Patent Description:
It is known to control machines, for example land, sea or air vehicles, using stick controllers. In particular, aircraft are fitted with passive stick controllers (i.e. inceptors or "joy sticks").

For aircraft, there are currently two types of side stick controllers in use that provide pilot inputs into a vehicle's control system (e.g. its Flight Control System). One type is "passive" and the other is "active".

Passive inceptors have fixed force/feel characteristic that are provided by springs and dampers, but do not provide tactile cues about the aircraft's current situation to the pilots. Flight control systems that use passive side sticks rely on the flight control laws within the aircraft's Flight Control System to keep the aircraft within a safe operating envelope. That is, the Flight Control System does not allow the aircrafts' limits to be exceeded, whatever inputs the pilot applies to the system via the sticks control. This is sometimes referred to as "carefree" handling.

Active inceptors are more complex. In addition to springs and dampers that are used to provide a reversionary force/feel characteristic, they also have a servo-actuator mechanism that allows the force/feel characteristic of the stick to be continuously modified throughout a flight.

Movement of either passive or active inceptors generates positional information which is interpreted to control the vehicle. If the inceptor mechanism jams (for example, due to mechanical failure) then the operator is not able to move the inceptor, and hence no positional data will be generated and the vehicle cannot be controlled.

For land or water based vehicles, while serious, this problem may be mitigated by shutting down the vehicle so as to come to a halt. For many aircraft, the problem may be mitigated by provision of a second set of controls, which is commonplace as many air vehicles have two flight control positions, and the chance of both failing at the same time is very small.

However, for aircraft having only one set of controls, or dispatched with only one pilot, there is a customer need to further mitigate the problem of inceptor jamming.

Hence an inceptor apparatus with a failsafe which provides for control of a vehicle (for example an aircraft) in the event of the inceptor becoming physically immovable, and hence unable to produce positional inputs to a control system for the aircraft, is highly desirable.

<CIT> discloses an inceptor system and apparatus for generating a virtual real-time model.

<CIT> discloses an active hand controller system.

<CIT> discloses a motor vehicle control device.

<CIT> discloses a variable compliance joystick with compensation algorithms.

According to the present disclosure there is provided apparatus and method as set forth in the appended claims.

Accordingly, according to a first aspect of the invention there is provided an active inceptor apparatus for operating a machine, the apparatus comprising: a stick member having a grip portion, the stick member being pivotably mounted relative to a housing; a position sensor responsive to, and for generating signals indicative of stick member position; a force sensor provided on the stick member responsive to, and for generating signals indicative of force applied to the stick by a user; and a control unit, operable: to receive the position and force signals from the position and force sensors respectively; to process the signals according to a predetermined relationship to determine a value FD proportional to a force applied by the user, as indicated by signals generated by the force sensor, to achieve any indicated displacement of the stick member, as indicated by signals generated by the position sensor; and to generate machine control signals as a function of position signals and force signals in dependence upon the value FD, for communication to the machine.

The control unit may be operable to generate control signals in dependence upon the force signals and position signals when the value FD is below a predetermined tolerance limit.

The control unit may be operable to generate control signals in dependence upon position signals but not force signals when the value FD is below a predetermined tolerance limit.

The control unit may be operable to generate control signals in dependence upon the force signals but not position signals when the value FD exceeds the predetermined tolerance limit.

The stick member may be coupled to an actuator operable in response to a signal from the control unit. The actuator may be operable to urge the stick member to a predetermined position in response to a signal received from the control unit.

The actuator may also be operable to be locked in position relative to the housing, thereby locking the stick member into position in response to a signal received from the control unit.

The actuator may also be operable to be disabled in response to a signal received from the control unit.

The stick member may be operable to pivot in a first direction and second direction, the first direction being perpendicular to the second direction.

During the step of generating machine control signals, the control unit may apply a first variable gain multiplier to force signals, and may apply a second variable gain multiplier to position signals, the values of the gain multipliers being varied relative to one another in dependence upon the position signal.

There is also provided a vehicle control apparatus comprising an inceptor apparatus as described in any one of the preceding claims.

There is also provided, according to a second aspect of the invention, a method for controlling a machine by means of an active inceptor apparatus according to the first aspect, the method comprising the steps of: receiving position and force signals from the position and force sensors respectively; determining a value FD proportional to a force applied by the user, as indicated by the received force signals, to achieve any indicated displacement of the stick member, as indicated by the received position signals; and generating machine control signals as a function of position signals and force signals in dependence upon the value FD for communication to the machine.

The method may generate a control signal in dependence upon the force signals and position signals when the value FD is below a predetermined tolerance limit.

During the step of generating machine control signals, the method may apply a first variable gain multiplier to force signals, and may apply a second variable gain multiplier to position signals, the values of the gain multipliers being varied relative to one another in dependence upon the position signal.

The method may generate control signals in dependence upon the position signals but not force signals when the value FD is below a predetermined tolerance limit.

The method may generate control signals in dependence upon the force signals but not position signals when the value FD exceeds the predetermined tolerance limit.

There is thus provided an inceptor apparatus, and method of controlling a machine by means of an inceptor apparatus, which in normal operation provides positional inputs to a control system for the control of the machine, but in the event that the stick member cannot be moved, the inceptor is operable to provide inputs to a control system for the control of the machine based on force applied to the stick member.

<FIG> shows an example passive inceptor apparatus <NUM> which forms part of a vehicle control system of the present disclosure.

The inceptor <NUM> is intended for operation of a machine, for example a static device, a land base vehicle, a water based vehicle or an air vehicle. In the examples shown in <FIG> and <FIG> the system presented is suitable for piloting an aircraft.

The inceptor comprises a stick housing <NUM> and a stick member <NUM> (or "control stick", "side stick" or just "stick"), which are arranged such that the stick member <NUM> is pivotally mounted to the stick housing <NUM> at pivot point <NUM>. In the example shown, the pivot point <NUM> acts to divide the stick member <NUM> into a first member section <NUM>, contained within the stick housing <NUM>, and a second member section <NUM>, external to the stick housing <NUM>. Normally, the stick housing <NUM> is fixed to a vehicle carrying the passive active stick apparatus <NUM>. The pivot point <NUM> allows the stick member <NUM> to pivot with respect to the stick housing <NUM>, as indicated by directional arrows <NUM> and <NUM>. The control stick <NUM> is pivotably mounted about the pivot point <NUM> such that it may move in at least one of a first direction and second direction, the second direction being at right angles to the first direction. That is to say, the stick member <NUM> is pivotably mounted relative to the housing <NUM>. The first direction may be an "x" direction (i.e. left and right, as shown in <FIG>), or may be a "y" direction which is effectively in and out of the page as shown in <FIG>. In this way, in use, the control stick may control an aircraft in pitch and roll directions.

A gaiter <NUM> can be provided between the second member section <NUM> and stick housing <NUM> to inhibit ingress of unwanted foreign material into the stick housing <NUM>. At the one end of the second member section <NUM>, distal from the pivot point <NUM>, there is provided a grip (or grip portion) <NUM> suitable for engagement by an operator of the passive active stick apparatus <NUM>, so that the operator can move the stick member <NUM> in either direction "x" shown by directional arrow <NUM>, and at right angles to the direction shown (i.e. in the "y" direction).

A solid mass <NUM> may be attached to the first member section <NUM> at an end distal from the pivot point <NUM>. The solid mass <NUM> is arranged to act as a counter balance to movement of the stick member <NUM> about pivot point <NUM> under external acceleration forces exerted on the stick member <NUM> and associated grip <NUM>.

Also attached to the first member section <NUM>, between the solid mass <NUM> and the pivot point <NUM>, is a first link <NUM>. A first end <NUM> of the first link <NUM> is pivotally coupled to the first member section <NUM> and a second end <NUM> is pivotally coupled to a second link <NUM>. The second link <NUM> is pivotally attached to the first link <NUM> at a first end <NUM> and a second end <NUM> of the second link <NUM> is fixedly attached to an output drive axle <NUM> of a position sensor <NUM> responsive to, and for generating signals indicative of, stick member position. The position sensor <NUM> further comprises a housing <NUM> which is fixedly attached to the stick housing <NUM>.

The position sensor <NUM> may be responsive to signals in the "x" and "y" directions. Additionally, two such position sensors <NUM> may be provided, one responsive to motion in the "x" direction, the other responsive to motion in the "y" direction.

Additional or alternative features to those described above may also form part of the apparatus <NUM>, and features may be provided in a different form to that shown in the figures. For example, the connection of the stick member <NUM> to the position sensor <NUM> and/or the means by which the stick member <NUM> is pivotable relative to the housing <NUM> may have a different configuration.

There is also provided a force sensor <NUM> provided on the stick member <NUM> responsive to, and for generating signals indicative of, force applied to the stick member <NUM> by a user. The force sensor <NUM> may be provided under the grip <NUM>, and in one example, may be responsive to forces in the "x" and "y" direction by being sensitive to the stress and/or strain imposed on the stick member <NUM> material.

There is also provided a control unit <NUM> operable to receive the position and force signals from the position sensor <NUM> and force sensor <NUM> respectively, via communication lines <NUM>, <NUM>. In the examples where the system presented is for an aircraft, and the control unit <NUM> may be a Flight Control Computer.

As shown in <FIG>, the control unit <NUM> outputs signals containing information and data to parts of the vehicle indicated generally at <NUM>, <NUM>, <NUM> as shown in <FIG>, and thereby controls the vehicle.

<FIG> shows an example of a device of the present disclosure which includes an active inceptor <NUM>. Features such as a support casing and the machine being operated by the inceptor apparatus <NUM> are not shown so as to avoid obscuring details of more relevant features of the device. In this example the stick member <NUM> is shown in a truncated form. That is to say the stick member <NUM> may extend further (i.e. be longer) as shown in <FIG>. In this example the stick member <NUM> has a base portion <NUM> and a grip portion <NUM> which extends from the base portion <NUM>. The grip portion <NUM>, as its name suggests, is the part which will be handled by an operator, for example a pilot. Although shown as a plane tube in <FIG>, and as with the example of <FIG>, the grip portion <NUM> may comprise an ergonomic grip to make handling easier, and buttons for the operation of the vehicle.

The base portion <NUM> of the stick member <NUM> comprises a gimbal arrangement having a first base member <NUM>, from which the stick member <NUM> extends, and a second base member <NUM>. The stick member <NUM> extends from the first base member <NUM> in only one direction. That is to say, the stick member <NUM> terminates on the top side of the base member <NUM>, and does not extend beneath the base portion <NUM>. The first base member <NUM> is pivotably coupled to the second base member <NUM> to permit the stick member <NUM> and first base member <NUM> to rotate about a first axis of rotation <NUM> independently of the second base member <NUM>. The second base member <NUM> is pivotably mounted such that the stick member <NUM>, first base member <NUM> and second base member <NUM> are rotatable about a second axis of rotation <NUM> together. A force sensor <NUM> is provided on the stick member <NUM>. The force sensor <NUM> provided on the stick member <NUM> is responsive to, and is operable to generate signals indicative of, force applied to the stick <NUM> by a user.

A first actuator <NUM> is coupled to the stick member <NUM> via the first base member <NUM>. A second actuator <NUM> is coupled to the stick member <NUM> via the second base member <NUM>. The actuators are operable in response to a signal from a control unit <NUM> to provide positional feedback to the stick member. For example, the actuators may be employed to prevent the pilot from moving the stick to an undesirable position, as determined by the control unit <NUM>. In the example shown the first actuator <NUM> is coupled to the first base member <NUM> via a first arm <NUM>. The arm <NUM> comprises a link 130a and link 130b which are joined at a pivotable joint <NUM> such that the arm <NUM> is articulated. The arm <NUM> is coupled to the first base member <NUM> by a bearing <NUM>. The second actuator <NUM> is coupled to the second base member <NUM> by a second arm <NUM>. The second arm <NUM> comprises a link 144a, link 144b and link 144c. Links 144a, 144b are joined at a pivotable joint 136a, and links 144b, 144c are joined at a pivotable joint 136b. Hence arm <NUM> comprises a double articulation. Link 144c is rigidly attached to the second base member <NUM>. In the example shown actuators <NUM>, <NUM> each comprise a motor held within a housing, and a shaft extending from the housing. The arms <NUM>,<NUM> are fixably connected to their respective shafts. Hence rotation of the shaft of the first actuator <NUM> will cause the stick <NUM> to rotate about the first rotational axis <NUM> in a first direction, indicated as "x" in <FIG>. Likewise, rotation of the shaft of the second actuator <NUM> will cause rotation of the stick member <NUM> about the second rotational axis <NUM> in a second direction, shown as "y" in <FIG>. In alternative examples the actuators may be provided as hydraulic devices, or any other appropriate type of actuator.

The first axis of rotation <NUM> is at right angles to the second axis of rotation <NUM>. Likewise the first direction "x" and second direction "y" are at right angles to one another.

At least one of the first or second base members <NUM>,<NUM> is provided with a position sensor <NUM> (shown in different locations as 28a, 28b) configured to generate a position signal indicative of angle of rotation about their respective rotational axis. The position sensors <NUM> are operable to generate actual stick member position data. Hence the first base member <NUM> may be provided with a first position sensor 28a, and the second base member <NUM> may be provided with a second position sensor 28b.

The control unit <NUM> is configured to receive signals from the force sensor <NUM> and positional sensors 28a, 28b, for example by communication lines shown as lines <NUM>, <NUM>, <NUM>, respectively. A processor <NUM> may be provided in series with the inceptor <NUM> and the control unit <NUM> to process and/or filter the data obtained from the sensors <NUM>, <NUM> before the signals are passed to the control unit <NUM> via lines <NUM>,<NUM>.

The control unit <NUM> outputs signals containing various information to parts of the vehicle indicated generally at <NUM>, <NUM>, <NUM> as shown in <FIG>, and thereby controls the vehicle.

In both examples shown in <FIG> and <FIG>, the control unit <NUM> is operable to process the signals according to a predetermined relationship to determine a value FD indicative of force applied to the stick member <NUM> relative to displacement of the stick member <NUM>. The control unit <NUM> is also operable to generate machine control signals as a function of position signals and force signals in dependence upon the value FD for communication to the machine.

The inceptor and control unit <NUM> (flight control computer) may be provided as separate units and, in practice, may be spaced apart from one another, situated in different zones of the vehicle. The control unit <NUM> may also fulfil other functions as well as processing the signal data as herein described. The inceptor <NUM>,<NUM> and control unit <NUM> thereby combine to provide a flight control system.

For the main part, control of a machine using either of the inceptor apparatus' described above is identical.

In summary the method of operating an inceptor apparatus, according to the present disclosure, for controlling a machine, comprises the steps of receiving position and force signals from the position sensors <NUM> and force sensor <NUM> respectively; determining a value FD indicative of force applied to the stick member relative to displacement of the stick member, and generating machine control signals as a function of position signals and force signals in dependence upon the value FD for communication to the machine. The method is described in more detail below.

The control unit <NUM> is operable to process the position and force signals received from the position sensors <NUM> and force sensor <NUM> respectively. The position signals are indicative of angle of the stick member relative to a datum position. The sensors are intended to generate signals at all times unless specifically turned off. The control unit uses the signals to determine a value FD indicative of force applied to the stick member <NUM> relative to displacement of the stick member <NUM>. That is to say the control unit <NUM> uses the signals to determine a value FD which is proportional to force applied to the stick member <NUM> as it is moved from one angle to another angle relative to a datum position (for example, a null "centred" position). The value FD may be determined incrementally as the stick is moved, for example for a fraction of a degree moved at a time.

The control unit <NUM> is operable to generate control signals in dependence upon the value FD for communication to the machine in dependence of the position signals and/or force signals.

When the control unit <NUM> determines that the value FD is below a predetermined tolerance limit, the control unit <NUM> generates machine control signals in dependence upon the force signals and position signals. Whilst operating within the predetermined tolerance limit, the inceptor apparatus <NUM>,<NUM> is deemed to be working normally.

In generating machine control signals, the control unit <NUM> varies its sensitivity to force signals and position signals dependent upon the amount of stick member <NUM> displacement. That is to say, during the step of generating machine control signals, the control unit applies a first variable gain multiplier to force signals, and applies a second variable gain multiplier to position signals, the values of the gain multipliers being varied relative to one another in dependence upon the amount of stick displacement.

For example, the function used to generate machine control signals is such that when the amount of stick member <NUM> movement is relatively small (i.e. when the user is making small adjustments to the position of the stick member), the force signal has a greater weighting than the position signal in controlling the machine (e.g. the first variable multiplier is set relatively high, and the second variable multiplier is set relatively low). When the stick member is at a centred (i.e. "null" position), the function is such that the machine is controlled in dependence on the force signals alone, and independent of the position signals (e.g. the second variable multiplier is set to zero). As the amount of displacement increases, the relative weighting (i.e. gain) applied to the force and position signal changes such that the machine is controlled upon force and position signals, or just position signals.

Additionally, or alternatively, where a passive inceptor is operating normally, or an active inceptor is operating normally in active mode, and the control unit determines the value FD is below a predetermined tolerance limit, the control unit <NUM> generates control signals in dependence upon the position signals but not force signals.

f the stick member <NUM> gets jammed, for example because the resistance to motion in the links increases due to wear, damage or foreign objects, then the force per degree of movement of the stick member <NUM> will exceed the predetermined tolerance limit. When the value FD exceeds the predetermined tolerance limit the control unit <NUM> generates control signals in dependence upon the force signals but not position signals. Having determined this, the control unit <NUM> will thus generate control signals to control the machine based on force signals only.

As described above with reference to <FIG>, the control unit <NUM> generates signals for control of the actuator coupled to the stick member <NUM>, the actuator control signals being determined in dependence upon the value FD.

When the control unit <NUM> determines the value FD exceeds the predetermined tolerance limit, the control unit <NUM> generates a signal to instruct the actuator to urge the stick member to a predetermined position. For example, the predetermined position may be a null inceptor position (i.e. centred, or "straight and level" for an aircraft). Thus the actuator will move the stick member <NUM> to an ergonomically easier position for the user to operate the machine when the stick member <NUM> is becoming overly difficult to move. The actuator <NUM>,<NUM> may be operable to slowly (i.e. over several seconds) motor back the stick member <NUM> to the null position.

When the control unit <NUM> determines the value FD exceeds the predetermined tolerance limit the control unit generates a signal to lock the actuator relative to the housing, thereby locking the stick member <NUM> relative to the housing. Thus, having determined there is a problem with the stick member and it may be difficult to move, but not yet immovable, the actuator will lock into a position so the stick member <NUM> is definitively fixed in position relative to the housing, and hence control of the machine will be done using force signals but not position signals.

When the control unit determines the value FD exceeds the predetermined tolerance limit the control unit generates a signal to disable the actuator. That is to say, in order to reduce current to the actuator, and in order to bring stability and certainty to the operation of the inceptor, the actuator will be turned off. This may happen after the actuator has been locked in position, or independently of the actuator being locked in position.

Likewise, the amount of current required by the actuators <NUM>,<NUM> (where present) to achieve desired stick position may also be used to determine if the stick member <NUM> is becoming jammed, even if not yet fully jammed. In this case the control unit <NUM> will generate control signals in dependence upon force and position signals, only position signals, or only force signal in response to the measured current being drawn by the actuators.

This arrangement is advantageous because although, in rare circumstances, the inceptor may lose positional input to control the machine (as described above) it is unlikely to lose position and force inputs. The probability of a dual event of both a jammed inceptor and loss of force sensor signals is very small, for example substantially less than <NUM> x <NUM>-<NUM> pfh. Hence the force sensor <NUM> provides a useful mitigation against the stick member becoming immovable.

Thus provision of a force sensor <NUM> in/on the stick member <NUM>, above any potential jamming point (for example above the stick member pivot point, towards or under the grip of the stick member), is advantageous because the force being applied to the stick member <NUM> by a pilot can be detected independently of the positional data generated by the inceptor <NUM>,<NUM>.

Thus there is provided a means and method of controlling a machine even with a jammed inceptor <NUM>,<NUM>. In an example where the machine is an aircraft, this is especially beneficial, as it increases the probably of a safe return to ground of the aircraft in the event of inceptor jam.

Although this clearly is advantageous in a single piloted aircraft, the device of the present disclosure may also be applied to aircrafts have more than one set of piloting controls.

The invention is not restricted to the details of the foregoing embodiment(s).

Claim 1:
An active inceptor apparatus for operating a machine, the apparatus comprising:
a stick member (<NUM>) having a grip portion (<NUM>), the stick member (<NUM>) being pivotably mounted relative to a housing (<NUM>);
a position sensor (<NUM>) responsive to, and for generating signals indicative of stick member (<NUM>) position;
a force sensor (<NUM>) provided on the stick member (<NUM>) responsive to, and for generating signals indicative of force applied to the stick by a user; and
a control unit (<NUM>), operable:
to receive the position and force signals from the position (<NUM>) and force (<NUM>) sensors respectively;
to process the signals according to a predetermined relationship to determine a value FD proportional to a force applied by the user, as indicated by signals generated by the force sensor (<NUM>), to achieve any indicated displacement of the stick member (<NUM>), as indicated by signals generated by the position sensor (<NUM>); and
to generate machine control signals as a function of position signals and force signals in dependence upon the value FD, for communication to the machine.