part by said independent damping means. 
Of course, the coupling system 1 according to the invention may also be 
applied to an aircraft which has an automatic pilot. 
In this case, said coupling system 1 comprises: 
in a first alternative, priority-action means, not depicted, which keep the 
control columns 2A and 2B in a determined set position, preferably the 
neutral position along the axis Z--Z, when the aircraft is being 
controlled by said automatic pilot; and 
in a second alternative, means, also not depicted, which when the aircraft 
is being controlled by said automatic pilot, make said control columns 2A 
and 2B follow the tilting, with an amplitude that corresponds to said 
control.